JPS6341405B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a digital weight measuring device that converts a weight value into a pulse number and displays it digitally.

Generally, digital weight measuring devices use a sensor such as a load cell to detect weight, and the weight detection output is amplified by an amplifier and then converted to a pulse number signal corresponding to the output level by an A/D converter. The pulse number signal is input to a data processing device to be converted into weight data, which is then digitally displayed.

Conventionally, when manufacturing two weight measuring devices with different weighing capacities in such digital weight measuring devices, for example, it is necessary to replace the weight sensor, adjust the amplification degree of the amplifier, or change the resolution of the A/D converter. There is a problem in that it requires the same amount of process time and cost as manufacturing two weighing devices to switch the weighing capacity of one weighing device and use it as two weighing devices. Ta.

This invention was devised in order to solve such problems, and it provides two scale functions with different weighing amounts and different weight values per scale, and performs both scale functions when the weighing value is the one with the smaller weighing value. When the weighing value is exceeded, it is automatically switched to the one with a larger weighing value, so it can be used differently. Therefore, when the weighing value is small, it is possible to use a fine scale, and relatively heavy items can also be weighed, improving practicality. Moreover, it is an object of the present invention to provide a digital weight measuring device that can smoothly return to the zero point by performing auto-zero processing when a load is removed while a weighing function with a large weighing capacity is selected. .

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a weight detecting section consisting of a load cell or the like, and this detecting section 1 outputs a voltage signal corresponding to the weight of the object to be weighed. The voltage signal output from the weight detecting section 1 is amplified by a differential amplifier 2, and furthermore, high frequency components such as noise are removed by a low pass filter 3, and the signal is input to an A/D converter 4. The A/D converter 4 is of a double integration type, for example, and converts one signal every 200 msec.
A digital signal corresponding to the input voltage is output by repeating sampling times. For example, it is adjusted so that two pulses of digital signals are output per gram. Digital weight data sampled by the A/D converter 4 is supplied to a data processing device 6 via an I/O port 5. The data processing device 6 includes a CPU (central processing unit) 7,
RAM (Random Access Memory) 8, ROM
(Read-only memory) Consists of 9
The CPU 7, RAM 8, ROM 9 and the I/O port 5 are coupled by a data bus 10 and an address bus 11 so that data can be exchanged. The CPU 7, RAM 8, and ROM 9 are also coupled via the data bus 10 and address bus 11 to a display and keyboard controller 14 that controls a display 12 and a keyboard 13, so that data can be exchanged.

The RAM 8 is, for example, 16× as shown in FIG.
It consists of 16 256 words, each word consisting of 4 bits, forming various registers and various flag memories. To describe the main memory configuration of the RAM 8, each word is indicated by M[X, Y] and each bit is indicated by <>. M[F, 1] is one scale for setting the unit of one scale. formed into a register, M[F,
2] to M[O, 2] are formed into an accumulator,
M[6, 3] and M[5, 3] are formed into a timer register that takes the timing when switching weighing, and M[F,
4] to M[O, 4] are formed in the key buffer register. Also, M[F, 5] to M[A, 5] are formed in the price display register, and M[9, 5] to M[5,
5] in the unit price display register, and M[4, 5]
~M [O, 5] is formed in the weight display register, and M
[F, 6] to M[O, 6] are formed as working registers, and M[F, 9] to M[O, 9] are formed as display content storage registers. Also M [F, A]
~M[B, A] is formed in the net weight count register, M[A, A] ~M[6, A] is formed in the weight count value input register, M[E, B] ~M[A,
B] into a weight zero value register, and M[4,
B] to M[0, B] are formed in an actual weight count register. Also, M[8,C] to M[4,C] are formed in the tare weight count register, and M[F,C],
Form M[E, C], M[2, D] to M[0, D] in the weight true value register, and M[7, D] to [3, D].
is formed into a stable weight counting register. Furthermore, M[C, D] to M[8, D] are set to weight count registers A, M[F, D] to M[D, D], M[1,
E], M[0, E] into weight count registers B, M
[6, E] to M[2, E] to weight count register C, M[B, E] to M[7, E] to weight count register D, M[F, E] to M[C, E] , M[O,
F] to weight count register E, M[5, F] ~
M [1, F] to weight count register F, M [A,
F] to M[6, F] to weight count register G,
M[F, F] to M[B, F] are formed in the weight count register H, respectively. Further M [0, 3]
<1> is the zero point over flag, M [0, 3] <2>
is formed as a weighing over flag, and M[3,3]<2> is formed as a 15Kg flag.

