KR900006180B1 - Digital Multimeter Bar Graph Display - Google Patents

Abstract

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Description

Digital Multimeter Bar Graph Display

1 and 2 are block diagrams of a conventional bar graph display device of a digital multimeter.

3 is a block diagram of a digital multimeter bar graph display device according to the present invention;

4 is an internal block diagram of the one-chip microprocessor shown in FIG.

5 is a flowchart according to the present invention.

6 is a view for explaining backplane data according to an operation method of the LCD unit.

7 is a diagram showing bar graph display conversion data according to the present invention;

8 is a view showing an LCD unit for explaining Embodiment 1 of the present invention.

9 is a view for explaining an operation of converting segment data into bar graph display data according to Embodiment 1 of the present invention.

* Explanation of symbols for main parts of the drawings

11,21: Analog / digital (A / D) converter for segment data change

12,25: LCD

13: Analog / Digital (A / D) Converter for Bar Graph Display Data Conversion

14,26: bar graph display section 22: LCD and bar graph drive circuit

23 control logic circuit 24 IC device

31: Analog / Digital (A / D) Converter

32: LCD 33: one-chip microprocessor

34: bar graph display part 35: input port

36: CPU 37: RAM

38: ROM 39: system clock generation circuit

41: stack 42: LCD driving circuit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar graph display device of a digital multimeter. In particular, the present invention relates to a bar graph display device of a digital multimeter. The present invention relates to a bar graph display device of a digital multimeter capable of obtaining an effective effect.

In general, a digital multimeter processes analog data measured from a measuring object into digital data, and then displays a number and a sign on a display unit of an LCD device. Because it can not be displayed only by the numerical concept, there was a disadvantage in the visual judgment effect on the measurement data achieved by the conventional analog measuring instrument.

Accordingly, in order to achieve the visual effect required by the digital multimeter as described above, an LCD device which displays the measurement data for the measurement object as 7-segment numeric data is displayed as graph data corresponding to the numerical data. After a bar graph display device is provided, a method has been proposed in which the measured data is processed as bar graph display data and displayed on the bar graph display device. The configuration is shown in FIG.

That is, in the bar graph display device of the conventional digital multimeter shown in FIG. 1, the LCD unit 12 is connected to an analog / digital converter (hereinafter referred to as an A / D converter) in which the measurement input signal has an LCD driving function. Digitized into 7-segment data for driving a digital signal, and then displayed as numeric data on the LCD unit 12. In addition, the measurement input signal is a dedicated A / D converter having a built-in bar graph data processing function. 13) to be digitized to the bar graph display data, and then applied to the bar graph display unit 14 formed integrally with the LCD unit 12 to convert the numerical data displayed on the LCD unit 12 to the corresponding graph data. It is designed to promote visual effects on the measured data.

By the way, according to the bar graph display device of the digital multimeter shown in FIG. 1, since a dedicated bar graph display A / D converter 13 must be used, the range of selection for the device is limited due to the circuit configuration. However, since the measurement input signal, which is analog data, is branched and digitized by separate dedicated A / D converters 11 and 13, respectively, the measurement input signal is adversely affected by, for example, noise generated on a transmission path. If received, an error of noise occurs between the numerical data displayed on the LCD unit 12 as a display device and the graph data displayed on the bar graph display unit 14 after being digitally processed by the respective A / D converters 11 and 13. As a result, numerical data cannot be represented accurately with corresponding bar graph data.

On the other hand, a bar graph display device of the digital multimeter shown in FIG. 2 has been proposed and put into practical use as a method for eliminating the drawbacks as described above, and according to the circuit configuration shown in FIG. Digital input data and digital input data using an integrated circuit (IC) device 24 composed of an A / D converter 21, an LCD and a bar graph drive circuit 22, and a control logic circuit 23. The bar graph display data is processed and then applied to the LCD section 25 and the bar graph display section 26 to display the measured data as 7-segment numeric data and corresponding bar graph data.

Here, according to the circuit configuration shown in FIG. 2, instead of using a separate AD converter to process the measurement input signal, a dedicated IC element 24 is used to process digital numeric data and bar graph display data. Although it is possible to avoid the problem of error in the data display, it is necessary to newly develop and design a dedicated IC device with the processing function of digital numeric data and bar graph data. In addition to the deterioration, the development time and the cost of the dedicated IC device are increased, thereby increasing the price of the product.

