JP2011095402A - Projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection display device which is capable of suppressing the video degradation due to noise when using a color wheel including a white segment. <P>SOLUTION: A projector includes a color wheel 31 for separating white light from a light source lamp 10 into light beams of a plurality of colors in time division, a DMD 70 for modulating the light beams of respective colors separated by the color wheel 31, a signal processing circuit 104 for processing a video signal input from the outside, and a DMD driving circuit 106 for driving the DMD 70 in accordance with a signal from the signal processing circuit 104. The color wheel 31 includes a white segment 31W which transmits the white light from the light source lamp 10 as it is. When saturation of an video generated by the input video signal exceeds a preset threshold α, the signal processing circuit 104 attenuates RGB signals for pixels displaying a white component, out of respective pixels of a display element. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a projection display apparatus that modulates light from a light source by a display element and enlarges and projects the light on a projection surface, and in particular, color-separates light from the light source by a color wheel, It is suitable for use in a projection display device that modulates.

  Conventionally, only one display element such as a DMD (Digital Micro-mirror Device) is used as one type of projection display device (hereinafter referred to as “projector”) that enlarges and projects an image on a projection surface (screen or the like). A so-called single-plate projector is known.

  In this type of projector, a color wheel is disposed between the light source and the display element. For example, the color wheel has a configuration in which segments (transmission regions) that transmit only light of three primary colors (red, green, and blue) are arranged in the rotation direction, and are driven to rotate by a motor. Light from the light source is separated into red, green, and blue light by a color wheel, and each light is irradiated onto the display element in a time-sharing manner. In the display element, modulation corresponding to each light is performed, and the modulated light is sequentially projected on the projection surface. At this time, since each light is switched at a high speed, the image of each light on the projection surface is synthesized and displayed as one image to the user's eyes.

  In such a projector, in order to increase the brightness of the projected image, a color wheel in which a segment (white segment) that transmits white light from the light source as it is in addition to the above three primary color segments can be used (patent) Reference 1).

JP 2006-113276 A

  However, when a white segment is added as described above, noise due to this becomes conspicuous on the video. As a result, there are problems such as flickering of the video, or white spots in dark portions on the video.

  FIG. 9A is a diagram showing the relationship between the xy chromaticity and the luminance when the four color wheels of red, green, blue, and white are used, and FIG. It is a figure which shows the relationship between xy chromaticity at the time of using the color wheel of three colors of blue, and a brightness | luminance.

  As shown in the drawing, in the configuration using the four color wheels, the luminance of the white component becomes extremely high. This is due to the white light from the light source passing through the white segment. Therefore, when a four-color wheel is used, the brightness of white increases rapidly at a period synchronized with the rotation of the color wheel. This is considered to be the cause of the noise becoming noticeable on the video.

  Such noise is particularly noticeable in high-saturation images, that is, dark and vivid images. For this reason, if a color wheel with a white segment added is used, there is a possibility that such an image cannot be clearly displayed.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a projection display device that can suppress image deterioration due to noise when a color wheel including a white segment is used. .

  A projection display device according to the present invention includes a color wheel that separates white light from a light source into a plurality of colors in a time division manner, a display element that modulates the light of each color separated by the color wheel, and an external input. A signal processing unit that processes the processed video signal to generate a control signal for causing each pixel of the display element to perform a predetermined modulation operation, and drives the display element according to the control signal from the signal processing unit A drive unit. Here, the color wheel includes a segment that directly transmits white light from the light source. Furthermore, the signal processing unit processes the video signal based on the saturation of the video generated by the input video signal so that the luminance of the pixel displaying the white component among the pixels of the display element is reduced. Then, the control signal is generated.

  More specifically, the signal processing unit attenuates an RGB signal for a pixel that displays the white component when the saturation exceeds a preset threshold value.

  According to the configuration of the present invention, when a highly saturated image is projected, the luminance in the pixel displaying the white component is reduced, so that it is possible to suppress noise caused by the segment that transmits white light as it is. it can. Therefore, noise appearing on an image with high saturation can be suppressed.

  In the projection display device according to the aspect of the invention, the signal processing unit may be configured to determine the saturation in units of one frame and attenuate an RGB signal for a pixel displaying the white component in the frame.

  In this case, for example, the signal processing unit obtains the saturation for each pixel, and when the average or the sum of the saturations of all the pixels exceeds a preset threshold, the RGB signal for the pixel displaying the white component It can be set as the structure which attenuates.

  With such a configuration, since the video signal is adjusted for each frame, noise can be suppressed satisfactorily.

  In the projection display device according to the aspect of the invention, the signal processing unit may increase the luminance of the pixel that displays the white component among the pixels of the display element based on the saturation of the video generated by the input video signal. The video signal may be processed so as to generate the control signal.

  More specifically, the signal processing unit amplifies the RGB signal for the pixel displaying the white component when the saturation is lower than a preset threshold value.

  With such a configuration, it is possible to increase the luminance of an image in which noise is not noticeable due to low saturation.

  In the first to sixth aspects, the “white component” is a concept indicating not only white but also an achromatic color including white, and a color in the vicinity of an achromatic color that may cause the problem of the present invention. The same applies to the following embodiments.

  As described above, according to the present invention, when a color wheel including a white segment is used, it is possible to provide a projection display device that can suppress image deterioration due to noise.

  The effects and significance of the present invention will become more apparent from the following description of embodiments. However, the following embodiment is merely an example when the present invention is implemented, and the present invention is not limited to what is described in the following embodiment.

It is a figure which shows the structure of the projector which concerns on embodiment. It is a figure which shows the structure of the circuit system of the projector which concerns on embodiment. It is a figure which shows the drive timing of the color wheel unit which concerns on embodiment, and DMD. It is a flowchart of the signal processing by the video signal processing circuit which concerns on embodiment. It is a figure for demonstrating threshold value (alpha) and (beta) used for the signal processing of FIG. It is a figure for demonstrating specifically about the signal processing of FIG. 10 is a flowchart of signal processing by a video signal processing circuit according to a first modification. 10 is a flowchart of signal processing by a video signal processing circuit according to a second modification. It is a figure which shows the relationship between xy chromaticity at the time of using the color wheel of 4 colors of red, green, blue, and white, and the brightness | luminance at the time of using the color wheel of 3 colors of red, green, and blue.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a projector according to the present embodiment. FIG. 1A shows the configuration of the optical system, and FIG. 1B shows the configuration of the color wheel unit 30.

  As shown in FIG. 1A, the projector includes a light source lamp 10, a UV filter 20, a color wheel unit 30, a rod integrator 40, a relay optical system 50, a TIR (Total Internal Reflection) prism 60, A DMD 70, a projection optical system 80, and a cooling device 90 are provided.

  The light source lamp 10 includes an arc tube 10a and a reflector 10b. For the arc tube 10a, a metal halide lamp, an ultra-high pressure mercury lamp, a xenon lamp or the like is used. The reflector 10b is formed in an elliptical shape or a parabolic shape. The white light emitted from the lamp 10a is reflected by the reflector 10b and travels forward while converging.

  White light emitted from the light source lamp 10 passes through the UV filter 20 and the color wheel unit 30 and is collected on the incident surface of the rod integrator 40. The UV filter 20 removes ultraviolet rays.

  The color wheel unit 30 is arranged so that the color wheel 31 is positioned near the condensing point of the white light emitted from the light source lamp 10. The color wheel unit 30 is easily attached and detached so that it can be replaced by the user, for example, by being fitted and fixed to a holding portion (not shown).

  The color wheel unit 30 includes a color wheel 31, a motor 32, and a position sensor 33. As shown in FIG. 1B, the color wheel 31 has a ring shape and includes red, green, blue, and white segments 31R, 31G, 31B, and 31W.

  The red segment 31R has an optical characteristic of transmitting only light in the red wavelength band (hereinafter referred to as “R light”). The green segment 31G has an optical characteristic of transmitting only light in the green wavelength band (hereinafter referred to as “G light”). The blue segment 31B has an optical characteristic of transmitting only light in the blue wavelength band (hereinafter referred to as “B light”). The white segment 31W has an optical characteristic of transmitting visible light as it is. That is, the white segment 31W is a transparent region, and white light (hereinafter referred to as “W light”) is transmitted as it is.

  A rotating plate 32 a that is rotated by a motor 32 is fixed to the opening at the center of the color wheel 31. Thereby, when the motor 32 is driven, the color wheel 31 rotates.

  The position sensor 33 is for detecting the rotation state of the color wheel 31. The color wheel 31 is provided with a marker 31a, and a position sensor 33 is provided at a predetermined position on the rotation path of the marker 31a. Each time the color wheel 31 makes one rotation, the position sensor 33 detects the marker 31a and outputs a detection signal (position detection signal). For example, the position sensor 33 is composed of a light emitting element and a light receiving element, and the marker 31a is composed of a reflecting member. In this case, the marker 31a can be detected by receiving light emitted from the light emitting element and reflected by the marker 31a with the light receiving element.

  Thus, when the color wheel 31 rotates, light is sequentially incident on the segments 31R, 31G, 31B, and 31W, and the R light, G light, B light, and W light transmitted through the segments 31R, 31G, 31B, and 31W are The light is emitted from the color wheel 31 in a time division manner.

  The light transmitted through the color wheel 31 enters the rod integrator 40. The rod integrator 40 has a shape bent substantially at a right angle. The light incident on the rod integrator 40 is reflected by the reflecting surface 40a and changes its direction substantially vertically, and travels toward the exit surface while the illuminance is uniformed in the rod.

  The light emitted from the rod integrator 40 is guided by the three relay lenses 51, 52, 53 and the mirror 54 constituting the relay optical system 50 and is incident on the TIR prism 60. Then, the light is reflected by the TIR prism 60 and applied to the DMD 70.

  The DMD 70 is sequentially irradiated with R light, G light, B light, and W light in time division. The DMD 70 includes micromirrors arranged in a matrix, and the micromirrors are driven on and off based on drive signals corresponding to incident R light, G light, B light, and W light, and modulate these lights. . One micromirror constitutes one pixel. The light modulated by the DMD 70 passes through the TIR prism 60 and enters the projection optical system 80, and is projected on the screen by the projection optical system 80.

  Since the switching of the light by the color wheel unit 30 is performed at a very high speed, an image by the light sequentially projected on the screen appears as one image to the user's eyes.

  During operation, the color wheel unit 30 is cooled by the cooling device 90. The cooling device 90 includes a cooling fan 91, and the cooling air generated by driving the cooling fan 91 is blown to the color wheel unit 30 from an outlet 92 disposed in the vicinity of the color wheel unit 30.

  FIG. 2 is a diagram showing a configuration of a circuit system of the projector according to the present embodiment.

  The input switching circuit 101 is a circuit that switches an input terminal portion to be connected from among a plurality of input terminal portions. A video signal is input from an input terminal connected by the input switching circuit 101. The input video signal is converted into a digital signal by the A / D converter 102 and input to the scan conversion circuit 103.

  When a video signal having a screen size (for example, 4: 3 screen size) different from a preset screen size (for example, 16: 9 screen size) is input, the scan conversion circuit 103 The signal is converted so as to be a video signal having a set screen size. The video signal output from the scan conversion circuit 103 is input to the video signal processing circuit 104.

  The video signal processing circuit 104 controls each color wheel unit 30 and the DMD 70 based on the video signal supplied from the scan conversion circuit 103.

  A color wheel motor drive circuit (hereinafter referred to as “motor drive circuit”) 105 drives the color wheel unit 30 based on a control signal from the video signal processing circuit 104. The motor drive circuit 105 sends a pulse signal (rotation speed detection signal) to the video signal processing circuit 104 each time the motor 32 in the color wheel unit 30 rotates by a predetermined angle that is equally divided by 360 degrees (one rotation). Output. For example, the motor drive circuit 105 is provided with a rotation sensor that detects that the motor 32 has rotated by a certain rotation angle, and a detection signal from the rotation sensor is supplied to the video signal processing circuit 104 as a rotation speed signal. Is done.

  The video signal processing circuit 104 controls a motor control signal (for controlling the voltage applied to the motor 32) to the motor 32 based on the rotation speed signal supplied from the motor drive circuit 105 and the position detection signal supplied from the color wheel 30. And the generated motor control signal is output to the motor drive circuit 105. The motor drive circuit 105 drives the motor 32 according to the motor control signal. Here, for example, PWM control is performed as a rotation control method. That is, the amount of current applied to the motor 32 is adjusted in accordance with the rotational speed of the motor 32 set during operation, whereby the rotational speed of the motor 32 is maintained at a desired rotational speed.

  During operation, the video signal processing circuit 104 and the motor drive circuit 105 detect the position detection signal from the position sensor 33 and the motor drive circuit 105 so that the rotation of the color wheel 31 is synchronized with the vertical synchronization signal in the video signal supplied from the scan conversion circuit 103. Each motor 32 is driven at a predetermined rotational speed based on the rotational speed signal from the motor.

  In addition, the video signal processing circuit 104 causes each pixel (micromirror) of the DMD 70 to perform a modulation operation according to the R light, G light, B light, and W light incident on the DMD 70 based on the input video signal. A DMD control signal to be performed is generated and output to the DMD driving circuit 106. The DMD driving circuit 106 drives the DMD 70 according to the DMD control signal.

  The video signal processing circuit 104 drives the DMD 70 so as to synchronize with the vertical synchronization signal in the video signal supplied from the scan conversion circuit 103. As described above, during operation, since the rotation of the color wheel 31 and the vertical synchronization signal are synchronized, the DMD 70 is driven to synchronize with the rotation of each color wheel 31 together with the vertical synchronization signal.

  The operation input circuit 107 accepts input from various operation buttons and outputs an input signal corresponding to the input to the CPU 108.

  The CPU 108 outputs control signals to the cooling fan drive circuit 109, the lamp drive circuit 110, and the LED drive circuit 111 based on various inputs. The cooling fan drive circuit 109 drives the cooling fan 91 in the cooling device 90 in accordance with a control signal from the CPU 108. The lamp driving circuit 110 drives the light source lamp 10 according to a control signal from the CPU 108. The LED drive circuit 111 drives the power LED 112 in accordance with a control signal from the CPU 108.

  Further, the CPU 108 controls the start / stop of the power supply circuit 113. By starting the power supply circuit 113, it is possible to supply power to the color wheel unit 30, the DMD 70, the cooling fan 91, the light source lamp 10, the power supply LED 112, and the like.

  FIG. 3 is a diagram illustrating driving timings of the color wheel unit 30 and the DMD 70. In FIG. 3, the emission timing of the R light, G light, B light, and W light from the color wheel 31 is shown superimposed on the position detection signal.

  As shown in FIG. 3, the color wheel 31 rotates in synchronization with a vertical synchronization signal based on the video signal. For example, the color wheel 31 rotates twice during one period of the vertical synchronization signal. When the color wheel 31 is as shown in FIG. 1B, R light, G light, B light, and W light are emitted from the color wheel 31 at regular intervals. At this time, a DMD drive signal corresponding to each color light is transmitted from the DMD drive circuit 106 to the DMD 70 in synchronization with the vertical synchronization signal and the rotation of the color wheel 31. As a result, at the timing when predetermined light (for example, R light) is applied to the DMD 70, the modulation operation of the DMD 70 corresponding to the light (for example, R light) is performed.

  In this way, the image by the R light, G light, B light and W light modulated by the DMD 70 is sequentially projected by the projection optical system 80, and a color image is projected on the screen. Note that an image for one frame is projected twice on the screen during one period of the vertical synchronizing signal. In other words, since the switching of the image by the light of each color is performed in a shorter time, flickering of the synthesized image is prevented.

  In the present embodiment, the brightness of the entire video can be increased by using the color wheel 31 having white segments. However, along with this, there is a possibility that noise as described above may occur.

  Therefore, in the present embodiment, in order to suppress such noise, the video signal processing circuit 104 analyzes the input video signal for each frame, and based on the saturation of the video in one frame, Signal processing for reducing the luminance of a pixel that displays a white component (hereinafter referred to as a “white component pixel”) among the pixels is executed. Hereinafter, a specific processing operation will be described.

  FIG. 4 is a flowchart of signal processing by the video signal processing circuit 104. FIG. 5 is a diagram for explaining the threshold values α and β used in the signal processing of FIG. The circle shown in FIG. 5 shows a cross section of the color space.

First, the video signal processing circuit 104 calculates the saturation of each pixel using the input RGB signal (S1). At this time, if the video signal is input as a color difference signal, the color difference signal is first converted into an RGB signal. The video signal processing circuit 104 extracts the maximum value and the minimum value from the three signals R, G, and B for each pixel, and calculates the saturation of the pixel from the following equation. Here, the RGB signal is an 8-bit (0 to 255) signal.
Saturation = (maximum value−minimum value) / maximum value × 255 (1)

  Next, the video signal processing circuit 104 uses the saturation of each pixel to calculate average saturation (total value of saturation of all pixels ÷ total number of pixels) in the video of one frame (S2). Then, it is determined whether or not the average saturation exceeds the threshold value α (S3).

  As shown in FIG. 5A, in the color space, the saturation increases and the color becomes darker from the center of the circle toward the outer periphery. In the present embodiment, when the average saturation is greater than the threshold value α, it is determined that the image is dark and vivid, and when the average saturation is less than the threshold value α, the color is light and close to an achromatic color. Judged as video.

  When the video signal processing circuit 104 determines that the average saturation exceeds the threshold value α (set to 150 in the example of FIG. 6) (S3: YES), the gain of the RGB signal of the white component pixel is subtracted (S4). ).

  That is, the video signal processing circuit 104 determines whether or not the pixel is a white component pixel by comparing the saturation of each pixel with the threshold value β. As shown in FIG. 5B, since the center of the circle is white in the color space, the threshold value β is set at the boundary of the range corresponding to the white component.

  If the saturation is smaller than the threshold β (set to 40 in the example of FIG. 6), the video signal processing circuit 104 determines that the pixel is a white component pixel. Then, the RGB signals for all the white component pixels detected by this determination are multiplied by a coefficient a having a value smaller than 1 (set to 0.7 in the example of FIG. 6).

  In this way, the gain of the RGB signal for all white component pixels in one frame is reduced. As a result, the luminance of the white component pixel in the image of one frame is lowered.

  When the correction of the RGB signal is completed, the video signal processing circuit 104 generates a DMD control signal corresponding to the R light, the G light, the B light, and the W light based on the corrected RGB signal, and outputs the DMD control signal to the DMD driving circuit. (S5).

  On the other hand, when the video signal processing circuit 104 determines in step S3 that the average saturation is equal to or less than the threshold value α (S3: NO), the video signal processing circuit 104 generates a DMD control signal corresponding to each color light without correcting the RGB signals. And output to the DMD driving circuit 106 (S5).

  Note that the optimum value of the threshold value α varies depending on the rotation direction angle (area width) of each segment 31R, 31G, 31B, 31W and the filter characteristics. Further, the optimum value of the coefficient a also varies depending on the angle of the white segment 31W. As the angle of the white segment 31W increases, the luminance of the white component shown in FIG. 9A increases. For this reason, as the angle of the white segment 31W increases, the coefficient a is decreased so that the attenuation amount of the white component increases. Actually, the threshold values α and β and the coefficient a are adjusted to values that can satisfactorily suppress noise while confirming an actual image through experiments or the like.

  Further, instead of obtaining the average saturation and comparing it with the threshold value α as described above, the total value of the saturations of all the pixels may be obtained and the obtained total value may be compared with a predetermined threshold value. In this case, a value obtained by multiplying the threshold α by the total number of pixels is a threshold corresponding to the total value.

  FIG. 6 is a diagram for specifically explaining the processing contents in the signal processing of FIG. 4.

  FIG. 6 shows some pixels in one frame. FIG. 6A shows R, G, and B signals corresponding to colors displayed by the pixels for each pixel. First, using these RGB signals, the saturation of each pixel is calculated based on the above equation (1). FIG. 6B shows the saturation calculated for each pixel.

  Next, an average value (average saturation) of saturations of all pixels is obtained, and if this exceeds a threshold value α (for example, 150), it is determined that the entire frame is an image having a dark color on average. The In this case, the white component pixel in one frame is determined by comparing the saturation of each pixel with a threshold value β (for example, 40). In FIG. 6C, the white component pixel is shown in a different display form from the other pixels.

  Next, the RGB signal of the white component pixel is multiplied by a coefficient α (for example, 0.7). FIG. 6D shows a state where the RGB signal of the white component pixel is corrected.

  If it is determined that the average saturation is equal to or less than the threshold value α and the entire frame is an image with an average light color, the RGB signal is not corrected as shown in FIG.

  As described above, according to the present embodiment, the saturation of the video is determined based on the video signal, and the RGB signal for the white component pixel is attenuated for a video with high saturation. Therefore, when an image with high saturation is projected, the luminance of the white component pixel is reduced, so that it is possible to suppress noise caused by transmission of white light from the light source lamp 10 through the segment 31W. .

  Further, according to the present embodiment, since the saturation of the video is determined for each frame and the video signal is adjusted, noise can be suppressed satisfactorily.

<Modification 1>
FIG. 7 is a flowchart of signal processing by the video signal processing circuit 104 according to the first modification.

  In the above embodiment, when it is determined that the average saturation is equal to or less than the threshold value α, the video signal is not corrected.

  However, when the video signal processing circuit 104 determines that the average saturation is equal to or less than the threshold value α (S3: YES) as in the process illustrated in FIG. 7A, the gain of the RGB signal with respect to the white component pixel is set. A configuration of adding (S6) can also be adopted. In this case, the RGB signals for all the white component pixels are multiplied by a coefficient b having a value greater than 1 (for example, 1.3). At this time, if the value after multiplication exceeds the upper limit value (255), it becomes the upper limit value.

  With such a configuration, it is possible to increase the luminance of an image in which noise is not noticeable due to low saturation.

  In addition, in an image having a saturation close to the threshold value α, noise may become conspicuous if the gains of the RGB signals for the white component pixels are added.

  Therefore, when the video signal processing circuit 104 determines that the average saturation is equal to or less than the threshold γ (<threshold α) as in the process illustrated in FIG. 7B (S7: NO), the white component pixel It is also possible to add the gains of the RGB signals to (S8), and if the average saturation is equal to or less than the threshold value α and greater than the threshold value γ (S7: YES), the RGB signal is not corrected.

  In this way, it is possible to prevent noise from appearing in the video by adding the gains of the RGB signals for the white component pixels.

<Modification 2>
In the embodiment described above, the saturation of the video for the entire frame is determined based on the average saturation, but the saturation of the video for the entire frame may be determined using other methods.

  FIG. 8A is a flowchart of signal processing by the video signal processing circuit 104 according to the second modification. In this modification, steps S2 and S3 in FIG. 4 are replaced with steps S11 and S12. The other steps are the same as in FIG.

  In this modification, the total area of the pixels whose saturation exceeds a predetermined reference, that is, a predetermined threshold value is calculated (S11), and when the calculated total area exceeds the predetermined threshold value X (S12: YES), white The gains of the RGB signals for the component pixels are subtracted (S4).

