JP2009003318A - Image display and control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display capable of restraining glaringness felt when restored from an image muting state, and a control method therefor. <P>SOLUTION: An input image gets bright stepwise at 0.2 sec intervals, when a muting key is operated after continuing the A/V muting state for a prescribed time T1 (10 sec.) or more, and is displayed at an inherent brightness after about 1.8 sec. Meanwhile, the input image is displayed instantaneously at the inherent brightness, when the muting key is operated before a time of continuing the A/V muting state reaches the prescribed time T1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image display device that displays an image according to input image information and a control method thereof.

  An image display device such as a projector is known that has an image mute function for temporarily stopping image display (see, for example, Patent Document 1). This image mute function is used, for example, when you are giving a presentation while displaying an image and you do not want to show the audience the process of switching files, or if you want to focus the audience on the presenter's explanation. Yes. In the image display device described in Patent Document 1, a user can display a black image or the like instead of a normal image by instructing image mute via a user interface. Further, the user can return to a state in which a normal image is displayed by instructing cancellation of the image mute via the user interface.

JP 2003-280087 A

  However, if the image mute state, that is, the state where the black image is displayed continues for a long time and the eyes get used to the dark environment, a bright image is displayed suddenly when the image mute is released, and the user is strongly dazzled. There was a case where I felt it.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 An image display device according to this application example includes a display unit that displays an image based on input image information, and a display state of the display unit, in which the image is displayed with a predetermined brightness. A mute unit that switches from a display state to a dark display state darker than the normal display state, a time measuring unit that measures a duration after the mute unit switches to the dark display state, and a display state of the display unit, A mute return unit for returning from the dark display state to the normal display state, and when the mute return unit returns to the normal display state, the longer the duration measured by the time measuring unit, The display state of the display unit is gradually brightened over time.

  According to this image display device, when the mute return unit returns to the normal display state, the longer the dark display state continues, the slower the display state of the display unit becomes brighter over time. It is possible to suppress glare caused by sudden brightening from the dark display state. On the other hand, the shorter the duration of the dark display state, the shorter the time required for the return, so that it is possible to suppress the feeling of waiting until the return.

  Application Example 2 In the image display device according to the application example described above, the image display device further includes an audio output unit that outputs audio corresponding to input audio information, and the mute unit changes the display state of the display unit to the normal display state. The output state of the sound output unit is changed from a normal sound volume state where the sound is output at a predetermined sound volume level to a low sound volume state whose sound volume level is smaller than the normal sound volume state. Preferably, the mute return unit gradually increases the volume level from the low volume state to return to the normal volume state as the display state of the display unit returns to the normal display state. .

  According to this image display device, as the mute return unit returns to the normal display state, the volume level is slowly increased to return to the normal volume state. It is possible to suppress the user from being surprised when the level returns.

  Application Example 3 In the image display device according to the application example, the display unit modulates light emitted from the light source and the light source according to the image information to form image light. And a projection optical system that enlarges and projects the image light formed by the light modulation device and displays the image on a projection surface.

  This image display apparatus is often used when displaying a large screen in a dark environment because the display unit is configured to display an image on a projection plane by enlarging and projecting image light. In this case, when the display state suddenly becomes brighter, the user can more easily feel the glare, so that the suppression of the glare by slowly brightening the display state becomes even more effective.

  Application Example 4 In the image display device according to the application example, the mute unit and the mute return unit switch between the normal display state and the dark display state by adjusting the gradation represented by the image information. It is desirable.

  According to this image display apparatus, when adjusting the gradation represented by the image information, the brightness of the light source that takes time to reach a stable light emission state is changed in order to switch between the normal display state and the dark display state. Compared to the above, the brightness of the display state can be easily controlled.

  Application Example 5 A method for controlling an image display device according to this application example includes a display unit that displays an image according to input image information, and the display state of the display unit is determined so that the image has a predetermined brightness. A first display step of switching from the normal display state to the dark display state, and a control method of the image display device capable of switching from the normal display state to a dark display state darker than the normal display state; A second step of accepting an instruction for returning from the dark display state to the normal display state; a third step of measuring a time until the instruction is received after switching to the dark display state; and according to the instruction A fourth step of returning from the dark display state to the normal display state, and in the fourth step, when returning to the normal display state, the third step The longer the Oite measured the time, characterized by bright gradually over a display state of the display unit time.

