JP2007292823A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain high power saving effect in a projector provided with an optical modulation element for modulating light into projection light in response to a video signal. <P>SOLUTION: CPU 5 detects the maximum brightness value in one screen from brightness information of an input video signal, makes a light quantity regulation part 11 regulate a light quantity of a light source 9 to the light quantity of a rate corresponding to the level of the maximum brightness value, and makes a gradation conversion part 3 increase the allocation magnification of a brightness region having the video signal to expressable gradation by a projection device 8 into the allocation magnification compensating the brightness deterioration of the projection light by making the light quantity of the light source 9 the light quantity of the rate corresponding to the level of the maximum brightness value to maintain brightness of video of the projected light. Power consumption of the light source can be suppressed by automatically lowering the light quantity of the light source during a period projecting the video without lowering contrast of the video of to the projected light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projection apparatus including a light modulation element that modulates light from a light source into projection light corresponding to a video signal.

2. Description of the Related Art Conventionally, there is a projector that enlarges and displays a video based on a video signal on a projection target such as a screen as a projection apparatus including a light modulation element.
As light modulation elements used in projectors, there are transmissive and reflective liquid crystal devices and digital micromirror devices (DMD).

Also, in this type of projector, when there is no video signal input during operation, that is, when no image is projected, the brightness of the light source lamp is reduced to save power and silence. For example, Japanese Patent Application Laid-Open No. 2004-133620 discloses a technique that makes it necessary to achieve the above.
JP 2003-5147 A

  However, in the above technique, the period during which the brightness of the light source lamp is reduced is only the period during which no image is projected. For this reason, there is a problem that the power saving effect and the like obtained by the method are not so satisfactory.

  The present invention has been made in view of such conventional problems, and it is an object of the present invention to provide a projection apparatus and a display control method capable of obtaining a high power saving effect, and a program used for realizing the projection apparatus. And

  In order to solve the above-mentioned problem, in the invention of claim 1, in a projection apparatus including a light modulation element that modulates light from a light source into projection light corresponding to a video signal, the maximum in one screen from the video signal is obtained. Detection means for detecting a luminance value; and light source control means for controlling the light quantity of the light source to a light quantity in a proportion corresponding to a level position in a luminance region of the video signal at the maximum luminance value detected by the detection means; A factor for increasing the allocation magnification of the luminance region of the video signal for the gradation that can be expressed by the light modulation element to an allocation magnification that complements the decrease in luminance of the projection light accompanying the light amount control of the light source by the light source control means. Key control means.

In such a configuration, when the maximum luminance value in one screen in the video signal is lowered, the light amount of the light source is automatically reduced accordingly.
At the same time, the allocation magnification of the luminance area of the video signal for the gradation that can be expressed by the light modulation element is increased to an allocation magnification that complements the decrease in the luminance of the projection light accompanying the decrease in the light amount of the light source, and the luminance of the image by the projection light is increased. Maintained.
Therefore, the power consumption of the light source can be suppressed by automatically reducing the light amount of the light source during the period when the image is projected. In addition, the contrast of the projected image is not reduced thereby.

  Further, in the invention of claim 2, there is further provided judging means for judging which of the plurality of predetermined brightness level areas the maximum brightness detected by the detecting means belongs, The light source control means controls the light quantity of the light source to a predetermined quantity of light corresponding to the luminance level region determined by the determination means.

  According to a third aspect of the present invention, the light source control means controls the power supplied to the light source, whereby the light quantity of the light source is changed to the video signal at the maximum luminance value detected by the detection means. The amount of light is controlled to a proportion corresponding to the level position in the luminance region of the.

  In the invention of claim 4, the light source control means controls the lighting time of the light source within a predetermined time, whereby the light quantity of the light source is determined at the maximum luminance value detected by the detection means. The amount of light is controlled to a proportion corresponding to the level position in the luminance region of the video signal.

  According to a fifth aspect of the present invention, the light modulation element is configured to express gradation by being turned on and off in units of pixels, and the light source control means is configured to drive the light modulation element at a driving timing. By turning on the light source synchronously, the light amount of the light source is controlled to a light amount in proportion to the level position in the luminance region of the video signal at the maximum luminance value detected by the detection means; did.

  In the invention of claim 6, the detecting means detects a maximum luminance value in one screen from the video signal for each RGB color component, and the light source control means determines the light quantity of the light source, The light intensity is controlled to a proportion corresponding to the level position in the luminance region of the video signal at the maximum luminance value for each of the RGB color components detected by the detection means, and the gradation control means is controlled by the light modulation element. Increasing the allocated magnification of the luminance area of the video signal for the expressible gradation to an allocated magnification that complements the decrease in luminance of the projection light accompanying the light amount control of the light source for each RGB color component by the light source control means It was.

  The invention according to claim 7 is a display control method in a projection apparatus including a light modulation element that modulates light from a light source into projection light in accordance with a video signal, and includes within one screen from the video signal. The light intensity of the light source can be expressed by the light modulation element at the same time that the light intensity of the light source is controlled to a light quantity in proportion to the level position in the luminance area of the video signal at the detected maximum brightness value. And increasing the assigned magnification of the luminance area of the video signal for a certain gradation to an assigned magnification that compensates for the decrease in the brightness of the projection light accompanying the light amount control of the light source by the light source control means.

According to this method, when the maximum luminance value in one screen in the video signal is lowered, the light amount of the light source is automatically lowered accordingly.
At the same time, the allocation magnification of the luminance area of the video signal for the gradation that can be expressed by the light modulation element is increased to an allocation magnification that complements the decrease in the luminance of the projection light accompanying the decrease in the light amount of the light source, and the luminance of the image by the projection light is increased. Maintained.
Therefore, the power consumption of the light source can be suppressed by automatically reducing the light amount of the light source during the period when the image is projected. In addition, the contrast of the projected image is not reduced thereby.

  According to an eighth aspect of the present invention, a computer having a projection apparatus including a light modulation element that modulates light from a light source into projection light according to a video signal has a maximum luminance within one screen from the video signal. And a gradation that can be expressed by the light modulation element at the same time as controlling the light amount of the light source to a light amount in proportion to the level position in the luminance region of the video signal at the detected maximum luminance value. And a process for increasing the assigned magnification of the luminance region of the video signal to an assigned magnification that complements the reduction in the brightness of the projection light accompanying the light amount control of the light source by the light source control means.

  As described above, according to the present invention, the power consumption of the light source can be suppressed by automatically reducing the light amount of the light source during the period when the image is projected, and the contrast of the projected image is thereby reduced. I will not let you. Therefore, a high power saving effect can be obtained while maintaining the quality of the projected image.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a block diagram showing a schematic configuration of a projector according to the present invention, which has the following configuration.

  That is, the projector according to the present embodiment includes an A / D converter 2 that converts various analog video signals (for example, analog RGB signals and video signals) input from the video input terminal 1 into digital signals. In this embodiment, the number of quantization bits of the A / D converter 2 is 10 bits, and the video data converted here is output to the gradation conversion unit 3 and the luminance extraction unit 4, respectively.

  The luminance extraction unit 4 extracts luminance components from the 10-bit video data output from the A / D converter 2, and sequentially outputs luminance information for one screen, that is, all pixels, to the CPU 5 for each frame.

  The gradation converting unit 3 converts the 10-bit video data output from the A / D converter 2 into 8-bit video data corresponding to the number of gradations that can be expressed by the projection device 8 described later, that is, the number of bits. , The 1024 gradation video data is converted to 256 gradation video data, and the converted video data is output to the image processor 3.

Further, the gradation conversion unit 3 has three gradation conversion modes of 1 × mode, 2 × mode, and 4 × mode as operation modes when performing the above-described gradation conversion, and the CPU 5 receives each frame from the frame. The gradation conversion is performed in a predetermined gradation conversion mode in accordance with the command sent.
Here, the 1 × mode is a mode in which the upper 8 bits of data are extracted from the input 10-bit video data, and the 2 × mode is the most significant bit and the least significant bit from the input 10-bit video data. The quadruple mode is a mode for extracting lower 8-bit data from input 10-bit video data.

