JP2013121068A - Projection-type image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration of detection accuracy of a control signal to an external device superimposed on projection light.SOLUTION: An optical modulator 8 modulates light emitted from a light source 1 in accordance with an image signal. A projector projects the light modulated by the optical modulator 8. A controller 10 adjusts the output level of the light source 1. On the image signal, the control signal for transmitting control information to the external device is superimposed. The controller 10 adjusts the output level of the light source 1 in a period including the control signal, in accordance with ambient light.

Description

  The present invention relates to a projection display apparatus capable of adjusting an output level of a light source.

  In recent years, the functions of a projection display apparatus have been expanded. For example, a 3D-compatible projection display device (see, for example, Patent Document 1) and a projection display device (see, for example, Patent Document 2) equipped with an interactive function have been put into practical use.

  The shutter glasses method is prominent as a 3D-compatible projection display device. In the shutter glasses method, the projection display device alternately displays left-eye images and right-eye images having parallax, and the shutter glasses alternately open and close the left-eye shutter and right-eye shutter in synchronization with the image switching. . Thereby, the observer wearing the shutter glasses can recognize the stereoscopic image. In this shutter glasses method, there is a method of superimposing a synchronization signal on projection light.

  Among projection-type image display devices equipped with an interactive function, there is a projection-type image display device that projects a pixel-level position coordinate signal superimposed on image light, and the light receiving element of the interactive pen receives this position coordinate signal. To detect the position of the pen relative to the display surface.

JP 2011-176792 A JP 2011-108251 A

  The above-described synchronization signal and position coordinate signal are superimposed on the projection light and transmitted from the projection display apparatus 100, and received by shutter glasses or an interactive pen. When the projection display device is used in a bright place, when the user is too far away or too close to the projection display device, and the detection accuracy of the superimposed synchronization signal and position coordinate signal is reduced. There is.

  The present invention has been made in view of such a situation, and an object thereof is to provide a technique for suppressing a decrease in detection accuracy of a control signal to an external device superimposed on projection light.

  A projection display apparatus according to an aspect of the present invention includes a light source, a light modulation element that modulates light emitted from the light source according to a video signal, and a projection unit that projects light modulated by the light modulation element. And a control unit for adjusting the output level of the light source. A control signal for transmitting control information to an external device is superimposed on the video signal, and the control unit adjusts the output level of the light source during the period in which the control signal is included according to the ambient light.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that the detection accuracy of the control signal to the external apparatus superimposed on projection light falls.

1 is a diagram showing a configuration of a projection display apparatus according to Embodiment 1. FIG. It is a figure which shows the structure of a color wheel. It is a figure which shows the structure of shutter glasses. FIGS. 4A to 4C are diagrams illustrating a relationship example between the ramp modulation pattern and the output level of the synchronization signal according to the first embodiment. It is a figure which shows an example of the table which linked | related the ambient light and lamp | ramp modulation pattern which concern on Embodiment 1. FIG. 5 is a flowchart for explaining synchronization signal detection sensitivity optimization control by the projection display apparatus according to the first embodiment. It is a figure which shows the structure of the interactive pen which concerns on Embodiment 2. FIG. FIGS. 8A to 8C are diagrams illustrating a relationship example between the ramp modulation pattern and the output level of the position coordinate signal according to the second embodiment. It is a figure which shows an example of the table which linked | related the ambient light and lamp | ramp modulation pattern which concern on Embodiment 2. FIG. 10 is a flowchart for explaining detection sensitivity optimization control of a position coordinate signal by the projection display apparatus according to the second embodiment.

(Embodiment 1)
First, Embodiment 1 of the present invention will be described. In the first embodiment, a shutter glasses 3D-compatible projection display apparatus will be described. FIG. 1 is a diagram showing a configuration of a projection display apparatus 100 according to the first embodiment. The projection display apparatus 100 includes a light source 1, an optical unit 50, a mirror 7, a light modulation element 8, a projection lens 9, a control unit 10, a wheel driving unit 11, a lamp driving unit 12, a light modulation element driving unit 13, and a video signal. An input unit 14 and a receiving unit 15 are provided.

  The light source 1 irradiates the optical unit 50 with light according to control by the lamp driving unit 12. As the light source 1, a halogen lamp having a filament type electrode structure, a metal halide lamp having an electrode structure for generating arc discharge, a xenon short arc lamp, a high pressure type mercury lamp, an LED lamp, or the like can be used. The light emitted from the arc tube 1 a provided at the center of the light source 1 is collected by the reflector 1 b formed of an elliptical surface or a hyperboloid and enters the optical unit 50.

  The color wheel 2 has a disk shape and is disposed perpendicular to the optical axis of the light emitted from the light source 1. The color wheel 2 rotates around a rotation axis parallel to the optical axis. A motor 3 is attached to the color wheel 2, and the motor 3 rotates the color wheel 2 in accordance with control by the wheel drive unit 11. The position detection sensor 4 is installed in the vicinity of the color wheel 2. The position detection sensor 4 detects a specific position of the color wheel 2 and outputs a detection signal to the control unit 10.

  The rod integrator 5 is disposed on the optical axis via the color wheel 2. The rod integrator 5 equalizes the illuminance of the light incident from the incident surface 5a and emits the light from the output surface 5b. Although FIG. 1 illustrates an example in which a hollow rod having a mirror surface on the inside is used, a solid rod formed of a glass rod may be used.

  The condenser lenses 6a and 6b are arranged on the optical axis so as to face the emission surface 5b of the rod integrator 5. The condenser lenses 6 a and 6 b collect the light emitted from the emission surface 5 b of the rod integrator 5 and emit it to the mirror 7.

  The mirror 7 is disposed on the optical axis with a predetermined inclination with respect to the optical axis. The mirror 7 reflects the light emitted from the condenser lenses 6 a and 6 b and emits it to the light modulation element 8. As described above, the condenser lenses 6 a and 6 b and the mirror 7 have a function of forming an image of the emission surface 5 b of the rod integrator 5 on the light modulation element 8.

  The light modulation element 8 modulates incident light in accordance with control by the light modulation element driving unit 13. FIG. 1 illustrates an example using a DMD (Digital Micromirror Device). The DMD is composed of a plurality of micromirrors. The plurality of micromirrors are independently movable. In principle, one micromirror corresponds to one pixel. DMD changes the angle of each micromirror according to the video signal. Thereby, it can be switched for every display pixel whether incident light is reflected in the projection lens 9 side. Note that tone control is possible by controlling the time of reflection to the projection lens 9 side.

  As shown in FIG. 1, in the single-plate DLP (registered trademark) configuration, a plurality of different color lights (at least red light, green light, and blue light) are incident on the DMD in a time-division manner during a unit frame period. Therefore, color image light can be generated with a single DMD.

  The light modulation element driving unit 13 controls each micromirror of the DMD according to the video signal set by the control unit 10. In the first embodiment, in order to project a 3D video, the left eye video signal and the right eye video signal are time-divisionally or alternately set in the light modulation element driving unit 13 from the control unit 10.

  The projection lens 9 projects the light modulated by the light modulation element 8 onto a projection surface such as a screen (not shown). At this time, the projection lens 9 forms an image of the light modulated by the light modulation element 8, so that the image formed by the light modulation element 8 is enlarged and displayed on the projection surface. In the first embodiment, left-eye image light and right-eye image light are projected in a time-division or alternately manner.

  The video signal input unit 14 reads a video file from a recording medium or a PC connected to the projection video display device 100 and outputs the video file to the control unit 10. The receiving unit 15 receives a signal transmitted from an external device (shutter glasses in the first embodiment) that operates in cooperation with the projection display apparatus 100 and outputs the signal to the control unit 10.

  The control unit 10 controls the wheel driving unit 11, the light modulation element driving unit 13, and the lamp driving unit 12. More specific description will be given below. The control unit 10 grasps the position and rotation speed of the color wheel 2 according to the detection signal input from the position detection sensor 4. The control unit 10 controls the wheel driving unit 11 and the light modulation element driving unit 13 so that the rotation of the color wheel 2 and the light modulation by the light modulation element 8 are synchronized. That is, control is performed so that the timing at which specific color light is emitted from the color wheel 2 is synchronized with the timing at which the gradation value of the color light is set in the light modulation element 8.

  The control unit 10 superimposes a control signal for transmitting control information to an external device on the video signal set in the light modulation element driving unit 13. In the first embodiment, a synchronization signal to the shutter glasses is superimposed on the video signal. This synchronization signal is a signal for synchronizing the projection timing of the left eye image and right eye image of the projection display apparatus 100 and the opening / closing timing of the left eye shutter and right eye shutter of the shutter glasses. The control unit 10 superimposes the synchronization signal on the video signal during a period in which specific color light is incident on the light modulation element 8. That is, the control unit 10 superimposes the synchronization signal on a specific color segment of the video signal.

  The control unit 10 adjusts the output level of the light source 1. In a projection display apparatus that projects a color image using a color wheel, it is difficult to adjust a color balance by adjusting physical elements. If the color wheel is replaced, the color balance can be adjusted, but this is a complicated operation. In a single-plate DLP (registered trademark) projection display apparatus, there is a method of modulating the output of a lamp in synchronization with color light separated in time series. That is, the output of the lamp is changed for each separated color segment. In order to realize this, for example, a plurality of lamp modulation patterns are held and selectively used. According to this, a state in which a plurality of color wheels are selectively used can be created in a pseudo manner.

  The first embodiment uses this method. The control unit 10 adjusts the output level of the light source 1 during the period in which the synchronization signal is included, according to the ambient light. For example, when the ambient light is stronger than the first reference value, the output level of the light source 1 during the period in which the synchronization signal is included is increased, and when the ambient light is weaker than the second reference value, the light source 1 in the period in which the synchronization signal is included. Reduce the output level.

  As described above, the synchronization signal is superimposed on the color segment of the specific color. Therefore, the control unit 10 can adjust the output level of the light source 1 during the period including the synchronization signal by selecting one of the plurality of lamp modulation patterns according to the ambient light and setting it in the lamp driving unit 12.

  FIG. 2 shows the configuration of the color wheel 2. The color wheel 2 is divided into six sector regions. The six fan-shaped regions are a G region that transmits green light, a Y region that transmits yellow light, an R region that transmits red light, a W region that transmits white light, a C region that transmits green-blue (cyan) light, and blue. This is a B region that transmits light, and is arranged clockwise in this order. Of these regions, the essential regions are the R region, the G region, and the B region, and the other regions are optional. In FIG. 2, a Y region and a C region are additionally provided in order to increase color expressiveness, and a W region where the amount of light does not decrease is additionally provided.

  The transmission part 2a is an optical path through which incident light passes, and its position is fixed. It arrange | positions so that incident light may pass the circumference side instead of a center side (refer FIG. 1). The color wheel 2 rotates with the incident direction as the rotation axis direction, and transmits green light, yellow light, red light, white light, green blue light, and blue light in a time-sharing manner.

  FIG. 3 is a diagram illustrating a configuration of the shutter glasses 200. The shutter glasses 200 include a control unit 20, an optical signal receiving unit 21, a left eye shutter drive unit 22, a left eye shutter 23, a right eye shutter drive unit 24, a right eye shutter 25, and an illuminance sensor 26.

  The optical signal receiving unit 21 receives a synchronization signal superimposed on the image light projected from the projection display apparatus 100. The optical signal receiving unit 21 includes a photodiode. This photodiode is a photodiode having sensitivity in a color segment including a synchronization signal. The photodiode converts the optical signal into an electrical signal and outputs it to the control unit 20.

  The control unit 20 controls the left eye shutter driving unit 22 and the right eye shutter driving unit 24 according to the synchronization signal input from the optical signal receiving unit 21. The left eye shutter drive unit 22 opens and closes the left eye shutter 23 according to control by the control unit 20. The right eye shutter drive unit 24 opens and closes the right eye shutter 25 according to control by the control unit 20.

  In general 3D video, left-eye video and right-eye video are each displayed at 60 Hz, and both are alternately displayed. When the left eye image and the right eye image are combined, they are displayed at 120 Hz. The shutter glasses 200 need to operate in synchronization therewith. That is, the left eye shutter 23 and the right eye shutter 25 are each driven at 60 Hz, and both are alternately opened and closed. The entire shutter glasses 200 are driven at 120 Hz.

  The illuminance sensor 26 detects the brightness around the shutter glasses 200. The illuminance sensor 26 converts light into an electrical signal and outputs it to the control unit 20. The control unit 20 supplies an output value of the illuminance sensor 26 (hereinafter referred to as an illuminance value) to the transmission unit 27, and the transmission unit 27 transmits the illuminance value to the projection display apparatus 100 wirelessly or by wire. For example, transmission is performed using short-range wireless communication or infrared communication.

  The signal transmitted from the transmission unit 27 is received by the reception unit 15 of the projection display apparatus 100. The receiving unit 15 outputs the illuminance value included in the signal transmitted from the shutter glasses 200 to the control unit 10. The control unit 10 adjusts the output level of the light source 1 during the period in which the synchronization signal is included, according to the illuminance value.

  FIGS. 4A to 4C are diagrams illustrating a relationship example between the ramp modulation pattern and the output level of the synchronization signal according to the first embodiment. Each of the lamp modulation patterns in FIGS. 4A to 4C indicates the lamp output level for one turn of the color wheel 2 shown in FIG. That is, the output levels of light emitted in the order of green light, yellow light, red light, white light, green blue light, and blue light are shown.

  In the example shown in FIGS. 4A to 4C, the above-described synchronization signal is superimposed on the white segment. In the 3D video, no significant video is displayed during the white segment period, and a black video is displayed. The control unit 10 of the projection display apparatus 100 superimposes the synchronization signal in the blank period in which this image is displayed, and the optical signal receiving unit 21 of the shutter glasses 200 is not recognized by human eyes from the image in the blank period. Instantaneous blinking is detected.

  4A shows the relationship between the ramp modulation pattern A and the output level of the synchronization signal, FIG. 4B shows the relationship between the ramp modulation pattern B and the output level of the synchronization signal, and FIG. ) Shows the relationship between the ramp modulation pattern C and the output level of the synchronization signal. In the lamp modulation pattern B shown in FIG. 4B, the output level of the lamp is constant in all the color segments. This is the basic ramp modulation pattern used in the normal state.

  In the lamp modulation pattern A shown in FIG. 4A, the output levels of the yellow, white, and green-blue segments are high, and the output levels of the green, red, and blue segments are low. On the other hand, the ramp modulation pattern C shown in FIG. 4C has high output levels for the green segment, yellow segment, red segment, and blue segment, and low output levels for the white segment and green-blue segment.

  The sum of the output levels of all color segments of the ramp modulation pattern must be constant. Therefore, as shown in lamp modulation pattern A, when the output level of the green segment, red segment, and blue segment is lowered, the output level of the other segments (yellow segment, white segment, green-blue segment in ramp modulation pattern A) is raised. ing. Similarly, as shown in the lamp modulation pattern C, when the output levels of the green segment, red segment, and blue segment are increased, the output levels of the other segments (white segment and blue segment in the ramp modulation pattern C) are decreased. In the ramp modulation pattern C, the output level of the yellow segment is increased.

  When the lamp modulation pattern A is selected, the control unit 10 of the projection display apparatus 100 increases the output intensity of white light, so that the optical signal intensity of the synchronization signal can be increased. Further, when the lamp modulation pattern C is selected, the output intensity of the white light decreases, so that the optical signal intensity of the synchronization signal can be lowered.

  FIG. 5 is a diagram illustrating an example of a table in which the ambient light and the lamp modulation pattern are associated with each other according to the first embodiment. The control unit 10 of the projection display apparatus 100 classifies the illuminance value received from the shutter glasses 200 into one of the first class, the second class, and the third class using two reference values. The first class is a class with bright ambient light, the second class is a class with normal ambient light, and the third class is a class with dark ambient light. The two reference values are values set in advance by the designer.

  The table shown in FIG. 5 associates the first class with the lamp modulation pattern A, associates the second class with the lamp modulation pattern B, and associates the third class with the lamp modulation pattern C. The control unit 10 of the projection display apparatus 100 refers to the table and selects a lamp modulation pattern based on the illuminance value received from the shutter glasses 200.

  FIG. 6 is a flowchart for explaining synchronization signal detection sensitivity optimization control by the projection display apparatus 100 according to the first embodiment. First, the projection display apparatus 100 starts projecting image light onto the projection surface (S10). A synchronization signal is superimposed on the video light. The illuminance sensor 26 of the shutter glasses 200 detects ambient brightness, and the transmission unit 27 transmits the illuminance value to the projection display apparatus 100. The projection display apparatus 100 acquires the illuminance value (S11).

  The control unit 10 of the projection display apparatus 100 classifies the illuminance value into classes (S12). When the illuminance value is classified into the first class (bright in S12), the control unit 10 selects the lamp modulation pattern A and sets it in the lamp driving unit 12 (S13). When the illuminance value is classified into the second class (ordinary in S12), the control unit 10 selects the lamp modulation pattern B and sets it in the lamp driving unit 12 (S14). When the illuminance value is classified into the third class (dark in S12), the control unit 10 selects the lamp modulation pattern C and sets it in the lamp driving unit 12 (S15).

  When the projection of the image light onto the projection surface is finished (Y in S16), the detection sensitivity optimization control is finished. During projection of image light (N in S16), when a predetermined period (for example, several seconds) elapses from the previous lamp modulation pattern selection process (Y in S17), the process proceeds to step S11, and the processes from step S11 to step S16 repeat.

  As described above, according to the first embodiment, the synchronization signal in the shutter glasses is changed by adaptively changing the output intensity of the color segment on which the synchronization signal to the shutter glasses is superimposed according to the surrounding environment of the shutter glasses. The detection accuracy can be improved or at least the detection accuracy can be prevented from decreasing. Therefore, 3D video projection with high detection accuracy is realized without depending on the use environment. The shutter glasses can be stably operated even in a place where the detection accuracy of the optical signal is poor, such as a place that is too bright or too dark.

  In addition, an illuminance sensor is attached to the shutter glasses, the ambient light around it is fed back to the projection display, and the output intensity of the color segment that superimposes the synchronization signal is dynamically adjusted, making it ideal for the receiving environment. Sensitivity can be adjusted. The reception sensitivity of the synchronization signal depends on the use environment. For example, since it is difficult to receive in a bright place, adjustment is made to facilitate reception by increasing the strength of the synchronization signal.

(Embodiment 2)
Next, a second embodiment of the present invention will be described. In the second embodiment, a projection display apparatus equipped with an interactive function will be described. In the second embodiment, an electronic device (hereinafter referred to as an interactive pen) that operates in cooperation with the projection display apparatus and can perform an interactive operation is used. The configuration of the projection display apparatus 100 according to the second embodiment is basically the same as that of the projection display apparatus 100 according to the first embodiment shown in FIG. In the following description, differences from the first embodiment will be described.

  The control unit 10 superimposes a position coordinate signal for specifying the position of the pixel displayed on the projection plane on the video signal set in the light modulation element driving unit 13. The interactive system according to the present embodiment is a system that does not require a special screen or the like and has no projection plane restrictions. Instead, a position coordinate signal is embedded in the pixel displayed on the projection surface. This position coordinate signal is an optical signal indicating the position of each pixel.

  When DMD is used for the light modulation element 8, the gradation of each pixel is given by a pulse pattern. Accordingly, the position coordinate signal is also defined by a pulse pattern, and a pulse pattern that uniquely identifies the pixel is assigned to each pixel. Note that the position coordinate signal need not be assigned to all pixels, and need not be embedded in all frames. The position coordinate signal can be thinned out spatially and / or temporally.

  The control unit 10 superimposes the position coordinate signal on the video signal during a period in which specific color light is incident on the light modulation element 8. That is, the control unit 10 superimposes the position coordinate signal on a specific color segment of the video signal. The control unit 10 adjusts the output level of the light source 1 during the period in which the position coordinate signal is included, according to the ambient light. For example, the control unit 10 can select one of a plurality of lamp modulation patterns according to the ambient light and set it in the lamp driving unit 12.

  FIG. 7 is a diagram showing a configuration of the interactive pen 300 according to the second embodiment. The interactive pen 300 includes a control unit 30, an optical signal reception unit 31, an illuminance sensor 32, an operation unit 33, and a transmission unit 34. The optical signal receiving unit 31 receives a position coordinate signal superimposed on the image light projected from the projection display apparatus 100. The optical signal receiving unit 31 includes a photodiode. This photodiode is a photodiode having sensitivity in a color segment including a position coordinate signal. The photodiode converts the received signal into an electrical signal and outputs it to the control unit 30. The photodiode is attached to the tip of the interactive pen 300.

  The illuminance sensor 32 detects the brightness around the shutter glasses 200. The illuminance sensor 32 converts light into an electrical signal and outputs it to the control unit 30. The control unit 30 supplies an output value of the illuminance sensor 32 (hereinafter referred to as an illuminance value) to the transmission unit 34, and the transmission unit 34 transmits the illuminance value to the projection display apparatus 100 wirelessly or by wire. For example, transmission is performed using short-range wireless communication or infrared communication.

  The signal transmitted from the transmission unit 34 is received by the reception unit 15 of the projection display apparatus 100. The receiving unit 15 outputs the illuminance value included in the signal transmitted from the interactive pen 300 to the control unit 10. The control unit 10 adjusts the output level of the light source 1 during the period in which the position coordinate signal is included, according to the illuminance value.

  Returning to FIG. The operation unit 33 receives a user operation and outputs an operation signal indicating the operation to the control unit 30. For example, a drawing button is provided on the operation unit 33 and when the user presses the drawing button, the drawing mode is set, and the user can write characters or the like on the projection surface with the interactive pen 300. That is, the projection surface looks like an electronic blackboard.

  In the interactive system according to the present embodiment, the photodiode detects the position coordinate signal of each pixel on the projection surface, thereby enabling interactive operation with the interactive pen 300. For example, when the user taps the projection plane with the interactive pen 300, the photodiode detects a position coordinate signal embedded in the pixel at the tapped position. This position coordinate signal is output to the control unit 30. The control unit 30 supplies this position coordinate signal to the transmission unit 34, and the transmission unit 34 transmits this position coordinate signal to the projection display apparatus 100.

  The signal transmitted from the transmission unit 34 is received by the reception unit 15 of the projection display apparatus 100. The receiving unit 15 outputs a position coordinate signal included in the signal transmitted from the interactive pen 300 to the control unit 10. The control unit 10 identifies the position tapped with the interactive pen 300 based on the position coordinate signal.

  When the projection display apparatus 100 is connected to an information processing apparatus such as a PC and receives a video signal from the information processing apparatus, the control unit 10 notifies the information processing apparatus that the position has been tapped. The information processing apparatus executes processing according to the tap at that position. For example, when a web page is displayed as a projected video, if the tapped position is a hyperlink position, the video is switched to the linked web page.