  According to this control method, when returning to the normal display state, the longer the dark display state lasts, the slower the display state of the display unit becomes brighter over time. It is possible to suppress glare caused by brightening. On the other hand, the shorter the duration of the dark display state, the shorter the time required for the return, so that it is possible to suppress the feeling of waiting until the return.

  In addition, when the above-described image display device and its control method are constructed using a computer (CPU) provided in the image display device, the above-described form and the application example are programs for realizing the functions. Alternatively, the program may be configured in a recording medium or the like in which the program is recorded so as to be readable by the computer. Recording media include flexible disks, CD-ROMs, magneto-optical disks, IC cards, ROM cartridges, punch cards, printed matter on which codes such as barcodes are printed, internal storage devices of image display devices (memory such as RAM and ROM) ), And an external storage device can be used.

(First embodiment)
Hereinafter, as a first embodiment of an image display device, a projector that projects an image (input image) based on input image information and displays the input image on a screen, a wall surface, or the like will be described. The projector according to the present embodiment can temporarily stop the display of the input image in accordance with a user instruction.

FIG. 1 is a block diagram illustrating a schematic configuration of a projector according to the present embodiment.
As shown in FIG. 1, the projector 1 includes an image projection unit 10, a control unit 20, a storage unit 21, an operation panel 22, a remote controller 23, an operation signal reception unit 24, an image signal input unit 31, an image processing unit 32, and a light source control. A unit 33, an audio signal input unit 41, an audio signal processing unit 42, an audio output unit 43, two speakers 44L and 44R, and the like.

  The image projection unit 10 includes a light source 11, three liquid crystal light valves 12 R, 12 G, and 12 B as light modulation devices, a projection lens 13 as a projection optical system, a light valve drive unit 14, and the like, and is emitted from the light source 11. The image light is modulated by the liquid crystal light valves 12R, 12G, and 12B to form image light, and the image light is projected from the projection lens 13 to function as a display unit that displays an image on the screen SC or the like.

  The light source 11 includes a discharge-type light source lamp 11a made of a high-pressure mercury lamp, a metal halide lamp, or the like, and a reflector 11b that reflects light emitted from the light source lamp 11a toward the liquid crystal light valves 12R, 12G, and 12B. Yes. Light emitted from the light source 11 is converted into light having a substantially uniform luminance distribution by an integrator optical system (not shown), and red (R), green (G), and blue, which are the three primary colors of light, by a color separation optical system (not shown). After being separated into each color light component of (B), it enters the liquid crystal light valves 12R, 12G, and 12B, respectively.

  The liquid crystal light valves 12R, 12G, and 12B are configured by a liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates. The liquid crystal light valves 12R, 12G, and 12B are formed with a plurality of pixels arranged in a matrix, and a driving voltage can be applied to the liquid crystal for each pixel. When the light valve driving unit 14 applies a driving voltage corresponding to the input image information to each pixel, each pixel is set to a light transmittance corresponding to the image information. Therefore, the light emitted from the light source 11 is modulated by passing through the liquid crystal light valves 12R, 12G, and 12B, and image light corresponding to image information is formed for each color light. The formed image light of each color is synthesized for each pixel by a color synthesis optical system (not shown) to become image light representing a color image, and then enlarged and projected onto the screen SC or the like by the projection lens 13.

  The control unit 20 includes a CPU (Central Processing Unit), a RAM (Random Access Memory) used for temporary storage of various data, and the like, and operates according to a control program stored in the storage unit 21 to operate the projector 1. Centrally control the operation. That is, the control unit 20 functions as a computer together with the storage unit 21. In addition, the control unit 20 is provided with a timer 20a as a time measuring unit in order to measure time required for various controls.

  The storage unit 21 includes a non-volatile memory such as a mask ROM (Read Only Memory), a flash memory, or an FeRAM (Ferroelectric RAM). The storage unit 21 stores a control program for controlling the operation of the projector 1, various setting data for defining operation conditions of the projector 1, and the like.

  The operation panel 22 and the remote controller 23 correspond to an input operation unit that receives an input operation from the user, and include a plurality of operation keys for the user to give various instructions to the projector 1. The operation keys provided on the operation panel 22 and the remote controller 23 include a “power key” for switching power on / off, a “menu key” for displaying a menu image for performing various settings, a cursor movement in the menu image, and the like. There are a “cursor key”, a “mute key” for temporarily stopping image display and sound output, a “volume up key” for adjusting the sound volume level, a “volume down key”, and the like. When the user operates various operation keys on the operation panel 22, the operation panel 22 outputs an operation signal corresponding to the operation content of the user to the control unit 20. When the user operates various operation keys of the remote controller 23, the remote controller 23 emits an infrared operation signal corresponding to the user's operation content, and the operation signal receiving unit 24 receives this and transmits it to the control unit 20.