  FIG. 2 is a diagram showing the relationship between the input luminance and the output luminance in each gradation conversion mode in the gradation converting unit 3. FIG. 2A shows the change in the 1 × mode. b) shows the change in the 2 × mode, and FIG. 5C shows the change in the 4 × mode.

  As shown in the figure, in each gradation conversion mode, when the input luminance changes from the minimum luminance value 1 to the maximum luminance value 256 due to different bit ranges from which 8-bit data is extracted, the output luminance is as follows. Change.

  That is, in the double mode (b), the output luminance value changes from 1 to 256 every time the input luminance value increases by 128 levels, and in the quadruple mode (c), the output luminance value increases from 1 every time the input luminance value increases by 64 levels. It changes up to 256.

  Although not shown, the actual change in the output luminance value is a step-like change that increases by one level every time the input luminance value increases by four levels in the 1 × mode (a), and the input luminance value in the 2 × mode (b) changes. Every time 2 levels increase, it becomes a step-like change that increases 1 level.

  The image processor 6 fetches 8-bit video data that has undergone gradation conversion in any of the gradation conversion modes described above into a frame memory (not shown) at a constant frame rate for each screen, and in accordance with an instruction from the CPU 5. Then, deformation processing such as enlargement / reduction, trapezoidal distortion correction, and image processing such as hue adjustment are performed on the captured video (image) data, and the processed video signal is sequentially output to the projection processing LSI 7.

  The projection processing LSI 7 generates a drive signal based on the gradation information for each pixel included in the 8-bit video signal, and drives the projection device 8 at a predetermined frame rate by the drive signal.

  The projection device 8 is a light modulation element such as DMD, transmissive liquid crystal, or reflective liquid crystal, and the projection processing LSI 7 generates a predetermined drive signal corresponding to the projection device 8 to drive the projection device 8.

  The projection device 8 is driven by the drive signal to modulate the light beam having a constant light amount from the light source 9 by changing the reflection angle for each pixel or changing the transmittance for each pixel, for example. .

  Then, the modulated light beam is diffused by the projection optical system 10 and irradiated onto an arbitrary screen as projection light, whereby an image based on the input image signal is projected and displayed on the screen.

  The light source 9 is capable of adjusting the light emission amount and has sufficient responsiveness. For example, the light source 9 is an LED or the like, and its light amount (brightness) is adjusted by the light amount adjusting unit 11.

  The light amount adjustment unit 11 adjusts the light amount of the light source 9 to a proportion of light amount according to the instruction of the CPU 5 by changing the power supplied to the light source 9 from a power supply unit (not shown). In this embodiment, the adjustment is performed in three stages of 100%, 50%, and 25% as described later.

  As described above, the CPU 5 controls the operations of the gradation converting unit 3, the image processor 6, and the light amount adjusting unit 11, and controls the entire projector according to the control program stored in the program memory 12. The control program includes a program that causes the CPU 5 to function as a detection unit, a light source control unit, a gradation control unit, and a determination unit of the present invention.

  FIG. 3 is a flowchart showing a process according to the present invention that is executed by the CPU 5 when the projector displays an image based on an arbitrary image signal on the screen.

  That is, every time the luminance information for one screen is input from the luminance extraction unit 4 for each frame, the CPU 5 detects the maximum luminance among them (step S1).

  Next, it is confirmed whether the detected maximum luminance belongs to a predetermined luminance level region (luminance range) (step S2). That is, in the present embodiment, as the luminance level region, a low luminance level region with a luminance range of “1 to 64”, a middle luminance level region with a luminance range of “65 to 128”, and a luminance range of “129 to 256”. Are divided into three luminance level regions, and in step S2, it is confirmed to which of the luminance level regions the detected maximum luminance belongs.

  Then, when the confirmed luminance level region is a high luminance level region, for example, when there is a very bright part in the input image, the light amount adjustment unit 11 adjusts the light amount of the light source 9 to 100%, and The gradation conversion unit 3 is caused to perform gradation conversion in the 1 × mode (step S3).

  As a result, when there is a portion having the maximum absolute luminance value (luminance value 256) in the video having normal luminance, that is, the input video, the maximum luminance (luminance value) that can be expressed by the projection device 8. 256) is displayed.

  Further, when the luminance level region confirmed in step S2 is a medium luminance level region and, for example, there is no extra bright portion in the input video, the light amount adjustment unit 11 adjusts the light amount to 50% (1/2). The gradation conversion unit 3 is caused to perform gradation conversion in the double mode (step S4).

  By such processing, power consumption of the light source 9 is first suppressed. At the same time, a luminance region having a luminance value of 1 to 128, which is a luminance region (hereinafter, referred to as an effective luminance region) including all luminances existing in one screen of a frame at that time in the video signal with respect to the gradation expressed by the projection device 8 The gradation allocation magnification (hereinafter referred to as gradation allocation magnification) is twice the normal (1 to 256) gradation conversion in the 1 × mode, that is, the reciprocal of the light amount reduction rate of the light source 9. By doing so, the amount of decrease in the luminance of the projected video accompanying the decrease in the light amount of the light source 9 is complemented. Thereby, the same brightness as that in the case where the light amount of the light source 9 is not reduced is ensured in the projected image.

  Note that the difference in gradation allocation magnification between the 1 × mode (normal) and the 2 × mode is the inclination angle of the change in output luminance with respect to the input luminance shown in FIG. 2 (a) and FIG. 2 (b). It corresponds to the difference.

  Furthermore, when the luminance level region confirmed in step S2 is a low luminance level region and, for example, the input image is a dark image as a whole without any bright part, the light amount adjustment unit 11 is supplied with the light amount of the light source 9. The gradation conversion unit 3 is adjusted (reduced) to 25% (1/4), and the gradation conversion unit 3 performs gradation conversion in the quadruple mode (step S5).

  With this processing, the power consumption of the light source 9 is first suppressed as in the previous case. At the same time, the gradation allocation magnification of the luminance region of luminance values 1 to 64, which is the effective luminance region in the video signal, with respect to the gradation expressed by the projection device 8 is four times the normal gradation conversion in the 1 × mode (1 256), that is, by making the reciprocal times the rate of decrease in the light amount of the light source 9, the decrease in luminance of the projected video accompanying the decrease in the light amount of the light source 9 is complemented. Thereby, the same brightness as that in the case where the light amount of the light source 9 is not reduced is ensured in the projected image.

  Thereafter, the above-described processing is repeated for each frame, so that the amount of light (brightness) of the light source 9 by controlling the supply power and the projection device according to the change in the maximum luminance (Y) within one screen of the input video signal. The assigned magnification of the gradation of the video signal with respect to the expression gradation of 8 automatically changes.

  FIG. 4 is a diagram showing an example thereof. For the sake of convenience, this figure shows the maximum luminance (Y) of the input video signal as 100% when the maximum luminance value is 256, 50% corresponds to the luminance value 128, and 25% Corresponds to the luminance value 64.

  Therefore, in the projector according to the present embodiment, the power consumption of the light source 9 can be suppressed by automatically reducing the light amount of the light source 9 even during the period when the image is projected. In addition, the contrast of the projected image is not reduced thereby. Thereby, a high power saving effect can be obtained while maintaining the quality of the projected image.

  In addition, since the above-described control of the light amount of the light source 9 and the gradation allocation magnification is automatically performed for each frame according to the maximum luminance value in one screen at that time, a specific operation mode is set for the user. There is no need and it is easy to use.

In the present embodiment, the light intensity of the light source 9 and the gradation allocation magnification are controlled in three stages according to the luminance level region to which the maximum luminance value in one screen of the input video signal belongs. It may be controlled in a plurality of stages of four or more stages, or may be controlled linearly according to the change in the maximum luminance value.
In that case, for the control of the gradation allocation magnification, for example, an arbitrary method different from the method described above for the gradation converting unit 3, for example, the luminance component of the input video signal is set to the maximum luminance within one screen for each frame. The gradation conversion operation may be performed by a method of performing amplification at a corresponding amplification factor.

  Further, although the description has been given of the gradation converter 3 provided in the preceding stage of the image processor 6 that performs various image processing prior to projection, the gradation converting part 3 may be provided in the subsequent stage of the image processor 3.

  In addition, the configuration for detecting the maximum luminance value in one screen of the input video signal, and controlling the light amount of the light source 9 and the gradation allocation magnification is not limited to the above-described configuration, and is arbitrary. Unlike a form, it is good also as a structure which performs only those with hardware, or a structure performed only with software (CPU5).

  In the present embodiment, it is assumed that the light source 9 is an LED or the like having sufficient responsiveness in controlling the amount of light in order to cope with the case where the input video signal is a moving image signal. The light source 9 can be a halogen lamp, a metal halide lamp, a high-pressure mercury lamp, or the like.

  Even in such a case, the effects described above can be obtained when the input video signal is a still image signal. In that case, when the light quantity is reduced, the power consumption can be more effectively reduced by reducing the rotational speed of the cooling fan for heat radiation of the lamp. In particular, the effect is great when a still image that is a dark video as a whole is not projected at all.

Further, in the above, for convenience, the present embodiment has been described on the assumption that the projection light is monochromatic light. However, the above-described projector may be configured to project a color video (image). An effect can be obtained.
In this case, the color expression method may be either a single plate type or a three plate type, and in the case of a single plate type, an arbitrary method such as a color plane sequential method (field sequential color method) can be adopted.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. This embodiment is different from the first embodiment in that the light amount adjusting unit 11 is turned on by duty driving and the duty ratio, that is, the lighting rate within a unit time, in the configuration shown in FIG. It is changed in three stages of 100%, 50% and 25% according to the instruction of the CPU 5. Other than this, the second embodiment is the same as the first embodiment. However, the usable light source 9 is a light emitting element such as an LED that can adjust the amount of light by changing the duty ratio and has excellent responsiveness.

  FIG. 5 is a diagram corresponding to FIG. 4 illustrating the operation when the projector according to the present embodiment displays a video based on an arbitrary video signal on the screen.

  Therefore, also in the present embodiment, the light amount of the light source 9 and the gradation allocation magnification of the video signal are controlled in three steps according to the luminance level region to which the maximum luminance value in one screen of the input video signal belongs. The power consumption of the light source 9 can be suppressed even during the image projection period without reducing the contrast of the projection image on the screen, and the power can be saved while maintaining the quality of the projection image. be able to.

  In addition, since the above-described control of the light amount of the light source 9 and the gradation allocation magnification is automatically performed for each frame according to the maximum luminance value in one screen at that time, a specific operation mode is set for the user. There is no need and it is easy to use.

In addition, since the light amount of the light source 9 is adjusted by changing the duty ratio, the light source 9 having a narrow control range of the light amount that can be controlled by the supplied power is used, and the control range of the light amount is increased. Can do.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. This embodiment relates to the case where a DMD is used as the projection device 8 in the projector described in the second embodiment.

  In that case, when the light amount adjusting unit 11 drives the light source 9 with duty, the driving (light emission) timing is synchronized with the driving timing of the DMD, so that the DMD micromirror is in the ON operation period. The light source 9 is turned on. FIG. 6 is a diagram showing an example thereof. Also in this embodiment, the same effect as in the first and second embodiments can be obtained.

In the case where each pixel is driven on / off and the gradation is expressed by the ratio of being driven to the on operation state within a unit time, not only the DMD but also another light modulation element is used as the projection device 8. As with the present embodiment, the driving timing of the light source 9 may be synchronized with the driving timing of the light modulation element.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. In this embodiment, in the projector described in the first embodiment, the light source 9 is provided for each RGB color component using light emitting elements such as LEDs that can adjust the light amount and have excellent responsiveness. The present invention relates to a case where a single plate type and color plane sequential color expression is possible.

  In this case, the gradation conversion unit 3 performs gradation conversion on the input video data for each RGB color component, and the light amount adjustment unit 11 determines the light emitting elements for each RGB color within one frame. Assuming that the time-division emission is performed in order and the light emission amount at that time is adjusted in three stages for each color by adjusting the supply power, when the projector displays an image based on an arbitrary video signal on the screen, the CPU 5 displays FIG. The same processing as the above processing is performed for each color component.

  That is, first, the luminance information for each RGB is acquired from the image processor 3 for each frame, and it is confirmed whether the maximum luminance value in one screen belongs to the high, medium, or low luminance level region for each RGB. . Then, as a light emission amount of each color light emitting element, a light amount in a proportion corresponding to a luminance level region for each RGB is set, and a gradation conversion mode for each RGB in the gradation conversion unit 3 is set to a predetermined mode. Note that the amount of light corresponding to each luminance level region and the control content of the gradation conversion mode for each of RGB are the same as in the first embodiment.

  Accordingly, as shown in FIG. 7, in accordance with the change in the maximum luminance (Y) within one screen of the input video signal, the light amount (brightness) for each RGB in each RGB display period within one frame, And the assigned magnification of the gradation for each RGB of the video signal with respect to the expression gradation by the projection device 8 is automatically changed.

  That is, when projecting a dark image or the like, the light amount of the light source 9 (light emitting element) is reduced to a predetermined ratio for each RGB, and at the same time, the assigned magnification of the gradation for each RGB of the video signal is set to the light amount reduction rate for each RGB. By compensating for the amount of decrease in the luminance of the projection image due to the decrease in the amount of light from the light source 9, the same luminance as in the case where the amount of light from the light source 9 is not decreased is ensured in the projection image.

  As a result, even when the color representation is possible by the single plate type and the color plane sequential method, the same effects as those of the first to third embodiments can be obtained.

Here, the case where the present invention is applied to a configuration having a light source for each of RGB color components has been described. However, the present invention is not limited to this, and the present invention is shown in FIG. In this configuration, a color wheel including three color filters of RGB is provided between the projection device 8 and the projection optical system 9, and a motor and a drive circuit for rotating the color wheel are added. It can also be used in other projectors.

(Embodiment 5)
Next, a fifth embodiment of the present invention will be described. In this embodiment, in the projector described in the second embodiment, as in the fourth embodiment, the light source 9 is composed of light emitting elements such as LEDs for RGB color components, and is a single plate type. The present invention relates to a case where color expression by a color plane sequential method is possible.

  In this case, the gradation conversion unit 3 performs gradation conversion on the input video data for each RGB color component, and the light amount adjustment unit 11 performs the order in which the light emitting elements of each RGB color are determined within one frame. In this case, the light emission amount is adjusted in three stages for each color by adjusting the duty ratio (lighting rate within unit time).

  When the projector displays a video based on an arbitrary video signal on the screen, the same processing as that described in the fourth embodiment is performed, and as shown in FIG. In accordance with the change in the maximum luminance (Y) in one screen of the input video signal, the light quantity (brightness) for each RGB in each RGB display period in one frame, and the video for the expression gradation by the projection device 8 The assigned magnification of gradation for each RGB of the signal is automatically changed.

  Therefore, also in this embodiment, the same effects as those of the first to third embodiments can be obtained in a configuration that is a single plate type and that can perform color expression by the color plane sequential method.

Here, the case where the present invention is applied to a configuration having a light source for each of the RGB color components has been described. However, the present invention is not limited to this, and the present invention may be applied to a general single-plate projector. it can.

(Embodiment 6)
Next, a sixth embodiment of the present invention will be described. This embodiment relates to a case where DMD is used as the projection device 8 in the projector described in the fifth embodiment.

  In that case, when the light amount adjusting unit 11 drives the light emitting elements for each of the RGB color components, the DMD micromirror is turned on by synchronizing each drive (light emission) timing with the DMD drive timing. The light emitting elements of the respective color components are turned on within the ON operation period. FIG. 9 is a diagram showing an example thereof. Also in this embodiment, the same effects as those of the fourth and fifth embodiments can be obtained.

  In the case where each pixel is driven on / off and the gradation is expressed by the ratio of being driven to the on operation state within a unit time, not only the DMD but also another light modulation element is used as the projection device 8. Similarly to the present embodiment, the driving timing of the light emitting element may be synchronized with the driving timing of the light modulation element for each of the RGB color components.