  In the drawing mode, the control unit 10 of the projection display apparatus 100 synthesizes a point at the tapped position in the image. Note that the projection surface and the interactive pen 300 do not need to be in contact with each other and may be in non-contact. Therefore, the user can use the interactive pen 300 to write characters or the like in the video even in a non-contact state with the projection plane.

  FIGS. 8A to 8C are diagrams illustrating a relationship example between the ramp modulation pattern and the output level of the position coordinate signal according to the second embodiment. The ramp modulation patterns AC in FIGS. 8A to 8C are the same as the ramp modulation patterns AC in FIGS. 4A to 4C.

  In the example shown in FIGS. 8A to 8C, the position coordinate signal described above is superimposed on the green segment, the red segment, and the blue segment. The controller 10 omits the video data during the period in which the position coordinate signal is superimposed. For example, when the number of pixels in which the position coordinate signal is embedded is one in several pixels or several tens of pixels, even if the video data of the pixel in which the position coordinate signal is embedded is omitted, there is no significant effect. Further, the control unit 10 may correct the video signal so as to generate an image that approximates the original image of the pixel in another color segment.

  8A shows the relationship between the ramp modulation pattern A and the output level of the position coordinate signal, and FIG. 8B shows the relationship between the ramp modulation pattern B and the output level of the position coordinate signal. (C) shows the relationship between the ramp modulation pattern C and the output level of the position coordinate signal.

  When the lamp modulation pattern A is selected, the control unit 10 of the projection display apparatus 100 decreases the output intensity of the green light, red light, and blue light, so that the optical signal intensity of the position coordinate signal can be decreased. Further, when the lamp modulation pattern C is selected, the output intensity of green light, red light, and blue light increases, so that the optical signal intensity of the position coordinate signal can be increased.

  FIG. 9 is a diagram illustrating an example of a table in which environmental light and a lamp modulation pattern are associated with each other according to the second embodiment. The control unit 10 of the projection display apparatus 100 classifies the illuminance value received from the interactive pen 300 into one of the first class, the second class, and the third class using two reference values. The table shown in FIG. 9 associates the first class with the lamp modulation pattern C, associates the second class with the lamp modulation pattern B, and associates the third class with the lamp modulation pattern A. The control unit 10 of the projection display apparatus 100 refers to the table and selects a lamp modulation pattern based on the illuminance value received from the interactive pen 300.

  FIG. 10 is a flowchart for explaining detection sensitivity optimization control of a position coordinate signal by the projection display apparatus 100 according to the second embodiment. First, the projection display apparatus 100 starts projecting image light onto the projection surface (S10). A position coordinate signal is superimposed on the image light. The illuminance sensor 32 of the interactive pen 300 detects ambient brightness, and the transmission unit 34 transmits the illuminance value to the projection display apparatus 100. The projection display apparatus 100 acquires the illuminance value (S11).

  The control unit 10 of the projection display apparatus 100 classifies the illuminance value into classes (S12). When the illuminance value is classified into the third class (dark in S12), the control unit 10 selects the lamp modulation pattern A and sets it in the lamp driving unit 12 (S13). When the illuminance value is classified into the second class (ordinary in S12), the control unit 10 selects the lamp modulation pattern B and sets it in the lamp driving unit 12 (S14). When the illuminance value is classified into the first class (bright in S12), the control unit 10 selects the lamp modulation pattern C and sets it in the lamp driving unit 12 (S15).

  When the projection of the image light onto the projection surface is finished (Y in S16), the detection sensitivity optimization control is finished. During projection of image light (N in S16), when a predetermined period (for example, several seconds) elapses from the previous lamp modulation pattern selection process (Y in S17), the process proceeds to step S11, and the processes from step S11 to step S16 repeat.

  As described above, according to the second embodiment, the position coordinate signal is detected in the interactive pen by adaptively changing the output intensity of the color segment on which the position coordinate signal is superimposed in accordance with the surrounding environment of the interactive pen. The accuracy can be improved or at least the detection accuracy can be prevented from decreasing. Therefore, an interactive function with high detection accuracy that does not depend on the use environment is realized. The interactive function can operate stably even in places where the light signal detection accuracy is poor, such as places that are too bright or too dark.

  In addition, an illuminance sensor is attached to the interactive pen, the ambient light around it is fed back to the projection display, and the output intensity of the color segment that superimposes the position coordinate signal is dynamically adjusted, making it ideal for the usage environment. It can be adjusted to the reception sensitivity.

  The present invention has been described based on some embodiments. It is understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. By the way.

  In the first and second embodiments, the example in which the illuminance sensor is attached to the shutter glasses 200 and the interactive pen 300 has been described, but the illuminance sensor may be attached to the projection display apparatus 100. Alternatively, the illuminance value may be acquired from the projection display apparatus 100 or an existing illuminance sensor installed indoors.

  In the first and second embodiments, for the sake of simplicity, three examples of lamp modulation patterns have been described. However, two or four or more types may be used.

  In the first and second embodiments, an example in which the single-plate DLP (registered trademark) projection display apparatus 100 is used has been described. However, the projection display apparatus uses a reflective or transmissive liquid crystal panel instead of the DMD. The present invention is also applicable. Moreover, it is applicable not only to a single plate type but also to a three plate type. In either case, the output light of the color segment on which the synchronization signal or the position coordinate signal is superimposed may be adjusted.

  DESCRIPTION OF SYMBOLS 1 Light source, 2 Color wheel, 2a Transmission part, 3 Motor, 4 Position detection sensor, 5 Rod integrator, 6ab, Condenser lens, 7 Mirror, 8 Light modulation element, 9 Projection lens, 10 Control part, 11 Wheel drive part, DESCRIPTION OF SYMBOLS 12 Lamp drive part, 13 Light modulation element drive part, 14 Video signal input part, 15 Receiving part, 50 Optical unit, 100 Projection type video display apparatus, 20 Control part, 21 Optical signal receiving part, 22 Left eye shutter drive part, 23 Left-eye shutter, 24 Right-eye shutter drive unit, 25 Right-eye shutter, 26 Illuminance sensor, 27 Transmitter, 200 Shutter glasses, 30 Control unit, 31 Optical signal receiver, 32 Illuminance sensor, 33 Operation unit, 34 Transmitter 300 Interactive pen.

Claims (5)

A light source;
A light modulation element that modulates light emitted from the light source according to a video signal;
A projection unit that projects light modulated by the light modulation element;
A control unit for adjusting the output level of the light source,
The video signal is superimposed with a control signal for transmitting control information to an external device,
The control unit adjusts an output level of the light source during a period including the control signal according to ambient light. A plurality of different colored lights are incident on the light modulation element in a time division during a unit frame period,
The projection display apparatus according to claim 1, wherein the control signal is superimposed on an image signal during a period in which specific color light is incident on the light modulation element. The external device is equipped with a sensor for detecting brightness,
The projection display apparatus according to claim 1, wherein the control unit adjusts an output level of the light source during a period in which the control signal is included, according to an output value of the sensor. In the light modulation element, a left eye video signal and a right eye video signal are set in a time-sharing manner,
The projection unit projects the left eye image and the right eye image in a time-sharing manner,
The external device is shutter glasses that alternately open and close the left eye shutter and the right eye shutter,
The control signal is a synchronization signal for synchronizing the projection timing of the left eye image and the right eye image and the opening / closing timing of the left eye shutter and the right eye shutter,
4. The projection display apparatus according to claim 1, wherein the control unit adjusts an output level of the light source during a period in which the synchronization signal is included. The control signal is a position signal for specifying the position of a pixel displayed on the projection plane,
The external device is an electronic device that detects the position signal and performs interactive input,
The projection display apparatus according to claim 1, wherein the control unit adjusts an output level of the light source during a period in which the position signal is included.

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