  Further, the saturation of the image of the entire frame may be determined based on the number of pixels instead of the total area of the pixels whose saturation exceeds a certain reference. FIG. 8B is a diagram showing a flowchart in this case. In FIG. 8B, the total number of pixels whose saturation exceeds a predetermined reference, that is, a predetermined threshold value is counted (S21), and when the total number of the counted pixels exceeds the predetermined threshold value Y (S22: YES) ) The RGB signal gains for the white component pixels are subtracted (S4).

  Furthermore, the processing in FIGS. 8A and 8B may be applied to the configuration of the first modification. In this case, steps S2 and S3 in FIGS. 7A and 7B are replaced with steps S11 and S12 in FIG. 8A or steps S21 and S22 in FIG. 8B.

<Others>
The embodiment of the present invention can be variously modified in addition to the above.

  For example, in the above embodiment, the attenuation amount (coefficient a) of the RGB signal with respect to the white component pixel is constant, but the attenuation amount is set to the saturation of the image of the entire frame (“average saturation” in the above embodiment). Alternatively, it may be changed stepwise or continuously according to “the total area and number of pixels exceeding a certain standard” in the second modification. In this case, the amount of attenuation is increased as the saturation of the image of the entire frame increases.

  Similarly, in the first modification, the RGB signal amplification amount (coefficient b) for the white component pixels may be changed stepwise or continuously in accordance with the saturation. In this case, the amount of amplification is increased as the saturation of the image of the entire frame becomes lower.

  In the present embodiment, a color wheel 30 having red, green, blue, and white segments is used. However, the present invention is not limited to this, and for example, a color wheel in which segments such as yellow, cyan, magenta, and the like are further added to the above four colors may be used. In short, a color wheel including not only a chromatic segment but also a white segment may be used.

  Furthermore, although DMD is used as the display element in the above embodiment, the present invention is not limited to this, and for example, a reflective liquid crystal panel may be used.

  Furthermore, the present invention can be applied to a projector other than a projector having one lamp and a color wheel. For example, the present invention can be applied to a projector having a configuration in which two color wheel units are arranged in each optical path from two light source lamps. Also, the present invention can be applied to a projector having a configuration in which two color wheel units are arranged in the front-rear direction in the optical path from the light source lamp.

  In addition, various modifications can be made as appropriate within the scope of the technical idea shown in the claims.

10 Light source lamp (light source)
30 Color wheel unit 31 Color wheel 70 DMD (Display element)
104 Signal processing circuit (signal processing unit)
106 DMD drive circuit (drive unit)

Claims (6)

In a projection display device,
A color wheel that separates white light from the light source into light of multiple colors in a time-sharing manner;
A display element for modulating light of each color separated by the color wheel;
A signal processing unit that processes a video signal input from the outside and generates a control signal for causing each pixel of the display element to perform a predetermined modulation operation;
A drive unit that drives the display element in accordance with the control signal from the signal processing unit,
The color wheel includes a segment that directly transmits white light from the light source,
The signal processing unit processes the video signal based on the saturation of the video generated by the input video signal so that the luminance of the pixel displaying the white component among the pixels of the display element is reduced. Generating the control signal;
A projection display device characterized by that. The projection display device according to claim 1,
The signal processing unit attenuates an RGB signal for a pixel displaying the white component when the saturation exceeds a preset threshold;
A projection display device characterized by that. The projection display device according to claim 1 or 2,
The signal processing unit determines the saturation in units of one frame and attenuates RGB signals for pixels displaying the white component in the frame.
A projection display device characterized by that. The projection display device according to claim 3,
The signal processing unit obtains the saturation for each pixel, and attenuates the RGB signal for the pixel displaying the white component when the average or sum of the saturations of all the pixels exceeds a preset threshold value,
A projection display device characterized by that. The projection display device according to any one of claims 1 to 4,
The signal processing unit processes the video signal based on the saturation of the video generated by the input video signal so that the luminance of the pixel displaying the white component among the pixels of the display element is increased. Generating the control signal;
A projection display device characterized by that. The projection display device according to claim 5, wherein
The signal processing unit amplifies an RGB signal for a pixel displaying the white component when the saturation is lower than a preset threshold;
A projection display device characterized by that.

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