Accordingly, the present invention has been made in view of the above circumstances, and in order to solve various problems occurring in the bar graph display circuit of the conventional digital multimeter, the measurement input signal, which is analog data, has only a numerical data display function. Digitization processing is performed on the general purpose A / D converter equipped with the digital data and then displayed on the LCD. Numerical data of a plurality of higher digits among the digitized measurement data is displayed on a one-chip microprocessor equipped with a conventional LCD driving circuit. It recognizes and converts it to the corresponding bar graph display data, and then displays it on the bar graph display unit so that the measured input signal can be digitally processed and its numeric data without using a dedicated A / D converter or a dedicated IC device. Can be displayed as bar graph data corresponding to To provide a bar graph display device of a digital multi-meter to achieve the effect that there is a purpose.

Hereinafter, the configuration, operation, and effect of the first embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The present invention outputs from an analog / digital (A / D) converter 31 and a digital / digital (A / D) converter 31 for digitally processing a measurement input signal Din, which is analog data, and converting it into segment numeric data. In the digital multimeter comprising an LCD unit 32 for displaying the segment data, the segment data output from the A / D converter 31 and the numeric segment data for a predetermined upper digit number and the LCD unit ( 32, the backplane data according to the driving method of the input means 35, the memory means (37, 38) for storing the backplane data and the segment data to be input or bar graph display conversion data and programs, etc., Detect an active state of the backplane data applied via the input means 35 and segment the plurality of higher digits based on the backplane data in this active state. Control means 36 for recognizing data and converting and controlling numerical segment data values for a plurality of higher digits into bar graph display data with reference to bar graph display conversion data stored in the memory means 38; A one-chip microprocessor 33 composed of a drive unit 42 for driving the bar graph display unit 34 provided in the LCD unit 32 on the basis of the bar graph display data converted by the means 36, It is characterized in that the numerical data displayed on the LCD unit 32 is displayed as the corresponding bar graph data.

3 shows a bar graph display device of a digital multimeter according to the first embodiment of the present invention, which is configured as described above. The measurement input signal Din converts analog data measured from a measurement target into an A / D converter 31. A / D converter 31 is sent from the signal converter not shown to convert the level of the measurement signal, etc. to suit the input signal condition of Digital conversion of the measured input signal Din to the corresponding 7-segment number and sign (+,-) data, and then the back according to the operation method of the LCD unit 32 described later together with the converted number and sign segment data. The plan data is applied to the LCD unit 32 so that numeric and sign data are displayed.

Here, the driving method and the back plan (COMMON) data for the LCD unit 32 will be described. In general, when the LCD device is operated with a direct current, an electrode reaction occurs inside the liquid crystal cell, and the display quality rapidly deteriorates. It is necessary to drive with a signal, and as the AC driving method, a static driving method and a time division driving method have been proposed. In each of the driving methods, the backplane voltage as the backplane data is added to the segment to be turned on for the 7-segment. In other words, the voltage waveform of the reverse phase is applied to the common terminal voltage) while the voltage waveform of the phase with the backplane voltage is applied to the segment to be turned off. Therefore, the voltage waveform of the common terminal (COM MON) side and the segment side voltage waveform The combination controls the ON / OFF of each segment so that the segment data is displayed on the LCD device.

Therefore, in the A / D converter 31, the segment data is transmitted in parallel along with the back plan data according to the driving method of the LCD unit 32. Therefore, the LCD unit 32 measures the input signal Din based on the back plan data. The backplane data and the segment data outputted from the A / D converter 31 are applied to the one chip microprocessor 33 so that the numeric data for the LCD is displayed under the control of the one chip microprocessor 33. The bar graph data corresponding to the numeric data displayed in the section 32 is displayed on the bar graph display section 34. That is, in the one-chip microprocessor 33 built-in LCD driving circuit as the segment data recognition and bar graph driver, a plurality of high order digits (for example, the LCD unit) is output from the A / D converter 31 and applied to the LCD unit 32. If 32 is 3. _{1/2 digits} , the upper 3 digits, and 3. _{3/4 digits} , the segment data for the upper 2 digits) and the backplane data according to the operation method of the LCD unit 32. Reads and generates bar graph display data corresponding to the numeric data displayed on the LCD unit 32 by referring to the bar graph display conversion data embedded by the program, and then the LCD unit 32 through an internal LCD driving circuit. FIG. 4 shows the internal block circuit configuration of the one-chip microprocessor 33. As shown in FIG.

