A&D released the newly developed HR-AZ/HR-A series of analytical balances in January 2012. Before discussing the development of these analytical balances, I’d like to talk about the definition of an analytical balance.

In the measurement instrument industry, all weighing instruments are called “scales”. Within the category of “scales”, instruments that have a fulcrum in their mass sensor section and a mechanism to balance the object being weighed via the fulcrum are defined as “balances”. Balances can weigh the lightest weights among weighing instruments. A high resolution (capacity divided by minimum display) can be achieved thanks to the mechanism to counterbalance the object via a fulcrum and return the beam that is supported by the fulcrum back to its original balance point – a function commonly called the zero method.

There are two types of balances: general purpose and analytical. Generally, general purpose balances have a minimum display of 1 mg or larger and analytical balances have a minimum display of 0.1 mg or smaller. Incidentally, minimum display is expressed as “dig” and analytical balances express their minimum display in the following manner: “1 dig = 0.1 mg”. Traditionally, one finger, or digit, was used to express a minimum unit. “Digit” was shortened to “dig” and used to express the minimum display digit for balances.

As you know, standard analytical balances have a capacity of 200 g and a minimum display of 0.1 mg. For example, weighing in the pharmaceutical industry for Chinese herbal medicine and Western medicine is performed with a minimum display of 10 and 1 mg, respectively, so balances have historically been required to have one more digit of precision in their measurement performance, or 0.1 mg.

Let’s consider the resolution of a standard analytical balance like the one above with a specification of 200 g × 0.1 mg.

   200,000 mg ÷ 0.1 mg = 2,000,000

In other words, this analytical balance has a resolution of 2 million to one. The resolution of measuring instruments is usually around 0.1 to 0.01%, which is a resolution of 10 thousand to 1. For example, even a micrometer of a mechanical contact method, the resolution is merely several hundreds of thousands to one.

We can better understand the high resolution of an analytical balance using length as an example. The distance between Tokyo and Osaka is 500 km. Therefore, 1 dig at 2 million to one can be calculated as follows:

   500 km = 500 × 1000 m ÷ (200 × 10,000) = 0.25 m = 25 cm

Accordingly, this balance can be said to have the ability to measure the distance between Tokyo and Osaka in increments of about 22 cm (or the distance between an outstretched thumb and little finger).

If we used Mt. Fuji as an example, the increment is as follows:

   3776 m ÷ (200 × 10,000) = 0.019 m = 1.9 cm

In this case, if we were to slice Mt. Fuji by height into 2 cm slices (about the width of a thumb), the balance would be able to detect each slice. From these examples, we can see that determining the minimum display digits of an analytical balance is not easy.

After that slightly long introduction, let’s return to the development of the HR-AZ/HR-A series of analytical balances. As we mentioned in another installment, the current HR series was developed around 20 years ago as our first top-loading analytical balance. At the time, an analytical balance meant an instrument with a large mass senor in the back and a weighing chamber in the front. This type of balance had an extremely large mechanism so it had a high heat capacity and the magnetic circuit to generate balancing power was powerful so its lever ratio was small. Because of its high thermal stability and performance, it is still well regarded as a high-precision analytical balance. In terms of sales volume, however, the top-loading, general-purpose balance systems that first came out 20 years ago are now mainstream items even in the case of analytical balances.

The HR series, which pioneered top-loading analytical balances, became a very long-selling product that continues to sell today, even after its contemporary competitors have long since disappeared. However, it is true that as the years have passed, its liquid crystal display and overall design have made it seem a little old. Furthermore, analytical balances are involved in a fierce price war outside Japan, particularly in Asia, and the HR series has long been due for a price and feature refresh.

Under these circumstances a long development process started. Since the cost of developing a new mass senor would be in the hundreds of millions of yen, I initially thought it would be best to repurpose an existing sensor. I came to the easy conclusion that if we reused a sensor, it would be relatively easy to come up with a new product in terms of time. Consequently, we started development of a new analytical balance with 1 dig at 0.1 mg using the C-SHS mass sensor developed for general purpose balances. The C-SHS sensor developed for the FZ-i/FX-i series has excellent span stability and other performance features, and I thought that it would be possible to get the performance we needed quickly.

However, once we started, we struggled hard to achieve reproducibility at 0.1 mg. When I look back now, I can see that I didn’t realize that we needed to develop breakthrough technology in two areas: the sensitivity of the machine parts that make up the sensor and the electronic circuits of existing general purpose balances.

We spent hours achieving basic performance. We changed the way we processed parts to overcome processing limits and tested repeatedly to limit the variation caused by the individual differences in characteristics of the electrical parts. After repeated confirmation testing and discussions, we managed to reach our product goals. Nevertheless, it took three full years from the start of development to reach the sales stage.

While I had plenty of experience developing new products by this time, when we hit the required level of performance after a long period of resignation among the development team, it felt like we had finally found the light at the end of a long tunnel that we thought was a dead end.

HR-AZ/HR-A Series

For the newly developed HR-AZ/HR-A series of analytical balances, we raised the capacity of the existing HR series of 200 g to 250 g and achieved a high-speed response with real-world weighing stabilization of 2 seconds. For the display, we used a reverse-backlit LCD for visibility of weighing values in low light settings. The AZ series uses a highly reliable internal calibration weight mechanism that employs a unique operation method. The breeze break comes as standard and detaches with one touch for ease of cleaning and operation without a breeze break. Furthermore, all components of the breeze break are made of plastic and coated with a durable antistatic coating. These features were added to solve two issues: static electricity, the most troublesome aspect of using an analytical balance, and requests for a glass-free product, which is required for medicine and food production lines subject to FDA/HACCP regulations.

The breeze break also offers installation advantages, such as the ability to set up the balance with its rear surface close to the wall, since its doors do not come out at the rear of the balance when the side doors are opened. In addition, the balance can be embedded in an automatic production line and placed in a particular isolated space thanks to the one-touch, removable breeze break and the compact size of the balance.

While it took longer than expected to develop, we believe we have created a balance that is unprecedented in price/performance ratio, simplicity, compactness, and usability. As a result, we expect the new HR-AZ/HR-A series of analytical balances to offer users a number of convenient features that create opportunities for weighing in new fields and open up new markets.