  The image signal input unit 31 includes various connection terminals for connecting to an external image supply device (not shown) such as a PC (personal computer) or a video reproduction device via a cable. Image signal is input. The image signal input unit 31 converts the input image signal into image information (image data) in a format that can be processed by the image processing unit 32, and outputs the image data to the image processing unit 32. Here, the image data output from the image signal input unit 31 is generated for each color light of R, G, and B, and is based on a plurality of pixel values corresponding to all the pixels of the liquid crystal light valves 12R, 12G, and 12B. It is configured. The pixel value determines the light transmittance of the corresponding pixel, and the intensity (gradation) of light emitted from each pixel is defined by the pixel value.

  The image processing unit 32 adjusts brightness, contrast, sharpness, hue, and various image quality adjustments such as gamma correction for the image data input from the image signal input unit 31 based on instructions from the control unit 20. Apply. The image data whose image quality has been adjusted by the image processing unit 32 is output to the light valve driving unit 14.

  When the light valve driving unit 14 drives the liquid crystal light valves 12R, 12G, and 12B according to the input image data, the liquid crystal light valves 12R, 12G, and 12B form image light corresponding to the image data, and the image light is The projection lens 13 projects the image onto the screen SC.

  The light source control unit 33 controls the supply and stop of power to the light source 11 based on an instruction from the control unit 20, and switches between turning on and off the light source 11.

  The audio signal input unit 41 receives an audio signal (audio information) accompanying the image signal from the image supply device. The audio signal input unit 41 converts the input audio signal into an audio signal in a format that can be processed by the audio signal processing unit 42, and outputs this to the audio signal processing unit 42.

  The audio signal processing unit 42 adjusts the output characteristics of the audio signal input from the audio signal input unit 41 based on an instruction from the control unit 20 (for example, volume level adjustment processing, sound quality adjustment processing, etc. ). The audio signal that has been adjusted by the audio signal processing unit 42 is output to the audio output unit 43.

  The audio output unit 43 includes an amplifying circuit (not shown) and the like, and outputs audio based on the audio signal adjusted by the audio signal processing unit 42 from the speakers 44L and 44R. The user can adjust the volume level of the output sound by operating the volume up key and the volume down key provided on the operation panel 22 and the remote controller 23. When the volume up key is operated by the user, the control unit 20 instructs the audio signal processing unit 42 to increase the volume level, and when the volume down key is operated, the control unit 20 instructs to decrease the volume level. .

Next, the operation of the projector 1 will be described.
When the commercial power is turned on to the projector 1 and the power key of the operation panel 22 or the remote controller 23 is operated, the control unit 20 starts an operation according to the control program stored in the storage unit 21, and On the other hand, an instruction for starting image display and audio output is issued. As a result, an image (input image) corresponding to the image signal input from the image supply device is projected from the image projection unit 10, and sound corresponding to the audio signal input from the image supply device is output from the speakers 44L and 44R. The In this specification, the state where the input image is displayed and the sound is output is referred to as a normal state in this specification.

  In this state, the user operates the mute key provided on the operation panel 22 or the remote controller 23 to temporarily stop the display of the input image (image mute) and temporarily stop the output of the audio (audio mute). ). In this specification, the state where both the display of the input image and the output of the sound are stopped is referred to as an A / V mute state. After the mute key is operated to enter the A / V mute state, when the user operates the mute key again, the A / V mute state is canceled and the normal state is restored, and the display of the input image and the output of the sound are resumed. To do.

  FIG. 2 is a flowchart for explaining the operation of the projector 1 when the mute key is operated. When the operation panel 22 or the remote controller 23 accepts the operation of the mute key, the control unit 20 operates according to the flow shown in FIG.

  As shown in FIG. 2, in step S <b> 101, the control unit 20 refers to a flag included in the control unit 20 and determines whether or not it is currently in the A / V mute state. As a result, in the case of the A / V mute state, the process proceeds to step S106, and in the normal state other than the A / V mute state, the process proceeds to step S102.

  When the mute key is operated in the normal state and the process proceeds to step S102, the control unit 20 instructs the image processing unit 32 to output image data representing a black plain image instead of the input image. . In response to an instruction from the control unit 20, the image processing unit 32 sets all pixel values included in the image data to the minimum value (0) so that the light transmittance of all the pixels is minimized. As a result, the image projection unit 10 is hardly irradiated with light, that is, the image projection unit 10 displays a black plain image on the screen SC (image mute state).

  In subsequent step S103, the control unit 20 instructs the audio signal processing unit 42 to output an audio signal representing a silence state instead of the input audio signal, thereby stopping the output of the audio ( Audio mute state). As a result, the A / V mute state in which the display of the input image and the output of the sound are stopped is obtained.

  In step S104, the control unit 20 starts time measurement by the timer 20a in order to measure the duration of the A / V mute state (timer start). In step S105, the control unit 20 changes the flag contents to A The content is rewritten to indicate the / V mute state, and the process is terminated.

  On the other hand, when the mute key is operated in the A / V mute state and the process proceeds to step S106, the control unit 20 stops the timer 20a that started timing in step S104, and in the subsequent step S107, the control unit 20 Based on the time measurement result of the timer 20a, the duration of the A / V mute state, that is, from when the mute key is operated in the normal state to shift to the A / V mute state until the mute key is operated again. It is determined whether or not the time is equal to or longer than a predetermined time T1 (10 seconds in the present embodiment). As a result, when the duration of the A / V mute state is equal to or longer than the predetermined time T1, the process proceeds to step S108, and when it does not reach the predetermined time T1, the process proceeds to step S116.

In steps S108 to S113, the control unit 20 performs processing for canceling the image mute state and restarting display of the input image. In resuming the display of the input image, the control unit 20 instructs the image processing unit 32 to adjust the brightness of the input image when the display is resumed.
FIG. 3 is an explanatory diagram for explaining the adjustment of the brightness of the input image, and is a graph showing input / output characteristics to be applied to the image data input to the image processing unit 32.
As illustrated in FIG. 3, the image processing unit 32 according to the present embodiment includes pixels included in the image data using any one of the 10 input / output characteristics represented by the straight lines L1 to L10. The value can be adjusted (gradation conversion), and the brightness of the input image can be adjusted in 10 steps. Among these, when the input / output characteristic represented by the straight line L1 having the smallest inclination is applied, the pixel value (output level) after adjustment is about 1/10 of the pixel value (input level) before adjustment. The input image is displayed in the darkest state among the above 10 levels. Further, when the input / output characteristic represented by the straight line L2 having the next smallest inclination is applied, the pixel value after adjustment becomes about 2/10 (about 1/5) before the adjustment. As the inclination increases to L4,..., L10, the adjusted pixel value increases and the input image is displayed brightly. Here, when the input / output characteristic represented by the straight line L10 is applied, the pixel value before adjustment and the pixel value after adjustment are the same value, and the input image is the same as when gradation conversion is not performed. In actuality, gradation conversion is not performed.
In step S102, when displaying a black plain image, gradation conversion that outputs 0 for all input levels, that is, gradation conversion by the straight line L0, may be performed.

  Returning to FIG. 2, in step S108, the control unit 20 instructs the image processing unit 32 to perform gradation conversion by the straight line L1 on the input image data, and is the darkest of the above 10 steps. The display of the input image is resumed in the state.

  In step S109, the control unit 20 starts time measurement (timer start) by the timer 20a in order to measure the elapsed time after the brightness of the input image is adjusted by gradation conversion. The unit 20 determines whether or not a predetermined time T2 (0.2 seconds in the present embodiment) has elapsed since the brightness of the input image is adjusted based on the time measurement result of the timer 20a. As a result, when the predetermined time T2 has not elapsed, step S110 is repeated, and when the predetermined time T2 has elapsed, the process proceeds to step S111 and the timer 20a is stopped.

  In subsequent step S112, the control unit 20 instructs the image processing unit 32 to switch the input / output characteristics to be applied so that the input image is brightened by one step. For example, when gradation conversion is performed using the input / output characteristic represented by the straight line L1, the gradation conversion is performed using the input / output characteristic represented by the straight line L2 by switching to the input / output characteristic represented by the straight line L2. If so, the input / output characteristics represented by the straight line L3 are switched. When gradation conversion is performed using the input / output characteristics represented by the straight line L9, the input / output characteristics represented by the straight line L10, that is, the state in which gradation conversion is not performed is switched.

  In step S113, the control unit 20 determines whether or not the input / output characteristic after switching is the input / output characteristic represented by the straight line L10, that is, whether or not the input image is displayed in its original brightness. As a result, when the input image is displayed in the original brightness, the process proceeds to step S114. On the other hand, if the brightness is darker than the original brightness, the process returns to step S109, and after the elapse of the predetermined time T2, the input image is again brightened by one step.

  When the process proceeds to step S114, the control unit 20 instructs the audio signal processing unit 42 to restart the output of the audio corresponding to the input audio signal. In step S115, the control unit 20 sets the flag. Is replaced with the content indicating the normal state, and the process is terminated.

  On the other hand, when the duration of the A / V mute state is less than the predetermined time T1 in step S107 and the process proceeds to step S116, the control unit 20 instructs the image processing unit 32 to perform the original brightness. To resume displaying the input image. Then, in step S114, the audio output is resumed, and after the flag is rewritten in step S115, the process is terminated.

  Since the projector 1 operates as described above, when the mute key is operated after the A / V mute state continues for the predetermined time T1 (10 seconds) or longer, the input image is stepped in steps of 0.2 seconds. It becomes brighter and is displayed at its original brightness after about 1.8 seconds. On the other hand, if the mute key is operated before the duration of the A / V mute state reaches the predetermined time T1, the input image is immediately displayed with the original brightness.

As described above, according to the projector 1 of the present embodiment, the following effects can be obtained.
(1) According to the projector 1 of the present embodiment, when the A / V mute state continues for a predetermined time T1 or longer, the input image is gradually brightened and returned to the normal state. After a long period of time, it is possible to suppress glare caused by sudden brightening. On the other hand, when the A / V mute state is less than the predetermined time T1, the normal state is immediately restored, so that the sensation of waiting until the return can be suppressed.

  (2) According to the projector 1 of the present embodiment, the normal state and the image mute state are switched by adjusting the gradation (pixel value) represented by the image data. The brightness of the display state can be easily adjusted as compared with the case where the luminance adjustment of the light source 11 is performed.

  Note that the normal state in this embodiment corresponds to the normal display state because the input image is displayed with a predetermined brightness (original brightness represented by the straight line L10), and the sound is at a predetermined volume level. Since it is output at (the volume level adjusted by the user with the volume up key and the volume down key), it corresponds to the normal volume state. On the other hand, the state in which the image is muted, that is, the state in which the black plain image is displayed in step S102 corresponds to the dark display state that is darker than the normal display state, and the state in which the audio mute is performed, that is, in step S103. The state where the audio output is stopped corresponds to a low volume state in which the volume level is smaller than the normal volume state. Further, the control unit 20, the image processing unit 32, and the audio signal processing unit 42 when executing steps S102 to S105 to display a black plain image and stop the audio output correspond to a mute unit, and step S106. The control unit 20, the image processing unit 32, and the audio signal processing unit 42 when executing S <b> 116 and resuming the display of the input image and the audio output correspond to the mute return unit.

(Second Embodiment)
The second embodiment will be described below with reference to the drawings. In the projector 1 according to the present embodiment, when the A / V mute state continues for a predetermined time T1 or more, the sound output from the speaker is interlocked with gradually increasing the input image according to the operation of the mute key. However, the volume level is gradually increased to return to the original volume level (the volume level adjusted by the user with the volume up key and the volume down key).

  In increasing the volume level step by step, the control unit 20 sets 10 volume levels that maximize the original volume level, as well as the brightness of the input image, and increases the volume level one step at a time from the minimum volume level. I will raise it. Note that the control unit 20 adjusts each volume level so that the sound pressure level (dB) when a predetermined sound is output is substantially equidistant in 11 levels including the state where the sound is stopped. Set.

  FIG. 4 is a flowchart for explaining the operation of the projector 1 when the mute key is operated in the present embodiment. In addition, since operation | movement of step S101-S107 is the same as 1st Embodiment, the description is abbreviate | omitted.

  In step S107, when the duration of the A / V mute state is equal to or longer than the predetermined time T1 and the process proceeds to step S108, the control unit 20 instructs the image processing unit 32 to input image data. Gradation conversion is performed by the straight line L1 (see FIG. 3), and the display of the input image is resumed in the darkest state among the 10 levels. In subsequent step S108b, the control unit 20 causes the audio signal processing unit 42 to adjust the volume level, and resumes outputting the audio at the lowest volume level among the 10 levels.

  In step S109, the control unit 20 starts time measurement (timer start) by the timer 20a in order to measure the elapsed time since the brightness and volume level of the input image are adjusted, and in the subsequent step S110, the control unit 20 20 determines whether or not a predetermined time T2 (0.2 seconds) has elapsed since the brightness and volume level of the input image were adjusted based on the time measurement result of the timer 20a. As a result, when the predetermined time T2 has not elapsed, step S110 is repeated, and when the predetermined time T2 has elapsed, the process proceeds to step S111 and the timer 20a is stopped.

  In step S112, the control unit 20 instructs the image processing unit 32 to switch the input / output characteristics to be applied so that the input image is brightened by one level. In the subsequent step S112b, the control unit 20 The processing unit 42 is instructed to adjust the volume level so that the volume level is increased by one level.

  In step S113, the control unit 20 displays whether or not the input / output characteristic after switching in step S112 is the input / output characteristic represented by the straight line L10, that is, the input image is displayed with the original brightness, and the sound is displayed with the original volume. It is determined whether or not the output state is level. As a result, when the input image is displayed at the original brightness and the sound is output at the original volume level, the process proceeds to step S115. On the other hand, if it is darker than the original brightness and lower than the original volume level, the process returns to step S109, and after a predetermined time T2, the input image is brightened by one step and the volume level is set to 1. Increase the stage.

  In step S115, the control unit 20 rewrites the content of the flag with content indicating that it is in the normal state, and ends the process.

  On the other hand, when the duration of the A / V mute state is less than the predetermined time T1 in step S107 and the process proceeds to step S116, the control unit 20 instructs the image processing unit 32 to perform the original brightness. To resume displaying the input image. In step S116b, the sound output is resumed at the original volume level, and after the flag is rewritten in step S115, the process is terminated.

  As described above, according to the projector 1 of the present embodiment, when the A / V mute state continues for the predetermined time T1 or more, the input image is gradually brightened according to the operation of the mute key. As for the sound output from the speaker, the volume level is increased step by step, so that it is possible to prevent the user from being surprised when the volume level suddenly recovers from the quiet state of the A / V mute state.

(Modification)
The embodiment may be modified as follows.
In the first and second embodiments, the normal state and the A / V mute state are switched by operating the mute key provided on the operation panel 22 or the remote controller 23. For example, as in a so-called screen saver. When the input operation is not performed for a predetermined time in the normal state, the state may be changed to the A / V mute state, and when any input operation is performed, the normal state may be restored. Alternatively, an image signal detection unit that detects the input of the image signal to the image signal input unit 31 is provided, and when the input of the image signal is interrupted, the A / V mute state is entered and the input of the image signal is resumed. In such a case, the normal state may be restored.

  In the first embodiment, the audio output is resumed after the display of the input image is resumed at the original brightness. However, the timing at which the display of the input image and the output of the audio are resumed is limited to this. Instead, the display of the input image may be resumed after the audio output is resumed.

  In the first and second embodiments, the input image is gradually brightened according to whether the duration of the A / V mute state is equal to or longer than the predetermined time T1 (steps S108 to S113), and immediately brightened. Although the two modes of the mode (step S116) are switched, if the configuration is such that the longer the duration of the A / V mute state is, the more slowly it becomes brighter, 3 in accordance with the duration. You may make it switch the above aspect.

  In the first and second embodiments, the brightness of the input image is changed by performing gradation conversion in the image processing unit 32, but the brightness adjustment method is not limited to this. For example, the light source control unit 33 may control the power supplied to the light source 11 to adjust the light emission luminance of the light source 11 so that the input image is gradually brightened.

  In the first and second embodiments, when the A / V mute state continues for a predetermined time T1 or more, the original brightness is restored from the A / V mute state through 10-level gradation conversion. However, the number of steps is not limited to 10, and may be less than 10 or 11 or more. Or you may make it brighten more smoothly by changing brightness continuously. Further, in the second embodiment, the number of steps when the volume level is gradually increased need not be the same as the number of steps of brightness (10), and may be less or more than that, The volume level may be increased more smoothly by continuously changing the volume level.

