JPS6247245B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bar graph display using liquid crystal, and more particularly to a method for driving a display that displays signal levels of industrial measuring instruments, audio equipment, etc. in bar graphs.

In a bar graph display using a liquid crystal and using a series of short rectangular segments, it is possible to reduce the number of electrode lead terminals and simplify the peripheral drive circuit when increasing the number of display segments of the bar graph to improve its resolution. As shown in FIG. 1, a so-called block division type driving method is often used in which the entire segment 3 to be displayed is divided into a plurality of blocks 2 and driven.
Segment electrode 3 in block division type driving method
The connection pattern between the electrodes of the block electrodes 4 is as shown in FIG. 2 in order to eliminate the complexity of external connections and to prevent the electrode lead wires from intersecting each other. The lighting and non-lighting indications are displayed on the third screen.
As shown in the figure, the signals applied to the liquid crystal layer are applied to the liquid crystal layer by the combination of the three-state signals "on", "active", and "off" applied to the block electrodes and the two-state signals "on" and "off" applied to the segment electrodes. The voltage applied to the light is changed to indicate whether the light is on or off.

In a bar graph display with such a configuration, if the number of block electrodes is m blocks and the number of segments per block is n segments, "on" state signals are applied to the segment electrodes in sequence according to the input signal level. In addition to switching S ₁ → Sn and Sn → S ₁ , it is necessary to sequentially switch the state of the signal applied to each block electrode from "off" → active → "on".Input signal level and segment FIG. 4 shows the relationship between the signal states applied to the electrodes and the block electrodes.

An example of a drive circuit for applying voltage to the block and segment electrodes of a conventional bar graph display is shown in the fifth section.
As shown in the figure. In FIG. 5, an analog input signal amount V _IN is converted into a digital signal by an A/D converter 10, and the digital output signal is statically converted by a logic conversion circuit 11' on the segment side and a logic conversion circuit 11 on the block side. According to the input signal amount _VIN , the segment side converts it into a 2-state signal and the block side converts it into a 3-state signal, and multiplexers 12 and 12' select the signal.
It is applied to each block and segment electrode. This method has the disadvantage that when the number of display segments increases, the logic conversion circuits 11 and 11', which determine the state of the voltage applied to each electrode, become considerably complex.

The feature of the present invention is that it consists of 1st to mth block electrodes of a block divided into m pieces, and an opposing segment electrode having n segments in each block. Each block includes a bar graph display section commonly connected to segments of other blocks, and a drive circuit that drives the display section by a combination of a two-state signal applied to the segment electrode and a three-state signal applied to the block electrode. In a bar graph display having
The drive circuit includes a pulse generation circuit that outputs a number of pulses corresponding to the input amount to be displayed, and a pulse signal that outputs a pulse signal corresponding to a value obtained by dividing the output of the pulse generation circuit by the number n of segments included in each block. a counting circuit that applies pulses to the segment electrodes according to the outputs of the pulse generating circuit and the counting circuit;
a segment electrode side drive circuit that selects one of the state signals; a shift register with m outputs that selects the state of the block electrode according to the output of the counting circuit; and (m-1) of the shift register. m by the combination of the th output and the m th output
and a multiplexer for selecting one of the three-state signals to be applied to the block electrode.

An embodiment of the present invention is shown in FIGS. 6, 7 and 8.
This will be explained using figures. Here, it is assumed that the total number of segments to be displayed is 100, the blocks are divided into 10, the number of segments in one block is 10, and the input level is 32 relative to the full scale of 100. FIG. 6 shows the connection state of the segment electrodes and block electrodes and the display state of the bar graph for 32 input amounts. In this embodiment, the "on" signal is applied to segment electrode terminals S ₉ and S ₁₀ , and the other S ₁ to
S ₈ has an “off” signal and also block electrode terminal B ₁
A predetermined display can be obtained by applying an "on" signal to _B3 , an "active" signal to _B4 , and an "off" signal to the other _B5 to _B10 . FIG. 7 shows an embodiment of the drive circuit according to the present invention, and FIG. 8 shows its timing chart.

In FIG. 7, 21 is a pulse generation circuit that outputs the number of pulses according to the amount of the input voltage signal V _IN ;
22 is a counting circuit 25 which generates a pulse signal every time the same number of pulses as the number of 10 segments in one block is input; 30 is a driving circuit on the segment electrode side;
is the drive circuit on the block electrode side. 23 is a shift register operated by the output of the counting circuit, and 24 is a multiplexer which selects three states of "on", "active" and "off" to be applied to the block electrodes using a signal from the shift register 23.
23 and 24 constitute a drive circuit 30 on the block electrode side. 25 has almost the same configuration. In this embodiment, the outputs B ₁ ′ to _{B 10} ′ of the shift registers are shifted to “1” by the output pulse CPB of the counting circuit 22, and the output signal of the multiplexer is shifted when the inputs (x, y) are (0, 0 ) is "off", (0, 1) is "active", and (1, 1) is "on".

First, the parallel output signals B ₁ ', B ₂ ', . . . of the shift register 23 are activated by the main reset signal MR.
Set all B ₁₀ ' to "0". 21 comprises, for example, a voltage-frequency converter 27, a gate signal generating circuit 28 with a constant pulse width capable of displaying all segments, and an AND element 29. The only number of pulses due to the input voltage that pass during the gate time interval of the 28 outputs becomes the 21 outputs. Therefore, as the input voltage V _IN increases or decreases, the number of clock pulses CP applied to the counting circuit 22 and the segment electrode side drive circuit 25 increases or decreases. The segment electrode side drive circuit 25 includes a clock pulse CP and a counting circuit 2.
This circuit is operated by the output CPB of 2, and turns segment electrodes S ₁ to S ₁₀ “on” or “off” according to the number of clock pulses CP, that is, the input signal amount V _IN .
This is a circuit that generates a status signal. Output waveforms of each part in 21, CP and counting circuit 22 output waveforms
The CPB will be as shown in Figure 8. The output pulse CPB of the counting circuit 22, that is, the pulse generated every time the output CP of the pulse generating circuit 21 applies 10 pulses, causes the outputs B ₁ ′ to B ₁₀ ′ of the shift register 23 to sequentially become an output signal of “1”. Become. multiplexer 24
The input signal of 24a is (0, 1) when the clock pulse number CP is up to 9 pulses, and (0, 1) for all others.
0), a signal is applied to the block electrode _B1 that is "active" and all others are in the "off" state. When the clock pulse CP becomes 10 pulses, the output _B1 of the shift register 23 becomes "1" and all others are "0", so in 24a, (1,
1), 24b becomes (0, 1), and the others become (0, 0), so B ₁ changes from "active" to "on", B ₂ changes from "off" to "active", and the others become " becomes "off" state. Similarly, the signal that the clock pulse CP applies to the block electrode every 10 pulses changes sequentially from "off" to "active" to "on" and is held at the final state of the output pulse CPB from the counting circuit 22. If the output waveforms of each part in this embodiment are plotted in chronological order, they become as shown in Fig. 8. At the end of the 32 pulses of the input level, the block electrodes B ₁ -
An "on" signal is applied to _B3 , an "active" signal is applied to _B4 , and an "off" signal is applied to _E5 to _B10 .

Therefore, in combination with the signals applied to the segment electrodes described above, 32 segments out of 100 segments are lit up, and the others are not lit up, resulting in a predetermined display.

In fact, it is clear that flicker-free display can be obtained by making the signal processing time shorter and holding the signal longer.

In the above embodiment, the number of segments per block is 10 and the number of blocks is 10, but in general, the number of segments per block is 10, but in general, the number of segments per block is n and m, respectively.
If 2 is a 1/n counter and the shift register 23 is an m-bit output, it can be easily expanded.

FIG. 9 is a diagram showing another modification of the voltage-to-pulse number conversion circuit section in the embodiment of the present invention. Even if the logical product of the output of the circuit 31 that generates a pulse width corresponding to the input voltage and the output of the constant frequency reference clock pulse generation circuit 32 is calculated by the logic element 29 and used as input to the counting circuit, the above-mentioned embodiment will not work. You can get exactly the same effect.

According to the present invention, the circuit configuration of the block electrode drive section can be simplified. Another advantage is that even if the number of block electrodes and the number of segment electrodes change depending on the display scale, they can be easily changed.

[Brief explanation of the drawing]

Figure 1 shows the structure of the liquid crystal bar graph display, and Figure 2 shows the structure of the liquid crystal bar graph display.
The figure shows the connection diagram of block and segment electrodes,
Fig. 3 is a voltage state diagram applied to the segment and block electrodes with respect to the input level, Fig. 4 is a diagram showing conventional electrode selection in the block division drive method, Fig. 5 is a conventional drive circuit configuration diagram, and Fig. 6 teeth,
The bar graph display and electrode connection diagram in the embodiment of the present invention, FIG. 7 is an embodiment diagram of the drive circuit of the present invention, FIG. 8 is a timing chart of each part signal, and FIG. 9 is a diagram of the drive circuit of the present invention. It is a figure which shows the modification of a part. 2...Block electrode, 3...Segment electrode, 21
...Voltage-pulse number conversion circuit, 22...Counting circuit, 2
3...Shift register, 24...Multiplexer, 3
0...Block side electrode drive circuit, 25...Segment side electrode drive circuit.

Claims (1)

[Scope of Claims] Consisting of 1st to mth block electrodes of a block divided into 1m pieces, and opposing segment electrodes having n segments in each block, each of the segment electrodes has n segments. a bar graph display section commonly connected to segments of other blocks;
In the bar graph display device, the bar graph display includes a drive circuit that drives a display section by a combination of a two-state signal applied to the segment electrode and a three-state signal applied to the block electrode, and the drive circuit is configured to control the input amount to be displayed. a pulse generating circuit that outputs a corresponding number of pulses; a counting circuit that outputs a pulse signal corresponding to a value obtained by dividing the output of the pulse generating circuit by the number n of segments included in each block; a segment electrode side drive circuit that selects one of the two-state signals to be applied to the segment electrodes according to the output of the counting circuit; and m outputs that select the state of the block electrode according to the output of the counting circuit. a shift register; and a multiplexer for selecting one of the three-state signals to be applied to the m-th block electrode by a combination of the (m-1)th output and the m-th output of the shift register. A bar graph display device comprising: 2. In claim 1, the multiplexer selects the "on" signal when both the (m-1)th and mth outputs of the shift register have a first truth value. , if the (m-1)th output of the shift register is the first truth value and the mth output of the shift register is the second truth value, select the signal in the "active" state, and select the signal in the "active"state; A bar graph display, characterized in that it is a multiplexer that selects an "off" state signal when the (m-1)th and mth outputs of the register are both a second truth value. 3. In claim 1 or 2, the multiplexer applies the voltage to the first block electrode by a combination of the first truth value and the first output of the shift register. A bar graph display, characterized in that it is a multiplexer that selects one of the status signals.