A&D has developed a new weighing environment logger, the AD-1687. This logger can simultaneously and chronologically record weighing values and the following environmental factors: temperature, humidity, atmospheric pressure, and vibration. This installment of the development story series explains the circumstances behind the planning and development of this product, our development goals, and the demands of the market.

As can be expected, environmental conditions that influence the performance of weighing instruments are recorded in labs that use analytical balances. This is done because the minimum display of analytical balances is 0.1 mg (1/10, 000 of a gram) or less. Furthermore, the resolution, which is the capacity divided by this minimum display, has reached 2 to 20 million to 1, and, as a result, standard weighing instruments require incredibly high resolutions and are very sensitive to their surrounding environments.

As a side note, pen recorders and recording paper were long used in manner similar to a meteorograph to record temporal changes in temperature, humidity, and atmospheric pressure. Our balance development team also used a meteorograph for a long time. However, we would have troubles recording data in this way, such as paper or ink running out and being unable to record at critical times. Another problem was that the data was difficult to handle and couldn’t be processed freely. For instance, the weighing data had to be checked using an analog readout, which made it difficult to determine the values, and the results obtained couldn’t be graphed. These issues created a demand for devices that can record various meteorological parameters digitally. Due to this demand, various types of loggers that can record data such as temperature, humidity, and atmospheric pressure were developed and are used in many labs and production facilities today.

These circumstances exist at all sites that use weighing instruments. In particular, users of weighing instruments use instruments that measure these environmental parameters in locations where balances and scales are used in order to verify calibrations of weighing values over a long period or evaluate basic performance such as repeatability by reference to the environmental data.

Meanwhile, when users at weighing sites want to link environmental and weighing data and graph the results or process the values, they find it difficult to integrate data from various recording devices. While data can be recorded to a PC to guarantee extensibility, dedicating a PC for this purpose is wasteful. In addition, special software has to be used, which makes this method complicated. There are also many other inconveniences to deal with, such as procedural rules against bringing PCs into environments such as clean rooms and security rules against bringing storage media like USB sticks into work sites.

To solve these problems, we had to find a way to collect and manage weighing data from the balance and environmental data like temperature, humidity, atmospheric pressure, and vibration from the setup environment.

Consequently, we planned and developed a logger that had never been offered before–one that can simultaneously record weighing data and setup environment data. Several years earlier, we had developed the AD-1688, a logger that records weighing data only. This time, however, we decided to develop a more advanced logger, which became the AD-1687 weighing and environmental data logger. During development of this logger, we encountered some difficult-to-handle parameters that were outside our areas of expertise, such as temperature, humidity, atmospheric pressure, and vibration. However, we solved these problems relatively easily by using recently released compact sensors that output data digitally.

When the AD-1687 is connected to a weighing instrument, weighing data (zero point and weight value) and the time, temperature, humidity, atmospheric pressure, and vibration are simultaneously recorded each time the Print key is pressed. Even when the logger is not connected to a weighing instrument, it can be used to log environmental data in locations ranging from clean rooms and labs to production facilities. In addition, by connecting the AD-1687 to a PC, recorded data can be imported into software such as Microsoft Excel for data analysis without using special data transfer software. When AD-1687 is connected to a PC, the PC recognizes it as USB storage.

The trends of the data stored on the AD-1687 can be graphed using automatic scaling and the display of environmental data for example can be limited to temperature and humidity. Furthermore, acquired data saved to a PC can be used to calculate span values and repeatability from span values. Thanks to these features, the AD-1687 is more than just a data storage device. It is a tool to proactively evaluate weighing environments.

While the AD-1687 is not tiny, it is compact and portable. To take advantage of its portability, we gave the AD-1687 heavy duty specifications. It has an IP65 waterproof construction (main unit) and enough shock resistance to avoid breakage from falls from as high as 1.5 m. We made the logger this tough because we assumed it would be used for the measurement of factory waste water and various other difficult measurement situations.

This industry-first weighing and environment logger answers the latent demands of people working where weighing instruments are used. Because of its utility, we believe that the AD-1687 offers many benefits for locations where weighing is performed and will be acknowledged as a helpful weighing management tool.

A new model with sensitivity of 1 μg has been added to the AD-4212 series of production-line weighing instruments. In this installment, I will continue the discussion from Story 2 and further discuss the development of production-line weighing instruments. Product development for the AD-4212 series moved forward with the minimum weighing value progressing in the following order: 0.1 mg, 0.01 mg, 1 mg, and 10 mg. One of reasons that the 0.1 mg model was developed first was that we had been selling a balance for production lines with a sensitivity of 0.1 mg, considered the level of analytical balances, for about 20 years as a special order item. In places where weighing at a sensitivity of 1 mg or greater is performed, the items to be weighed and the weighing jigs tend to be fairly large and heavy so we decided that ordinary precision balances sufficed and the demand for a more compact balance was low.

At the time, the new mass sensor developed for the HX Series of general-purpose balances was being used in production lines. At the time it was developed, the HX Series of general-purpose balances had excellent characteristics compared to most previous general-purpose balances, including a fast response time. Furthermore, the mass sensor that was developed at the time is still being used today in the HR Series of analytical balances, around 20 years after its release.

The HX Series was developed near the end of the “bubble economy” in Japan and boasted unusual level of high performance for the time. It was a top loader (referred to as a general-purpose or precision balance) that had a pan on top of the mass sensor, and it had a quick response speed. At the same time, it had a capacity of 100 g and a minimum weighing value of 0.1 mg, which put it in line with an analytical balance. However, because it had so many added functions, the balance was quite expensive and consequently did not sell well as a general-purpose balance. Nevertheless, thanks to its fast response and high repeatability as a production-line balance, it was adopted by fields with production lines that were said to require a weighing time of one second or less. The HX Series was held in high esteem because its fast response allowed for highly accurate weighing in moving production lines, something that production sites had been given up trying to achieve until then.