  In the first and second embodiments, a black plain image is displayed in the A / V mute state. However, in each color light, a pixel value smaller than the normal state (a pixel value for reducing the light transmittance). ) Is used, the present invention is not limited to a black plain image. Alternatively, the image may partially include a manufacturer's logo or the like.

  In the first and second embodiments, the transmissive liquid crystal light valves 12R, 12G, and 12B are used as the light modulator, but a reflective light modulator such as a reflective liquid crystal light valve may also be used. Is possible. In addition, it is possible to use a micromirror array device that modulates light emitted from a light source by controlling the emission direction of incident light for each micromirror as a pixel.

  In the first and second embodiments, the light source 11 is constituted by a discharge-type light source lamp 11a. However, a solid light source such as an LED (Light Emitting Diode) light source or other light sources may be used. it can.

  In the first and second embodiments, the projector 1 that modulates and projects the light emitted from the light source 11 is described as an example of the image display device. However, the image display device is integrally provided with a transmissive screen. The present invention can also be applied to a rear projector, a liquid crystal display, a plasma display, an SED (Surface-conduction Electron-emitter Display), an organic EL (Electro Luminescence) display, or the like. However, among these image display devices, the projector is often used when performing a large screen display in a dark environment, and if the display state suddenly becomes bright in this situation, the user is more dazzled. It becomes easier to feel. For this reason, when applied to a projector, suppression of glare by gradually brightening the display state becomes even more effective.

1 is a block diagram showing a schematic configuration of a projector according to a first embodiment. 6 is a flowchart for explaining the operation of the projector when a mute key is operated in the first embodiment. 6 is an explanatory diagram for explaining adjustment of brightness of an input image, and is a graph showing input / output characteristics to be applied to image data input to an image processing unit. FIG. 12 is a flowchart for explaining the operation of the projector when a mute key is operated in the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Projector, 10 ... Image projection part, 11 ... Light source, 11a ... Light source lamp, 11b ... Reflector, 12R, 12G, 12B ... Liquid crystal light valve, 13 ... Projection lens, 14 ... Light valve drive part, 20 ... Control part, 20a ... timer, 21 ... storage unit, 22 ... operation panel, 23 ... remote control, 24 ... operation signal receiving unit, 31 ... image signal input unit, 32 ... image processing unit, 33 ... light source control unit, 41 ... audio signal input unit 42 ... Audio signal processing unit, 43 ... Audio output unit, 44L, 44R ... Speaker, SC ... Screen.

Claims (5)

A display unit for displaying an image based on input image information;
A mute unit that switches the display state of the display unit from a normal display state in which the image is displayed at a predetermined brightness to a dark display state that is darker than the normal display state;
A time measuring unit for measuring a duration after the mute unit switches to the dark display state;
A mute return unit for returning the display state of the display unit from the dark display state to the normal display state;
With
The mute return unit, when returning to the normal display state, the display state of the display unit is gradually brightened over time as the duration time measured by the timer unit is longer. Display device. The image display device according to claim 1,
An audio output unit that outputs audio corresponding to the input audio information;
The mute unit switches the display state of the display unit from the normal display state to the dark display state, and changes the output state of the audio output unit to a normal volume level at which the sound is output at a predetermined volume level. Switch from a state to a low volume state where the volume level is lower than the normal volume state,
The mute return unit gradually returns the volume level from the low volume state to return to the normal volume state as the display state of the display unit returns to the normal display state. Display device. The image display device according to claim 1 or 2,
The display unit
A light source;
A light modulation device that modulates light emitted from the light source according to the image information to form image light;
A projection optical system that enlarges and projects the image light formed by the light modulation device and displays the image on a projection surface;
An image display device comprising: The image display device according to claim 3,
The image display apparatus, wherein the mute unit and the mute return unit switch between the normal display state and the dark display state by adjusting a gradation represented by the image information. A display unit that displays an image according to input image information, and the display state of the display unit is a normal display state in which the image is displayed at a predetermined brightness, and a dark display state that is darker than the normal display state A method for controlling an image display device that can be switched to
A first step of switching from the normal display state to the dark display state;
A second step of receiving an instruction for returning from the dark display state to the normal display state;
A third step of measuring a time until the instruction is received after switching to the dark display state;
A fourth step of returning from the dark display state to the normal display state in response to the instruction;
With
In the fourth step, when returning to the normal display state, as the time measured in the third step is longer, the display state of the display unit is gradually brightened over time. For controlling an image display apparatus.

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