The CPU 7 controls the RAM 8 based on the program set in the ROM 9, and the main program control is performed based on the flowchart shown in FIG. That is, when the power is turned on, preprocessing is first performed, followed by key processing, count data import processing from the A/D converter 4, flicker processing, auto zero processing, and display processing. After completing, return to the above key processing. And from now on, this key processing~
The routine up to the display process is repeated, and when a key input or count data is received, the process is placed on standby so that the process can be performed immediately.

In the preprocessing, everything in the RAM 8 is cleared, all digits on the display are displayed as zero, and a display is checked. Next, count data is taken in from the A/D converter 4 for zero value setting,
The data is subjected to flickering processing, is taken into the weight true value register, and finally taken into the weight zero value register as zero value data.

In the next key processing, preset processing is performed based on various key inputs from the keyboard 13.

In the next A/D converter data acquisition process, processing is performed based on the flowchart of FIG. 4. First, the count data from the A/D converter 4 is input to the weight count value input register M [A, A].
~M[6,A], then subtract the count data of the weight zero value register from the count data of the weight count value input register, and send the result to the actual weight count registers M[4,B]~M[0, B]
Store in. Next, it is checked whether the contents of the actual weight count register are greater than 12,000 counts. For example, if the weight is 15Kg in ROM9, 1
Weighing function with 5g scale and weighing capacity of 6Kg, 1 scale is 2g
Weighing function (maximum number of effective scales for both functions is 3000)
If this is programmed and 1g is set as 2 counts, 12000 counts will be the upper limit count for a weighing weight of 6 kg. Therefore, if the contents of the actual weight count register are 12,000 counts or less, it indicates that the weight value is 6 kg or less, and 12,000 counts or less.
If it is larger than the count, it indicates that the weight value exceeds 6 kg. If it is checked that the count is greater than 12,000, the 15Kg flag is set to "1" and the timer registers M[6, 3], M[5,
3] and set 5g in the 1 scale register, after which the scale functions as a scale with a weight of 15Kg and 1 scale of 5g (10 counts). If the count is less than 12000, +1 is added to the timer register. Next, check whether the timer register has exceeded the timer, and if the timer has exceeded, clear the 15Kg flag to zero,
Set 2g in the 1 scale register to function as a scale with a weight of 6 kg and 1 scale of 2g (4 counts).

In the next flickering process, the count data taken into the weight count value input register is sequentially taken into weight count registers A to H, and the changes before and after the count data taken into each weight count register are compared. Possibly a stable weight count register M[7,
D] to M[3, D] are changed or kept as they are to prevent flickering. Then, the result of subtracting the contents of the tare weight count register from the contents of the stable weight count register is taken into the weight true value register.

In the next auto-zero process, as shown in FIG. 5, it is first checked whether the 15Kg flag is set to "1". If the 15Kg flag is set to "1", is the absolute value of the difference between the contents of the weight zero value register and the contents of the weight true value register within 5 counts of the auto-zero processing range of the 15Kg/5g scale? Check whether or not.
Also, if the 15Kg flag is not set to "1", it is checked whether the absolute value of the above difference is within 2 counts of the auto-zero processing range of 6Kg/2g weighing. In any check, if the count is within the set count value, the contents of the weight true value register are set as a new zero point in the weight zero value register. When the above processing is completed, the upper and lower limits of the zero range corresponding to the weight are sequentially sent to the accumulator, and the count value of the weight zero value register is compared with the count value of the weight zero value register. If the absolute value is greater than the count value, the zero point over flag is set to "1" to notify that the zero point is over. For example, if you set the zero point range to within ±300 counts for a 15Kg/5g scale and within ±120 counts for a 6Kg/2g scale, then set the accumulator to ±300 counts for a 15Kg/5g scale. Load and compare counts, 6
When using a Kg/2g scale, the accumulator has a ±120
Load and compare counts.

In the display process, as shown in Figure 6, 5 is added to the count data of the 5-digit actual weight count register.
The count is added up, rounded down to 4, and then the 15Kg flag is checked. When this flag memory is "1", the scale is 15Kg/5g, so calculate the weight value by multiplying the upper 4 digits of the actual weight count register by 5g of the 1 scale register, and send that value to the weight display register. Forward. Also, when the 15Kg flag is “0”, the scale is 6Kg/2g, so there is a 1 scale register in the upper 4 digits of the actual weight count register.
Multiply by 2g and transfer the value to the weight display register. Next, it is checked whether the zero point over flag is set to "1" or the weight over flag is set to "1". If either one is set to "1", the display 12 is turned off. Note that the weight over flag becomes "1" when the weight of the object to be weighed exceeds 15 kg. When either flag is "0", a zero suppression code such as "F" is set in the upper digits of the weight display register where the count data has not been taken in, and then the contents of the weight display register are displayed on the display 12. do. Therefore, if the content of the weight display register is "00200", it will be "FF200" and the display will be "200".
becomes.

