JPS6131877B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bar graph display device using liquid crystal, and particularly to a bar graph display device suitable for displaying a plurality of bar graphs.

FIGS. 1a and 1b are diagrams of the electrode structure of the conventionally known block division type driving method, which is often used when displaying a bar graph using a liquid crystal.
In a display using a liquid crystal, when an electric field is applied to a liquid crystal layer 2 sandwiched between two upper and lower glass substrates 1 and 1A, the liquid crystal is excited and the arrangement of molecules changes.
Light transmission state (here, tentatively referred to as lighting state)
become. In a bar graph display, short segment electrodes are arranged in a bar shape, and the lighting amount of the segment is displayed in accordance with the input amount. Now, in the electrode structure of the block division type driving method shown in FIG. 1, transparent segment electrodes 3 are formed in a bar graph shape on one glass substrate 1, and are connected in a meandering manner so as not to intersect with each other. Pull out S ₁ , S ₂ , ...S ₄ . Further, on the other glass substrate 1A, the segment electrode 3 is divided into a plurality of blocks to form a block electrode 4, and block-side electrode terminals B ₁ , B ₂ , and B ₃ are drawn out from each electrode. . When driving a bar graph display with such a structure, on, off, and input signals are applied to the segment electrode side and the block electrode side, respectively, depending on the input amount.
One of ON, ACT, and OFF drive voltage signals is applied, and the lighting or non-lighting state of each segment is determined by the combination of these signals.

An example of a conventional drive circuit for this display is shown in FIG. In FIG. 2, 11 is an A/D conversion circuit;
12 is a drive voltage generation circuit, 13 is a selection circuit, 14
is the display device (display panel) shown in FIG.
The input signal V _IN is converted into an appropriate digital signal by the A/D conversion circuit 11 according to its input amount. Then, this digital signal is sent to the selection circuit 1.
3, the segment side and block side drive voltage waveforms 15 and 16 generated by the drive waveform generation circuit 12 are selected and the liquid crystal panel 14 is
The voltage is applied to the electrode terminal of , and a display is performed.

However, when displaying multiple bar graphs on the same glass substrate using exactly the same method,
The configuration is as shown in FIG. FIG. 3 shows an example of two bar graphs. Two input signals V _i
o . _A.Vio . For B, A/D converters 11 and 11A and selection circuits 13 and 13A are provided, respectively. The drive waveform generation circuit 12 includes two selection circuits 1
It is composed of one piece to send the drive waveform to 3 and 13A. Segment side drive voltages 15A, 1 are applied to the display panel 14A from the selection circuits 13, 13A.
5B, and generates block side drive voltages 16A and 16B. The display panel 14A has two bar graph display panels for independently displaying two bar graphs. These two bar graph display panels each have a configuration as shown in FIG. 1, and are completely independent of each other. Therefore, although the name is unified as display panel 14A, two display panels as shown in FIG. 1 are simply provided in parallel. Each segment electrode terminal S _A , S
_B and block electrode terminals B _A B _B are also on each display panel.

According to such a configuration, the number of electrode terminals increases on the liquid crystal display panel 14A side, reducing the reliability of the connection part, and increasing the space for meandering connection lines that are not related to bar graph display, resulting in an increase in the number of electrode terminals on the liquid crystal display panel 14A side. Invalid space increases. Furthermore, on the drive circuit side, the same number of A/D conversion circuits and selection circuits as the number of bar graphs are required, resulting in a disadvantage of complication and increased cost.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above drawbacks and provide a bar graph display device that can display a plurality of bar graphs with a simple configuration.

The gist of the present invention is that segment electrodes in a plurality of bar graphs are commonly connected to drive each bar graph in a time-division manner. Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 4 is a diagram showing an embodiment of the display panel.
This example is an example of a two bar graph display.
In the display panel of this embodiment, the segment electrodes of the two bar graphs A and B are connected in common, and the connections of each segment are connected so as not to intersect with each other.
Pull out the electrode terminals S ₁ , S ₂ , ...S ₄ . On the other hand, the block electrode has the same configuration as the case of one bar graph, and each electrode terminal is connected to the divided electrode.
Draw out B ₁₁ , B ₂₁ , B ₃₁ , and B ₁₂ , B ₂₂ , B ₃₂ .
By adopting such an electrode structure, the number of electrode lead-out terminals can be reduced, and the space occupied by the meandering connection line connecting each segment electrode is reduced, making it possible to increase the effective space of the glass substrate. . Next, a circuit for driving a liquid crystal bar graph display having the above-described electrode structure will be explained using the embodiment shown in FIG.