The one-chip microprocessor 33 shown in FIG. 4 executes a program with an input port 35 to which segment data and backplane data for the plurality of upper digits are input, and performs an active state of the backplane data. CPU (Central Processing Unit) 36 for recognizing the input segment data and converting the received segment data into bar graph display data, RAM 37 storing the input data or the variables necessary for program execution, and bar graph input data. An oscillation signal applied from a ROM 38 or an external oscillator circuit (OSC) storing a bar graph display conversion data referred to for converting the input data into bar graph display data or a program executed to convert the display data into bar data display data. System clock generation circuit (39) for dividing a signal into an internal clock signal, and a program count for counting the progress of a program sequence. (40) When a subroutine call or the like occurs while executing a program, a stack 41 for storing a position in a program to be returned after executing the subroutine and the bar graph display conversion data are applied. It is comprised by the LCD drive circuit 42 which drives the bar graph display part 34 in response.

In this configuration, as the backplane data is supplied together with the number and the sign segment data to display the measured scale on the bar graph display section 34, the one chip microprocessor 33 operates by the flowchart shown in FIG. First, in step S1 and S2, RAM 37 is cleared while performing system initialization, and then the CPU 36 sends the number and the number transmitted from the A / D converter 31 in steps S3 and S4. When the back plan data is input through the input port 35 together with the code segment data, the back plan data according to the driving method of the LCD unit 32 is read out of the data to determine whether the back plan data is active. .

Here, the driving method of the LCD and the back plan data will be described in more detail with reference to FIG. 6. As described above, the potential level of the back plan data is set differently according to the driving method of the LCD, for example, a static driving method. In Fig. 6 (a), the duty ratio of the AC voltage waveform with respect to the common terminal COM is the same, while in the time division driving method, the duty ratio is set at 1/2 duty as shown in Fig. 6 (b). When driving to the LCD device, the AC voltage waveform has the potential level of V1, V2, VDD as the backplane data applied to the common terminals COM1 and COM2. Also, in the 1/3 duty time division driving method, FIG. As shown in Fig. 2), the AC voltage waveforms applied to the common terminals COM1, COM2, and COM3 have potential levels of V1, V2, V3, and VDD.

Therefore, in the one-chip microprocessor 33, when the CPU 36 determines the segment data by making the high level active when there are a plurality of levels in the backplane data as described above, for example, it is higher than the lowest level (for example, V1). As the level is determined to be a high level, the active period becomes longer, and thus, the read period of the segment data becomes longer and an error may occur during data read. As shown in FIG. 6 (a) (b) (c) Similarly, the segment data is read out by making the lowest level (low level) of the levels of the AC waveform applied according to each driving method active.

That is, the CPU 36 determines whether the backplane data input in step S4 is a low level active state, and returns to step S3 if the low level active state is not. If a plurality of upper digits of the corresponding segment data, for example, the unit 32 is composed of 3. _{1/2 digits} , the first, second, and third digits of segment data are read and then the first, second, and third digits are read. The three-digit numeric data is determined and stored in the RAM 37. Then, in step S6, the bar graph display conversion data corresponding to the segment data for the upper three digits is stored in the ROM 38 as shown in FIG. The converted numerical data corresponding to the hexadecimal data is read from the segment data conversion table stored in the table.

The bar graph display data converted in this way is applied to the built-in LCD driver circuit 42. In the LCD driver circuit 42, the bar graph display data and the bar of the bar graph display unit 34 provided in the LCD unit in step S7. The backplane data COM1 and COM2 according to the driving method of the graph display unit 34 are driven to a degree corresponding to the numerical data displayed on the LCD unit 32.

Here, the bar graph display operation as described above will be described with specific examples.

First, as shown in FIG. 8, the LCD unit 32 provided in the digital multimeter is 3. _{1/2 digits} having a maximum display rating of " 1999 " As shown in Fig. 6 (a), when the duty ratio is applied at a constant level, code data is applied from the A / D converter 31 to the terminal P, and is turned on and off based on the backplane COM1 data. The sign (+,-) is displayed, and the first digit (K) has a high level or a low level at the terminal (K) as the two segments are integrally connected to represent "0" or "1". The first digit is displayed on the basis of the backplane COM1 data, and the second (L) and the third (L) to the terminals a ₁ to g ₁ , a ₂ to g ₂ , and a ₃ to g ₃ . M), 7-segment data for the 4th (N) digits is applied to turn on / off the segment of the corresponding digits (L, M, N) based on the backplane data. It is good.

Here, when the numeric data displayed on the LCD device 32 is, for example, "220", the one-chip microprocessor 33 reads the back plan data of the LCD device 32 in an active state in which the back plan data is at a low level, and the back plan. The period in which the data is at the low level is determined to be in an active state, and the segment data corresponding to the plurality of upper digits, namely, the first (K), the second (L), and the third (M) is read.

Subsequently, the CPU 36 of the one-chip microprocessor 33 determines the segment data for the upper three digits (K, L, M) read in the active state where the backplane data is at the low level as shown in FIG. First, since the first (K) digit is in phase with the backplane data, the first (K) digit is determined to be "0", and the segment data (a ₁ to g ₁ ) for the second (L) digit is hexadecimal "DA". The hexadecimal data " DA " determined in the bar graph display conversion table of FIG. 7 stored in the ROM 38 determined from " is recognized as " 2 ", and the segment data (a) for the third digit M is then recognized. ₂ ~ g ₂ ) also recognizes "2" by the same operation as above, and then outputs bar graph display data through the LCD driving circuit 42 to the bar for "22" through the terminals BG ₀ to BG ₂₀ . juneunde drives the graph, in the operation of the bar graph in this case 3. If the _{half digit} from the first digit (K) Up to the rated value for a digit 3 (M), so that "199" is able to drive the astute bar graph of the 40 levels on the basis of a multiple of five. That is, when the "22" is displayed as a bar graph, four bar graphs for "20" are driven, while the remaining "2" is less than 5, and thus not displayed. In this case, when the numerical data is 000 to 004, the bar graph display unit 34 drives one scale.

In this way, since the numeric data displayed on the LCD device 32 is processed as bar graph data by the one-chip microprocessor 33, the bar graph corresponding to the numeric data can be displayed without error.

In the bar graph display of the digital multimeter of the present invention wherein the embodiment is an LCD unit 32, unlike the embodiment 3. In addition, for example, to use a _{one-half digit} display example up rating of "3999" _{3.3 Even when / 4 digits} are used, the segment data for the upper two digits can be displayed in a bar graph, and the bar graph display operation for them is performed similarly to the above embodiment.

As described above, according to the present invention, the digitized segment data is processed into bar graph display data to display bar graph data corresponding to the numeric data, thereby achieving a visual effect, and a circuit element dedicated for the circuit configuration. There is an advantage that the price of the product is relatively low because it does not use.

Claims (1)

LCD to display the analog / digital (A / D) converter 31 which digitally processes the measurement input signal Din and converts it into segment data and the segment data applied by the analog / digital (A / D) converter 31. In the digital multimeter including the unit 32, the segment data output from the A / D converter 31 and the numerical segment data for a predetermined upper plural digit and the back according to the driving method of the LCD 32 Input means 35 into which plan data is input, memory means 37 and 38 stored in the backplane data and segment data to be input, bar graph display conversion data and programs, and the input means 35; Detects the active state of the backplane data applied via the < RTI ID = 0.0 >), < / RTI > and then segments the plurality of higher order digits in the segment data based on the backplane data in this active state. Control means 36 for determining the numeric data and converting the numeric segment data value into corresponding bar graph display data with reference to the bar graph display conversion data stored in the memory means 38; and the control means 36 The one-chip microprocessor (33) comprising a driver (42) for driving the bar graph display (34) integrally formed with the LCD (32) based on the bar graph display data converted by A bar graph display device of a digital multimeter, characterized in that the numerical data displayed in (32) is displayed in a corresponding bar graph.

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