JPH0239794B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a liquid crystal display section that is dynamically driven by n-digits with a duty ratio of 1/n (n is an integer of 2 or more) and is composed of a group of segments arranged in a matrix (lattice). The present invention relates to a liquid crystal display device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device in which a leak defect occurs between segments due to an error in the manufacturing process in a matrix-structured liquid crystal display panel, in which the defective panel can be easily removed.

Liquid crystal display devices have recently been used in devices such as watches and calculators due to their characteristics of low power consumption, low driving voltage, and miniaturization. Furthermore, as these devices become more multifunctional, liquid crystal display panels capable of displaying a variety of information are required. Therefore, multiplex driving has become the mainstream driving method for liquid crystal display devices. Furthermore, dot matrix display panels have come into use in the direction of multifunctionality. This is a display device that performs display using pixels formed by intersections of a plurality of mutually parallel scanning electrodes and a plurality of mutually parallel signal electrodes. Using this matrix-structured liquid crystal display device, pictures, numbers, characters, etc. can be displayed by combining pixels (segments), and the display panel can provide a much wider variety of information than conventional liquid crystal display devices with a 7-segment structure. can.

Defects that are likely to occur during the production of such matrix panels include leakage between adjacent segments or disconnection of segment electrodes. In a conventional liquid crystal display device having a seven-segment configuration, for example, in the case of a digital electronic wristwatch, a method is used in which disconnection of segment electrodes is detected by lighting up all segments. As for leaks between segments, since the number of segments is small (compared to the matrix configuration) and the gaps between segments have a certain width, leak defects are difficult to occur and easy to detect. It was hot.

However, the matrix. Even if the above-mentioned all-segment lighting test is performed on the panel, erroneous lighting of segments due to leakage defects caused by the proximity of the segments cannot be detected.

In the present invention, in order to easily discover leakage defects in liquid crystal segments, in the test pattern generation mode of the liquid crystal display circuit, one segment of adjacent segments is turned on, and the other adjacent segment is turned off. To provide a method of generating a liquid crystal driving signal to inform the user of the presence or absence of a leak defect just by looking at a liquid crystal panel.

An embodiment of the present invention will be described below.

2 is an example of the circuit configuration of the liquid crystal driving device according to the present invention shown in FIG. 1. FIG. 101 is a liquid crystal matrix display section. A common electrode group 101C is arranged in the column direction as the panel upper electrode, and a segment electrode group 101S is arranged in the row direction as the lower electrode. common electrode,
Dot segments 1A-1E are provided as the intersections of the segment electrodes. Leak between segments is 1A in the column direction of 1C, 1E, 1B,
This is about a leak with a total of 4 segments in the row direction of 1D.

Note that the matrix in this example. The number of driving digits of the panel is 7, and it is driven at a 1/7 duty ratio.

108 is a 1/3 frequency division counter, 1024Hz
Divide the signal to generate a 341.3Hz signal. 107
is a 1/7 frequency division counter, and the counter logic counts in binary numbers. Configure 107 counters
The 3-bit Q output (Q ₁ to _{Q 3} ) is input to the decoder 106 and counted by the decoder 107, 341.3÷7=48.8Hz.
is decoded into 7 states.

Corresponding to the 7bit signal output by 106, 10
The common signal drive circuits CD1 to CD7 of No. 2 are driven. Details are shown in CD1. CD1 has 107
When (Q ₁ , Q ₂ , Q ₃ ) = (0, 0, 0), a signal that becomes “1” is input, and the 48.8/
2 = Depending on the state of the 24.4Hz signal, the analog switches 103 and 104 are turned on and off with inversion and non-inversion.
control. Analog switches 103 and 104 select the level of either V _CH or V _CL . V _CH V _CL is formed by 102 level forming circuits. In 102, 4 of V _DD , V _SS1 , V _SS2 , V _SS3
V CH , V CL (for common signal), V SH , and V _CH , V _CL (for common signal), V _SH ,
Forms V _SL (for segment signals). Figure 2 shows a timing chart of common signals.

The segment signal drive circuit 109 operates on the same principle as the common signal drive circuit 102. SD1～
The analog switch in SD5 is controlled by the drawing pattern generation circuits 114 to 117.
In charge of 5-bit output. In this embodiment, the drawing pattern generation circuit is composed of a ROM. This is done by a signal line specifying the address of the drawing pattern. 118
The signal is generated from, for example, an electronic clock circuit, a calculator circuit, etc. 114 and 116 are ROMs and their addresses for storing drawing patterns for normal display, respectively. It is a decoder, 115, 11
7 are a ROM for storing test patterns and its address decoder, respectively.

When a certain drawing pattern is designated by 118, the pattern is read out from the ROM seven times in 5-bit parallel fashion in synchronization with 341.3Hz.

In the normal display state, for example, the alphabet "A" is displayed as shown in FIG. The output from the segment drive circuit 109 at this time is as shown in FIG. 2 for SD1. At this time 7
For this common signal, each segment on the SD1 segment signal line corresponds to CD1 to CD7,
(OFF, OFF, ON, ON, ON, ON, ON).

When a test pattern is designated by 118, the test pattern is generated from ROM 115.

FIG. 4 is the first example. Since adjacent columns are arranged so that they are not lit or unlit, leakage between segments in the row direction can be inspected. Regarding FIG. 1 101, 1
You can check for leaks in A, 1B, and 1D. Note that a and b in FIG. 4 are inverted patterns of each other, and if a and b are displayed alternately in the test pattern state, a more detailed leakage test can be performed.

FIG. 5 is a second example of a test pattern.
In this pattern, it is a matrix. It is possible to check for leaks between the column-wise segments of the panel.
Regarding Fig. 1 101, 1A, 1C, 1E
You can check for leaks.

Similar to the example of FIG. 4, FIGS. 5a and 5b are inverted patterns of each other.

Figure 6 is a test. This is a third example of a pattern.
The pattern is a check pattern and a matrix. You can check for leaks between segments in both the rows and columns of the panel. Regarding FIG. 1 101, it is possible to check for leaks from 1A, 1B, 1C, 1D, and 1E.

FIGS. 6a and 6b also have patterns that are inverted from each other.

In this way, adjacent segments in rows or columns can be drawn in a drawing pattern in which lighting and non-lighting do not occur consecutively, or in a drawing pattern obtained by overlapping these drawing patterns (Fig. 6 can be said to be an example). By turning on the light, you can easily identify leak defects in the panel.

For example, in the case of an electronic watch, such a drawing pattern can be displayed by turning on all external switches or by a specific combination of switch inputs, making it easy to inspect the finished product and reducing inspection costs. will be promoted. The same applies to calculators or other devices using liquid crystal matrices.

In this embodiment, the liquid crystal matrix driving method is set to 1/7 duty, but it goes without saying that the present invention is also applicable to other multiplex driving methods.

[Brief explanation of drawings]

Fig. 1...Example of liquid crystal display device circuit according to the present invention, Fig. 2...Timing of common signal and segment signal in the circuit of Fig. 1, chart, Fig. 3...Example of normal drawing pattern, Fig. 4 a, b...Test・Pattern example (1), Figure 5 a, b...Test pattern example (2),
Figure 6 a, b...Test pattern example (3).

Claims (1)

[Claims] 1. A liquid crystal display section with a matrix structure that is dynamically driven with at least n digits (n is an integer of 2 or more), a liquid crystal display drive circuit that drives the liquid crystal display section, and pictures, animations, and numbers displayed on the liquid crystal display section. , a drawing pattern generation circuit that generates a drawing pattern for characters, etc., and a test pattern for checking whether each segment of the liquid crystal display section is good or bad; A liquid crystal display device characterized by consisting of patterns that are alternately continuous in the vertical, horizontal, or diagonal directions.