JPH0235492A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To eliminate a counter and a register and to simplify a circuit by supplying an output at the final stage of a shift register to a field end detection flip flop. CONSTITUTION:A reset state (RESET 115) is at a high level, and the flip flop of a field detection part 13 is set, which leads an STF-114 at a high level to output to a common shift register 31. Receiving the STFs 114, the register 31 sequentially transfers them when a DLAT 113 rises. A drive row is advanced in order, and a common liquid crystal driving circuit 32 displays a liquid crystal panel 4. When data is transferred to the flip flop at the final stage of the com mon shift register, its output QY 311 turns into the input of the flip flop of the detecting part 13. By the rise of the DLAT 113, the end of a field is detected to reset the STF 114 at a high level, and a next field is started. Thereafter, these actions are repeated, whereby the row number counter in the vertical direction and a row number setting register in the vertical direction are needed not to significantly simplify the circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid crystal display device adapted to equipment having a dot matrix type liquid crystal display.

2. Description of the Related Art In recent years, liquid crystal displays and their control devices have been used in devices such as personal computers and word processors.

FIG. 5 is a diagram showing a block configuration of a conventional liquid crystal display device. In Fig. 5, 1 is a liquid crystal controller;
is display data (hereinafter referred to as DATAIII) and a data shift clock (hereinafter referred to as DSHC11) that shifts the display data.
2), 12 is a horizontal control unit that outputs a data latch (hereinafter referred to as DLAT113) that has a built-in counter and becomes active for every horizontal line; 14 has a built-in counter and becomes active for every 1 field. A vertical control unit outputs a start frame signal (hereinafter referred to as 5TF114), 2 is a segment driver that drives a liquid crystal element corresponding to display data in each line, and 21 is an X-bit segment shift register that shifts display data DATA111 by DSHC112. , 22 DL the data stored in the segment shift register 21.
Segment latches 22 and 23 of the X bits latched by AT113 are segment liquid crystal drive circuits that drive the liquid crystal element by applying a voltage to the liquid crystal element. 3 is a common driver that selects a line to display and drives the liquid crystal; DLAT1
13, the start frame signal (hereinafter 5TF114
), and a common liquid crystal drive circuit 32 that drives a liquid crystal element. Reference numeral 4 denotes a liquid crystal panel composed of dot matrix liquid crystal elements, which serves as an actual display screen. FIG. 6 is an internal circuit diagram of the segment shift register 21.
The falling edge of C112 indicates that DATA All will be shifted in order. FIG. 7 shows the common shift register 31.
In the internal circuit diagram of 5TF1 at the falling edge of DLAT113.
14 in order. FIG. 8 shows a timing chart of the operation of the conventional example.

Explaining based on the timing chart of FIG. 8, input data DATAI 11 is sequentially transferred to the segment shift register 21 at the falling edge of DSHC 112. 1
After the manual data transfer for a row is completed, DLAT113
At the falling edge of , the data in the segment shift register 21 is latched into the segment latch 22. The drive circuit then drives the liquid crystal panel according to the latched data. Also, at this time, in the common driver 3, 5TF114 becomes active on the first line of each field.
is latched to the top flip 70 block in FIG. 7 at the falling edge of DLA, T113, and the first row of the liquid crystal panel is driven by the common liquid crystal circuit. Further, while the first row is being displayed, the data on the second row is sequentially transferred to the segment shift register 21 in the same way as the first row.
Also, at this time, the common shift register 31 is DLAT11.
At the falling edge of 3, the data (
STF 114) is transferred and the second row of the liquid crystal panel is driven by the common liquid crystal circuit. Thereafter, the above operation is repeated until the counter in the vertical control section reaches the set value, that is, the number of vertical display lines on the liquid crystal panel 4, and then the process moves to the next field and the above operation is repeated.

Problems to be Solved by the Invention However, the above configuration has the disadvantage that a vertical counter is required within the liquid crystal controller, increasing the circuit scale.

An object of the present invention is to provide a liquid crystal display device that solves the above problems and makes it possible to construct a liquid crystal display system with a minimum circuit configuration.

