JPH034094B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to an electronic scale that can easily correct span errors caused by differences in gravitational acceleration. <Prior art> As is well known, the span of a scale is affected by the gravitational acceleration on the earth, so when the span of scales used in areas with different gravitational accelerations is adjusted all at once at the manufacturer's factory, etc. It is necessary to prepare a large number of weights for each area (hereinafter referred to as area weights) that take into account the gravitational acceleration of the area where the scale is used, and when adjusting the span, check the area of use for each scale. The district weight for the scale must be selected. For this reason, it takes a lot of effort for the manufacturers mentioned above to adjust the spans for each area, and especially when the area of use changes due to fluctuations in demand, they have to readjust the spans again. However, such changes in the area of use have placed a heavy burden on manufacturers. Additionally, the cost of managing various district weights was a major burden. <Purpose of the invention> This invention was made in view of the above circumstances, and it is possible to adjust the span of all scales using a standard weight without using a district weight, and then adjust the span of all scales according to the specified use. Just by inputting the area into the scale, the span adjustment suitable for the area can be automatically made.
Therefore, it is an object of the present invention to provide a new electronic scale that eliminates the need to prepare district weights for each district of use and allows extremely easy changes in the district of use of the scale. <Structure of the Invention> In order to achieve the above object, the present invention is characterized by the following structure. That is, the primary integration time of the double integration type A/D converter that converts the weight signal into a digital value is controlled by a software timer, and the software
By adjusting the operating time of the timer, the output value of the A/D converter can be increased or decreased in units of one count.
The span change caused by changing the area where the scale is used is corrected by correcting the operating time of the soft timer. In other words, there is a means for specifying the area in which the scale is to be used from among multiple areas divided by differences in gravitational acceleration, and software for each area that calculates the span in each area to be constant.・The scale is equipped with a memory that stores the operating time of the timer, and a control means that reads the operating time of the soft timer in a designated area from the memory and controls the operating time of the soft timer based on this. This is to correct span changes that occur due to changes in the area of use. In addition, the memory can store the deviation of the operating time of each district's soft timer based on the operating time of the soft timer of a specific district. The deviation time is read from the memory, added to or subtracted from the operating time of the soft timer in the specific area, and the added or subtracted time is configured to control the operating time of the soft timer in the specified area. <Configuration of Embodiment> Embodiments of the present invention will be described below based on the drawings. FIG. 1 is a block diagram showing the main parts of an embodiment of the present invention. In this figure, A is a weight sensor consisting of a load cell, B is an amplifier circuit that amplifies the output signal of the sensor A, and C is a discrete double integration type A/D converter. This double integration type A/D converter C includes an analog switch 1, an integrator 2, a comparator 3, a counter 4, and a CPU that controls the analog switch 1.
It consists of 5. The analog switch 1 is configured to selectively input the reference voltage (Vref), amplifier output voltage (analog signal), and ground voltage to the integrator 2, and the switching of the switch is controlled by the CPU.
5 and a count stop signal Sb from the comparator 3. That is, when the count stop signal Sb is output from the comparator 3, the contact point of the analog switch 1 is switched to the c terminal, and the integrator 2
When the offset correction is performed and the switching command Sa is output from the CPU 5, the contact point of the switch 1 is switched to the a terminal, and the integration of the analog signal is started. When the next switching command Sa is output from the CPU 5, the contact point is switched to the b terminal, and the integration of the analog signal is switched to the inverse integration using the reference voltage (Vref). When the output voltage of the integrator 2 reaches the initial integration start voltage, the comparator 3 outputs a count stop signal Sb, which switches the above contact to the c terminal and issues the next switching command.
Offset correction of the integrator 2 is performed until Sa is output. In addition, in order to track the weight sensor A, the A/D converter C has an applied voltage (V1+
A value obtained by appropriately dividing V2) by voltage dividing resistors R1 and R2 and a variable resistor Vr is input as a reference voltage (Vref). When the output voltage of the integrator 2 reaches the initial integration start voltage, the comparator 3 switches between the analog switch 1 and the
A count stop signal Sb is output to the counter 4 and the CPU 5. Counter 4 is output at the same time as the inverse integration starts.
It is reset by a command Sc from the CPU 5 to start counting, and is stopped by a count stop signal Sb from the comparator 3. Further, this counter 4 is composed of a binary counter, but in order to enable counting exceeding its capacity, the CPU 5 counts this every time the counter 4 overflows, and the counter 4
When the counting operation is completed, the total output count number of the counter 4 is calculated from the output count number of the counter 4 at that time and the counted number of overflows. Then, the calculated total output count number is output as the output count number of the A/D converter C to a main CPU (not shown) that controls the entire scale. Of course, it is also possible to control the entire scale with the CPU 5. Further, this counter 4 is configured such that a count pulse Sd synchronized with one instruction cycle of a program set in the CPU 5 is supplied from the CPU 5. The CPU 5 mainly controls the primary integration time of the A/D converter C, and therefore
The CPU 5 is equipped with a soft timer that outputs the switching command Sa at a designated timing. The operating time of this soft timer is generally 1
The instruction cycle is given by the number of repetitions of a process (for example, a knob process, etc.) or the number of steps corresponding thereto, and the counter 4 is
As described above, it is counted in synchronization with one instruction cycle. Therefore, for example, as shown in the operating characteristic diagram of the double integration type A/D converter in FIG. 2, the input voltage of the A/D converter C and the reference voltage ( Vref) [i.e., the primary integration time (T1)
and the quadratic integration time (T2) are equal), the soft timer's 1
By adjusting the operating time corresponding to the step processing time, the output count number of the A/D converter C can be adjusted one count at a time. In other words, if the operating time of the soft timer is set to correspond to the processing time of 15,000 steps, the output of the A/D converter C can be 15,000 counts. D is a district designation means for designating the district in which the scale is to be used from among a plurality of districts divided according to differences in gravitational acceleration, and is comprised of, for example, a depth switch, a digital switch, or the like. By the way, scales with an accuracy of 1/3000 or higher divide Japan into 16 districts. E is a memory that stores the operating time of the soft timer for each district calculated so that the span in each district is a constant value, and the operating time is the operating time of the soft timer for each district. or the deviation time calculated based on these, i.e.
The deviation of the operating time of the soft timer in each district is stored when the operating time of the soft timer in the specific district is taken as a reference. Table 1 on the next page shows the gravitational acceleration of each district when the country is divided into 16 districts, and the first district of a scale designed to have an accuracy of 1/3000, weigh 3 kg, and 1 g = 5 counts. It shows the span deviation of other districts when used as a standard, as well as the operating time of the soft timer for each district that can maintain the span at a constant value in each district.

[Table] The numbers shown in the count column equivalent to weighing are
It shows the span amount of A/D converter C in each district when the scale whose span was adjusted in each district is transferred to another district, and the operating time of the soft timer is 15,000 times the span in each district. It shows the soft timer operating time in each district that can be counted. However, the operating time of the soft timer in this case is determined by adjusting the input voltage of the A/D converter C and the reference voltage equal to each other when a weight equivalent to a weighing device is loaded. With the adjustment,
This is a case where the output value of A/D converter C can be adjusted by one count. For example, in the first district.
In District 16, the output count of the A/D converter when a weight equivalent to weighing is loaded is 23 counts less than in District 1, so to offset this, the step is set to 15023. It is being done. On the other hand, the CPU 5 reads out the operating time of the software timer of the district designated by the district designation means D from the memory E, and executes the software timer based on this.
Control means (means that can be achieved by executing the procedure shown in the operation flow of FIG. 3) for controlling the operating time of the timer is provided. <Operation of the embodiment> Next, the operation of the main parts of the embodiment shown in FIG.
The explanation will be based on the flowchart shown in the figure. In order to simplify the explanation, here, by operating the variable resistor Vr, the reference voltage of the A/D converter C and the input voltage of the A/D converter C when a weight equivalent to a weighing device is loaded are adjusted to be equal. It is assumed that Further, it is assumed that at the initial time, the contact of the analog switch 1 is connected to the c terminal. When the program is run in this state, the CPU 5 first reads the area to be used set in the area specifying means D, and then reads the operating time of the soft timer for the area from the memory E (step 1, step 2). The operation time read here may be, for example, 15,000 steps for the first district and 15,002 steps for the second district, or the deviation of each district based on 14,998 steps, that is, Two steps may be read for the first district, and four steps may be read for the second district. However, in this case, the software
The 14,998 steps of the timer's operating time must be fixed as described below. but,
This makes it easier to adjust one step, which is the minimum variable unit of the soft timer, so here we will calculate Q and R for performing the above deviation from the following arithmetic expression, and calculate this. is stored in the memory E, and these Q and R are read out. Operating time (number of steps) = 14998 + 2Q + R Therefore, for 1 district (15000) Q = 1, R = 0 For 2 districts (15002) Q = 2, R = 0 For 3 districts (15003) Q = 2, R = 1 4 For district (15005), Q = 3 R = 1 〓 〓 〓 〓 For district 16 (15023), Q = 12 R = 1 When Q is read in this way, the next step 3
In step 4, Q is set as the number of processing times N that requires two steps in one loop processing, and then in step 4, a command Sa is outputted to switch the contact of the analog switch 1 from the c terminal to the a terminal. This starts the first-order integration for the unknown input voltage. Next, the CPU 5 has a fixed operating time,
The process corresponding to the 14997 step is executed (step 5), and then in the next step 6, the read R
is 1 or not. If the result of the judgment is 1, one step of processing is executed at the next step 7, and if it is 0, this step 7 is skipped and the process moves to the next loop processing. In this way, steps 5 and 6 execute processing equivalent to a total of 14,998 steps. Next, a process that requires two steps in one loop process is repeated N times. That is, in step 8, N is set to -1.
Then, in the following step 9, it is determined whether N is 0 or not. Then, if N is not 0, go to step 8 again.
Return to In this way, the above loop processing is repeated until N becomes 0. For example, in the 16th district, R=1, so after executing the process in step 7, this loop process is repeated 12 times. Now if you are in District 16, step 5
The processing from step 9 to step 9 results in the execution of 14998+1+2×12=15023 steps. When the processing of the number of steps corresponding to the predetermined operating time is completed in this way, a command Sa to switch the contact of analog switch 1 to the b terminal is outputted, and at the same time a command is issued to prompt the counter 4 to start a reset.
