JP2007264394A - Projection type video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type video display device capable of shortening the time required until a user can confirm the display of a screen by improving the brightness of the screen when starting a lamp for a light source. <P>SOLUTION: The projection type video display device displaying a video by modulating light from the lamp for the light source 4 based on a video signal and projecting the light is equipped with a brightness adjusting circuit 7 for adjusting the brightness of the video signal obtained when starting the lamp so that the brightness of an input video signal SIG_IN may be inversely corrected concerning the rising curve of the brightness obtained when starting the lamp for the light source 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projection display apparatus such as a liquid crystal projection television.

  A simplified configuration diagram of this type of conventional apparatus is shown in FIG. Since this diagram is a simplified configuration diagram for explaining the system configuration according to the present application, optical components of the color separation system and the color synthesis system are omitted, and only one liquid crystal panel is shown.

  In FIG. 5, the liquid crystal panel 1 is driven by a panel control signal SIG_OUT obtained by processing the input video signal SIG_IN for panel driving by the video signal processing circuit 3 controlled by the microcomputer 2. The light emitted from the light source lamp 4 is modulated and transmitted by the liquid crystal panel 1 based on the video signal, is enlarged and projected on the screen 6 by the projection lens 5, and is displayed as an image.

The relationship between the brightness (Y) of the input video signal SIG_IN and the panel control signal SIG_OUT is not subjected to any special correction related to brightness, as shown in the following (Equation 1).
Y (SIG_OUT) = Y (SIG_IN) (Formula 1)

  In general, the change in illuminance at the start-up of this type of light source lamp follows a locus as shown in FIG. The display screen illuminance obtained when the input video signal SIG_IN having a constant brightness level is input to the display device having the light source lamp as described above is substantially the same as the illuminance change of the lamp and is shown in FIG. Will follow the trajectory. In other words, when starting up with a certain brightness level, for example, a 50% white screen displayed, the change in screen illuminance becomes almost the same curve as the change in lamp brightness.

Patent Document 1 discloses a lamp lighting device in which the rise and fall of the lamp driving current during AC driving of the discharge lamp is minimized and suppresses the occurrence of light and darkness in the light amount of the discharge lamp, and a projector using the same. Has been.
JP 2003-282285 A (H05B 41/18)

  By the way, in general, in a projection type video display device such as a liquid crystal projection television that uses a discharge lamp such as a UHP lamp, compared to a direct view type liquid crystal television or a plasma display, the rise of the illuminance of the light source lamp is gradual. The time until the user can confirm the display is said to be slow.

  The technique disclosed in Patent Document 1 is a technique for controlling the lamp itself during AC driving after starting the discharge lamp, and thus cannot solve the above-described problem at the time of starting the lamp.

  Accordingly, the present invention has been made to solve such a problem, and the brightness of the screen when the light source lamp is activated can be improved, and the time until the user can confirm the screen display can be shortened. An object of the present invention is to provide a projection display apparatus.

  In order to achieve the above object, the invention according to claim 1 of the present application provides a projection-type image display apparatus that displays an image by modulating and projecting light from a light source lamp based on an image signal. Brightness adjusting means for adjusting the brightness of the video signal at the time of starting the lamp so as to reversely correct the brightness of the input video signal with respect to the brightness rising curve at the time of starting the light source lamp. It is a feature.

  The invention according to claim 2 is characterized in that the brightness adjusting means manages an elapsed time from the start of lamp activation and gradually reduces the brightness correction level of the video signal in accordance with the elapsed time. It is.

  The invention according to claim 3 is a temperature sensor for detecting the temperature of the lamp for light source, and controls the degree of brightness adjustment by the brightness adjusting means according to the lamp temperature at the start of lamp start detected by the temperature sensor. And a control means for controlling.

  The invention according to claim 4 includes a first temperature sensor disposed in the vicinity of the light source lamp and a second temperature sensor for detecting an outside air temperature, and the control means includes the first temperature sensor. The lamp temperature is judged to be higher as the value obtained by subtracting the temperature detected by the second temperature sensor from the detected temperature is determined, and the brightness adjustment degree by the brightness adjusting means is controlled.

  According to the first aspect of the present invention, the brightness of the video signal at the start of the lamp is adjusted so as to reversely correct the brightness of the input video signal with respect to the brightness rising curve at the start of the light source lamp. By adjusting, the brightness of the screen when the light source lamp is activated can be improved, and the time until the user can confirm the screen display can be shortened.

