JPS584963B2 - display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a display device that uses a plasma display to display the magnitude of an analog input signal in the form of a bar graph.

The plasma display used in this type of display device uses an anode and a cathode sealed in a discharge gas, and when a voltage is applied between the two electrodes, a discharge is generated between the two electrodes and the cathode lights up. A large number of cathodes are arranged on the back sheet surface of the display device at positions corresponding to the display scale, facing each other to the anode of a transparent conductive film formed on the inner surface of the windshield of the display device, and a pulse with a time width proportional to the analog signal level is applied to the anode. The analog input signal The size of the image is displayed in a bar graph.

FIG. 3 is a block diagram of a conventional display device equipped with such a plasma display (Electronics, 1
(See March 7, 1974 issue, pages 89-93).

By comparing the analog input signal E and the reference lamp voltage from the lamp voltage generator RA using the comparator COM, a voltage pulse with a time width proportional to the magnitude of the input signal E is obtained, and the anode driver DA is activated for this period. The anode voltage of the plasma display DP is increased through the DP.

On the other hand, the converter F which receives the clock from the clock generator CLK obtains an N-phase clock signal according to the number of cathodes of the plasma display DP, and drives the cathodes in a time-divisional manner by passing this signal through the cathode driver DK. do.

This allows the magnitude of the analog input signal to be displayed in the form of a bar graph.

Note that the counter C triggers the switch circuit SW at predetermined time intervals by counting clocks by the number of cathodes, and the switch circuit SW uses the pulse output to trigger the lamp voltage generator R.
A is driven at predetermined time intervals.

This type of plasma display has the characteristic of an analog display that allows the approximate value of the input amount to be recognized intuitively, just like a normal pointer-type meter, and the characteristic of a digital display that can increase the accuracy of indication by increasing the number of cathodes. It is something that has.

However, if the pitch of the cathodes is made narrower in order to increase the accuracy of indication, it becomes difficult to read, and if the display size is made longer with the same pitch, the display becomes larger, and high accuracy (for example, 0.1%) indication by a plasma display becomes difficult. was difficult.

Therefore, it is conceivable to convert the analog input signal into a digital value, display this digital value on a numeric display, and arrange this numeric display in parallel with the plasma display.

FIG. 2 shows an example of a prototype display device constructed based on this idea.

In this display device, an analog input signal E is applied to an analog-to-digital converter AD and converted into a digital value.

The output terminal Dout of this analog-digital converter AD
The digital value obtained from is stored in register R.

For this timing, a conversion end signal from the terminal Busy of the analog-to-digital converter AD is used.

The contents of register R are stored in decoder DG1. DG2. DG3.
DG4, and the output signal of this decoder is applied to numeric display units LDI, LD2 . LD3. Given to LD4.

The decoder and the number display constitute a number display.

On the other hand, the analog input signal E is also supplied to the comparator COM as in FIG. 1, compared with the reference lamp voltage from the rung voltage generator RA, and is applied to the plasma display DP via the anode driver DA.

By doing so, the display device shown in FIG. 2 can display bar graphs and numbers.

However, in this display device, the circuit configuration for displaying bar graphs and the circuit configuration for displaying numbers are provided completely independently, so the overall circuit configuration of the display device becomes complex and the number of parts increases. This is not preferable in terms of production since it requires a large number of steps.

The present invention has been made in view of these points, and an object of the present invention is to provide a display device whose overall circuit configuration can be simplified and the number of parts can be reduced.

As a result of repeated various research and experiments in order to further develop the prototype example shown in Fig. 4, the inventors of the present invention gave the digital value obtained by the analog-to-digital converter as the program value of the program counter, and this program It has been found that the intended purpose can be achieved by converting the digital value into a pulse signal with a time width corresponding to the digital value using a counter and supplying the pulse signal to the anode of the plasma display via an anode driver.

In other words, by doing this, it is possible to partially share the circuit configuration for displaying numbers and the circuit configuration for displaying bar graphs, and as a result, as will be described later, the circuit configuration for displaying numbers and bar graphs can be partially shared. It is possible to eliminate the need for a lamp voltage generator, a switch circuit for driving the lamp voltage generator, and a comparator for comparing the input signal with the reference lamp voltage, which were necessary for the above-mentioned operation.

Next, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

The analog input signal E is applied to an analog-to-digital converter AD for conversion into a digital value.

The digital value obtained from the output terminal Dout of the analog-to-digital converter AD is stored in a register R.

This timing uses the conversion end signal from the terminal Busy of the analog-to-digital converter AD.

Note that the register R is provided as a latch circuit in an ordinary analog-to-digital converter.

The program counter P uses the contents of the register R as a program value, and obtains a pulse having a time width proportional to the program value by counting clocks.

Reset counter CR is analog-to-digital converter A
The conversion end signal of D is made into a synchronous input, and the predetermined number of clocks (
Each time the number of cathodes of the plasma display device DP (N) is counted, the program counter P is caused to start counting operation.

The anode driver DA amplifies the voltage of the pulse signal from the program counter P and applies it to the anode of the plasma display.

Frequency divider T divides the clock pulses of clock generator CLK.

The selection switch SW1 supplies a clock selected from a plurality of divided outputs from the frequency divider T or a clock from the clock generator CLK to the reset counter CR and the converter F as the clock.

The converter F converts the clock into an N-phase clock according to the number N of cathodes of the plasma display DP, and sequentially applies voltages necessary for lighting the cathodes to the cathode group through the cathode driver DK.

The number display bodies LD, to LD4 display a total of four digits, and are arranged near the plasma display DP as illustrated in FIG. 2.

Decoders DG and ~DG are number display units LD and ~LD, respectively.
4 constitutes a numeric display, and the contents of the register R are decoded digit by digit to obtain signals necessary for driving the numeric displays LD, -LD4.

For example, if the number displays LD1 to LD4 are segment type light emitting diode displays, the segments and decimal point display dots necessary for displaying numbers according to the contents of the register R are driven.

With the above configuration, the analog input signal E is converted into a digital value by the analog-to-digital converter AD, and is stored in the register R upon completion of the conversion.

The contents of register R are digitally displayed on numerical displays LD, -LD4 through decoders DG1-DG4.

Further, the contents of the register R become the program value of the program counter P, which converts it into a pulse signal with a corresponding time width, and drives the anode of the plasma display DP through the anode driver DA.

On the other hand, the clock pulse 1/n clock of the program counter P passed through the frequency divider T is supplied to the converter F.
The cathodes of the plasma display device DP are sequentially driven by the N-phase clock from .

As a result, the plasma display DP displays a bar graph proportional to the magnitude of the analog input signal.

Here, if the clock of the converter F is 1/n of the time width of the pulse applied to the anode of the plasma display DP, then the number of cathodes lit on the plasma display DP will be relative to the digital display value. It becomes 1/n.

Therefore, the clock pulse given to converter F is changed to switch S.
If W1 is selected, the displayed value on the plasma display can be arbitrarily changed relative to the digital displayed value.

According to the invention, a digital display using a numeric display;
The analog display can be displayed simultaneously on the plasma display, and the lower digits of the analog display on the plasma display can be read on the digital display.

Moreover, the structure can be made simply by adding a numeric display to a display device using a conventional plasma display.

Then, a display device DP with the number display body as a plasma display body
If it is configured integrally with the decoder, the only circuit to be added is the decoder.

In addition, since the scale factor of the digital display and analog display can be changed arbitrarily, it is possible to display the entire input signal in analog on a plasma display, and also to display digitally the lower digits that cannot be read accurately with analog display. .

Further, according to the present invention, the contents of the register R provided for displaying numbers are given as the program value of the program counter P, and the program counter P counts the clocks generated from the clock generator CLK. Since a pulse with a time width proportional to the program is obtained and this pulse is supplied to the plasma display DP that displays the bar graph, there is no need for a lamp voltage generator and a switch circuit to drive it. can do.

As a result, the overall circuit of the display device can be simplified and the number of parts can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a display device according to the present invention, FIG. 2 is a block diagram showing an embodiment of the display section in the present invention, and FIG. 3 is a block diagram of a conventional display device of this type. , FIG. 4 is a block diagram of a prototype example in which a circuit for displaying numbers is incorporated into the display device shown in FIG. 3. AD: Analog-to-digital converter, R: Register, P Niprogram counter, CR: Reset counter, DG
, ~DG4: Decoder, LD, ~LD4: Number display body,
CLK: clock generator, T: frequency divider, SW: switch, F: converter, DP: plasma display, DA near node driver, DK: cathode driver.

Claims (1)

[Claims] 1. A large number of cathodes are arranged at positions corresponding to the display scale, and a pulse voltage with a time width proportional to the analog input signal is applied to the anode. A plasma display device that can display the magnitude of an analog input signal in a bar graph by sequentially applying a voltage for lighting up to the cathode, an analog-to-digital converter that converts the analog input signal into a digital value, and the plasma display device described above. a numeric display disposed near the plasma display device and displaying the digital value numerically; a program counter that uses the digital value as a program value and obtains a pulse voltage signal to be applied to the anode of the plasma display device by counting a clock;
A display device comprising: a converter that receives a clock synchronized with the count of the program counter and obtains a multiphase signal to be applied to the cathode of the plasma display device. 2. The display device according to claim 1, further comprising a frequency divider that divides the clock applied to the converter with respect to the clock applied to the program counter.