JPH0659655A - Image display device - Google Patents

Abstract

PURPOSE:To reduce electric power consumption of the whole of an image display device in accordance with existence of change of an image data. CONSTITUTION:By changing the contents of an image memory 4 by a command of a micro processor 7, detecting whether renewal of an image data by blinking and the like is carried out, and in the case where there is no change in the contents of the image data, stopping delivery of a image data signal (e) to a display control circuit 8 by way of stopping motion of a part or the whole of an image forming circuit 1 and continuing to display a data in a display memory 9, electric power consumption of the whole of an image display device is reduced without stopping blink display and the like.

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.

[0002]

2. Description of the Related Art Generally, in a battery-powered portable word processor, portable personal computer, or the like, there is a strong demand from the market for long-term operation and reduction in size and weight of the device. For this reason, it is important to reduce the power consumption of the device so that the battery can be made smaller and lighter, and a battery of the same size can be operated for a longer period of time.

Generally, in order to reduce the power consumption of the apparatus, an electronic device of a circuit portion having an unused function is put into a low power consumption state called a standby mode or a sleep mode, or the power source of the unused circuit portion is cut off. , Methods for stopping or lowering the operating clock frequency have been developed. In addition, it has a function to constantly monitor the keyboard, switches, etc., and when the operator does not perform an operation for a certain period of time, puts the circuit part that does not interfere with the operation into the low power consumption state or the power off state, and the operation clock frequency It has also been stopped or lowered.

On the other hand, in the conventional image display device, there is an image display circuit as one of the circuit parts which consumes a large amount of power in the device. In the conventional image display device, it is required to display an image at high speed, and therefore it is necessary to process image data at high speed. Therefore, the circuit portion that performs image processing usually operates with a clock having a very high frequency in many cases. Since the power consumption of the circuit is often proportional to the operation clock, the image data processing unit operating at high speed usually consumes a large amount of power.

The conventional image display device is usually a CRT.
A display device such as a display or an LCD panel does not have a function of retaining display data for a long time by itself, so if the data is not sent to the display device within a certain time, the display screen disappears or is disturbed. In order to avoid this, the display control circuit in the image display device generates various control signals such as a drive clock of the CRT display or the LCD panel and a synchronization signal, and at the same time, generates these control signals and the display data received from the image generation circuit. Are constantly transferred to the display device at a constant cycle.

[0006]

In this conventional image display device, the image generation circuit operates even when the contents of the image memory are not changed by an instruction from the microprocessor or the image data is not updated by blinking or the like. The image data is constantly sent to the display control circuit, and it operates with a high-speed clock, which consumes a lot of power. In particular, the operating time is short for battery-powered personal computers that do not take commercial power from the power source. In addition, there is a problem in that the weight of the apparatus becomes heavy because a battery having a large capacity is used to extend the operation time.

[0007]

An image display device of the present invention comprises an image generating means for generating image data to be displayed on the display device, and an image storing means for storing the image data generated by the image generating means. A first display unit for displaying the image data stored in the image storage unit on the display device; a detection unit for detecting that the image data does not change for a certain predetermined time; When the image data does not change for a certain period of time, a function stopping unit that stops or lowers some functions of the image generating unit to reduce power consumption, and some functions of the image generating unit are provided. Second display means for displaying the image data stored in the image storage means on the display device while the image data is stopped or lowered, and before the image data needs to be changed. The state of stopping or reduction of function and a function recovery means for returning to the normal state.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

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

In FIG. 1, a display device 10 for displaying image data, a display memory 9 for temporarily storing image data for display, and a display control circuit 8 for controlling the display device 10 and the display memory 9 are shown in FIG. The image memory 4 for storing the image data, the image generation circuit 1 for generating the image data stored in the image memory 4 into the image data for displaying on the display device 10, and the image data for display are predetermined. An image data change detection circuit 5 that detects whether or not it changes for a certain period of time, a clock control circuit 6 that controls the transmission and stop of a clock signal used in this embodiment, and controls the entire embodiment. The image generation circuit 1 comprises a microprocessor 7 and an image data conversion circuit 3 for converting image data in the image memory 4 into image data for display, and a display control circuit. And a picture generation control circuit 2 which sends a control signal for image generation to 8.

Next, the operation of the present embodiment will be described in the case where the clock of the image data conversion circuit 3 in the image generation circuit 1 is stopped according to the operation procedure shown below.

(Operation 1) First, in the image data change detection circuit 5, the blink control signal b of the image generation control circuit 2 in the image generation circuit 1 and the access signal a to the image memory 4 by the microprocessor 7 are sent. The vertical sync signal j output from the image generation control circuit 2 in the image generation circuit 1 is monitored to detect that the image data is not changed, and the image data change state signal c is sent to the clock control circuit 6. Informs that the image data has not been changed.

Specifically, in the image data change detection circuit 5, the image generation control circuit 2 in the image generation circuit 1 outputs the rising edge of the vertical synchronizing signal j output from the image generation control circuit 2 in the image generation circuit 1. When the state of the output blink control signal b is not different from the state of the blink control signal b at the rising of the next vertical synchronizing signal j, and the access signal a to the image memory 4 by the microprocessor 7 is the vertical direction. It is determined that the image data has not been changed when the synchronization signal j has not changed between the two rising edges.

(Operation 2) The clock control circuit 6, which has been notified by the image data change state signal c that the image data has not been changed, is controlled by the image data conversion circuit 3 in the image generation circuit 1.
Stop the clock signal d to.

(Operation 3) By stopping the clock signal d to the image data conversion circuit 3 in the image generation circuit 1,
The reading i of the image data from the image memory 4 is stopped,
At the same time, the image data signal e to the display control circuit 8 is also stopped.

(Operation 4) The display control circuit 8 stops writing the display data f for updating the display memory 9 because the image data signal e from the image generation circuit 1 has stopped, but the display control circuit 8 does not. The reading of display data from the display memory 9 is continued as it is, and the display signal h is sent to the display device 10 as it is to continue the display.

By the above (Operations 1 to 4), the power consumption can be reduced while the image data is not changed.

(Operation 5) Next, in the image data change detection circuit 5, the blink control signal b of the image generation control circuit 2 in the image generation circuit 1 and the access signal a to the image memory 4 by the microprocessor 7 are used. Is detected based on the vertical synchronizing signal j output from the image generation control circuit 2 in the image generation circuit 1 and it is detected that the image data has been changed, the clock control circuit 6 is activated by the image data change state signal c. Notify that the image data has been changed.

Specifically, in the image data change detection circuit 5, the image generation control circuit 2 in the image generation circuit 1 outputs the rising edge of the vertical synchronization signal j output from the image generation control circuit 2 in the image generation circuit 1. When the state of the output blink control signal b is different from the state of the blink control signal b at the time of rising of the next vertical synchronizing signal j, or when the access signal a to the image memory 4 by the microprocessor 7 is the vertical synchronizing signal. If the signal j has changed even once between the two rising edges, it is determined that the image data has been changed.

(Operation 6) The block control circuit 6, which has been notified by the image data change state signal c that the image data has been changed, sends the clock signal d to the image data conversion circuit 3 in the image generation circuit 1. Resume.

(Operation 7) By restarting the clock signal d to the image data conversion circuit 3 in the image generation circuit 1,
The reading i from the image memory 4 is restarted, and the sending of the image data signal e to the display control circuit 8 is restarted.

(Operation 8) The display control circuit 8 resumes the writing f of the display data to the display memory 9 to update the display memory 9 since the transmission of the image data signal e from the image generation circuit 1 is resumed. To do.

As described above, in the present embodiment, the image data conversion circuit 3 of the image generation circuit 1 operates only when the image data including the blink operation is changed, so that the power consumption can be reduced without stopping the blink function. .

Further, in the present embodiment, the power consumption is reduced by stopping the clock of the image data conversion circuit 3 in the image generation circuit 1. However, the present invention is not limited to this, and the power consumption in the image data conversion circuit 3 is reduced. Even if the electronic device is put into a low power consumption state or the power consumption is reduced by using the method of cutting off the power source of the image data conversion circuit 3 itself, it is clear that it becomes one of the embodiments of the present invention.

Further, in this embodiment, the image data change detection circuit 5 monitors the blink control signal b of the image generation control circuit 2 in the image generation circuit 1 in (Operation 1).
In the image generation control circuit 2 in the image generation circuit 1 having the blink function such as the integrated circuit μPD7220, in the image generation circuit 1 not having the blink function, the image generation circuit 1 is monitored from the image data change detection circuit 5. The blink control signal b by the image generation control circuit 2 in the inside is removed, the clock of the image generation control circuit 2 in the image generation circuit 1 is also stopped in (operation 3), and the access signal a to the image memory 4 by the microprocessor 7 The clock may be restarted by the occurrence of.

[0026]

As described above, according to the present invention, the image generating means for generating the image data to be displayed on the display device, the image storing means for storing the image data generated by the image generating means, and the image storing means. The first display means for displaying the image data accumulated in the display device on the display device, the detecting means for detecting that the image data does not change for a predetermined time, and the image data for a predetermined time. In the case where there is no change, a function stopping means for stopping or lowering a part of the function of the image generating means to reduce the power consumption, and a function stopping means for suspending or lowering a part of the function of the image generating means It has a second display means for displaying the accumulated image data on the display device, and a function recovery means for returning a state in which the function is stopped or lowered to a normal state when the image data needs to be changed. By doing so, it is possible to save the power consumption of the image display device without stopping the blink display, and as a result, for example, in the case of a battery-driven device, it is possible to extend the operating time with a battery of the same capacity. In addition, when compared with the same operating time, when the present invention is used, a small battery can be used, so that there is an effect that the size and weight of the device can be reduced.

[Brief description of drawings]

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

[Explanation of symbols]

 1 image generation circuit 2 image generation control circuit 3 image data conversion circuit 4 image memory 5 image data change detection circuit 6 clock control circuit 7 microprocessor 8 display control circuit 9 display memory 10 display device a access signal b blink control signal c image data Change status signal d Clock signal e Image data signal f Writing display data g Reading display data h Display signal i Reading image data j Vertical sync signal

Claims (1)

[Claims] 1. An image generating means for generating image data to be displayed on a display device, an image storing means for storing the image data generated by the image generating means, and image data stored in the image storing means. A first display means for displaying on the display device, a detection means for detecting that the image data does not change for a predetermined time, and a case where the image data does not change for the predetermined time. A function stopping means for stopping or lowering a part of the function of the image generating means to reduce power consumption, and a function stopping means for storing a part of the function of the image generating means in the image storing means while the function is stopped or lowered. Second display means for displaying the accumulated image data on the display device, and a state in which the function is stopped or lowered when the image data needs to be changed to a normal state. An image display device having a function recovery means for returning to the image display device.