  According to the second aspect of the present invention, the brightness correction level of the video signal is gradually reduced in accordance with the elapsed time from the start of lamp start, so that the brightness correction level in accordance with the elapsed time from the start of lamp start. Therefore, even if the brightness of the video signal is corrected, there is no sense of incongruity.

  According to the third aspect of the present invention, by controlling the brightness adjustment degree (correction coefficient) by the brightness adjusting means according to the lamp temperature at the start of lamp start detected by the temperature sensor, the lamp at the time of lamp start-up is controlled. Brightness adjustment can be performed according to the temperature without any sense of incongruity.

  According to invention of Claim 4, lamp temperature is so large that the value which deducted the detection temperature by the 2nd temperature sensor which detects external temperature from the detection temperature by the 1st temperature sensor arrange | positioned in the vicinity of the lamp | ramp for light sources is large. By controlling the brightness adjustment level by the brightness adjustment means, the temperature in the vicinity of the light source lamp is affected by the outside air temperature. The degree of brightness adjustment by the height adjusting means can be controlled more accurately.

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

  FIG. 1 is a simplified configuration diagram showing a projection type video display apparatus such as a liquid crystal projection television as an embodiment of the present invention. The same reference numerals as those in FIG. 5 denote the same or corresponding parts.

  In FIG. 1, the basic configuration and operation until an image is displayed are substantially the same as those of the prior art shown in FIG. That is, the liquid crystal panel 1 is driven by the panel control signal SIG_OUT ′ obtained by processing the input video signal SIG_IN for panel driving by the video signal processing circuit 3 controlled by the microcomputer 2. The light emitted from the light source lamp 4 is modulated and transmitted by the liquid crystal panel 1 based on the video signal, is enlarged and projected on the screen 6 by the projection lens 5, and is displayed as an image.

The difference from the prior art shown in FIG. 5 is that the brightness adjustment circuit 7 can correct the brightness (Y) of the video signal in accordance with, for example, the following (Equation 2) in order to compensate for the brightness at the time of starting the lamp. Is included in the video signal processing circuit 3, and a first temperature sensor 8 that detects the temperature in the vicinity of the light source lamp 4 in the casing of the apparatus and a second temperature that detects the outside air temperature outside the casing. These temperature sensors 9 are connected to the microcomputer 2.
Y (SIG_OUT ′) = Y (SIG_IN) + Y (SIG_IN) × (correction coefficient K− (correction coefficient K / correction duration t (seconds)) × elapsed time n) × 0.01 (Expression 2)
However, correction is performed every second, and correction is not performed after t seconds.

  As a result, the offset value set by the correction coefficient K is added to the input video signal SIG_IN only during the correction duration t (seconds) with respect to the brightness (Y), and the liquid crystal panel 1 is used as the panel control signal SIG_OUT ′. Will be output. Further, the correction amount decreases for each correction, and after t seconds, the brightness level of the input video signal is output without being corrected.

Next, a specific example is shown. Here, the following values are assumed as the parameters.
≪Without correction≫
Constant at Y (SIG_IN) = 512 (10-bit digital value and center value) Correction coefficient K = 0 (no correction), correction duration t (seconds) = 60
≪With correction≫
Constant at Y (SIG_IN) = 512 (10-bit digital value and center value) Correction coefficient K = 25 (with correction), correction duration t (seconds) = 60

When correction is performed, the value of Y (SIG_OUP ') for the first correction after 1 second of lighting (start of lamp activation) is calculated by the following formula.
Y (SIG_OUT ′) = 512 + 512 × (25− (25/60) × 1) × 0.01
= 637.9
The second time
Y (SIG_OUT ′) = 512 + 512 × (25− (25/60) × 2) × 0.01
= 635.7
The 60th
Y (SIG_OUT ′) = 512 + 512 × (25− (25/60) × 60) × 0.01
= 512

  FIG. 2 is a table showing the brightness levels of the panel control signal SIG_OUP ′ when not corrected and when corrected as described above.

  In this way, by correcting the video signal for a certain period immediately after lighting, the actual (uncorrected) brightness of the screen is offset to the original (uncorrected) brightness, as shown in FIG. Follow the trajectory. This means that the brightness for a certain period after lighting is moving in a bright direction.

