JPH0546118A - Image display device - Google Patents

Abstract

PURPOSE:To prevent a display image from shifting in position on the image display device which displays dot data even when the time relation between a synchronizing signal and display data is not accurate. CONSTITUTION:A control circuit 3 starts outputting a sampling signal (c) at set time after the synchronizing signal indicating transfer start timing is applied. A detecting circuit 5 decides whether or not the set time set in the control circuit 3 needs to be varied according to the display data (b) and sampling signal (c) and applies a variation indication signal 8d) indicating how much the set time should be varied to the control circuit 3 when deciding that the set time needs to be varied. The control circuit 3 varies the set time according to the variation indication signal (d) and outputs the sampling signal (c) according to the varied set time from the timing of the next application of a synchronizing signal (a).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device for displaying dot data.

[0002]

2. Description of the Related Art Conventionally, a dot position designation type display device, for example, a liquid crystal display device generates a sampling signal at a fixed timing with reference to a synchronization signal indicating a display data transfer start timing. Then, the display data is sampled based on the sampling signal,
I am trying to output to the display.

[0003]

As described above, in the prior art, since the sampling signal is generated at a fixed timing with reference to the sync signal, the timing relationship between the sync signal and the display data is deviated. If there is, there is a problem that the display position of the image is displaced.

An object of the present invention is to provide an image display device capable of displaying an image at a correct position even when there is a timing relationship between a synchronization signal and display data.

[0005]

In order to achieve the above object, the present invention outputs a sampling signal for the display data when a set time elapses after the synchronization signal indicating the transfer start timing of the display data is input. A control circuit that starts, a sampling circuit that samples the display data according to a sampling signal that is output from the control circuit, and outputs the sampled display data to a display, a sampling signal that is output from the control circuit, and dot data in the display data. A detection circuit that outputs a change instruction to the control circuit by determining whether it is necessary to change the set time based on The circuit changes the set time according to a change instruction from the detection circuit.

[0006]

The control circuit starts the output of the sampling signal for the display data when the set time elapses after the synchronization signal indicating the transfer start timing of the display data is input. The display data is sampled by the sampling circuit by this sampling signal and output to the display.

The sampling signal output from the control circuit is also applied to the detection circuit, and the detection circuit determines whether or not the set time needs to be changed based on the sampling signal and the display data. This determination is, for example,
This is performed based on whether or not there is dot data for which the corresponding sampling signal does not exist in the display data.

When it is determined that the set time needs to be changed, the time corresponding to the number of dot data in which the corresponding sampling signal does not exist is output to the control circuit as a change instruction.

When the detection circuit gives a change instruction, the control circuit changes the set time accordingly, and thereafter outputs a sampling signal based on the changed set time.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, in which an input terminal 1 for a synchronization signal a, an input terminal 2 for display data b, a control circuit 3, a sampling circuit 4, and a detection circuit 5 are provided. The display 6 is included.

The control circuit 3 outputs the sampling signal c indicating the sampling timing for the display data b when a set time elapses after the synchronizing signal a indicating the transfer start timing of the display data b is applied via the input terminal 1. Output. Further, the control circuit 3 changes the set time according to the change instruction signal d from the detection circuit 5.

The sampling circuit 4 samples the display data b in accordance with the sampling signal c output from the control circuit 3, and outputs the sampled display data e to the display 6 and the control signal f for displaying. To do.

The detection circuit 5 determines whether or not the set time set in the control circuit 3 needs to be changed. If it is determined that the set time needs to be changed, how much the set time is set for the control circuit 3. A change instruction signal d indicating whether to change is output.

Whether or not it is necessary to change the set time set in the control circuit 3 is determined by, for example, the dot data indicating "1" appearing first in the display data b and the dot data appearing last. This is performed based on whether or not the sampling signal c corresponding to the dot data indicating "1" exists. When the corresponding sampling signal c does not exist, the detection circuit 5 determines that the set time needs to be changed. To do.

Further, how much the set time is changed is determined based on, for example, the number of dot data in which the corresponding sampling signal c does not exist, and indicates "1" which appears first in the display data b. If there are i continuous dot data from the dot data and there is no sampling signal, the set time is shortened by T × i (T is the period of the sampling signal c), and the last "in the display data b" appears. In the case where there are j pieces of dot data in the reverse direction from the dot data indicating 1 ″ and there is no sampling signal c, the set time is lengthened by T × j.

2 to 4 are time charts of this embodiment. The operation of this embodiment will be described below with reference to the drawings.

First, the operation when the timing relationship between the synchronizing signal a and the display data b is accurate will be described with reference to FIG.

The control circuit 3 controls the synchronization signal a shown in FIG.
When the set time has elapsed after the addition of the sampling signal c, the sampling signal c shown in FIG. In this case, since the timing relationship between the synchronization signal a and the display data b shown in FIGS. 8A and 8B is accurate, as shown in FIGS. There is no dot data D1 to Dn for which the corresponding sampling signal c does not exist. Therefore, in this case, the change instruction signal d is not output from the detection circuit 5, and the control circuit 3
Outputs the sampling signal c at the same timing when the next synchronization signal a is added.

Next, the operation when the timing of the display data b is delayed with respect to the synchronizing signal a will be described with reference to FIG.

The control circuit 3 uses the synchronization signal a shown in FIG.
When the set time has elapsed after the addition of the sampling signal, the sampling signal c shown in FIG. In this case, since the timing of the display data b is delayed with respect to the synchronization signal a, the dot data Dn in which the corresponding sampling signal c does not exist in the display data b as shown in FIGS. Appears.

If this dot data Dn is "1",
This is detected by the detection circuit 5, and the detection circuit 5 outputs the change instruction signal d. In this example,
Since there is only one dot data in which the corresponding sampling signal c does not exist, and the dot data Dn is the last dot data in the display data b, the detection circuit 5 uses T
The change instruction signal d for instructing to increase the set time by x1 is output to the control circuit 3.

When the change instruction signal d is added, the control circuit 3 lengthens the set time set inside by T according to the change instruction signal d. As a result, next, the synchronization signal a
At the timing at which the sampling signal c is added, the sampling signal c shown in FIG. 3D, which is delayed by T from the sampling signal c shown in FIG. b is accurately sampled.

Next, the operation when the timing of the display data b is advanced with respect to the synchronizing signal a will be described with reference to FIG.

The control circuit 3 uses the synchronization signal a shown in FIG.
When the set time elapses after the addition of, the sampling signal c shown in FIG. In this case, since the timing of the display data b is earlier than the synchronization signal a, as shown in (b) and (c) of FIG.
The dot data D1 without the corresponding sampling signal c appears.

If this dot data D1 is "1",
This is detected by the detection circuit 5, and the detection circuit 5 outputs the change instruction signal d. In this example,
Since there is only one dot data in which the corresponding sampling signal c does not exist, and the dot data D1 is the first dot data in the display data b, the detection circuit 5 uses T
A change instruction signal d for instructing to shorten the set time by × 1 is output to the control circuit 3.

When the change instruction signal d is added, the control circuit 3 shortens the set time set internally by T. As a result, at the timing when the synchronization signal a is added next, the sampling signal c shown in FIG. 7C, which is advanced by T from the sampling signal c shown in FIG. In the circuit 4, the display data b is accurately sampled.

[0028]

As described above, the present invention determines whether or not the set time set in the control circuit needs to be changed based on the display data and the sampling signal output from the control circuit. However, a detection circuit that outputs an instruction to change the set time to the control circuit by determining that it needs to be changed is provided, so if there is a time relationship between the synchronization signal and the display data. However, there is an effect that the displacement of the display position can be eliminated.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a time chart of an example.

FIG. 3 is a time chart of an example.

FIG. 4 is a time chart of an example.

[Explanation of symbols]

 1, 2 ... Input terminal 3 ... Control circuit 4 ... Sampling circuit 5 ... Detection circuit 6 ... Display device a ... Sync signal b, e ... Display data c ... Sampling signal d ... Conversion instruction signal f ... Control signal

Claims (3)

[Claims] 1. A control circuit for starting output of a sampling signal for the display data when a set time elapses after a synchronizing signal indicating a display data transfer start timing is input, and a sampling circuit output from the control circuit. Whether or not it is necessary to change the set time based on a sampling circuit which samples the display data according to a signal and outputs the sampled display data to a display, and a sampling signal output from the control circuit and dot data in the display data. And a detection circuit that outputs a change instruction to the control circuit by determining that it is necessary to change the setting time according to the change instruction from the detection circuit. An image display device characterized by being changed. 2. The detection circuit determines that it is necessary to change the set time when there is dot data for which a corresponding sampling signal does not exist in the input display data. 1. The image display device according to 1. 3. The detection circuit determines that it is necessary to change the set time when there is dot data for which no corresponding sampling signal exists in the input display data, and the presence of the corresponding sampling signal is determined. The image display device according to claim 1, wherein a time corresponding to the number of dot data that is not output is output to the control circuit as a change instruction.