JPH0242481A - Driving method of liquid crystal display device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a liquid crystal display device, and specifically,
The present invention relates to a method of driving a liquid crystal display device having two or more liquid crystal display bodies and in which the display bodies display the same display content.

[Prior art]

A conventional liquid crystal display device having two or more liquid crystal display bodies driven by the same drive circuit, for example, a liquid crystal display device for a data imprinting device of a camera (this device has two liquid crystal display bodies and one is a negative type display used for data imprinting, and the other display is a normal positive type display for displaying the imprinted data on a monitor outside the camera). It is used. This is because a display with a contrast ratio for imprinting splash data is required.

In other words, a data imprinting device displays data in a negative white form on a liquid crystal display for imprinting, and imprints the data onto a photosensitive film by transmitting light from an imprinting light source.
If even a small amount of light passes through any part other than the data display area, that part will be exposed to light. Therefore, this display requires a large contrast ratio and sufficient opacity in the non-display area, but when using the multiplex drive method, voltage is applied to the liquid crystal in the non-display area, which was 0 V in the static drive method. Therefore, depending on fluctuations in the power supply voltage and environmental temperature, the voltage may exceed the threshold voltage of the liquid crystal, and the transmittance may increase. In addition to the liquid crystal display for data imprinting, this liquid crystal display device includes
There is another display that displays the imprint data on a monitor outside the camera, and the display device has two liquid crystal displays, but in order to reduce the number of drive circuits required for driving them, a separate display is used for each display. Instead of having a drive circuit, the image display body is driven in parallel by - number of drive circuits.

By the way, there is a demand for monitor display to display not only the imprint data but also a lot of information such as the sensitivity of the photosensitive film, a mark for checking imprinting, and even the number of film frames. However, if these were to be driven using the same static driving method as the imprint display, the number of connection terminals to the circuit would increase significantly, placing a heavy burden on the circuit, wiring, etc. In order to reduce the number of terminals, a multiplex driving method may be used to improve the display performance of the monitor display, but as described above, parallel driving reduces the contrast ratio of the imprinted display. There is also a method of using a static drive method for the imprint display and a multiplex drive method for the monitor display and using separate routes, but this would complicate the circuitry.

〔the purpose〕

The present invention provides a liquid crystal display device having a plurality of display bodies, while ensuring a sufficient contrast ratio of one of the display bodies.
An object of the present invention is to provide a method for driving a liquid crystal display device that can display a large amount of information by minimizing the number of connection terminals.

〔overview〕

A feature of the present invention is that a separate common drive signal is applied to each display body.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the present invention, which is an example of application to a liquid crystal display device having two display bodies.

The first liquid crystal display 1 includes a number display section 6 having a 7-segment configuration.
and symbols ("A" and "B" in the figure) display section 7, and the second liquid crystal display 11 has a display section 16 that displays the same content as the number display section 6 of the first display.

The first liquid crystal display 1 has an upper panel glass 3 having segment electrodes 2 and a lower panel glass 5 having a common electrode 4, and is enclosed by upper and lower polarizing plates and upper and lower panel glass, although not shown. It consists of a sandwiched liquid crystal. Similarly to the first liquid crystal display 1, the second liquid crystal display 11 has segment electrodes 12. Common electrode 14. The upper and lower panels consist of glass 13.15, polarizing plates, and liquid crystal. 20 is a drive circuit, and its segment drive signals 21 are connected in parallel to segment electrodes 2.12 of the first and second display bodies, respectively. That is, the segment drive signal 21a is connected to the segment electrodes 2a and 12a, which are the same display unit. Further, a segment drive signal 23 for driving the display 7 is applied to the segment electrode 2h.

On the other hand, a common drive signal 22a is applied to the common electrode 14 of the second display body, and common drive signals 22b and 22c are applied to the common electrodes 4a and 4b of the first display body. A signal waveform diagram of the segment drive signals 21, 23 and the common drive signal 22 is shown in FIG.

The common drive signal 22a is a signal with a voltage V and a period T.
The voltage switches from O to V every cycle. Common drive signal 22
b is a signal with voltages V and 'Av and a period T, and the voltage changes from 0 to 'A V -V -'A V → 0 every χ period.The common drive signal 22c has the same waveform as the signal 22b. However, the phase is shifted by A period. Also, as shown in the figure, the phase relationship between the common drive signals 22a and 22b is as follows: when the signal 22b switches from 〃■ to V and when the signal 22a switches from 0 to V. It becomes a matching relationship.

The segment drive signal 21 for displaying displays 6 and 16 has the same signal waveform as the common drive signal 22a, and has the opposite phase to the signal 22a when in the display state (ON), and when in the non-display state (OFF). are in phase. This is as described for the display 16, but at the same time on the display 6 side, because the phase relationship of the drive signal is as described above, it turns ON and OFF at the same time (the voltage applied to the liquid crystal becomes above and below the threshold). .

On the other hand, the stop segment drive signal 23 representing the display 7 is
Display “A”, “B” 0N-ON or 0N-OFF, 0F
Depending on the combination of F-ON and 0FF-OFF, the phase is shifted as shown in the figure.

〔effect〕

According to the above configuration of the present invention, if the display body 11 is used for data imprinting, for example, while being driven in parallel by the same drive circuit, a sufficient contrast ratio can be obtained since the display body 11 is a static drive method. If 1 is used for a monitor, a multiplex driving method is used, so a large number of displays can be performed with a small number of terminals. In this example, the common drive signal 22b having a binary voltage is applied to the common electrode 4a of the display body 1.
However, it is also possible to display by applying the common drive signal 22a of the display 11, but in that case, since it is different from the common drive signal of the display 7, not only does the number of terminals increase by one, but the drive voltage, temperature , differences in brightness and darkness occur in the display depending on the viewing angle.

A microcomputer-type IC with a liquid crystal drive circuit is often used as a drive circuit, but most of the liquid crystal drive circuits of general-purpose microcomputer-type ICs on the market use the multiplex drive method, and static drive methods are rare. It is difficult to obtain, its specifications are limited, and it cannot be used in liquid crystal display devices that require a partial static drive method. However, with the present invention, one of the segment drive terminals of the drive circuit can be used as the common drive terminal of the static drive method. Very effective.

Further, the present invention can be applied to a device having three or more display bodies.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the present invention. FIG. 2 is a waveform diagram of a drive signal of the liquid crystal display device of the example shown in FIG. 1......First liquid crystal display 1
1......Second liquid crystal display 2.12
...Segment electrode 4.14...Common electrode 20...River...Drive circuit 21.23...Segment drive signal 22...Old・Common W a 42 issue note
1 1'l or more -1 ~ -1 ~ -1 no

Claims (1)

[Claims] In a liquid crystal display device having first and second liquid crystal display bodies and a driving circuit thereof, a segment electrode is arranged on one substrate of the first liquid crystal display body, and a common electrode is arranged on the other substrate. In addition to the segment electrodes of the first liquid crystal display, other segment electrodes for other information are arranged on one substrate of the second liquid crystal display, and a plurality of common electrodes are arranged on the other substrate. The same segment drive signal is applied between the display bodies to each of the same segment electrodes of each liquid crystal display body, and the segment drive signal is applied to the common electrode of the first liquid crystal display body. Driving a liquid crystal display device, characterized in that a common drive signal for static driving is supplied in cooperation with a common drive signal, and a common drive signal for multiplex drive is applied to a plurality of common electrodes of the second liquid crystal display. Method.