  Therefore, the brightness of the screen at the time of starting the light source lamp is improved, and the time until the user can confirm the screen display can be shortened. In addition, by gradually reducing the brightness correction level of the video signal according to the elapsed time from the start of lamp activation, the brightness correction level gradually decreases according to the elapsed time from the start of lamp startup. Even if the brightness of the signal is corrected, there is no sense of incongruity.

  On the other hand, the brightness change of the lamp illuminance when the lamp is lit (when the lamp is activated) shows different changes when the lamp 4 is at a normal temperature and when the lamp is at a high temperature. . Therefore, if the same correction coefficient K is used when the lamp 4 is at room temperature and at high temperature, the brightness at high temperature becomes too bright and the image becomes uncomfortable. For this reason, in the present embodiment, for example, K = 25 at normal temperature and K = 15 at high temperature is used to compensate for this by using different values for the correction coefficient K. In this way, by adjusting the degree of brightness adjustment (correction coefficient K) by the brightness adjustment circuit 7 according to the lamp temperature at the start of lamp start-up, brightness adjustment without a sense of incongruity according to the lamp temperature at the time of lamp start-up is performed. It can be performed.

  Specifically, the temperature state of the lamp at the time of lighting (starting of lamp activation) is estimated by the difference between the first temperature sensor 8 disposed in the vicinity of the lamp and the second temperature sensor 9 for detecting the outside air temperature. It is assumed that the microcomputer (control means) determines that the lamp temperature is higher as the difference is larger. That is, when the difference Δt = Temp−Temp2 when the first temperature sensor 8 indicates Temp1 and the second temperature sensor 9 indicates Temp2, the value of the difference Δt and the correction coefficient K is previously set as a table value. By storing in the nonvolatile memory, the value of the correction coefficient K can be easily obtained from a table value prepared in advance based on the difference Δt.

  By doing so, the temperature in the vicinity of the light source lamp 4 is influenced by the outside air temperature to some extent, so that the lamp temperature is recognized more accurately and the brightness adjustment degree by the brightness adjustment circuit 7 (correction coefficient K). Can be controlled more accurately.

  The projection display apparatus according to the present invention is not limited to a liquid crystal projection television using a liquid crystal panel, but can be applied to a projection display apparatus having another image light generation system. That is, the present invention can be applied to a front projection type video display device in addition to a rear projection type. The present invention can also be applied to a DLP (Digital Light Processing; registered trademark of Texas Instruments (TI)) system.

BRIEF DESCRIPTION OF THE DRAWINGS The simplified block diagram which shows projection type video display apparatuses, such as a liquid crystal projection television, as one Embodiment of this invention. The figure which showed the brightness level of the panel control signal in the case of correction | amendment with and without correction | amendment as a table | surface. The figure which plotted and showed the illumination intensity transition of the lamp | ramp with and without correction | amendment. The graph which showed the temperature dependence of the lamp illuminance (when the lamp temperature is normal temperature and high temperature) in a graph. The simplified block diagram of the conventional apparatus. The figure which showed the lamp illumination intensity transition at the time of lamp starting in the graph. The figure which showed the screen illuminance transition at the time of lamp starting in the graph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal panel 2 Microcomputer 3 Video signal processing circuit 4 Light source lamp 5 Projection lens 6 Screen 7 Brightness adjustment circuit 8 1st temperature sensor 9 2nd temperature sensor

Claims (4)

In a projection display apparatus for displaying an image by modulating and projecting light from a light source lamp based on an image signal,
Brightness adjusting means for adjusting the brightness of the video signal at the time of starting the lamp so as to reversely correct the brightness of the input video signal with respect to the brightness rising curve at the time of starting the light source lamp. A projection-type image display device.   2. The projection type image display according to claim 1, wherein the brightness adjusting means manages an elapsed time from the start of lamp activation and gradually reduces the brightness correction level of the video signal in accordance with the elapsed time. apparatus.   A temperature sensor for detecting the temperature of the lamp for the light source; and a control means for controlling the degree of brightness adjustment by the brightness adjustment means in accordance with the lamp temperature detected by the temperature sensor at the time of starting the lamp. The projection display apparatus according to claim 1 or 2, wherein   A first temperature sensor disposed in the vicinity of the light source lamp; and a second temperature sensor for detecting an outside air temperature, wherein the control means determines the second temperature from the temperature detected by the first temperature sensor. 4. The projection display apparatus according to claim 3, wherein the brightness adjustment degree by the brightness adjusting means is controlled by determining that the lamp temperature is higher as the value obtained by subtracting the temperature detected by the temperature sensor is larger.

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