JPS5935029B2 - LCD drive circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for performing liquid crystal display by converting dynamically held information into static information suitable for driving a liquid crystal.

The present invention provides a configuration method that is smaller in size and consumes less power, and also enables a low-cost and highly reliable system.

Liquid crystal displays have characteristics such as low power consumption and the ability to display characters of any size, and are therefore used for displays on calculators, watches, and the like.

Static driving is the ideal driving method for liquid crystal display bodies, and for this reason, methods have been considered to convert dynamically held information into static information. FIG. 1 shows a conventional circuit for converting dynamically held information into static information. The shift register 1 stores display information in a circular loop. The display segment conversion circuit 2 converts the display information sent from the shift register 1 into segment signals, and sends the segment signals to the display shift register 4 as serial signals. The segment 6 of the liquid crystal display is one bit of the display shift register 4 and the holding circuit 5.
It is driven by one of the following. The display signal from the display segment conversion circuit 2 is written into the display shift register 4 after passing through the EX-OR gate 3. This is due to the necessity of driving the liquid crystal with alternating current. Writing is performed at the beginning of every half cycle of the AC voltage COM. The clock pulse CL for writing is the same as the number of bits of all display registers, and the serial information conforming to the clock pulse CL is stored at a predetermined position in the display shift register 4 when the clock pulse CL stops and is stored in the holding circuit 5. is held by the display segment 6 and drives the display segment 6. In this method, the display signal must be written to the display shift register using clock pulses at a relatively high frequency in order to drive the display body every half cycle of the AC voltage, so the consumption of the display shift register is reduced. It has the disadvantage that it consumes a lot of electricity.

The present invention solves this drawback.

This is intended to reduce power consumption by using a holding circuit instead of a display shift register to provide a similar function. FIG. 2 shows a liquid crystal drive circuit according to an embodiment of the present invention, and FIG. 3 shows timing signals used at various points in FIG.

The shift register sends dynamically held display information to the decoder □ as BCD signals 20 to 23.

Decoder T converts it into a 7 segment signal. The display signal converted to a 7-segment signal is a-F by EX-0R gate 8, b-G, EX-F by EX-0R gate 9,
By the 0R gate 10, it is converted into a dynamic display signal consisting of cmE, EX and p-d segment signals by the 0R gate 11, and then sent to the first holding circuits 12, 13, 14, .
Sent to...

A dynamic display signal composed of a-f segment signals is sent to the holding circuits 12-1, 13-1, and 14-1. The same applies to the other first holding circuits. Holding circuit 12
is D1・T3, holding circuit 13 is D2t3, holding circuit 1
4 is held by the timing signal D3/T3.

The first holding circuit uses a digit signal that controls the timing of the shift register as a timing signal. The timing signals Dlt3 to D3t3 are supplied to the liquid crystal display 16.
The Q signal is sent in synchronization with the Q signal to drive the AC drive. The timing signals of the holding circuits 12, 13, and 14 are different timing signals and cannot be synchronized with the AC drive voltage COM. Therefore, the second holding circuit 15 holds the timing signals Dn synchronized with the AC drive voltage COM and displays the display segment. A display signal is given to 16. In this embodiment, dynamic driving of the liquid crystal display is performed by the COM, , COM2 segment signals (output of the holding circuit 15) S. The present invention is not limited to dynamic drive, but can similarly be used in static drive display bodies such as conventional displays.

Further, the holding circuit may be provided with a level shift function. As described above, the present invention converts dynamically held display information into a display segment signal, holds this converted signal in a first holding circuit and statically converts it into information, and converts this static information into a second holding circuit. A display signal is given to a display segment via a circuit, and a liquid crystal drive circuit with low power consumption can be provided.

This will greatly contribute to devices with limited power supply capacity, such as watches and calculators.

[Brief explanation of the drawing]

Figure 1 shows a conventional liquid crystal drive circuit that converts dynamically held information into static information to drive a liquid crystal, Figure 2 shows a liquid crystal drive circuit according to the present invention, and Figure 3 shows a second liquid crystal drive circuit.
FIG. 3 is a waveform diagram of timing signals used in various places in the figure.

Claims (1)

[Claims] 1. In a dynamically driven liquid crystal drive circuit, a means for dynamically holding display information, a means for converting the dynamically held display information into segment signals for a liquid crystal display, and a means for dynamically holding display information, and a means for converting the dynamically held display information into segment signals for a liquid crystal display, and at least a number of segments larger than the total number of segments of the display. The first holding circuit holds the signal converted into the display segment signal using at least two timing signals, and the second holding circuit holds the signal converted into the display segment signal using the same timing signal. A liquid crystal drive circuit comprising means for applying a display signal to a display segment via a circuit.