JPS626190B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is directed to the residual capacity of silver oxide primary batteries and mercury primary batteries, which have flat discharge voltage characteristics in which the terminal voltage in normal use hardly changes until the end of discharge. This invention relates to a battery remaining capacity meter that measures battery residual capacity.

[Conventional technology]

As is well known, primary silver oxide batteries and primary mercury batteries, as shown in Figure 1, have flat discharge voltage characteristics in which the terminal voltage during normal use hardly changes until the end of discharge, allowing stable operation over long periods of time. It is widely used as a power source for watches, cameras, etc., which require high voltage, but on the other hand, because it has such a flat voltage characteristic, it cannot be used to detect a drop in terminal voltage like a manganese dry battery. It is impossible to measure the remaining capacity, so a rapid drop in terminal voltage at the end of discharge is detected to notify the user that the battery has almost no remaining capacity. There is.

[Problem that the inventor attempts to solve]

However, with this conventional detection method, by the time the user realizes that the battery needs to be replaced, there is almost no remaining capacity, so a replacement battery may not be readily available, for example during a long trip. This caused the machine to stop working, which was extremely inconvenient.

In addition, for storage batteries, etc., a method is used to measure the remaining capacity by detecting the voltage drop that occurs due to rapid discharge, but since the value of the voltage drop is not constant during short-term discharge, accurate measurement The disadvantage is that it cannot be done. To solve this,
For example, as shown in Japanese Unexamined Patent Publication No. 52-103638, a method has been proposed in which repeated rapid discharges are performed to stabilize the amount of voltage drop, thereby making accurate measurement possible.

However, although this method is effective for measuring storage batteries that have a relatively large capacity and can be used again by being charged, it is effective for measuring primary batteries that are virtually impossible to recharge. This is not preferable because it unnecessarily reduces the remaining capacity.

The present invention provides a battery remaining capacity meter that can accurately measure the remaining capacity of silver oxide primary batteries and mercury primary batteries in an extremely short time, which was virtually impossible, based on a measurement principle that was previously unknown. The purpose is to provide

[Means for solving problems]

That is, the battery remaining capacity meter of the present invention is a battery remaining capacity meter that measures the remaining capacity of silver oxide primary batteries and mercury primary batteries that have flat discharge voltage characteristics in which the terminal voltage in normal use hardly changes until the end of discharge. a load resistance element connected in series with the battery under test; a switch section for causing current to flow from the battery under test to the load resistance element to rapidly discharge the battery under test; a timing circuit that outputs a first timing signal after a time period has elapsed and a second timing signal after a second time period that is set longer than the first time period; A sample and hold circuit unit that stores the terminal voltage of the battery under test at a time, and calculates the difference between the terminal voltage recorded in the sample and hold circuit unit and the terminal voltage of the voltage to be measured that changes from time to time. a subtraction amplification circuit section; a comparison circuit section that compares the output voltage of the subtraction amplification circuit section with a preset reference voltage; and a comparison circuit section that latches the output of the comparison circuit section at the time when the second timing signal is issued. It is characterized by comprising a latch circuit section and a display section that displays the output of the latch circuit section.

[Effect]

The battery remaining capacity meter of the present invention measures the remaining capacity based on the following principle.

Taking as an example a silver oxide battery for watches, in which the anode is composed of silver oxide, the cathode is composed of zinc, and an alkaline solution is used as the electrolyte, the entire reaction can be expressed by the following equation.

However, electrode reactions are further divided into smaller parts, and the time course also affects the precipitation and dissolution of reaction products. Taking the case of the discharge of the above formula as an example,
In the range of alkali concentrations currently used, Zn+4H ₂ O→Zn(OH) ₂ +2OH ^- Zn(OH) ₂ →ZnO+H ₂ O becomes passivated. Under normal battery usage conditions, the reaction in which Zn dissolves into the electrolyte and transforms into ZnO progresses extremely slowly, and the reaction system maintains a balance. This is also the reason why the voltage between the terminals is constant in the discharge characteristics of the silver battery. However, if a heavy load discharge, which is more extreme than under normal usage conditions, is forcibly carried out for a short period of time, the reaction system will become unbalanced and the battery voltage will drop. In other words, in the case of a new battery (remaining capacity 100%), almost no ZnO is produced and there is plenty of electrolyte, so the voltage between the terminals will drop rapidly, but ZnO will continue to be produced, so the voltage will not exceed this level. There is no descent. However, batteries used in the past only generate ZnO in an amount proportional to the usage time, and the amount of electrolyte filled in the battery is limited, so ZnO is difficult to generate during forced heavy load discharge. in a state. Therefore, the way the voltage between the terminals drops depends on the remaining capacity.

Figures 2 1 to 4 show that the aforementioned silver oxide battery for watches with a capacity of 100mAH was
This shows the change in terminal voltage when forcedly discharged for a second. In Figure 2, 1 is an unused battery (remaining capacity
100%), 2 is 90% remaining capacity, 3 is 50% remaining capacity,
4 shows a battery with a remaining capacity of 10%.

As is clear from FIG. 2, although there is no significant difference in the amount of voltage drop between the unused battery and the discharged battery, there is a significant difference in the shape of the discharge curve.

That is, when an unused battery starts discharging, the instantaneous voltage drops due to the heavy load, but there is a tendency for the voltage to recover to some extent after that. On the other hand, as the battery is used and its remaining capacity decreases, the voltage drops rapidly at the same time as the battery is discharged, as described in the above principle.

Therefore, it is possible to estimate the remaining capacity of the battery from this discharge curve pattern. If we take the difference between V ₁ and V ₃ with current time T ₁ being 1 second after the start of discharge and T ₂ being 5 seconds, as shown in Figure 3, an almost linear relationship is established depending on the usage condition of the battery. do.

Therefore, by comparing the difference V ₁ −V ₂ (standard value) between V ₁ and V ₂ of an unused battery with V ₁ −V ₂ of a used battery in an arbitrary state, the remaining capacity of the battery can be estimated instantly.
Also, in the above example, T ₁ was 1 second and T ₂ was 5 seconds, but if T ₁ is 0.01 to 0.1 seconds and T ₂ is 5 seconds, V ₁
-V ₂ becomes as shown in Figure 4, and the slope of the straight line becomes steeper, making comparison easier. Note that the difference between V ₁ and V ₂ varies depending on the type of battery (capacity, type of electrolyte) and the value of the load resistance R, so the load resistance R should be changed depending on the type of battery. It is necessary to configure the comparison circuit so that the standard value can also be changed. For example, if we take silver batteries for watches as an example, low
For the DRAIN type, the load resistance R is 50 to 100 Ω for a capacity up to about 100 mAH, and for the 100 to 200 mAH capacity, the load resistance R is 20 to 50 Ω.For the HIGH DRAIN type, which uses KOH as the electrolyte, the load resistance R is 50 to 100 Ω.
Experimental results have shown that a value of about 10Ω or less is appropriate. Considering the amount of electricity caused by discharge, the larger the load resistance R is, the more desirable it is, but if it exceeds 100Ω, the difference between V ₁ -V ₂ will not be noticeable and determination will be difficult.

〔Example〕

The present invention will be described in detail below based on Examples. FIG. 5 is an overall block diagram showing an embodiment of the present invention, in which a load resistance value is determined in advance by a load resistance element 102 determined by the type of battery to be measured and a changeover switch 103 for switching it. . After that, when the battery to be measured is inserted into the battery to be measured setter 101, the auto trigger circuit 1
05 outputs a signal after 0.5 seconds to trigger the timing circuit 106.

The reason for the delay of 0.5 seconds is to eliminate the negative effects of chatter. The timing circuit 106
is composed of a 10 msec monostable oscillation circuit 107 and a 5 second monostable oscillation circuit 108. The terminal voltage of the battery under test is determined by the monostable oscillation circuit 108.
At the same time as the switch is turned on, the switch 104 is closed and current flows, resulting in a sudden change. The sample and hold circuit 109 stores the value of this changing voltage 10 msec after the start of measurement. The difference between the output of the sample and hold circuit 109 and the ever-changing terminal voltage of the battery to be measured is calculated by the subtraction amplifier circuit 1.
Calculated using 10. This output is connected to the reference source 118 of the reference voltage generation circuit section 117 and the voltage dividing resistor 11.
9, 120, 121, 122, 123, 124 and the comparison circuit section 111.
A plurality of comparators 112, 113, 114, 11
5 and 116, and their respective outputs are latched by a latch circuit section 127 to determine the state after the start of measurement. And this latch circuit 127
The output is displayed on the display unit 128. Therefore, the output of the latch circuit section 127 is 10 msec after the terminal voltage of the battery under test starts discharging during rapid discharging.
This shows how large the difference is between the values of 5 seconds and 5 seconds. The newer the battery, the smaller this difference, and the older the battery, the larger it is.

Further, during measurement, the terminal voltage is always compared by the discrimination circuit 129 with a set voltage set in advance by the resistors 125 and 126, and the result is displayed on the discrimination display section 130. In particular, in the case of a completely discharged battery or a defective battery, the above-mentioned difference may hardly be detected and the battery may be judged as a new battery, so in this case, the characteristic of an extreme voltage drop is used. This is because it is necessary to make a determination by

As shown in FIG. 8, in the auto trigger circuit, when the battery to be measured is set, its terminal voltage is applied, so the resistors 401 and 403 and the capacitor 40
2 and by the monostable oscillation circuit 404.
Resistor 406 and capacitor 40 so that the timing circuit 106 can be triggered after a 0.5 second delay.
It is designed to be differentiated by 5 and output. Furthermore, when the timing circuit 106 is integrated as a whole, the number of external components increases in the case of a monostable oscillation circuit, so a reference signal is generated using an oscillation circuit 201 and a frequency dividing circuit 202 as shown in FIG. ,R
-S flip-flops 203 and 204 may be used to output two timing signals of 10 msec and 5 seconds.

Further, the sample and hold circuit section 109 adopts a method as shown in FIG. 7 in order to be inexpensive and easy to integrate.

This circuit includes a capacitor 304, analog switches 301 and 302 for charging and discharging the capacitor, and a gate directly connected to the capacitor 304.
A source follower consisting of a FET 305 and a resistor 306, and a comparator for comparing the output and input of this source follower, driving the analog switch 302 until the output becomes the same as the input, and discharging the capacitor 302. 307. The capacitor 304 is set to VDD by the analog switch 301 except during measurement.
is charged up to. Furthermore, the display section may be a bar graph type as shown in FIG. 9 or a bar graph type as shown in FIG.
If 04 and 605 are red, the display effect will be obvious at a glance.

From the above, according to this embodiment, it is possible to construct a device that can accurately measure with simple operation at a low cost while dealing with variations due to the type of battery, etc., and depending on the selection of the elements used and the display This makes it possible to reduce power consumption. Furthermore, one-chip integration can be easily achieved. At the same time, an auto-trigger mechanism improves operation, and a mechanism for identifying defective batteries enables more accurate measurements. In addition, even an unskilled operator can recognize the display without error by adopting a bar graph display format, which is most suitable for a battery capacity meter, or a variation thereof.

〔Effect of the invention〕

As described above, the present invention is based on the novel finding that when silver oxide and mercury batteries are rapidly discharged, the discharge curve, that is, the way the voltage drops, differs depending on the remaining capacity. This system measures the remaining capacity of silver oxide and mercury batteries by detecting the difference between the terminal voltage at the following points and the terminal voltage after several seconds. The remaining capacity of the battery can be measured very easily and in a very short time, and its effects are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a discharge voltage characteristic diagram of silver oxide and mercury batteries used in wristwatches and the like. FIGS. 2 1 to 4 are diagrams showing differences in voltage drop characteristics depending on remaining capacity when a silver oxide battery is rapidly discharged. FIG. 3 and FIG. 4 are diagrams showing the relationship between the terminal voltage difference V ₁ −V ₂ at times T ₁ and T ₂ after the start of discharge and the remaining capacity of the battery. FIG. 5 is an overall block diagram showing one embodiment of the present invention. FIG. 6 is a diagram showing another embodiment of the timing circuit. FIG. 7 is a diagram showing a specific example of a sample and hold circuit. FIG. 8 is a diagram showing a specific example of an auto-trigger circuit. FIG. 9 is a diagram showing an embodiment of the display section. FIG. 10 is a diagram showing another embodiment of the display section. 1, 11, 21... Battery under test, 2, 12...
Load resistance R, 3, 13, 23...Switch, 4,
14, 24...Amplification circuit, 5, 16, 25...
A/D converter, 6... Subtraction circuit, 101... Battery setter to be measured, 102... Load resistance element array, 1
03...changeover switch, 104...switch,
105... Auto trigger circuit, 106... Timing circuit section, 107... 10 msec monostable oscillation circuit, 108... 5 second monostable oscillation circuit, 109...
Sample & hold circuit section, 110... Subtraction amplifier circuit section, 111... Comparison circuit section, 112, 11
3,114,115,116... Comparator, 117
...Reference voltage generation circuit section, 118 ...Reference source, 1
19, 120, 121, 122, 123, 12
4, 125, 126...Resistor, 127...Latch circuit section, 128...Display section, 129...Discrimination circuit section, 130...Discrimination display section.

Claims (1)

[Claims] 1. In a battery remaining capacity meter that measures the remaining capacity of a primary silver oxide battery or a primary mercury battery, which has flat discharge voltage characteristics in which the terminal voltage hardly changes until the end of discharge in normal use, a load resistance element connected in series; a switch section for causing current to flow from the battery under test to the load resistance element to rapidly discharge the battery under test; 1st
a timing circuit section that outputs a second timing signal after a second time period set longer than the first time period has elapsed; a sample and hold circuit section that stores the terminal voltage of the battery; a subtraction amplifier circuit section that calculates the difference between the terminal voltage stored in the sample and hold circuit section and the terminal voltage of the voltage to be measured that changes from moment to moment; a comparison circuit unit that compares the output voltage of the subtraction amplifier circuit unit with a preset reference voltage; a latch circuit unit that latches the output of the comparison circuit unit at the time when the second timing signal is issued; A battery remaining capacity meter comprising a display section that displays the output of a circuit section. 2. The remaining battery capacity meter according to claim 1, wherein the timing circuit section is comprised of two monostable oscillation circuits having different time constants. 3. A patent characterized in that the timing circuit section comprises an oscillation circuit, a frequency dividing circuit, and two R-S flip-flops that receive the output of the frequency dividing circuit and output the first and second timing signals, respectively. A battery remaining capacity meter according to claim 1. 4. The battery according to any one of claims 1 to 3, which has a determination circuit that compares the terminal voltage of the battery to be measured with a preset set voltage to determine the quality of the battery to be measured. Remaining capacity meter.