Output Sc (step 10). As a result, the integration of the unknown input voltage is completed, and then the inverse integration using the reference voltage and the counting operation by the counter 4 are started. When we enter this period of inverse integration (quadratic integration),
The CPU 5 checks whether the most significant bit (hereinafter referred to as MSB) of the counter 4 is high or low (hereinafter referred to as H or L) at a period shorter than a half period of the full count period of the counter 4, and thereby The number of overflows of the counter 4 mentioned above is counted. That is, first, in step 11, a process consisting of a certain number of steps is executed to gain time, and then the next step is started.
At 12, check MSB H and L of counter 4.
However, since the MSB is L during the half cycle of the full count period of the counter 4, the result of the check here is L. Therefore, initially, the flag is turned ON in the following step 13, and then the count stop signal of comparator 3 is turned on in step 14.
Check H and L of Sb. As a result of the check,
If it is H, the process moves to the next step 17, and if it is L, it returns to the original step 11. While repeating this loop process, half a cycle of the full count period of the counter 4 has passed, and the MSB changes from L to H.
When the switch changes to step 12, step
Move to 15. In step 15, it is determined whether the flag is ON. At this time, it is initially ON, so
In the following step 16, the flag is turned OFF, the overflow count is increased by 1, and the process jumps to step 14. Then, even if you return to step 11 and move from step 12 to step 15, the previous flag is OFF, so the MSB
During the half period in which is H, the step 16 is passed and the process jumps to step 14 again. In this way, the CPU 5 monitors the H and L levels of the count stop signal Sb of the comparator 3 while counting the number of overflows of the counter 4. Then, if the count stop signal Sb becomes H,
Since the inverse integration using the reference voltage and the switching of the contact point to the c terminal have been completed, the next step is
At step 17, the count number of the counter 4 is input, and the total output count number of the counter is calculated from this and the counted number of overflows. Then, the calculated results are output to the main CPU. Then, a process consisting of a fixed number of steps is executed, and time is spent to correct the offset of the integrator 2 (step 18), and then the process returns to step 1 again. In this way, the primary integration time is controlled each time based on the operating time of the soft timer for the area designated by the area designation means D. Therefore, in this example, after the span of the scale is adjusted to 15,000 counts in the first span adjustment performed by loading a weight equivalent to the weighing weight, it is difficult to determine where the area in which the scale will be used is designated. However, by simply adjusting the area designation means D to the area in question, the span in the area where the scale is used can be adjusted to 15,000 counts. However, in the first span adjustment performed by loading a weight equivalent to the weighing amount, the area designation means D must be designated to the area where the span adjustment is to be performed. <Effects of the Invention> As explained above, the present invention comprises a double integration type A/D converter that converts a weight signal into a digital value, and a soft timer that controls the primary integration time of the A/D converter. In an electronic scale comprising:
A district designation means for specifying the district in which the scale is to be used from among multiple districts divided by differences in gravitational acceleration, and a soft timer operating time for each district calculated so that the span in each district is constant. The control means reads the operating time of the soft timer for a specified area from the memory and controls the operating time of the soft timer based on this, so even span adjustment using a reference weight is not necessary. If you do this, then no matter where the scale is designated to be used, just by inputting the designated usage district into the scale, it will automatically adjust the span to suit that district. Therefore, there is no need to individually perform span adjustment for each district using district weights, and the span adjustment performed by the manufacturer can be streamlined. Furthermore, since there is no need to prepare district weights for each district of use, the cost of managing such district weights can be reduced. In addition, it is possible to easily change the usage area due to fluctuations in demand between districts, and it is also possible to quickly respond to fluctuations in demand.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of the main part of an embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining the operating characteristics of a double integration type A/D converter, and FIG. 2 is a flowchart showing an example of the operation of the embodiment of FIG. 1. FIG. A... Weight sensor, B... Amplifier circuit, C...
Double integral type A/D converter, 5...CPU (software/
(Built-in timer), D... District designation means, E... Memory.

Claims (1)

[Claims] 1. An electronic scale comprising a double integration type A/D converter that converts a weight signal into a digital value, and a soft timer that controls the primary integration time of the A/D converter. , a method for specifying a district to use a scale from multiple districts divided by differences in gravitational acceleration, and a soft timer for each district calculated so that the span in each district is constant. An electronic device comprising: a memory that stores an operating time; and a control means that reads the operating time of a soft timer in a designated area from the memory and controls the operating time of the soft timer based on this. Scales. 2. In the electronic scale according to claim 1, the operating time stored in the memory is determined by the deviation of the operating time of the soft timer in each area when the operating time of the soft timer in the specific area is taken as a reference. An electronic scale characterized by: 3. In the electronic scale described in claim 2, the deviation time of the specified area is added or subtracted from the operating time of the soft timer of the specified area, and the operating time of the soft timer of the specified area is controlled by the added or subtracted time. An electronic scale characterized by: