JP2008096805A - Projector and projector system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector capable of accurately measuring environment light without discontinuing image projection and correcting a projection image with high precision even when the environment light changes. <P>SOLUTION: The projector 20 which projects the image on a screen includes an image projection unit 120 having at least a light source and a light control part which controls whether the light source illuminates, an optical sensor 30 which measures brightness in a circumference of the projector 20 or brightness of the screen, a measurement signal processing unit 140 which converts the output of the optical sensor 30 into a digital signal and performs a predetermined operation to acquire measurement data, an image signal processing unit 110 which corrects an input image signal based upon the measurement data, and a timing signal generator 130 which generates a timing signal having a predetermined time width at predetermined time intervals. The light source control unit performs control such that the light source goes out for the time width in synchronism with the timing signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a projector and a projector system having a function for measuring the amount of peripheral light of a device.

  In general, a projector that projects and displays an image projects a front projection type that projects an image from the same side as the viewer on the screen, and projects an image from the opposite side to the screen by the image projection method. Divided into rear projection type. Recently, in response to a demand for a large screen, a so-called multivision device has been put into practical use that enables a large screen image to be displayed by combining a plurality of projectors as an event display, for example. Among such multi-vision devices, there is a so-called CUBE type in which screens are connected vertically, horizontally, and the joints of the connecting portions are made as thin as possible to make them inconspicuous.

  By the way, in recent years, projectors have been improved in definition and further improvement in color reproducibility has been demanded. However, the projected image of the projector is not limited to illumination in the room in which the projector is installed or external light (hereinafter, referred to as “projector image”). The visual environment of the projector and the projection screen changes due to the influence of the “environment light”), and the color reproducibility deteriorates.

Therefore, as a method of preventing deterioration in color reproducibility of the projected image, a CCD camera, an illuminance sensor, etc. are conventionally installed in the projector, the ambient light is measured, and the gamma characteristic of the projected image is determined according to the measured ambient light. A method for adjusting the color temperature (for example, see Patent Document 1) and a method for adjusting the amount of projection light according to ambient light (for example, see Patent Document 2) have been proposed.
JP 2002-125125 A JP 2004-279580 A

  However, in each type of projector and its system, when measuring ambient light using a light sensor mounted on the projector, the light projected from the projector is reflected on the screen depending on the position and orientation of the light sensor. The reflected light is mixed into the optical sensor and the exact brightness cannot be measured. Therefore, the optical sensor needs to be arranged so that the projection light of the projector does not enter directly or indirectly, and the arrangement place and direction are limited. Further, even if the brightness around the screen is measured by the optical sensor, there is a problem that if the projector is projecting an image, the light of the image is measured and the accurate brightness cannot be measured.

  In order to eliminate the influence of the projection light, there is also a method of performing measurement after temporarily erasing the projected image, but in that case, it is necessary for the user to stop the projected image each time measurement is performed. Will be interrupted. In addition, since it is necessary to measure each time the brightness of the ambient light changes, additional time is required.

  The present invention has been made in view of these problems, and a projector capable of accurately measuring ambient light without interrupting image projection, and capable of correcting a projected image with high accuracy even when ambient light changes, and The purpose is to provide a projector system.

  In order to solve the above-described problems, a projector according to the present invention is a projector that projects an image on a screen. At least a light source and an image projection unit having a light source control unit that controls turning on and off of the light source, An optical sensor that measures the brightness of the screen, a measurement signal processing unit that converts the output of the optical sensor into a digital signal, performs predetermined calculations to obtain measurement data, and an image that corrects the input image signal based on the measurement data A signal processing unit and a timing signal generating unit that generates a timing signal having a predetermined time width at predetermined time intervals, and the light source control unit turns off the light source during the time width in synchronization with the timing signal. It is characterized by controlling. Accordingly, the ambient light can be accurately measured without interrupting the image projection, and the projected image can be corrected with high accuracy even if the ambient light changes.

  In the projector according to the aspect of the invention, the light sensor may measure the brightness during the time width of the timing signal. As a result, the measurement signal processing unit can be simply configured because the measurement may be performed at an arbitrary position between the time widths of the timing signals.

  In the projector of the present invention, the light sensor may measure the brightness in synchronization with the timing signal. Thereby, the time from when the light source is turned off to when the measurement is performed can be made constant, so that the measurement accuracy is improved.