The HX Series was the first new product that I developed for the first time from the mass sensor a few years after I joined A&D. As I mentioned before, 20 years ago our sales department was quite demanding, and the product specifications ballooned during the planning stages, just like the economic bubble that Japan was in at the time. As an example, this was the first time that A&D included an internal calibration weight with a general-purpose balance. Other requests included a display section separated from the weighing section, a weighing section that could be operated via a cable, the ability to place the display section behind the weighing section, the display of weighing values on an analog display, and a communication port as standard, which was rare for a general-purpose balance at the time. As the R&D leader at the time, developing a device with these specifications as standard was a huge responsibility that required creative thinking and hard work.

In the end, we released the HX Series while meeting all the demands of the sales department, but its sales numbers as a general-purpose balance were dismal. I learned that, despite the many advanced functions available, users aren’t asking for much from weighing instruments. In other words, the HX development taught me that weighing instruments are just that, nothing more and nothing less. At the time, I struggled to meet the demands of the sales department as a product leader, but by not running away from unreasonable (or so I thought at the time) demands and making proactive proposals and responses, I feel that I was given an excellent opportunity to grow as a designer. Therefore, I am thankful for the various things brought to my attention by the sales department at the time.

This experience taught me the inevitable conclusion that users want balances that are compact, quick, and durable for production lines. For example, we ran counter to this conclusion about compactness by installing a calibration weight inside a production-line balance. Users of production-line balances that have a capacity of 100 g and a minimum weighing value of 0.1 mg do not weigh items of 100 g. The tare loaded as jigs are 100 g or less and the items weighed are several grams at most. If you think about how often calibration would be required, you realize that an internal calibration weight is not needed. And as an added benefit, you could make the weighing section that much smaller.

Let’s go into more detail about this. Many balances have a defined sensitivity drift of ±2ppm/˚C. If the capacity is 100 g and the temperature changes 5 ˚C, using the formula 100 g x 2 ppm/˚C x 5 ˚C, the drift is ±1 mg. For a 100.0000 g display, the change may be in the range of 99.9990 to 100.0010 g. If the weighing value to be confirmed is 1 g, this ±1 mg change drops to 1/100th, or ±0.01 mg. A balance with specifications of 100 g x 0.1 mg cannot detect this level of change. In other words, if the mass to be measured is within 10,000 times of the least significant digit, calibration itself is effectively no longer required, other than during installation. In production lines, if the items weighed in the line are managed separately and the weighing values are checked periodically, there is no need to stop the line for calibration.

The AD-4212B-23 has the SHS mass sensor that was developed for the GX/GF Series of general-purpose balances that followed the two generations of the HX Series. Fig. 1 is a graph of data that shows its 1 μg level of performance. The graph shows the weighing values (zero/span) obtained by raising and lowering a 1.25 g weight automatically over four days from July 8 to 12, 2011, along with the contemporaneous humidity, barometric pressure, and temperature (room temperature/internal temperature of balance).

The repeatability is indicated by the line connecting points (triangles) that represent the reproducibility (σn-1) of ten adjacent span values (capacity minus the zero point). The conclusions gained from the graph are listed below.

1. The repeatability of the span values is 2 μg or less. (The thick red line at the bottom, scale on the right axis)

2. Compared to the span values, which showed little change in the graph, the zero points changed greatly (5 mg or 5000 μg) over the four days in accordance with changes in humidity and air pressure.

3. The stability of the span values can be explained by the small temperature change of about 1.1 ˚C over four days. Furthermore, the temperature of the room was managed by air conditioning, and the area where the weighing instrument was located was separated by a partition, which meant that the air blown from the air conditioner did not influence the results.

4. The cause of the spike in repeatability at 10 AM on July 10th was determined to be the effects of a Magnitude 7.1 earthquake at 9:57 AM off the coast of Minamisanriku.

The results above showed that the SHS developed for general-purpose balances has a sensitivity of 1 μg and a basic performance level with an average repeatability of 1.6 μg. As the developer who proposed the SHS, I must say that I was surprised by the results. The SHS was developed for general-purpose balances, so a sensitivity of 1 μg, 1/1000th of the originally planned minimum weighing value of 1 mg, was amazing.

The data for Fig. 1 was obtained in our balance room. However, other data clearly shows that while repeatability is good at night when no one was moving in and out of the room, during microgram weighing blown air from air conditioning, temperature ripples, wind pressure and vibrations from disturbances caused by people moving in and out, and temperature changes from body temperatures cause instability in the display value and result in weighing errors. Details about the AD-4212B-23 were presented at the Sensing Forum held by the Society of Instrument and Control Engineers in October so I encourage people who are interested in learning more to access the published content on our website.

In the miniaturization field, which is a specialty of Japanese companies, the need for precision weighing is expected to range from research fields to production locations and grow further in the future. As a manufacturer of weighing instruments, A&D promotes the development of simple products that take the location of use into consideration, while at the same time focusing on technical support such as the evaluation of installation environments and working to expand into new markets. By providing a complete solution, we aim to improve our customers’ satisfaction with our products.

This time I would like to talk about the newly revised Japanese Industrial Standard JISZ8803: “Methods for Viscosity Measurement of Liquid”. The most significant change made this time was the addition of vibration-type viscometers as one of the standards. I would like to leave the details of the new standardization to the actual document itself or to published interpretations, and instead look at some of the background to its introduction.

The fundamental principles of the vibration viscometer were proposed a long time ago, but there were always many high technological hurdles that made its commercialization extremely difficult. As a consequence, it took around 20 years until it was finally commercialized. Meanwhile, the American car maker Ford Motors, which led the way in the mass production of car engines originally developed by a European manufacturer, first started viscosity control in its manufacturing processes more than 100 years ago. Since that time there have been various viscometers proposed and you could say the viscometer has a very long history in industrial production.

I’ll return to the new Japanese Industrial Standard. JIS standards on the measurement of viscosity were first enacted in 1959. The standards were supposed to be revised every five years, but the previous last revision occurred in 1991 so since that time more than 20 years passed without a rethink of the standards.

Naturally during this period there has been significant technological progress made around the world, and in Japan there have been major changes to society and the important industries that support it. In the field of viscosity measurement as well, the vibration viscometer has become well established as a new method of measuring viscosity during this period and its production has increased greatly. In today’s industries, many vibration viscometers can be found in use as an important tool for the management, control and analysis of liquids, in both research labs and on production lines.

