JPH09247487A - Auto-scan image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the power consumption of a display device by changing-over the power source voltage of a main amplifier. SOLUTION: A power source part 31 is provided with the two output terminals of a high voltage(VH) output for the main amplifier and a low voltage(VL) output for the main amplifier. A video kind identifying circuit 20 provided inside a control part 21 receives a synchronizing signal 71, identifies whether a video signal is the image of a personal computer, etc., of a TV image based on the synchronization and originates an identifying signal 51. A main amplifier power source voltage change-over part 13 changes-over the main amplifier power source voltage into high VH or low VL by the identifying signal from an image kind identifying circuit 20 inside the control part 21 in accordance with at the time of TV image display and at the time of personal computer image display. Since operation point current is decided by bias resistance regardless of the change-over of the power source voltage, a value becomes the almost same one so that power consumption is reduced for the portion of the reduction of the power source voltage with small current value change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to reduction of power consumption of an auto scan display device.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram of a conventional image display device (hereinafter referred to as a display device) similar to that disclosed in Japanese Patent Laid-Open No. 4-37791. In the figure, 8
Is a CRT that displays images (including characters). 7 is C
A deflection yoke added to RT8.

A signal generator 60 indicates a computer such as a personal computer or a video signal generator such as a television receiver (hereinafter simply referred to as a personal computer or a television), and a video signal 70
And the sync signal 71 is transmitted. Reference numeral 1 is a control unit for controlling deflection of the display device, 2 is a video signal processing unit for processing a video signal 70, a synchronization signal 71, etc. input from a personal computer or a television 60, 3 is a power supply unit, 4 is a deflection processing unit, 5
Is a video signal output unit that amplifies the signal 72 from the video signal processing unit 2 to control the brightness of the display point and the like, and 6 is a high voltage generation unit.

Next, the operation will be described. The display device of FIG. 7 sends horizontal and vertical deflection signals generated by processing the input video signal 70 and the synchronizing signal 71 in the video signal processing unit 2 to the deflection processing unit 4 to drive the deflection yoke 7.
The video signal processing unit 2 also processes the video signal 70 and sends it to the video signal output unit 5.

Next, the horizontal synchronizing signal 73 processed by the deflection processing section 4 is sent to the high voltage generating section 6 to generate a high voltage. The deflection coil current 74 processed by the deflection processing unit 4 drives the deflection yoke 7, and the high voltage generated by the high voltage generation unit 6 is applied to the anode of the CRT 8, and the video signal 72 from the video signal output unit 2 is supplied. The signal amplified by the video signal output unit 5 is applied to the cathode (not shown) to display the video on the CRT 8.

In a so-called auto-scan video display device, it is necessary to switch the horizontal scanning frequency depending on whether the signal generator 60 is a personal computer or a television, which can support a wide range of synchronizing signal frequencies. Is configured to be automatically processed by the control unit 1.

Therefore, even if any device within the range of a predetermined standard is connected to the signal generator 60,
The image is displayed for the time being. However, the signal generator 60
The brightness of the screen is darker (the image amplitude is smaller) for still images when connected to a computer that often displays still images and when connected to a TV that often displays movies. Unless it is set brighter (the video amplitude is large) in a movie, it will not look the same to the human eye.

Therefore, the video signal output section 5 has a circuit specification (for example, a high voltage for obtaining a large video amplitude, which is capable of displaying a video having a brightness suitable for displaying a television image,
It has a large load resistance).

[0009]

The conventional auto-scan display device is configured as described above, and when the screen is brightened, characters are displayed so as to correspond to a wide input frequency of television images and personal computers to workstations. To display an image of a personal computer or workstation that does not require large video amplitude, such as a crushed still image, or to display a so-called blue back to notify that the sync signal is not input, The image cannot be recognized unless the screen is brightened. The power supply voltage and load resistance suitable for TV images that require large image amplitude such as moving images are used as they are, so it is more than necessary during PC image display or blue background display. There was a problem of high power consumption.