  In the projector according to the aspect of the invention, the image projection unit may include a power supply unit to the light source, and the projection light amount may be adjusted by changing the power supplied to the light source based on the measurement data. Thereby, even if environmental light changes, the brightness of a projection image can be corrected easily.

  In the projector of the present invention, the image projection unit has an electronic or mechanical aperture mechanism between the light source and the screen, and adjusts the amount of projection light by changing the aperture amount of the aperture mechanism based on the measurement data. May be. Thus, the brightness of the projected image can be easily corrected even when the ambient light changes, and a highly accurate light amount adjustment function is not required for the light source, so that an inexpensive light source can be used.

  In the projector of the present invention, the time interval of the timing signal may be variable. Thereby, an optimal measurement time interval can be set according to the use environment of the projector.

  In the projector of the present invention, the time width of the timing signal may be variable. Thereby, the optimal measurement time width can be set according to the use environment of the projector.

  In the projector of the present invention, the variable range of the time width of the timing signal may be set to 10 μsec to 1 msec. Thereby, accurate ambient light can be measured without feeling flicker in the projected image.

  In addition, the projector according to the present invention may further include an input unit that receives an instruction as to whether or not to perform brightness measurement and input image signal correction. As a result, it is possible to appropriately correct the projection image in accordance with the use situation.

  In the projector of the present invention, the optical sensor and the measurement signal processing unit may measure the color of the projector periphery or the screen. Thereby, the color of the projected image can be corrected with high accuracy.

  A projector system according to the present invention includes a plurality of the projectors described above, and the timing signal generation unit of each projector generates a timing signal in synchronization with an input image signal. As a result, the timing of turning off the light source among the plurality of projectors can be accurately matched, so that the projection light does not affect the measurement of the ambient light of other projectors, and the accurate ambient light can be measured.

  According to the present invention, it is possible to provide a projector and a projector system that can accurately measure ambient light without interrupting image projection, and can correct a projected image with high accuracy even when ambient light changes.

  Hereinafter, a projector and a projector system according to embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
1, 2 and 3 are schematic configuration diagrams of a projector and a projector system according to the first embodiment of the present invention.

  1, 2, and 3, 10 is a screen, 20, 20 a, 20 b, and 20 c are projectors, and 30 is a projector 20 (hereinafter, a projector other than a CUBE type projector is represented by the projector 20). An optical sensor 40 is a housing for incorporating a projector, 50 is a viewer, and 60 is illumination of a room where the projector is installed. A projector 20 that is a type of projection display device projects and displays a presentation image that is a type of normal image on the screen 10 based on an image signal input from a personal computer or the like. At the same time, the projector 20 measures the brightness around the projector 20, the screen 10 to be projected, and the ambient light incident through the screen 10 by using the mounted optical sensor 30. The projected image is corrected based on the measured ambient light so that the projected image is not affected even if the ambient light changes. The present invention is characterized by a method for measuring ambient light, in which the light source of the projector 20 is turned off for a short period of time that is hardly perceivable by humans, and the ambient light is accurately measured by the light sensor 30 during that time. It is.

  FIG. 1 is a schematic configuration diagram of a system using a front projection type projector. An image is projected onto the screen 10 from the same side as the viewer 50. In the case of a front projection type projector, depending on the position and orientation of the optical sensor 30, the projection light is reflected directly on the screen 10 or reflected on the screen 10 and enters the optical sensor 30. By turning off the light, it is possible to accurately measure ambient light without being affected by this. Further, the location and orientation of the projector 20 and the optical sensor 30 are not limited in order to avoid the influence of the projection light as in the prior art.

  FIG. 2 is a schematic configuration diagram of a system using a rear projection type projector. An image is projected onto the screen 10 from the side opposite to the viewer 50. In the case of a rear projection type projector, the screen 10 exists between the projector 20 main body and the indoor space. This projected image is incident on the optical sensor 30 during image projection. However, since the light source is turned off during the measurement period, the projected image is not displayed, and accurate ambient light measurement is possible. Conventionally, it has been necessary to install the optical sensor 30 outside the housing 40 in order for the projection light of the projector 20 to be reflected by the screen 10 and wrap around the optical sensor 30. Since the front projection type projector can be used as it is as a rear projection type projector, no extra cost is required.

  FIG. 3 is a schematic configuration diagram of a system using a rear projection type CUBE type projector. An example of a so-called CUBE type in which the screens are connected vertically and horizontally, and the joints of the connecting portions are made as thin as possible to make them inconspicuous, and a multi-vision device is configured with three projectors 20a, 20b, and 20c. It is. Images projected from the projectors 20 a, 20 b, and 20 c installed in the housing 40 are displayed on the screen 10. If the screen 10 is huge like a CUBE type projector, the total amount of light output from the projectors 20a, 20b, and 20c increases. In such a case, conventionally, even if the optical sensor 30 is placed outside the housing 40, it has been difficult to install the optical sensor 30 in a place that is not affected by the light emitted from the screen 10. However, since the light sources of all the projectors 20a, 20b, and 20c are turned off during the measurement period, even if the projection type projector with the built-in optical sensor 30 is used as it is, it is not affected by the projection light and is accurately ambient light. Can be measured. Therefore, a multi-vision device can be easily configured without worrying about the place where the optical sensor 30 is installed.

  Next, the present embodiment will be described in detail with reference to FIGS. FIG. 4 is a block configuration diagram inside the projector 20. The projector 20 includes an image signal processing unit 110 that includes a signal processing circuit that performs format conversion and color conversion of the input image signal 100, an image projection unit 120 that includes an LED, a prism, a light modulation element, a projection lens, and the like, and incident light 170. A timing signal generator 130 for generating a timing signal for measuring the light, and an optical sensor 30 for measuring incident light 170 incident from the periphery of the screen 10 and the projector 20 based on the timing signal output from the timing signal generator 130, The measurement signal processing unit 140 calculates measurement data of the incident light 170 from the output of the optical sensor 30. Conventionally, the incident light 170 was measured as a mixture of ambient light and projection light 160.

  An input image signal 100 input from a PC or the like is subjected to color correction, gamma correction, and the like for removing the influence of ambient light based on measurement data of incident light 170 obtained from the measurement signal processing unit 140 by the image signal processing unit 110. The correction process is performed. The image projection unit 120 modulates the light from the light source by the light modulation element based on the signal output from the image signal processing unit 110 and outputs the projection light 160 toward the screen 10. Incident light 170 from the periphery of the projector 20 or from the screen 10 is received by the optical sensor 30, converted into an electrical signal, and output to the measurement signal processing unit 140. The measurement signal processing unit 140 calculates measurement data of the incident light 170 based on the measurement signal. On the other hand, the timing signal is also input to the image projection unit 120, and the projection light source is turned off while the incident light 170 is measured. As a result, accurate ambient light that is not affected by the projection light 160 can be measured. The timing signal is generated in synchronization with the input image signal 100, and the optimum measurement timing is determined depending on the use conditions such as the place where the projector is installed.

  FIG. 5 is a schematic configuration diagram illustrating an example of the image projection unit 120 of the projector according to the first embodiment of the invention. The image projection unit 120 has a configuration in which a DMD (Digital Micromirror Device) is used as a light modulation unit and an LED is used as a light source. DMD is a registered trademark of Texas Instruments Incorporated. The image projection unit 120 includes red, green, and blue light source LEDs 200R, 200G, and 200B, a prism 210, a light source control unit 250, a TIR (Total Internal Reflection) prism 220, a DMD element 230, a DMD element driving unit 260, and a projection lens 240. Has been.

  In order to display a full-color image with only one DMD element 230 as in the present embodiment, it is necessary to project images corresponding to red, green, and blue colors onto the screen 10 in a time-sharing manner. In the present embodiment, full color image display is realized by sequentially switching and lighting the three light source LEDs 200R, 200G, and 200B of red, green, and blue. By making this switching cycle sufficiently short in consideration of human visual characteristics, an image is synthesized and recognized as a full-color image in the human brain. The light source control unit 250 generates a lighting control signal for controlling lighting and extinguishing of each of the light source LEDs 200R, 200G, and 200B and supplies it to each light source. The directions of red, green, and blue light output from the light source LEDs 200R, 200G, and 200B are aligned by the prism 210, and irradiated to the DMD element 230 through the TIR prism 220. On the other hand, the projection image signal is input to the DMD element driving unit 260, and light of each color is modulated by the projection image signal by the DMD element 230 and projected onto the screen 10 through the projection lens 240.

  FIG. 6 is a timing chart for explaining lighting control of each light source LED 200R, 200G, 200B. The one field period Tf is divided into four segments, and the three light source LEDs 200R, 200G, and 200B are sequentially switched and turned on within the one segment period Ts. The LED control signals Lcnt_R, Lcnt_G, and Lcnt_B are signals for controlling the lighting of the red, green, and blue light source LEDs 200R, 200G, and 200B, respectively. A high level “H” indicates a lighting period, and a low level “L” indicates a lighting period. ing. The lighting time ratio of each of the light source LEDs 200R, 200G, and 200B is determined by the luminance of each light source, human visibility, picture creation, and the like. In this embodiment, the lighting time ratio is 1: 2: 1. Accordingly, the lighting times of the light source LEDs 200R, 200G, and 200B are TR = 0.25Ts, TG = 0.5Ts, and TB = 0.25Ts, respectively. Since the segment period Ts is about 4 msec (milliseconds), the lighting time is 1 msec, 2 msec, and 1 msec, respectively. In FIG. 6, the lighting order of the light source LEDs 200R, 200G, and 200B is set to red, green, and blue. However, this order changes depending on the driving content of the DMD element 230, and may be another order.

  By the way, when the incident light 170 is measured by the optical sensor 30, it is necessary to turn off the light source LEDs 200R, 200G, and 200B in synchronization with the measurement period. FIG. 7 shows that the time interval (hereinafter referred to as “measurement interval”) Tp for measuring the incident light 170 is 1 sec (seconds), and the time width (hereinafter referred to as “measurement period”) Tm is 10 μsec (microsecond). It is a figure which shows the relationship between a measurement timing signal, a segment, and the projection light 160 in the case of (second). In this case, the measurement period is inserted into one segment once per second. And all light source LED200R, 200G, 200B is light-extinguished during this measurement period, and environmental light is measured. For convenience of explanation, the segment into which the measurement period is inserted is called a measurement segment (hereinafter abbreviated as “measurement SEG”), and the other segment is called a display segment (hereinafter abbreviated as “display SEG”). I will decide. The measurement interval and the measurement period may be increased or decreased depending on the usage application and measurement environment of the projector. The measurement period is preferably as short as possible in order to reduce the influence on the projected image, but 10 μsec to 50 μsec is appropriate from the relationship of the response speed of the optical sensor 30. In general, the human eye cannot detect flicker of 1 msec or less, and if it is 10 μsec to 1 msec, there is no practical problem, so it may be set within this range. When there is a lighting fixture of a blinking light source typified by a fluorescent lamp around the optical sensor 30, it is desirable that the interval is not an integral multiple of the blinking cycle of the lighting fixture.

  FIG. 8 is a diagram for explaining a method of inserting a light extinction period in measurement SEG. In the present embodiment, the total lighting period of each of the red, green, and blue light source LEDs 200R, 200G, and 200B in the measurement SEG is made shorter by Tm / Ts than the display SEG, and the last blue light source LED 200B of the measurement SEG. A period of turning off after the lighting period of is created. In this way, the lighting time ratio of each of the light source LEDs 200R, 200G, and 200B in the measurement SEG is the same as that of the display SEG, and the color of the image can be accurately maintained. In addition, the light extinguishing period of the light source LEDs 200R, 200G, and 200B is the same as the measurement period Tm, which is 1% or less of the segment period Ts, and the difference in brightness from other display SEGs can hardly be recognized by human eyes. In this measurement SEG period, the brightness of the light source LEDs 200R, 200G, and 200B may be increased by 1% to make “brightness × time” constant. In the case of an LED, such brightness adjustment can be easily performed by adjusting the current flowing through the LED. Further, when the performance of the DMD element 230 and the like is improved in the future and the segment period Ts can be sufficiently shortened, the measurement SEG itself may be used as the measurement period. In FIG. 8, the measurement period is inserted at the end of each measurement SEG, but the position may be changed, for example, inserted between the projection light R and the projection light B. In any case, while the incident light 170 is measured by the optical sensor 30, all the light sources LEDs 200R, 200G, and 200B are turned off, so that the ambient light of the projector 20 is measured without being affected by the projection light 160. can do.

  Next, operations of the measurement signal processing unit 140 and the image signal processing unit 110 in FIG. 4 will be described in detail by taking as an example a case where the color of the input image signal 100 is corrected according to ambient light.

  FIG. 9 is a block configuration diagram showing a relationship among the optical sensor 30, the measurement signal processing unit 140, and the image signal processing unit 110. The measurement signal processing unit 140 samples the analog output waveform from the optical sensor 30 by the sample hold circuit 141 based on the measurement timing signal, converts it to a digital signal by the A / D converter 142, and then converts it into a microcomputer (hereinafter “ (Abbreviated as “microcomputer”) 143. The microcomputer 143 calculates measurement data to be output from the measurement signal to the image signal processing unit 110. The image signal processing unit 110 includes a color correction unit 111, a color correction table selection unit 112, and a color correction table storage unit 113. Here, the color correction unit 111 includes a lookup table (hereinafter abbreviated as “LUT”) and the like. For example, a color correction table when there is no ambient light (for example, in a dark room state) and a plurality of color correction tables corresponding to the amount of ambient light are created and stored in advance. In the color correction table selection unit 112, an optimal color correction table is selected based on the measurement data sent from the microcomputer 143 and transferred to the color correction unit 111. The color correction unit 111 corrects the color of the input image signal 100 according to the amount of ambient light, and outputs the color correction signal to the image projection unit 120.

  10 and 11 are diagrams for explaining the operation of the measurement signal processing unit 140. FIG. 10, (a) is an output of the optical sensor 30, (b) is an output of the sample-and-hold circuit 141, (c) is an output of the measurement signal processing unit 140, and is a waveform diagram showing temporal changes. Times t1, t2, t3,... Are measurement timings. When the output of the optical sensor 30 changes suddenly from time t2 to time t3, when the input image signal 100 is corrected in conjunction with it as it is, the projected image may be uncomfortable. In addition, when a person passes in front of the optical sensor 30 and the amount of light suddenly changes, it may react sensitively and be corrected erroneously. In order to prevent such a problem, the microcomputer 143 averages the measurement data from the A / D converter 142 with a predetermined number of samples in the past.

  FIG. 11 is a diagram showing in more detail how the incident light 170 is measured by the optical sensor 30 during the measurement period. As shown in FIG. 11, since the projection light 160 from the light source LEDs 200R, 200G, and 200B is mixed into the optical sensor 30 during the period other than the measurement period, the intensity of the incident light 170 increases or decreases in conjunction with the lighting of each light source. On the other hand, since the light source is turned off during the measurement period, the correct ambient light can be measured without being affected by the projection light 160. However, as shown in the enlarged view in FIG. 11, the measurement output varies during the measurement period due to the response characteristics of the optical sensor 30 and the like. In order to eliminate the influence of this change, measurement is performed at the midpoint tb of the measurement period. Alternatively, measurement may be performed at the first half point ta and the second half point tc, and the average of the two measurement values may be used. In this measurement, sampling pulses may be given to the sample hold circuit 141 in FIG. 9 at the timings ta, tb, and tc instead of the measurement timing signal. By doing so, stable and accurate measurement data can be obtained even if the output of the optical sensor 30 fluctuates during the measurement period. If the output of the optical sensor 30 does not fluctuate much during the measurement period, this measurement may be performed anywhere during the measurement period.

  In the present embodiment, the optical sensor 30 is always in the photometric state and holds and outputs the measurement value according to the measurement timing signal. However, the photosensor 30 may measure the light according to the measurement timing signal and output the measurement value. In addition, as a method of performing photometry in accordance with the measurement timing signal, an electronic or mechanical shutter may be provided in front of the optical sensor 30.

(Second Embodiment)
A projector according to a second embodiment of the present invention will be described with reference to FIG. The projector according to the present embodiment is different from the first embodiment in the configuration of the image projection unit 120 and the light source lighting control method, and the other configuration and processing method are the same. The projector according to the present embodiment has a configuration using a color wheel and a DMD for the image projection unit 120.

  FIG. 12 is a schematic configuration diagram of the image projection unit 120 according to the second embodiment of this invention. In order to project red, green, and blue images in a time-division manner, in the first embodiment, the three color light source LEDs 200R, 200G, and 200B are switched and turned on, but in this embodiment, one light source is used. This is realized by using 300 and a color wheel 310. As the light source 300, for example, a white LED or a white laser can be used. The light emitted from the light source 300 is converted into red, green, and blue light in a time-division manner by the rotating color wheel 310 and then irradiated to the DMD element 330 through the TIR prism 320. The color wheel 310 is controlled by the wheel control unit 370 to rotate in synchronization with the segment signal. On the other hand, the projection image signal is input to the DMD element driving unit 360, and light of each color is modulated by the projection image signal by the DMD element 330 and projected onto the screen 10 through the projection lens 340. The light source 300 is controlled to be turned on in synchronization with the measurement timing signal by the light source control signal Lcnt from the light source control unit 350.

  FIG. 13 is a diagram illustrating a relationship among the measurement timing signal, the segment, the light source control signal Lcnt, and the projection light 160 according to the second embodiment of this invention. In the present embodiment, the measurement period is inserted so as to extend over two adjacent segments. During this measurement period, the light source 300 is turned off and ambient light is measured.

  FIG. 14 is a diagram showing details of the lighting timing of the light source 300. As shown in FIG. 14, the period during which the light source 300 is turned off is provided in a section called a spoke while displaying red and blue. If it is provided in this section, the change in brightness is small and the influence on the projected image is small. The period during which the light is extinguished is not limited to the above, and may be another section. Further, when the rotation speed of the color wheel is sufficiently high, the measurement SEG itself may be the measurement period.

(Third embodiment)
A projector according to a third embodiment of the invention will be described with reference to FIG. The projector according to the present embodiment is different from the first embodiment in the configuration of the image projection unit 120 and the light source lighting control method, and the other configuration and processing method are the same.

  FIG. 15 is a schematic configuration diagram of the image projection unit 120 of the projector according to the third embodiment of the present invention. In the present embodiment, a configuration using a liquid crystal panel is shown. The light emitted from the light source 400 is decomposed into red, green, and blue light by the filters 410a and 410b, and then irradiated to the liquid crystal panels 420R, 420G, and 420B by the mirrors 470a, 470b, and 470c. As the light source 400, for example, a white LED or a white laser can be used. The liquid crystal panels 420R, 420G, and 420B are driven by the liquid crystal panel driving unit 460, modulated by the image signal, synthesized by the prism 430, and then projected by the projection lens 440. The light source controller 450 generates a light source control signal Lcnt based on the measurement timing signal, and controls lighting of the light source 400.

  FIG. 16 is a lighting timing diagram of the light source 400. In this case, in synchronization with the timing signal only once per second, the light source 400 is turned off and ambient light is measured during that period. In the present embodiment, unlike the first and second embodiments, it is not necessary to switch light of three colors by a segment signal, and therefore the insertion position of the measurement period can be set arbitrarily. Therefore, the measurement timing signal generation circuit can be configured easily.

(Fourth embodiment)
A projector according to a fourth embodiment of the invention will be described with reference to FIGS.

  FIG. 17 is a block configuration diagram inside the projector 21 according to the fourth embodiment of the present invention. The difference between the present embodiment and the projector of the first embodiment is the configuration of the image projection unit 121, and the other configurations are the same, so the same reference numerals as those of the first embodiment are assigned and description thereof is omitted. To do. The image projection unit 121 adjusts the projection light amount based on the measurement data of the ambient light from the measurement signal processing unit 140. If the ambient light amount is large, the projection light amount is increased. Conversely, if the ambient light amount is small, the projection light amount is adjusted. The brightness of the projected image on the screen 10 is not affected by the ambient light. That is, in the first embodiment to the third embodiment, the input image signal 100 is corrected based on the measurement data of the optical sensor 30 in order to remove the influence of the ambient light. Instead of or in addition to the correction, the light amount of the light source of the image projection unit 121 is adjusted.

  FIG. 18 is a diagram for explaining a method of adjusting the light amount of the light source. FIG. 18A is a block diagram of the light source and the part that controls the amount of light output from the light source. The light amount of the light source 500 changes according to the power supplied from the power supply unit 510. The power supply unit 510 receives ambient light measurement data from the measurement signal processing unit 140, and the power supplied to the light source is controlled based on the measurement data. The mechanical diaphragm mechanism 520 may be a mechanical diaphragm mechanism generally used in a camera or the like, and FIG. 18B shows a simple structural diagram thereof. This diaphragm mechanism 520 is configured by a diaphragm vane and a galvanometer with an angle encoder, and the area of the opening at the center is changed by controlling the current flowing through the drive coil of the galvanometer by the diaphragm drive unit 530, thereby projecting the projection. The amount of light can be adjusted. The above measurement data is input to the aperture driving unit 530, and the aperture amount is controlled based on this measurement data. The diaphragm mechanism is not limited to a mechanical type and may be an electronic type. The diaphragm mechanism may be installed between the light source 500 and the screen 10.

  Although the case where the number of the light sources 500 is one has been described in FIG. 18, the present invention can be similarly applied to a case where there are a plurality of light sources as in the first embodiment. As a method for adjusting the amount of projection light, either the above-described method of controlling the power supplied to the light source or the method of inserting an aperture mechanism may be used, or both methods may be used in combination.

  Up to now, the case of only one projector has been described. However, in the case of a CUBE type projector as shown in FIG. 3, if the timings of the measurement periods between the projectors do not coincide with each other, for example, during the measurement of a certain projector 20a The projector 20b may display an image, and a part of the projection light 160 of the projector 20b may be measured as the ambient light of the projector 20a. Therefore, when simultaneously projecting a plurality of projectors, it is necessary to accurately match the measurement timing between the projectors. As this method, for example, a timing signal may be generated in each projector 20a, 20b based on a synchronization signal included in the input image signal 100. Alternatively, instead of the input image signal 100, a timing signal may be separately generated using some kind of synchronization signal.

  As described above, according to the present invention, the light source of the projector 20 is turned off for a short time that humans can hardly detect, and the ambient light is accurately measured by the optical sensor 30 during that time. As a result, even if the projection light 160 is in a positional relationship where it enters the optical sensor 30, the projection image can be accurately corrected without the user performing a special operation and interrupting the operation.

  In the above description, the optical sensor 30 measures the brightness of the ambient light, but it may be only the brightness (Y), data indicating the XYZ values, or other data relating to the color. By using the color data, the accuracy of color correction can be further improved. Here, XYZ is an international standard defined by the International Lighting Commission (CIE) and is a kind of device independent color.

  The optical sensor 30 may output brightness like a phototransistor, or may output as a one-dimensional or two-dimensional luminance distribution like a CCD camera. If a CCD camera is used, accurate correction is possible even when there is a brightness distribution on the projection object, such as when an image is projected onto a wall of a room or the like.

  Further, although it has been described that the light source is turned off during the measurement period, it is sufficient that the projection light 160 can be blocked, so an electronic or mechanical shutter may be used in addition to turning off the light source. In this way, the projector of the present invention can be realized even using a light source (such as a lamp) that cannot be turned on and off at high speed.

  In addition, as a method for adjusting the amount of projection light based on the measurement data of ambient light, the method of changing the power supplied to the light source and the method of using an electronic or mechanical aperture mechanism have been described. Instead, for example, a liquid crystal filter that can electrically change the light transmittance may be used. Thereby, an image projection part can be reduced more in size than what uses an aperture mechanism.

  Further, the measurement timing may be generated using an internal circuit such as a transmitter without being synchronized with the input image signal. In this way, the timing signal generator can be configured with a simple circuit configuration.

  Moreover, although the optical sensor 30 is attached to the projector 20, it may be independently installed as an external device in a place away from the projector.

  The ambient light measurement may be performed automatically without any user operation, or by using an input means that is explicitly operated by the user, such as displaying a menu or sending a communication command. Also good. Also, automatic measurement may or may not be switched.

  According to the present invention, it is possible to measure the ambient light at a constant interval without the user's operation, so there is no need to interrupt the screen display and perform an adjustment operation each time. This is useful in an image display apparatus that performs control.

1 is a schematic configuration diagram of a system using a front projection type projector according to a first embodiment of the invention. 1 is a schematic configuration diagram of a system using a rear projection type projector according to a first embodiment of the present invention. 1 is a schematic configuration diagram of a system using a rear projection type CUBE type projector according to a first embodiment of the present invention. 1 is a block configuration diagram inside a projector according to a first embodiment of the present invention. 1 is a schematic configuration diagram of an image projection unit of a projector according to a first embodiment of the invention. Timing chart for explaining lighting control of each light source LED of the projector according to the first embodiment of the present invention The figure which shows the relationship of the measurement timing signal, segment, and projection light of the projector which concerns on the 1st Embodiment of this invention The figure explaining the method of inserting the light extinction period into measurement SEG of the projector which concerns on the 1st Embodiment of this invention. The block block diagram which shows the relationship between the optical sensor of the projector which concerns on the 1st Embodiment of this invention, a measurement signal processing part, and an image signal processing part The figure for demonstrating operation | movement of the measurement signal process part of the projector which concerns on the 1st Embodiment of this invention The figure for demonstrating operation | movement of the measurement signal process part of the projector which concerns on the 1st Embodiment of this invention Schematic configuration diagram of an image projection unit of a projector according to a second embodiment of the present invention The figure which shows the relationship of the measurement timing signal, segment, light source control signal, and projection light of the projector which concerns on the 2nd Embodiment of this invention. The figure which showed the detail of the lighting timing of the light source of the projector which concerns on the 2nd Embodiment of this invention Schematic configuration diagram of an image projection unit of a projector according to a third embodiment of the present invention Timing chart of lighting of light source of projector according to third embodiment of the present invention The block block diagram inside the projector which concerns on the 4th Embodiment of this invention It is a figure for demonstrating the method to adjust the light quantity of the light source of the projector which concerns on the 4th Embodiment of this invention, (a) is a block block diagram of the part which adjusts a light source and a light quantity, (b) is a mechanical type. Diagram showing the structure of the diaphragm mechanism

Explanation of symbols

10 Screen 20, 20a, 20b, 20c, 21 Projector 30 Optical sensor 40 Case 50 Viewer 60 Illumination of room 100 Input image signal 110 Image signal processing unit 111 Color correction unit (LUT)
112 Color correction table selection unit 113 Color correction table storage unit 120, 121 Image projection unit 130 Timing signal generation unit 140 Measurement signal processing unit 141 Sample hold circuit 142 A / D converter 143 Microcomputer 160 Projection light 170 Incident light 200R, 200G, 200B Light source LED
210, 430 Prism 220, 320 TIR prism 230, 330 DMD element 240, 340, 440 Projection lens 250, 350, 450 Light source controller 260, 360 DMD element driver 300, 400, 500 Light source 310 Color wheel 370 Wheel controller 410a , 410b Filter 420R, 420G, 420B Liquid crystal panel 460 Liquid crystal panel drive unit 470a, 470b, 470c Mirror 510 Power supply unit 520 Aperture mechanism 530 Aperture drive unit

Claims (11)

In a projector that projects an image on a screen,
An image projection unit having at least a light source and a light source control unit for controlling turning on and off of the light source;
An optical sensor that measures the brightness of the projector or the periphery of the screen;
A measurement signal processing unit for converting the output of the optical sensor into a digital signal, performing a predetermined calculation to obtain measurement data;
An image signal processor for correcting an input image signal based on the measurement data;
A timing signal generating unit that generates a timing signal having a predetermined time width at a predetermined time interval;
The light source control unit controls the light source to be turned off during the time width in synchronization with the timing signal. The projector according to claim 1, wherein the light sensor measures brightness during the time width of the timing signal. The projector according to claim 2, wherein the light sensor measures brightness in synchronization with the timing signal. The projector according to claim 1, wherein the image projection unit includes a power supply unit to the light source, and adjusts a projection light amount by changing power supplied to the light source based on the measurement data. . The image projection unit has an electronic or mechanical aperture mechanism between the light source and the screen, and adjusts the amount of projection light by changing the aperture amount of the aperture mechanism based on the measurement data. The projector according to claim 1. The projector according to claim 1, wherein the time interval of the timing signal is variable. The projector according to claim 1, wherein the time width of the timing signal is variable. The projector according to claim 7, wherein a variable range of the time width of the timing signal is 10 μsec to 1 msec. The projector according to claim 1, further comprising an input unit that receives an instruction as to whether or not to correct the measurement of the brightness and the input image signal. The projector according to claim 1, wherein the optical sensor and the measurement signal processing unit measure the color of the periphery of the projector or the screen. 2. A projector system comprising a plurality of projectors according to claim 1, wherein the timing signal generator of each projector generates the timing signal in synchronization with the input image signal.

Images