In this way, the weighing value and 1 scale are different 15Kg/
It has a weighing function of 5g (10 counts) and a weighing function of 6Kg/2g (4 counts), and when the weight value is less than 6Kg, the weighing function of 6Kg/2g takes priority over the weighing function of 15Kg/5g. This function allows weighing to be performed using fine scale values of 2g per division. Also, if the weight value exceeds 6Kg, 15
The function automatically switches to Kg/5g scale, and the maximum
It is possible to weigh up to 15Kg. Since the switching of the weighing function is completely controlled by software program, it is not necessary to replace the weight detection section 1 or adjust the differential amplifier 2 or A/D converter 4. This eliminates the need for a large number of parts, and there is no need for any troublesome work. In addition, the 15Kg/5g weighing function can be adjusted by removing the load.
When switching to the Kg/2g weighing function, a timer register is involved, and this timer register sets the 15Kg flag to "1" and holds the 15Kg/5g weighing function for a while until the timer expires. The scale performs auto-zero processing within the auto-zero processing range of the 15Kg/5g scale function, that is, the absolute value of the difference between the contents of the weight zero value register and the contents of the weight true value register is within 5 counts, and the zero point is determined. This allows a smooth return to the zero point. After the zero point is established, 6
The scale function will switch to Kg/2g, and the subsequent auto-zero processing will be performed so that the absolute value of the difference between the contents of the weight zero value register and the contents of the weight true value register is within 2 counts.

In addition, in the above example, one scale is 4 counts and 10
Although the case of counting has been described, the present invention is not limited to this. For example, one scale may be 2 counts and 5 counts, or 5 counts and 10 counts, etc. In short, the smaller number of counts per scale should be 2 or more.

In addition, in the above embodiment, a model with two weighing functions of 15Kg/5g and 6Kg/2g was described, but for example, 3Kg/1g and 6Kg/2g, 15Kg/5g and 30Kg/10g.
Various combinations of weighing functions are possible.

As detailed above, according to the present invention, two scale functions are provided that have different weighing amounts and different weight values per scale, and when the weighing value exceeds the smaller weighing value, The scale can be used for different purposes by automatically switching to the one with a larger weighing capacity. Therefore, when the weighing value is small, it is possible to measure on a fine scale, and relatively heavy items can also be weighed, improving practicality. Moreover, the scale function has a large weighing capacity. By performing auto-zero processing when the load is removed while the weight is selected, it is possible to provide a digital weight measuring device that can smoothly return to the zero point.

[Brief explanation of the drawing]

The figures show an embodiment of the present invention. Figure 1 is a block diagram showing the circuit configuration, Figure 2 is a diagram showing the RAM memory configuration, Figure 3 is a flowchart of main program control, and Figure 4 is a block diagram showing the circuit configuration. FIG. 5 is a flow chart of the data acquisition process from the /D converter, FIG. 5 is a flow chart of the auto-zero process, and FIG. 6 is a flow chart of the display process. 1... Weight detection section, 4... A/D converter, 7...
CPU (Central Processing Unit), 8...RAM (Random Access Memory), 9...ROM (Read Only Memory).

Claims (1)

[Claims] 1. In a digital weight measuring device that converts the weighing value into a number of pulses and displays it digitally, one scale is counted as A count in the number of pulses (however, A≧2).
Number of pulses generated during measurement ÷ A count x 1
The weight value on the scale is weighed to calculate the weight value, and if A is an even number, the auto-zero processing range is set to the absolute value of A/2 or less, or when it is an odd number, the auto-zero processing range is set to (A-1)/ The first measuring means has a relatively small weighing capacity, which is less than the absolute value of 2, and one scale is set to B count (however, B>A) with the number of pulses, and the number of pulses generated during measurement ÷ B count x 1 The weight value on the scale is weighed to calculate the weight value, and when B is an even number, the auto-zero processing range is set to the absolute value of B/2 or less, or when it is an odd number, the auto-zero processing range is set to (B-1)/ A second measuring means whose maximum effective scale number to be less than or equal to the absolute value of the first measuring means is approximately equal to that of the first measuring means and whose weighing capacity is relatively large; a selection means that selects the first measuring means and selects the second measuring means when the measured value exceeds the measured value of the first measuring means; and the selecting means selects the second measuring means; is selected and the weighed value becomes less than or equal to the weighed value of the first measuring means, and after a preset time has elapsed, the timer expires and the selection means selects the first measuring means. A digital weight measuring device equipped with a timer.