Behind the development of this vibration viscometer were advances in electrical circuitry technology based on semiconductor (IC) technology, and the resulting advances in control technology, as well as the digitalization of measuring and use of computers for visualizing analysis results.

As a method for assessing the physical properties of liquids, viscosity is the most fundamental physical quantity assessed. For example, when liquids are being conveyed on a production line, flow rates, which are based upon kinetic viscosity, form an important aspect of production line control. Also, engine oil’s viscosity in response to very high and low temperatures clearly affects not only the engine’s characteristics but also the possibility of burnout. In the case of engine oil in particular, as its performance within an engine can have such a dramatic influence on reducing mechanical energy loss, and hence lead to significant improvements in fuel consumption, there is fierce competition between oil makers to develop the most efficient product.

Or when flying, consideration of the viscosity of the oil circulating in the many hydraulic cylinders of the plane’s drive-train under enormous changes of temperature is extremely important.

In applications away from the industrial uses mentioned above, the measurement and analysis of low viscosity beverages to improve their drinkability is progressing significantly. In the food sector, for such uses as developing liquid meals or barium sulfate for X-ray scanning, viscosity measurement is necessary to pursue the ease of consumption as well as the prevention of accidental swallowing. Furthermore, in the medical sector measurement of viscosity of bile or blood with a small sample quantity is required, and vibration viscometers are being regarded as particularly useful in such applications.

For the newly revised JIS, there have been two additions for vibration viscometers: the tuning fork type and the rotational-vibration type. The special characteristics of vibration viscometers are their high sensitivity and wide dynamic range, which allows them to measure a vast range of liquids, from those with viscosities lower than water to those with ten thousand times the viscosity of water. They can also measure viscosity with a sample of just a few milliliters and can perform consecutive measurements over a period of time to measure viscosity over a change of temperature. Finally, since the energy applied to the sample is minimized, the measurement can be completed in a few dozen seconds.

In the development of new materials, new methods of measurement must also accordingly be introduced. Viscosity measurement in many of the above mentioned situations was previously difficult until the development and use of the vibration viscometer. It is anticipated that the vibration viscometer will contribute to the development and improvement of substances in new fields and be further effectively used as a viscosity measurement method that sustains Japanese advanced materials technology in a variety of fields.

Lastly, I would like to add the following comments. To all those who have shared the task of completing a very wide range of JIS revisions on viscosity over a short period of approximately just one year, I’m sure you will feel a big load lifted from your shoulders. While the positioning of JIS is less clear these days, we have accomplished world-leading standardization and I would like to take this opportunity here to express my thanks and appreciation for all your hard work and efforts.

This is Part II of “Solutions provided by the BM Series”.

The BM Series of micro-balances went on sale in December 2010 (in Japan). There were 2 development objectives for this series: a standard anti-static function as a countermeasure against static electricity and verification of microgram-level measurement performance in the field. These 2 objectives can be considered proposals for solutions to potential problems in the field.

In the micro-balance market, the most important point in question is whether the measurement performance as specified by the catalog can be ensured (especially in the case of repeatability) in the environment where the balance is set up. For example, the BM-20 demands high precision and achieves a resolution of 1/ 20,000,000 with a capacity of 20 g and a minimum display of 0.001 mg. Because 1 μg is such a small mass, changes in temperature, humidity, or atmospheric pressure, slight breezes from air conditioning, and minute vibrations of support tables can negatively affect results. These external factors create instability in measurement values (particularly the zero point) at the microgram level and cause poor repeatability.

Problems pertaining to the setup environment stem from the fact that the micro-balance is so much more sensitive than its users and can detect minute environmental variations that users can’t. Since users can’t easily solve problems they can’t sense, they have a constant feeling of uncertainty about the balance. To eliminate this uncertainty in end users, we offered the Measurement Environment Evaluation Tool (AND-MEET) when the BM Series first went on sale and started to monitor actual usage environments.

AND-MEET constantly monitors the setup environment of the balance while simultaneously raising and lowering the internal mass of the balance automatically. With this tool, we were able to evaluate temperature changes and the corresponding repeatability of weighing values over time. Monitoring of the environment and weighing values helped us clearly identify errors that arise from the setup environment. It started to become clear that various issues caused weighing values to become unstable. These included large temperature fluctuations; minute repeated temperature fluctuations sensed by the balance caused by flowing air after users arrive at work and switch on the air conditioning (even when the room temperature is stable); pressure changes from opening and closing doors; and building movements caused by low-pressure drafts and distant earthquakes.

By pinpointing the causes of weighing errors, we were able to provide concrete methods to stabilize weighing values. These included introducing anti-vibration stages, setting up an external covering (breeze break) to reduce blown air from air conditioning, moving the balance away from locations where people are working and where vibrating analysis equipment is operating, and moving the balance to locations with minimal room temperature changes caused by outside air temperature. We were also able to evaluate the tangible effects of these measures.

I’d now like to discuss the measurement results acquired by AND-MEET. Figure 1 is a graph of temperature and measurement (zero point and span value (the weighing value minus zero point)) data taken over 24 hours from 5:00 PM Thursday, February 17 to 5:00 PM Friday, February 18, 2011 using a BM-22 micro-balance.

The balance was powered on at 5:00 PM on Thursday. The internal mass was automatically moved up and down in 40-second cycles and the ambient temperature, zero point, and weight were logged using the AD-1688 data logger. The ambient temperature rose from 19 to 22 °C over about 5 hours. The zero point also changed greatly after being powered on. From 11 PM on the 17th, the ambient temperature was comparatively stable, as was the zero point. Accordingly, the span value showed fewer fluctuations and stabilized.

From 9 AM to around 4 PM on the 18th, the temperature was quite stable, likely due to workers arriving and switching on the air conditioning. After 4 PM, there was a sudden temperature increase and the zero point and span value changed. This data was obtained at a university research lab that uses the balance. While the cause of the temperature changes could not ultimately be determined, the location can be described as a measuring environment with sudden temperature changes at certain times.

Figure 2 is a graph of temperature changes and the repeatability of the span value. Span value is calculated by subtracting the zero point from the weighing value. The repeatability of the span value is the standard deviation (σ) of 10 consecutive calculations.

Each point represents the standard deviation of 10 span values. The balance used to acquire the data was a BM-22, which is a micro-balance with a capacity of 5 g and a precision of 1 µg. Its specifications stipulate a repeatability of 4.0 µg with a 1 g counterweight.

From Figure 2, we can see that there were ambient temperature changes for around 6 hours after the balance was switched on and that the repeatability average was higher than 4.0 µg. After this period, it is clear that temperature changes were minor, the span value was stable, and the repeatability was at the specified level of 4.0 µg or less. After 5:30 PM on the 18th, the zero point changed due to another sudden room temperature increase and an accompanying worsening of repeatability was confirmed.

The graph provides supporting evidence for two important points when stabilizing balance performance: avoid sudden temperature changes and take sufficient time for the balance to warm up to thermal equilibrium before measurement. This is especially true for analytical balances. It is clear that it is possible to obtain measurement performance equal to catalog specifications with a micro-balance in this lab by eliminating the causes of the temperature increase after 5 PM or by measuring during the daytime, particularly in the stable measurement environment between 10 AM and 5 PM.

While the results have been omitted for space, AND-MEET confirmed worsening repeatability due to distant earthquakes and variation in repeatability over several hours due to low-pressure drafts. By providing this information, we were able to quantify the intangible anxiety users have always felt about the performance of analytical balances and also to later release the data in graphical form. This series of work has clarified problems with measurement environments and pointed the way to improved environmental setups and made it possible to measure stably with better precision. Through the abovementioned countermeasures, we hope to finally remove the doubt users have about using balances and improve usability in the workplace.

The BM Series of micro-balances went on sale in December 2010 as A&D’s flagship line of analytical balances. The BM Series was considered a flagship line not because they are the only micro-balances made in Japan. We envisioned this series being used for research, development, and analysis in leading-edge fields in Japan. Our development objectives were 1) anti-static countermeasures and 2) the documentation of weighing performance in user environments. The “Development Stories” series will describe in detail how these objectives were met, including the processes used to arrive at the solutions. This installment covers countermeasures for static electricity and the next installment will cover the documentation of weighing performance in user environments.

When we investigated the needs for micro-level weighing during the planning stage of the BM Series, we found that microgram-level measurement is currently required with the following types of samples.

1.  Minute amounts of powders in the analysis of pharmaceuticals and food additives

2.  Samples placed in plastic containers such as microfuge tubes using micro-pipettes in bio-research and the quantitative analysis of protein

3.  Samples placed on drug packing paper in pharmaceutical fields

4.  Particulates trapped by filters made of Teflon (PTFE) and similar materials to measure environmental pollutants in the air

5.  Minute amounts of liquid ejected from dispensers in production lines for liquid crystals, LEDs, and electronic parts

The use of micro-balances in such applications can be difficult because powders, plastic containers, drug packing paper, and Teflon filters can become electrostatically charged very easily. Additionally, sample weights are usually 10 mg or less, and a minimum display of 0.01 to 0.001 mg, and in some cases 0.0001 mg, is required. For reference, 0.001 mg, or 1 microgram, is one millionth the weight of a paper clip (1 g). Since static electricity can cause weighing errors of several tens of milligrams, it is impossible to weigh at the micro level without first dealing with static electricity.

The minute amounts being measured in the abovementioned micro-level weighing applications require a balance with very acute sensitivity (minimum display) and the effects of electrically-charged samples and containers make it impossible to perform accurate weighing. Micro-balances are also used to measure minute amounts of liquid, powders, and solids in production lines in clean rooms dehumidified to a humidity of 0% to maintain quality. Most clean rooms must be free of dust and metallic contaminates so material such as polyoxymethylene (polyacetal) is frequently used in drive systems to reduce both slide resistance and the release of metallic particles. However, plastic is easily charged in low humidity. For example, vials and other weighing containers can become charged during delivery, which causes unstable weighing and other problems.

To eliminate static electricity, all models of the BM Series are equipped as standard with a direct-current ionizer. Direct-current ionizers generate a large number of ions over a wide area so they do not require a fan to blow the ions, which means that powder samples do not get blown away. What’s more, the strong anti-static performance of direct-current ionizers removes static electricity from samples in about 1 second, which means the breeze break door only has to be opened and closed once while eliminating static electricity and weighing the sample. Additionally, the balances are equipped with a dedicated anti-static chamber. Users can place samples here to eliminate static electricity from all samples before weighing. This allows the user to weigh the samples one after another without having to perform static elimination before each weighing. Storing samples before weighing in the anti-static chamber not only removes static but also allows samples to acclimate to the temperature of the weighing chamber. This reduces convective flow, which can be caused by temperature differences of 1 °C or less, and in turn reduces weighing error.

On BM Series models other than the micro-balance models (BM-20/22), the plate that separates the weighing and anti-static chambers inside the breeze break is removable. Removing this plate creates a large weighing chamber that allows users to open a side door of the weighing chamber, pass the sample near the static eliminator at the top of the weighing chamber to remove static electricity, and then place the sample on the weighing pan. In other words, they can remove static electricity from the sample and then weigh it immediately. The ion-generating discharging electrodes (needles) are covered to prevent users from touching them and can be exchanged simply by replacing the unit. This unit configuration provides a level of safety that conforms to the requirements for CE marking and allows users to perform maintenance themselves.

We hope that users aware of the problems of static electricity and researchers who feel their weighing results are unstable in dry winters will effectively use the anti-static function of the BM Series to achieve more stable weighing.

The following describes the newly developed MC Series of high-resolution electronic balances. The market for these balances will also be discussed, including the commercialization and technology of general-purpose electronic balances.

Mass sensors known as electronic balances have comprised a majority of the weighing instrument market for a considerable time. Electronic balances display measurement values digitally so no special knowledge of analog instruments is required to perform weighing. As a result, anybody can measure the mass of many types of items easily and accurately. This is one of the reasons that electronic balances have developed new markets, along with cost reductions of electronic components and control circuits.

Electronic balances have expanded their market scale through usability and low cost but their measurement principles have not fundamentally changed since they were developed. New measurement principles for weighing have not been proposed for decades and mass traceability is still guaranteed by 1 kg standard in France. Of the seven SI units (length, mass, time, current, temperature, luminous intensity, and substance (mole)), only mass requires a physical guarantee of accuracy. Because of this requirement, mass is considered a specialist field that requires accuracy management with a calibration weight. This is one reason that high-resolution balances are needed as mass comparators.

The practical measurement principles of general-purpose electronic balances fall under the following four methods: electromagnetic equilibrium, strain gauges (load cells), electrostatic capacitance, and tuning forks. The technological background of each method will be briefly described below.

1.    Electromagnetic equilibrium: This method uses a fulcrum and lever. For example, an unknown mass is placed on the left side of a lever and a balancing force is generated on the right side of the lever through the fulcrum. Electromagnetic force is used to generate this force. The electromagnetic force mentioned here is Lorentz force, as taught in high school physics classes using Fleming’s left-hand rule. In other words, when current flows perpendicular to magnetic flux flowing in the magnetic circuit, a force is generated in proportion to the current at a right angle to the flow of the current and the magnetic flux. The current required to balance the mass (force) on the left side of the fulcrum determines mass. The resolution acquired by this method is very high for a balance. For a general-purpose balance, the rate of the minimum display value called sensitivity against the capacity is about one over several hundred thousand. Mass sensors that use electromagnetic equilibrium are mainly used for high-resolution electronic balances and there are analytical balances with resolutions of one over several million to several hundred million. Analytical balances used in research require high sensitivity and currently most use the electromagnetic equilibrium method.

2.    Load cells: Using electrically resistant wires called strain gauges, load cells detect the strain caused by a load as a change in the electrical resistance. Several strain gauges are affixed to what is called a spring material, which has a Roberval structure. Since the strain of metal used in the elastic deformation is very small, a Wheatstone bridge circuit is used to detect the difference of the contraction and elongation detected by the strain gauges and increase output level. Commercial products using this method achieve practical resolutions of one over several thousand to a hundred thousand. Electronic balances that use strain gauges are used in a wide range of fields, including part management in production facilities and for academic experiments.

3.    Electrostatic capacitance: This method uses a Roberval mechanism with electrodes to detect capacitance changes in two areas, the area displaced (moveable area) and not displaced (fixed area) by the load. Displacement by the load changes positions among the electrodes. Accordingly, the change of electrostatic capacitance among the electrodes is used to measure mass. Resolution is typically one over several thousand or below so this method is generally used for low-resolution instruments like kitchen and bathroom scales.

4.    Tuning forks: With the tuning fork method, the natural frequency of a tuning fork is changed by tension (load) applied to the tuning fork. For example, a mass is placed on the left side and a vibrating mechanism placed on the right side via a fulcrum. The vibrating mechanism detects excitation and frequency using a piezoelectric element. If the mass is changed, the natural frequency varies accordingly. This results in a change in free vibration frequency with the same excitation, which is used to acquire the mass. Since the frequency is counted to acquire the mass, no analog/digital conversion is required, unlike the three methods above. The tuning fork method has a resolution of one over several tens of thousand to several hundred thousand, giving it a performance level between the electromagnetic equilibrium and load cell methods. It is used as the mass sensor of general-purpose balances.

While the four methods have their positives and negatives, the electromagnetic equilibrium method is fundamentally different from the other three methods from a technical point of view. In the electromagnetic equilibrium method, the force equilibrium is achieved without changing the lever position via the fulcrum. The mechanism is always controlled to return to its original state. This method follows the principles of balances made centuries ago. It is referred to as the null method because the balanced position of the lever is not changed. The other three methods are premised on the fact that the measurement mechanism is somehow displaced. Stated more clearly, they are like spring balances. The mass (load) displaces the measurement mechanism so this method is called the displacement method.

Balances using the null method and the displacement method have very different resolutions and stabilities. The reason for this difference is the mass sensor area, which is completely made of metal. Its elastic limits and mechanical features are too inadequate for the high resolution required for balances. Mathematically speaking, the limits of the displacement method can be exceeded by lowering the amount of displacement and improving the electrical sensitivity. In reality, reducing the displacement to be detected causes a drop in signal level and increases interference from noise. As a result, resistance to interference such as vibration weakens, which causes a significant drop in display stability and response speed. It can be said that the resolution performance of the displacement method is limited due to the features of metal. Until a low-cost metal that is lightweight and consistently high in elasticity is developed, the current practical resolution of one over several hundred thousand is the technical limit of the displacement method.

On the other hand, since the electromagnetic equilibrium method uses the null method, it is not affected by the features of the structural material in principle. Furthermore, a control method is used to constantly monitor the position of the lever. The magnetic damping effect provided by electromagnetic induction in the magnetic circuit makes it possible to provide control feedback at high gain. Because of these benefits, the electromagnetic equilibrium method has the strong vibration-proofing and high-speed response required for high resolution. This is why the high-resolution electronic balances for production lines, which require vibration-proofing and high-speed response, all use the electromagnetic equilibrium method.

The lineup of electric balances that A&D designs and sells are mostly electromagnetic equilibrium and load cell types. Recently, the market has been demanding balances with higher resolution. One reason for this demand is the establishment of Japan Calibration Service System (JCSS) standards for calibration weights and scales. These standards have increased the need for mass comparators, balances that can calibrate counterweights. In addition, demand has risen for high-precision measurement management for production line measuring devices. These requests from new markets mean that there is a need for balances that can display values with an extra decimal place over current general-purpose balances.

These demands pushed us to develop mass comparators using the GX/GX-K Series of general-purpose balances, which use the electromagnetic equilibrium method. In fact, the ability to stably display an extra decimal place was confirmed when product development started 10 years ago. However, the difficulty of dealing with corner errors and achieving adequate performance over the entire weighing capacity resulted in the product being shelved as a general-purpose product. This time, thanks to a complete set of options like the auto-centering pan, the MC Series is able to handle these issues. The specifications of the four models available at launch are listed below, and the maximum resolution is 1/10,000,000.

Model             Capacity           Minimum display          Resolution
MC1000             1 kg                    0.1 mg                     1/10,000,000
MC6100             6 kg                       1 mg                        1/6,000,000
MC10K             10 kg                      1 mg                      1/10,000,000
MC30K             30 kg                    10 mg                        1/3,000,000

Using the four models above, it is possible to perform calibration of standard weights from 500 g to 20 kg, which are OIML standard F1 level or lower (F2, M1, M2). We intend to expand our range of models of high-resolution balances to meet future market demands. We hope these new products are used not only as mass comparators for calibration weights, but also as equipment for testing and research, new fields in which Japanese companies are strong, and for quality control and production lines in production facilities. This will help create new measurement instrument markets and contribute to improved quality and productivity in the workplace.

A&D has been developing electronic balances since its inception 30 years ago. When the company was founded, it felt as if the company was always trying to catch up with industry leaders, who had over 100 years of experience. However, the company’s establishment coincided with a period of advancements in the digitization of measurement devices. Furthermore, we seriously pursued cost performance by both drawing out basic performance and cutting costs. This increased profits in a comparatively smooth manner short time after the company was founded. As a result, our share of weighing instruments in Japan is over 60% based on units sold. However, the high-precision end of our lineup has only reached semi-micro analytical balances with a minimum display of 10 µg.

There are currently no manufacturers producing micro-balances in Japan and there are only a few recognized manufacturers in the world. That is why entering the micro-balance market has been a longstanding issue for A&D. While the economy still has not recovered from the effects of the financial crisis of 2008, crisis can present opportunity. We felt that it was imperative for us to develop micro-balances in Japan, so several years ago we started product development.

During development, we focused on measurement performance, which we felt was the most important issue. In other words, our main goal was to somehow decrease the various disturbances that cause trouble during measurement at the microgram level, and yet make the balance easy to use. We knew from our experience producing balances that static electricity is the biggest problem for analytic balances with a minimum display of 0.1 mg or less. We have established that the biggest cause of error when measuring in the winter on the Pacific side of Japan, where the humidity is 40% or less, is static electricity, not only from the sample being measured, but also from the user.

In addition to static electricity, a slight temperature difference between the sample and atmosphere and the resulting convection also cause measurement errors. Buildings swaying from wind or vibrating slowly after earthquakes can also cause unstable measurements. People are generally not conscious of low frequency vibrations or static electricity, so the resulting unexplained variation in measurement results is seen as a hard-to-solve problem unique to the site.

There are three ways to eliminate the abovementioned problems (excluding vibration): (1) proactively eliminate static electricity from the sample, (2) reduce the influence of breezes, including convection from heat, and (3) shield the balance from external static electricity. When we set out to develop the new balance, we aimed to add these three features. It took three years to realize these advanced functions as we tackled these issues one by one. A fanless, direct-current ionizer to powerfully eliminate the charge of the sample without generating a breeze and a dedicated anti-static chamber were installed. A double-ring breeze break structure was used to retain usability. A glass breeze break with added electrical conductivity was used to create a strong shielding effect against external static electricity sources, including the operator.

The development of these technologies led to the release of the BM Series of micro-balances. The BM Series of analytical balances has many advanced functions. It can eliminate charges of several kilovolts from items in one second or less without generating a breeze. Its (open-space) weighing chamber, with no secondary breeze break inside the breeze break, retains a level of usability comparable to standard analytic balances and is capable of a repeatability of 2.5 µg. Finally, its static shielding keeps measurement values stable even when the user, who may have a charge buildup of 10 kV, comes near.

The BM Series has six models with a maximum resolution of 1/25,000,000, with the 3 main models having high resolutions of 20 g x 1 µg, 250 g x 10 µg, and 500 g x 0.1 mg. This series is positioned as an advanced analytic balance that can measure at the microgram level but is available at a reasonable price.

We envision the BM Series being used in many fields. For example, it can be used for measurement of dust required for environmental measurements, PM measurements as prescribed by European automobile gas emission regulations (Euro4, 5), sampling and injection for chemical analysis, and the management of micro-coating amounts, micro-extractions of powder, and quantity management of coating material.

We can see several target users for the BM Series. This includes researchers using current semi-micro balances (10 µg) who want to move up to measurements of 1 µg and quality control staff who want stricter measurement accuracy but are unsure about using the expensive micro-balances currently available. The BM Series provides these users with balances with the same level of usability as existing balances but a better level of precision. By stressing its quality performance, we hope that the BM Series will be widely known as an analytic balance that stresses performance and contributes to the analysis field through its strong cost performance.

In this installment, I would like to summarize the development of the HR Series of analytical balances, which occurred 17 years ago. The main focus will be on top loaders and new projects.

The HR Series is A&D’s first analytical balance with the same construction as a general-purpose balance. This development story starts about 20 years ago, just after I joined A&D. During the development of this new product, I experienced success and failure and learned many important lessons. The following are the events that occurred during this development.

In the balance industry, balances with a minimum display lower than 0.1 mg are called analytical balances. Nowadays, top-loader analytical balances make up a majority of the analytical balance market and can be considered the mainstream type. However, top-loader analytical balances had just made their first appearance when we developed the HR Series. As the name “top loader” implies, these balances have a weighing pan on their top surface. The term has become an industry term for current general-purpose pan balances.

When I joined A&D, the structure of general-purpose and analytical balances were clearly different. Most general-purpose balances were top-loader models. Meanwhile, analytical balances had a breeze break in front and a large weighing sensor in back. Stretching from this sensor area in the back to the breeze break (the weighing chamber) was an arm, which held the weighing platform on its tip. At the time, all analytical balances were built like this, and the industry took it for granted that analytical balances had this kind of structure. This was around the end of Japan’s economic bubble and when I had taken charge of and finished development of a general-purpose balance series, which is the HX Series, for the first time right after joining the company. The HX Series was a multi-function device. It used finite-element magnetic field analysis software that I had created and it had been newly designed from the magnetic circuit. I was proud of my work. However, its extravagant specifications and attendant high prices doomed it to failure. It sold poorly outside of automatic units for production lines, where it was praised for its quick response.

While the economy of the time is a factor in whether a product is successful, spending over 2 years and 100 million yen to create a product I was really proud of and having it not sell was quite troubling. Fortunately, the HX Series contained the HX-100 model, which had a capacity and minimum display of 100 g and 0.1 mg. At the time, it was rare for a top-loader analytic balance to have a capacity of 100 g. The fact that the development of the series produced a model with specifications of 100 g × 0.1 mg was evidence that the HX Series was of high quality. This experience, along with a review of our desire to make a sellable product based on the weighing sensor I spent so long developing, resulted in the idea of making a full-fledged series of analytical balances along the lines of the HX-100.

Compared with traditional analytical balances, top loaders have half the material costs, including the sensor area. For argument’s sake, if I could get a performance level of 0.1 mg at a capacity of 200 g, which is typical of analytical balances, the top loader would be an extremely attractive product owing to its excellent cost-performance ratio.

I therefore performed testing to confirm a basic performance level of 200 g × 0.1 mg with the goal of developing an analytic balance based on the HX-100. The results determined that there was potential for a commercial product. I later had a meeting with the sales department related with the new product to present the data and propose a project for the new product. I felt that contents of my presentation showed the promise and I was sure that the project would be endorsed at the meeting. However, the reaction within the company was quite surprising to me. I was showered with negative criticism such as, “there’s no way you can make a general-purpose, top-loader type analytic balance; putting out a half-baked product would just lower our market reputation”, and “the structure of analytical balances is fixed, customers will never accept a top-loader analytic balance”. In the end, I was told to stop development on the new product.

Obviously, I was disappointed. However, I didn’t have enough experience or ability to object and publicly accepted the official decision of the meeting. Privately, I refused to stop development and continued testing behind the scenes. After a period of constant worry, things eventually turned around.

The cause for this was that our European competitors took the lead in the market and started offering top-loader analytical balances at a low price in the Japanese market. After this, people in the company who opposed the commercialization of top-loader analytical balances disappeared.

In a comparatively short time, A&D completed its first top-loader analytical balances, the HR series, and put them on the market. The HR Series gradually became known in the market for its high cost-performance ratio. While 20 years have passed since sales started and our competitors have changed all of their products to new models, the HR Series remains a strong performer, with sales of several thousand units per year.

The fact that the series has maintained its marketability for so many years is evidence of its excellent integrated ability at development, including its performance, price, and specifications. The fact that it has been a consistent seller over the years makes me feel as if the development was blessed. Later on, the GR Series of semi-micro balances, which is a top-loader model with a sensitivity of 0.01 mg, was developed based on the HR Series. Recent top-loader products have reached the microgram level using the SHS/C-SHS, a next-generation sensor.

The experience of developing the HR Series played a large role in the development progress of these new products. It is often said that project and technological ideas that are unanimously approved at meetings never succeed. This occurs because most of the people at the meeting are naturally field specialists who understand the status quo, which becomes the criteria of evaluation. At such times, new projects designed to change the status quo no surprisingly run against conventional wisdom. Naturally, when the status quo is the reference point, these new projects can come off as bizarre ideas. This phenomenon seems to happen in many aspects of life, not just business.

The number of Japanese conscious of innovation is decreasing and a long time has passed since Japan became a country of critics. As a result, the allowance for change in society is declining and there is an increased sense of stagnation. This may go beyond this discussion but if a manufacturer’s developers are not innovators, there is no way to develop new products. If the next generation of engineers maintain their personal beliefs and develop the ability to plan new products in the course of day-to-day activities, I feel that business results will improve. I also think that this will finally reinvent the stagnating Japanese economy and society.

I am placing my hopes on the good sense and great efforts of the young engineers who will lead society forward, and, in some sense, stubborn individualists.

On a visit to a user who makes weighing instruments a few years ago, I was asked if there wasn’t an easy way to record the weight value displayed on balances.

At this site, they were using balances for measurement work. They wrote down the weight data and then manually entered it into a computer. The manager told me he had 3 problems: the work was too labor-intensive, errors sometimes occurred during the handwriting and manual data entry process, and it was a pain to carry the computer to the weighing location. Thinking about the user’s requests, I could see that simple paper-based records were not enough to get the job done. Many people enter large amounts of weight data into a computer, save it as files, and then make reports and presentations. I also realized that it was important that the PC input method be as easy as using a USB memory device.

USB memory can be used to pass data between computers as a batch without need for special software. Consequently, the AD-1688 weighing data logger we planned for development used dedicated cables to send weight data from the communication port of a weighing device (balance or scale) to its stereo jack and then to directly transfer this data to a computer via a USB port. All of this was done without any special software.

This idea was commercialized and resulted in the ability to batch connect weighing devices and computers just like using a USB memory device. The weight data imported into the computer could be directly entered into any open program, such as an Excel sheet or notepad application. Again, this did not require any special pre-installed software, making it a very convenient recording media.

For portability, AD-1688 was made about the size of a business card and the weight of a large egg (60 g). The unit also included a protective cap for the connector. When used, the unit met IP65 specifications (dustproof and rainproof), making it easily pocketable.

Mr. Dodate of the R&D division 5 was responsible for the mechanical design. He used 3 cases, including the cap to protect the communication ports, to achieve this dustproof and rainproof construction. The assembly does not require a single screw. When people see the finished product, the case structure seems ordinary, but completing the proposed new assembly and insertion case was a lot of hard work.

There has never been a product like the AD-1688 on the market. All manufacturing, from PCB wiring to assembly and outgoing inspection, has been entrusted to a high-quality factory in Mr. Dodate’s home prefecture of Akita.

The reason that domestic production was chosen was to speed up the product development cycle. In other words, it was decided it was best to increase focus on fundamental development work by cutting out the extra time and quality control issues that come with overseas production. Even industrial equipment, which is limited run unlike commercial-off-the-shelf products, naturally requires cost cutting. However, as a Japanese manufacturer, we prioritize guaranteed product quality over mass production efficiency and decided it was best to concentrate resources such as time on planning and development of new products.

We expect the conveniently handy AD-1688 weighing data logger to be recognized as a high-value product for wide use in the management of research and production lines and solve problems you might not even know you have.