[0010]

SUMMARY OF THE INVENTION An auto scan display device according to the present invention has an image of a television image that requires a large image amplitude, an image of a personal computer to a workstation that does not require a large image amplitude, and a smaller image. For the image at the time of blue back display, which has sufficient video amplitude, the power amplifier voltage switching unit of the main amplifier of the video signal processing unit, and the operating point switching switch of the amplifier circuit of the output unit,
It is equipped with a system that lowers the high voltage of the high-voltage generating unit, which enables reduction of power consumption of the display device.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a video signal output unit 2 of a display device according to the present invention. In FIG. 1, reference numeral 21 denotes a control unit for controlling the deflection of the display device and the like.
Is a video signal output unit that amplifies the signal 72 from the video signal processing unit 2 to control the brightness of the display point and the like, and 6 is a high voltage generation unit.

Reference numeral 9 denotes a preamplifier for amplifying the video signal 70,
Is the OSD section, 11 is the main amplifier for video signals, and 12 is the main
The load resistances RL and 22 of the amplifier 11 are the vias of the main amplifier 11.
The resistors RE and 13 are the power supply voltage switching unit for the main amplifier.
You. The power supply section 31 is a high voltage (VH) output for main amplifier and
Low voltage for in-amp (VL ) Has two output terminals
I do. 20 is the image type provided in the control unit 21
It is an identification circuit that receives the synchronization signal 71 and determines its cycle.
The video signal is an image of a personal computer or a TV image
Then, the identification signal 51 is transmitted.

The parts other than the video signal output section 5, the control section 21, and the power supply section 31 are the same as those of the conventional configuration shown in FIG. FIG. 2 is a main amplifier 11 for explaining the operation of the circuit of FIG.
FIG. 4 is an operation characteristic diagram of FIG. 4, in which the horizontal axis represents the collector voltage V of the main amplifier 11 and the vertical axis represents the collector current I of the main amplifier 11.

Reference numeral 101 in FIG. 2 is a VI characteristic line of the main amplifier in which the parameter is the base current, and 102 is the power supply voltage VH.
Is a collector load operation line when the load resistance 12 is RL, and 103 is a collector load operation line when the power supply voltage is VL and the load resistance 12 is RL.

The operation of the main amplifier 11 used for the video signal output section 5 of the CRT 8 is not limited to so-called class A amplification, but the main amplifier 11 is simply A because the purpose is to explain the power saving operation. The explanation will be given assuming that the class operation is performed.

Further, a bias capacitor for improving the frequency characteristic of the main amplifier 11 is connected to the bias resistor R _E 22, but it is not shown here because it is not directly related to the explanation of the power saving effect. ing.

Next, the operation will be described with reference to FIGS. The video signal from the video signal processing unit 2 is amplified by the preamplifier 9, and the main amplifier 11 amplifies the video signal 72 using the main amplifier power supply voltage from the main amplifier power supply voltage switching unit 13 and applies it to the cathode of the CRT 8. .

The power amplifier voltage switching unit 13 for the main amplifier controls the TV image display and the PC image display.
The main amplifier power supply voltage is switched to high VH or low VL by an identification signal 51 from the video type identification circuit 20 in 21.

Switching the power supply voltage for the main amplifier is
Since images of television broadcasting, VTR, and LD require a large video amplitude in order to approach the actual contrast, a high power supply voltage for the main amplifier is required. Further, in an image of a personal computer, a workstation or the like, since the screen is often stared at, the large contrast makes it easy for the eyes to be noticed, so that a large image amplitude is not required. Therefore, the power supply voltage for the main amplifier may be lowered.

The power supply voltage is a high voltage (VH) and a low voltage (VH).
Characteristic curves 102 and 103 shown in FIG. 2 are operation characteristic curves when switching to L). The current value of the operating point (indicated by P1 in the figure) when there is no signal is the value indicated by I1 in the figure, and even if the power supply voltage is switched, the operating point current is determined by the bias resistor RE22, so the current values are almost the same. There is little change in the value.

The average power consumption (not the collector power consumption) when the power supply voltage is VH is VH · I1. Since the average power consumption when the power supply voltage is VL is VL · I1, the power consumption can be reduced by the amount corresponding to the lower power supply voltage.