It is a block diagram showing a schematic configuration of a projector according to the present invention. It is the figure which showed the difference in the relationship between input luminance and output luminance by the difference in gradation conversion mode. It is a flowchart which shows operation | movement of the projector in 1st Embodiment. It is the figure which showed the relationship between the maximum brightness | luminance of an input video signal, a gradation allocation magnification, and the light quantity of a light source. It is a figure corresponding to FIG. 4 which shows operation | movement of 2nd Embodiment. It is a figure corresponding to FIG. 4 which shows operation | movement of 3rd Embodiment. It is a figure corresponding to FIG. 4 which shows operation | movement of 4th Embodiment. It is a figure corresponding to FIG. 5 which shows operation | movement of 5th Embodiment. It is a figure corresponding to FIG. 6 which shows operation | movement of 6th Embodiment.

Explanation of symbols

1 Video Input Terminal 2 A / D Converter 3 Gradation Conversion Unit 4 Luminance Extraction Unit 5 CPU
6 Image processor 7 Projection processing LSI
8 Projection device 9 Light source 10 Projection optical system 11 Light amount adjustment unit 12 Program memory

Claims (8)

In a projection apparatus including a light modulation element that modulates light from a light source into projection light corresponding to a video signal,
Detecting means for detecting a maximum luminance value in one screen from the video signal;
A light source control means for controlling the light quantity of the light source to a ratio of the light quantity according to the level position in the luminance region of the video signal at the maximum luminance value detected by the detection means;
A gradation that increases the assigned magnification of the luminance region of the video signal for the gradation that can be expressed by the light modulation element to an assigned magnification that complements the decrease in brightness of the projection light accompanying the light amount control of the light source by the light source control means. And a control unit. A judgment means for judging which of the plurality of predetermined brightness level areas the maximum brightness detected by the detection means belongs to;
The projection apparatus according to claim 1, wherein the light source control unit controls the light amount of the light source to a predetermined amount of light corresponding to the luminance level region determined by the determination unit.   The light source control means controls the power supplied to the light source, whereby the light quantity of the light source is a ratio according to the level position in the luminance region of the video signal at the maximum luminance value detected by the detection means. The projection apparatus according to claim 1, wherein the amount of light is controlled.   The light source control means controls the lighting time of the light source within a predetermined time, thereby changing the light amount of the light source to a level position in the luminance region of the video signal at the maximum luminance value detected by the detection means. The projection apparatus according to claim 1, wherein the light quantity is controlled to a proportion corresponding thereto. The light modulation element is configured to express gradation by being turned on and off in units of pixels,
The light source control means turns on the light source in synchronization with the drive timing of the light modulation element, whereby the light quantity of the light source is a luminance region included in the video signal at the maximum luminance value detected by the detection means. The projection apparatus according to claim 4, wherein the amount of light is controlled to a proportion corresponding to the level position. The detecting means detects the maximum luminance value in one screen from the video signal for each RGB color component,
The light source control unit controls the light amount of the light source to a light amount of a proportion corresponding to a level position in a luminance region of the video signal at the maximum luminance value for each RGB color component detected by the detection unit,
The gradation control means determines the assigned magnification of the luminance area of the video signal for the gradation that can be expressed by the light modulation element, and the projection light accompanying the light amount control of the light source for each RGB color component by the light source control means. The projection apparatus according to claim 1, wherein the allocation ratio is increased to compensate for a decrease in luminance. A display control method in a projection apparatus including a light modulation element that modulates light from a light source into projection light according to a video signal,
Detecting a maximum luminance within one screen from the video signal;
At the same time as controlling the light quantity of the light source to a light quantity in proportion to the level position in the luminance area of the video signal at the detected maximum luminance value, the video signal for the gradation that can be expressed by the light modulation element has And a step of increasing the assigned magnification of the brightness area to an assigned magnification that compensates for a decrease in brightness of the projection light accompanying the light amount control of the light source by the light source control means. A computer having a projection device including a light modulation element that modulates light from a light source into projection light according to a video signal,
A process for detecting the maximum luminance within one screen from the video signal;
At the same time as controlling the light quantity of the light source to a light quantity in proportion to the level position in the luminance area of the video signal at the detected maximum luminance value, the video signal for the gradation that can be expressed by the light modulation element has And a process for increasing the assigned magnification of the luminance region to an assigned magnification that complements the reduction in brightness of the projection light accompanying the light amount control of the light source by the light source control means.

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