JP2000069397A - Liquid crystal projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means that reduces wasteful power consumption in the liquid crystal projector with a sound circuit. SOLUTION: This liquid crystal projector, that uses a liquid crystal panel to projects the image of a television video signal or the like onto the its screen, is incorporated with a sound circuit 2 that amplifiers an audio signal S1 of a television signal and outputs the amplified signal to a speaker 3. However, when there is no audio signal, the power consumed by the sound circuit 2 becomes wasteful. Then an MPU 5 or the like is used to detect the presence of input of the audio signal S1, and when there is no audio signal, a power supply control section 4 that applies on/off control to the power supply of the sound circuit 2 interrupts a power supply voltage V1 of the sound circuit 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector with an audio circuit that reduces unnecessary power consumption.

[0002]

2. Description of the Related Art A liquid crystal projector using a liquid crystal panel is frequently used as a small device capable of displaying television images and the like on a large screen. LCD projectors include:
In many cases, an audio circuit is provided for television audio or the like. However, when displaying an output video signal from a personal computer for use in a conference or the like, audio is often unnecessary,
In that case, useless power is consumed in the audio circuit.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has as its object to provide means for reducing unnecessary power consumption in a liquid crystal projector with an audio circuit.

[0004]

A liquid crystal projector for projecting and displaying an image such as a video signal of a television on a screen by using a liquid crystal panel and amplifying an audio signal of the television by incorporating an audio circuit and outputting the amplified signal to a speaker. A voice detection unit that detects the presence or absence of the input of the voice signal and outputs a voice detection signal, and a power supply control unit that controls on / off of the power of the voice circuit based on the detected voice detection signal, If there is no audio signal input, the power of the audio circuit is turned off.

[0005] The audio detection section detects the presence or absence of connection of an audio signal input connector, and outputs an audio detection signal based on the detection result.

The detection of the presence or absence of the connection of the input connector is performed by short-circuiting two vacant terminals provided in the input connector, and detecting whether the two terminals are opened or short-circuited on the receiving side.

[0007] The sound detection section detects the setting state of the sound volume, and outputs a sound detection signal depending on whether the sound volume is set to the sound 0 state.

[0008] The sound detection section detects the setting state of the sound mute, and outputs a sound detection signal depending on whether or not the sound mute is set.

The sound detection unit is provided with a logical sum unit for calculating a logical sum of a detection signal indicating the presence or absence of connection of an input connector for a sound signal, a signal for setting a sound volume to a sound 0 state, and a sound mute setting signal. The logical sum is output as a voice detection signal.

The power supply control section of the audio circuit is controlled using an MPU, and the logical sum is obtained by the MPU.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic block diagram of an audio circuit portion of an embodiment of a liquid crystal projector according to the present invention. A liquid crystal projector (not shown) for projecting and displaying an image such as a video signal of a television on a screen by using a liquid crystal panel, amplifies the audio signal S1 of the television or the like, and a speaker 3
The audio circuit 2 for outputting the audio signal is built-in. However, when there is no audio signal, the power consumed by the audio circuit 2 is wasted. Therefore, the presence or absence of the input of the audio signal S1 is detected by using the MPU 5 or the like, and when there is no audio signal, the power supply control unit 4 that controls on / off of the power of the audio circuit 2 causes the power supply voltage V1 To be cut.

The audio detector detects the presence or absence of the connection of the input connector 1 for the audio signal S1. When the input connector 1 is not connected, it can be determined that there is no audio signal. Specifically, for example, two vacant terminals of the input connector are short-circuited and the receiving side detects the release of the two terminals or the short circuit by the MPU 5, and when the two terminals are released, the sound signal of the audio signal is output. There can be no connection.

Alternatively, the sound of the sound from the remote
When the down signal is received by the MPU 5 and the audio volume of the audio circuit is controlled by the MPU 5, the audio volume setting state is detected by the MPU 5 and the audio signal is set to the audio 0 state when the audio volume is set to the audio 0 state. As a result, the power supply of the audio circuit 2 is cut off. Alternatively, the audio mute setting state from the remote
When it is detected in step 5 that the audio mute is set, the power of the audio circuit 2 can be turned off.

Further, the MPU 5 determines whether or not the input connector for the audio signal is connected, and determines whether the audio volume of the audio volume is zero.
The state and the setting of the audio mute are detected, the logical sum of these signals is obtained, and the power supply of the audio circuit 2 is cut off by the logical sum.

[0015]

According to the liquid crystal projector of the present invention, an image such as a video signal of a television is projected and displayed on a screen using a liquid crystal panel, and an audio circuit is built in to amplify the audio signal of the television and output to a speaker. A voice detection unit that detects the presence or absence of a signal input and outputs a voice detection signal; and a power supply control unit that controls on / off of the power of the voice circuit based on the detected voice detection signal. If there is no power supply, the power of the audio circuit is turned off, so that useless power consumption can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an audio circuit portion of an embodiment of a liquid crystal projector according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Input connector 2 Audio circuit 3 Speaker 4 Power supply control unit 5 MPU 6 Remote controller S1 Audio signal V1 Power supply voltage

Claims (7)

[Claims] 1. A liquid crystal projector that projects and displays an image such as a video signal of a television on a screen using a liquid crystal panel, and amplifies an audio signal or the like of the television by incorporating an audio circuit and outputs the amplified signal to a speaker. A voice detection unit that detects the presence or absence of a signal input and outputs a voice detection signal; and a power supply control unit that controls on / off of the power of the voice circuit based on the detected voice detection signal. A liquid crystal projector device wherein the power supply of the audio circuit is turned off when there is no audio circuit. 2. The liquid crystal device according to claim 1, wherein the audio detector detects whether or not the audio signal input connector is connected, and outputs an audio detection signal based on a result of the detection. Projector device. The detection of the presence or absence of connection of the input connector is performed by short-circuiting two empty terminals provided in the input connector and detecting whether the two terminals are open or short-circuited on the receiving side. 3. The liquid crystal projector device according to claim 2, wherein: 4. The sound detection unit according to claim 1, wherein the sound detection unit detects a setting state of the sound volume and outputs a sound detection signal depending on whether the sound volume is set to a sound 0 state. The liquid crystal projector device as described in the above. 5. The liquid crystal projector device according to claim 1, wherein the audio detector detects a setting state of the audio mute and outputs an audio detection signal depending on whether the audio mute is set. . 6. A sound detection unit, comprising: a detection signal for the presence or absence of connection of an input connector of a sound signal; a signal for setting a sound volume to a sound 0 state; 2. The liquid crystal projector device according to claim 1, wherein the logical sum is provided as a sound detection signal. 7. The liquid crystal projector device according to claim 6, wherein the power supply control unit of the audio circuit is controlled using an MPU, and the logical sum is obtained by the MPU.