JP2013080090A - Projection type display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption without impairing convenience even in a state where a light source is turned on in a projection display device having a function of temporarily turning off a projected image.
A projection display device having a function of temporarily disabling a projected image, a liquid crystal panel that modulates light from a light source in accordance with a drive signal, and an input image signal that includes the liquid crystal Video signal processing means for generating a signal for driving the panel; power supply means for supplying power to each unit; and power supply control means for controlling power supply from the power supply means, in the non-display state, The power supply of the video signal processing means is stopped while the power supply of the liquid crystal panel is supplied.
[Selection] Figure 1

Description

  The present invention relates to a projection display device, and more particularly to driving a video signal processing circuit and a liquid crystal panel when a projected image is temporarily hidden (blank).

  The projection display device has a function (a blank function) for temporarily hiding an image on the screen. This blank function is a function that supports the presentation by temporarily hiding the video on the screen, such as when the presenter in the presentation wants to warp the audience's line of sight in addition to the projected video.

  The normal blank function is realized by projecting an all black image regardless of the input video signal. Also, the light source is often left on so that the input video signal can be projected immediately.

  In addition, there is a projection display device having a power management mode function. The power management mode function is a function that helps save power by automatically turning off the lamp when there is no signal input for a certain period of time. In addition, some projection display devices are equipped with a light source (eg, a high-pressure mercury lamp) that has a lifetime such as luminance deterioration and non-lighting due to destruction, and the power management mode function also helps to improve the life of the light source. Fulfill.

  Patent Document 1 discloses a technique for minimizing the light source power when there is no input signal, when there is an input video signal but the input video is not projected, or when the input video is an all-black video. .

  Patent Document 2 discloses a technique for reducing the luminance of a light source when it is detected that input video signal input has been interrupted in a projection display device including a light source composed of a solid light source element (such as an LED or a laser). Is disclosed.

JP 2006-025054 A JP 2007-334092 A

  In the blank function and the power management mode, since it is not necessary to project an image, the power consumed by the light source lighting and the image signal processing circuit is basically wasted power. For this reason, the power management function realizes power reduction by turning off the light source.

  However, since both functions are based on the assumption that the input signal is projected again, when the light source is turned off, the light source is turned on again in a short time.

  When a high-pressure mercury lamp or the like is used as a light source, repeated lighting and extinguishing in a short time leads to a shortened life of the light source. Further, when the light is turned on again after the light is turned off, the light source may not be turned on unless the light source is cooled to a certain temperature.

  In addition, since it takes time until the brightness is stabilized depending on the light source, it takes time until the projected image is stabilized when the projection of the input image signal is resumed.

  For this reason, the prior art discloses a technique that realizes a reduction in power without deteriorating convenience by reducing the brightness without turning off the light source (power is reduced).

  However, in recent years, the projection display device has a large amount of digital signal processing due to high image quality and high functionality, such as digitization of input signals, higher resolution, higher gradation, advanced color management technology, and keystone distortion correction. It is increasing. For this reason, a large number of digital ICs operating at high speed are mounted, and as a result, power consumption other than light sources tends to increase.

  In the prior art disclosed in the above-mentioned patent document, only the power consumption of the light source is reduced. Therefore, in order to further reduce the power consumption, a video signal processing circuit, a liquid crystal panel, and a driving circuit for the liquid crystal panel are used. It is also necessary to reduce power consumption.

  However, if the power supply of the video signal processing circuit, the liquid crystal panel, and the liquid crystal driving circuit is simply stopped while the light source is turned on, an unnecessary video is displayed in the projected video. For example, when the liquid crystal panel is normally white, if the power supply to the liquid crystal panel is stopped, the light source is turned on and the projected image is displayed in all white.

  Accordingly, an object of the present invention is to provide a projection display device that can reduce power consumption without impairing convenience even when a light source is turned on.

  In order to achieve the above object, a projection display device having a function of temporarily disabling a projection image, a liquid crystal panel that modulates light from a light source according to a drive signal, and an input image signal Video signal processing means for generating a signal for driving the liquid crystal panel, power supply means for supplying power to each unit, and power supply control means for controlling power supply from the power supply means, In the display state, the power supply of the video signal processing means is stopped while the power of the liquid crystal panel is supplied.

  An object of the present invention is to provide a projection display apparatus that can reduce power consumption without impairing convenience even when a light source is turned on.

1 is a block diagram showing a system configuration of a projection display apparatus according to Embodiment 1. FIG. The figure which shows the flowchart of the projection type display apparatus in Example 1. FIG. The figure which shows the relationship between the applied voltage and the transmittance in the liquid crystal panel

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[Example 1]
FIG. 1 shows a system configuration of a projection display apparatus according to the first embodiment.

  In FIG. 1, the video signal processing circuit 3 converts an external input video signal 10 into a predetermined video signal 11. For example, when the input video signal 10 is an analog RGB signal, it is converted into a digital signal by AD conversion, and the video size is scaled as necessary.

  When the input video signal 10 is a digital signal such as DVI or HDMI, decoding is performed according to each format, and scaling is performed as necessary.

  The liquid crystal drive signal generation circuit 4 generates a liquid crystal drive signal 12 for driving the liquid crystal panel 7 from the video signal 11 generated by the video signal processing circuit 3. Depending on the type of the liquid crystal panel 7, the digital data is again D / A converted and driven by an analog signal.