Although FIG. 1 shows switching between two steps of high and low, a) when displaying a television image ... High, b) when displaying a personal computer image ... Low, c) blue back display In the case of ... Very low, three-stage switching may be performed. It is easy to make the image identification circuit 20 capable of identifying the above states a) b) c) by the scanning frequency, but since the connectors connected by the image source such as a personal computer and a TV are different, which connector the image source is The type of video source may be identified depending on whether the video source is connected to.

Embodiment 2 FIG. If the power supply voltage is simply lowered as shown in FIG. 1, the operating point is biased toward the end within the operable range as shown by the characteristic 103 in FIG. Although it is extremely smaller than the voltage drop width, and the effect of power saving can be obtained, it is not a good idea.

FIG. 3 shows the configuration of the video output unit 2 of the display device according to the second embodiment of the present invention. In the figure, 41 is a bias resistance R inserted in series with the bias resistance RE 22.
It is E2. Reference numeral 42 denotes a short-circuit switch connected in parallel to the bias resistor RE2 41, which receives the switching signal 51 from the control unit 21 like the power supply voltage switching unit 13 and closes the short-circuit switch 42 when high voltage is selected, and when low voltage is selected. Open.

FIG. 4 is a characteristic diagram of the main amplifier 11 for explaining the operation of the video output unit 2 of FIG.

Next, the operation will be described. When the power supply voltage switching unit 13 selects high voltage (VH), the short-circuit switch
Since 42 is closed and only RE22 is inserted as the bias resistor, there is no difference from the circuit of FIG.
Therefore, the description in this case is omitted.

Next, when the power supply voltage switching unit 13 selects the low voltage (VL), the short-circuit switch 42 is opened and the bias resistance becomes (RE + RE2). As a result, the current at the operating point P2 when there is no image signal on the operating characteristic diagram is shown in FIG.
It becomes as low as the level of I2 shown in.

The average power consumption when the power supply voltage is VH is VH.I1, but it becomes VL.I2 when the power supply voltage is VL, and the power is further reduced as compared with the case of FIG. Moreover, by selecting the position of the operating point P2 so that the operating range is equally divided on both sides of P2, the amplitude of the video signal that can be output does not become extremely small.

Embodiment 3 Since the purpose of displaying the blue background is only to notify that the sync signal is not input, there is no problem even if the brightness of the screen at that time is dark as described in the first and second embodiments. At the same time, the size of the screen does not have much significance at this time. Therefore, in the third embodiment, it is intended to save power by changing the size of the screen during blue background display.

There are mainly two methods for changing the screen size that leads to power saving. FIG. 5 shows the configuration of a display device that implements these at the same time. The first method is to reduce the current used for vertical or horizontal deflection, and the second method is to reduce the high voltage used for accelerating the electron beam of the CRT8.

In the first method, the screen becomes small, and in the second method, the screen becomes large. When the blue background is displayed,
Electric power can be reduced by using either the first or second method alone or simultaneously.

In FIG. 5, for convenience of explanation, the above-mentioned first and second
Although only the signal flow directly related to the above method is described, the signal flow originally necessary for the image display shown in FIG. 7 naturally exists.

In FIG. 5, reference numeral 75 is a sync non-detection signal for notifying the screen size change command circuit 61 of the next stage when the video type identification circuit 20 detects that the sync signal 71 does not come in. Is.

A screen size change command signal 76 is sent from the screen size change command circuit 61 to the deflection processing section 4 and the high voltage generating section 6 in response to the synchronization non-detection signal 75. Reference numeral 74 denotes the deflection current (vertical or horizontal deflection) originally sent to the deflection coil 7 by the deflection processing unit 4.

Reference numeral 78 indicates a high voltage which the high voltage generator 6 originally supplied to the high voltage terminal of the CRT 8. Reference numeral 79 denotes an image signal in which the video signal processing unit 2 sends a blue back as a video to the CRT 8 via the video signal output unit 5 when no synchronization is detected. FIG. 6 is a flow chart for explaining the signal flow of FIG.

The operation of FIG. 5 will be described below with reference to the flowchart of FIG. When the sync signal is input in ST61, the input video is displayed. When the sync signal is not input, in ST62, the video identification circuit 20 transmits the sync non-detection signal 75, and the video signal processing unit 2 causes the blue background.
Send 79. In ST63, the control section 21 outputs the screen size change signal 76.

Then, in ST64, the control unit 21 controls to reduce the currents of the horizontal deflection output and the vertical deflection output. Further, the control section 21 outputs a command 78 for lowering the high voltage value data in ST65. Control unit 21
By performing the above-mentioned two controls, the display device enables low power consumption during blue back, and lowers the high voltage value data while outputting the screen size reduction data from the control unit. The effect is that the screen size of the blue background does not change apparently.

[0038]

As described above, according to the first to third aspects of the present invention, the power source voltage of the video signal output section is switched according to the identified image type by the identification circuit for identifying the image type. Thus, the power consumption of the display device can be reduced.

Further, according to the fourth and fifth inventions, it is possible to reduce the power consumption of the display device by reducing the deflection current or lowering the high voltage during blue back display.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a video signal output unit according to a first embodiment.

FIG. 2 is a characteristic explanatory diagram of FIG.

FIG. 3 is a configuration diagram of a video signal output unit according to a second embodiment.

FIG. 4 is a characteristic explanatory diagram of FIG.

FIG. 5 is a signal flow chart of the display device according to the third embodiment.

FIG. 6 is a flowchart illustrating the flow of FIG.

FIG. 7 is a configuration diagram of a conventional display device.

[Explanation of symbols]

1 control section, 2 video signal processing section,
3 power supply generation section, 4 deflection processing section, 5 video signal output section, 6 high voltage generation section, 7 deflection yoke,
8 CRT, 9 preamplifier, 11
Main amplifier, 12 load resistors, 13 main amplifier power supply voltage switching unit, 20 video type identification circuit,
21 control section, 22 bias resistance RE,
31 power supply, 41 bias resistor RE2, 42 short-circuit switch, 51 video identification signal, 61 screen size change command circuit 70 video signal, 71 synchronization signal,
72 video signal, 73 horizontal sync signal, 74 deflection coil current, 75 sync no detection signal, 76 screen size change command signal, 78 high voltage, 79 blue back image signal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomohiro Nakagawa 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd. (72) Akiyoshi Matsunaga 2--6-2 Otemachi, Chiyoda-ku, Tokyo Sanryo Electric Engineering Co., Ltd. (72) Inventor Yoshiyuki Kojima 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Sanryo Electric Co., Ltd.

Claims (5)

[Claims] 1. A display unit for displaying an image, a control unit for receiving a video signal and a synchronizing signal, and controlling deflection of the display unit in synchronization with the synchronizing signal, and a video output unit for controlling brightness. In the auto-scan image display device, the control unit has an image type identification circuit that identifies the type of the image and outputs an identification signal, and the image output unit receives the identification signal and supplies power to the image output unit. An auto-scan video display device having a power supply voltage switching unit for switching a voltage in two or more steps. 2. The type of image identified by the image type identification circuit includes three types: television broadcasting, VTR and LD images, computer output images, and blue background representing a state in which no sync signal is input. The automatic scan image display device according to claim 1, wherein 3. The video output unit has an amplifier for outputting a video signal to the next stage, and the power supply voltage switching unit operates in conjunction with the operation of the power supply voltage switching unit to switch the operating point of the amplifier. The auto-scan image display device according to claim 1, wherein the auto-scan image display device comprises: 4. The video type identification circuit is configured to be able to identify a state in which no sync signal is input, and to output a command to change the screen size that is not displayed on the display section in this state. The auto-scan image display device according to claim 1. 5. The display unit is a cathode ray tube having a deflection coil for flowing a deflection coil current and a high voltage anode for accelerating an electron beam, and a command for changing the screen size is to reduce the deflection coil current of the display unit, Alternatively, the high-voltage image display device according to claim 4, wherein the high voltage of the display unit is lowered.