In FIG. 5, 14C is the display panel shown in FIG. 4, 21 is an input signal selection circuit, and 22
23 is an output signal selection circuit, and 23 is a clock generation circuit. Further, numerals 11, 12, and 13 are the same as those described in the conventional example, and are an A/D conversion circuit, a drive voltage generation circuit, and a selection circuit, respectively. The input signal operates the input signal selection circuit 21 according to the signal CL of the clock generation circuit 23, and selects two types of input signals V _{I
N. A.VIN} . Select one of B, A/D
It is applied to the conversion circuit 11. Here, V _IN . A represents bar graph A, V _IN . B is a signal that displays bar graph B. The digital output signal of the A/D conversion circuit 11 is converted into a segment side drive voltage signal and a block side drive voltage signal according to the input amount by a drive voltage generation circuit 12 and a selection circuit 13, just as in the conventional example. . On the other hand, output signal selection circuit 2
2 selects either the OFF signal for driving the block side or the drive voltage signal 16 for the block side according to the input amount obtained by the selection signal circuit 13, and the input signal V _IN . When A is selected, all block electrode terminals B ₁₂ , B ₂₂ ,
The driving voltage of the OFF signal is selected and applied to B ₃₂ , and the input signal V _IN . When B is selected, all block electrode terminals B ₁₁ ,
The drive voltage of the OFF signal is selected and applied to B ₂₁ and B ₃₁ . If you draw this operation timing chart, it will look like Figure 6. A section including periods T _A and T _B is one scanning section, and this one scanning section is divided into periods T _A and T _B. The period T _A is the display period of the bar graph A, and the period T _B is the display section (field) of the bar graph B. That is, 1
Divide one scan interval into two bar graph intervals,
This will be driven in a time-division manner. Therefore, during the period T _A , the input V _IN . A driving voltage corresponding to the amount of A is applied to the common segment electrode terminal S and the block electrode terminals B ₁₁ , B ₂₁ , B ₃₁ of the bar graph A. During this period, since the OFF signal is applied to block electrode terminals B ₁₂ , B ₂₂ , and B ₃₂ on the side of bar graph B, all segments of bar graph B are not lit regardless of the voltage applied to the segment electrodes. Become. That is, only bar graph A is displayed during the period T _A. Do the same thing for period T _B ,
Only bar graph B is displayed, and bar graph A is not lit. In this way, by repeating displaying and non-lighting of the bar graphs A and B alternately and appropriately setting one scanning period T _A +T _B , two bar graph displays can be obtained at the same time. Incidentally, FIGS. 7a and 7b show examples of drive voltage waveforms applied from the segment electrode terminals and the block electrode terminals. However, a>b>1. Here, Vo is selected to have a value slightly smaller than the threshold voltage V _th of the liquid crystal. Further, as the output signal selection circuit 22, for example, 22A and 22B controlled by a clock signal CL as shown in FIG.
It consists of a group of analog multiplexers consisting of: In this circuit, the block electrode terminal groups B ₁₁ , B ₂₁ , B ₃₁ and
This is a circuit for applying an OFF signal or a drive voltage signal to B ₁₂ , B ₂₂ , and B ₃₂ .

Therefore, according to one embodiment of the present invention, when displaying two bar graphs, the effective space of the liquid crystal display panel is increased, the number of electrode terminals can be reduced, and the configuration of the peripheral drive circuit can be simplified. This has the effect of reducing costs.

In the embodiment of the present invention, a case has been described in which two bar graphs are driven. However, even in the case of displaying a large number of bar graphs, the timing of the input signal selection circuit, output signal selection, and clock generation circuit and the number of selected channels can be controlled in the bar graph. This can be achieved by changing the number according to the number.

According to the present invention, even in the case of displaying a plurality of bar graphs, the peripheral drive circuit can be simplified, so that the cost can be reduced.

[Brief explanation of the drawing]

Figures 1a and b are electrode structure diagrams of a bar graph display using liquid crystal, Figure 2 is a circuit diagram for driving the bar graph display, and Figure 3 is a circuit diagram for displaying multiple bar graphs. Conventional circuit diagram, 4th
The figure is an electrode structure diagram in one embodiment of the present invention.
The figure is a configuration diagram of a drive circuit in an embodiment of the present invention.
FIG. 6 is a diagram showing the operation timing of the signals of the drive circuit, FIGS. 7a and 7b are diagrams of an embodiment of the drive voltage applied from the electrode terminals, and FIG. 8 is a diagram of the internal configuration of the output signal selection circuit. S ₁ ~ _{S 4} ... Common segment electrode terminal, B ₁₁ ,
B ₂₁ , B ₃₁ , B ₁₂ , B ₂₂ , B ₃₂ ... block electrode terminal, 11 ... A/D conversion circuit, 12 ... drive waveform generation circuit, 13 ... selection circuit, 14C ... liquid crystal panel, 21 ...Input signal selection circuit, 22...Output signal selection circuit, 23...Clock generation circuit.

Claims (1)

[Claims] 1 Consists of a block-side electrode for the liquid crystal divided into a plurality of blocks and a plurality of segment-side electrodes for the liquid crystal opposing this, and the segment electrodes are commonly connected between the plurality of bar graphs to be displayed. It also has an electrode structure in which one segment corresponding to each block is commonly connected to each other, and drive waveforms in three states are applied to the block electrode terminal drawn out from the block electrode of each bar graph. Drive waveforms in two states are applied to the segment electrode side terminals drawn out from the segment electrodes commonly connected between each bar graph to display a bar graph on the liquid crystal panel, and when applying the drive waveform, one scan A bar graph display device that performs time division driving in which the period is divided into the number of fields corresponding to the number of first half bar graphs.