  In the liquid crystal panel 7, the light from the light source is modulated by changing the transmittance (or reflectance) according to the liquid crystal drive signal 12.

  The light transmitted (or reflected) through the liquid crystal panel 7 is enlarged and projected by the projection lens 8 to display an image corresponding to the input video signal 10 on the screen.

  The power generation circuit 1 converts AC power input from the AC cable 101 into DC power and supplies power to each unit.

  The control circuit 2 is usually composed of a CPU such as a microcomputer, and controls the supply of power generated by the power generation circuit 1. The power control signal A24 and the power control signal B25 control power supply to the video signal processing circuit and the liquid crystal drive signal generation circuit 4.

  The ballast control signal 26 controls power supply to the light source 6 and performs not only lighting / extinguishing control but also power mode control. Common projection display devices are equipped with an eco-mode that turns on the light source with lower power than during normal projection, aiming to reduce power consumption and extend the life of the light source instead of making the projected image darker than normal. Is the projected mode.

  The ballast 5 performs control and power supply for turning on and off the light source 6. When a lighting instruction is received by the ballast control signal 26 from the control circuit 2, a high-voltage pulse necessary for lighting the light source 6 is generated, and a constant power is supplied after the lighting is started. Also, when receiving the above-described eco-mode instruction, control for adjusting the power is also performed.

  Next, the operation in the first embodiment will be described. FIG. 2 is a flowchart showing a series of flows from the start of the non-display mode of the projection display apparatus to the end of the non-display mode canceling operation.

  When the non-display mode of the projected image is started by the blank function or the power management function, first, the non-display image is written on the liquid crystal panel 7 in step S01. Normally, the non-display image is all black display, but the present invention is not limited to this.

  Since the liquid crystal panel 7 performs an operation to write the liquid crystal drive signal 12 from the liquid crystal drive signal generation circuit 4 as needed, a separate circuit for switching the input of the drive signal to a fixed voltage is prepared, and scanning is always performed at the fixed voltage. Thus, a non-display image can be displayed. FIG. 3 shows a general relationship between applied voltage and transmittance (reflectance) of a liquid crystal panel. The mode of the liquid crystal panel usually has two modes, normally black and normally white, which are divided according to transmittance (reflectance) when no voltage is applied.

  Normally black has a low transmittance (reflectance) when no voltage is applied, so that light from the light source is blocked and the projected image is black. On the other hand, normally white is a white projected image when no voltage is applied.

  When the drive signal input is switched to a fixed voltage, by setting the applied voltage according to the mode of the liquid crystal panel 7, a non-display image can be projected even on a normally white liquid crystal panel.

  The liquid crystal panel 7 may be provided with a circuit for switching input of drive signals or an equivalent function.

  By switching the input of the drive signal, even if the power supply to the liquid crystal drive signal generation circuit 4 is stopped, the projected image can be prevented from being disturbed, and the user can switch to the non-display image without feeling uncomfortable.

  After the drive signal is switched, the control circuit 2 issues a dimming command to the ballast 5, and the ballast 5 reduces the output power to dimm the light source 6 (step S02).

  The power supply to the video signal processing circuit 3 and the liquid crystal drive signal generation circuit 4 is stopped by the power control signal A24 and the power control signal B25 (step S03).

  With the above control, a non-display mode in which both the light source power and the video display system power are reduced can be realized.

  When the non-display mode is canceled due to the return from the blank function or the detection of the video input signal in the power management function (step S04), power is first supplied to the circuit whose power supply was stopped in step S03. Resume (step S05).

  The video signal processing circuit 3 and the liquid crystal drive signal generation circuit 4 need to be initialized after starting normal power supply, such as a reset operation for stabilizing the operation and initial value setting for the register (step S06). ). Depending on the circuit configuration (IC specifications), circuit initialization may not be necessary.

  After the operations of the video signal processing circuit 3 and the liquid crystal drive signal purification circuit 4 are stabilized, the light source 6 is released from the dimming and returned to the normal projection brightness (step S07).

  Finally, it is possible to return from the non-display mode by switching the input signal of the liquid crystal panel 7 to the drive signal 12 from the liquid crystal drive signal generation circuit 4.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

DESCRIPTION OF SYMBOLS 1 Power supply circuit 2 Control circuit 3 Video signal processing circuit 4 Liquid crystal drive signal generation circuit 5 Ballast 6 Light source 7 Liquid crystal panel 8 Projection lens 9 Optical unit 10 Input video signal 11 Video signal 12 Liquid crystal drive signal 20 Ballast power supply 21 Video signal processing circuit Power supply 22 LCD drive signal purification circuit power supply 23 LCD panel power supply 24 Power supply control signal A
25 Power control signal B
26 Ballast control signal 100 Projection display 101 AC cable

Claims (1)

A projection display device having a function to temporarily hide a projected image,
A liquid crystal panel that modulates the light from the light source according to the drive signal;
Video signal processing means for generating an input video signal for driving the liquid crystal panel; and
Power supply means for supplying power to each unit;
Power supply control means for controlling power supply from the power supply means,
In the non-display state, the power supply of the video signal processing means is stopped while the power of the liquid crystal panel is supplied.