Means for Solving the Problems To achieve this object, the liquid crystal display device of the present invention feeds back the output of a circuit that resets the shift register of the common driver and the flip-flop at its final stage to the display controller, and detects it. It has a field end detection section.

With this configuration, when data is latched into the final stage flip-flop of the common driver's shift register, that is, when a field ends, the LCD controller detects this and outputs a signal to start the next field. do. This eliminates the need for a counter in the liquid crystal controller to detect the end of the field, and eliminates the need for a conventional vertical control section.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings. FIG. 1 shows a liquid crystal display control device of the present invention. Reference numeral 1 in FIG. 1 is a liquid crystal controller, which replaces the vertical control section 14 of the conventional example shown in FIG. 5 and becomes a field end detection section 13. The rest is the same as the conventional example. 2 in FIG. 1 is a segment driver, which is the same as the conventional example. 3 in Figure 1 is a segment driver, and 31 is a shift register with reset that outputs the final stage (QY31 in Figure 2).
1) is supplied to the field end detection section 13 of the liquid crystal controller l, and 32 is a common liquid crystal drive circuit, which is similar to the conventional example. Further, 4 in FIG. 1 is a liquid crystal panel, which is the same as the conventional example. Figure 2 shows common segment shift register 3.
The circuit diagram in No. 1 is the same as the conventional example except that RESET 115 is at high level and the flip-flop output is at low level. FIG. 3 shows a circuit diagram of the field end detection unit 13, in which DLAT'131 is a signal skewed by 1.5 DSHC112 cycles with the same cycle as DLAT113, RESETI 15 is high level, and STF 1
14 is the low level. FIG. 4 shows a timing chart of the operation. The operation will be explained below based on FIG. 4 above.

The operation of the segment driver 2 is the same as that of the conventional example, so the explanation will be omitted. First, the reset state (RESE
TI15) is at a high level, and the flip-flop of the field detector 13 is set at A in FIG.
The TF 114 becomes high level and outputs it to the common shift register 31. The common shift register 31 receives the 5TF 114 and transfers DLAT1 in the same manner as in the conventional example.
By sequentially transferring the data at the falling edge of signal 13, the driving operation progresses in order, and the common liquid crystal drive circuit 32 displays the liquid crystal panel 4. When the data is transferred to the final stage of the common shift register, the 7th flip-flop, its output (QY311) becomes the input to the flip-flop of the field end detection section, and when DLAT'131 rises (B in Figure 4) detect the end of
The 5TF 114 is set to high level again to start the next field. This operation is repeated in the same way.

Effects of the Invention As described above, according to the present invention, by attaching a reset to the common shift register 31 and supplying the output of the final stage flip-flop to the field end detection flip-flop provided in the liquid crystal controller. ,
A counter for counting the number of vertical lines and a register for setting the number of vertical lines, which were required in conventional liquid crystal controllers, are no longer required, and the number of circuits can be significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the configuration of a liquid crystal display device in an embodiment of the present invention, FIG. 2 is a circuit diagram of a common shift register in the embodiment of FIG. 1, and FIG. 3 is a field end detection circuit in the embodiment of FIG. 1. 4 is a timing chart of the operation in the embodiment of FIG. 1, FIG. 5 is a block diagram of the configuration of a liquid crystal display device in the conventional example, and FIG. 6 is a circuit diagram of a segment shift register in the embodiment of FIG. 7th
5 is a circuit diagram of the common shift register in the embodiment shown in FIG. 5, and FIG. 8 is a timing chart of the operation in the conventional example shown in FIG. 1...Liquid crystal controller, 2...Segment driver, 3...Common driver,
4...Liquid crystal panel, 11...Data output section, 12...Horizontal control section, 13...
Field end detection section, 14... Vertical control section, 21... Segment shift register, 22.
... Segment latch, 23 ... Segment liquid crystal drive circuit, 31 ... Common shift register, 32 ... Common liquid crystal drive circuit. Name of agent Patent attorney Shigetaka Awano et al.

Claims (1)

[Claims] A liquid crystal common driver that sequentially drives the display rows of a liquid crystal panel equipped with a shift register with a reset, and a field end detection device that detects the end of a field based on the final output of the shift register and then outputs a start signal for the next field. A liquid crystal display device comprising: