JP2014053844A - Projector, projection control method and projection control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector for projecting two bright and dark patterns on a screen during projection, obtaining two screen reflection light beams of ambient light and projection light from the patterns and adjusting luminance.SOLUTION: A projector 10 includes: an illuminance sensor; a light source device; a display element; a light source control section for controlling the light source device; a display element control section for controlling the display element; measurement timing setting means for setting first measurement timing in one first period of a light emission switching period of individual colors in one frame and setting second measurement timing in one second period of the light emission switching period of the individual colors in the one frame; and a control section for controlling luminance of a projected image on the basis of measurement values by the illuminance sensor at the first measurement timing and the second measurement timing.

Description

  The present invention relates to a projector, a projection control method, and a projection control program that appropriately control projection brightness according to external light.

  2. Description of the Related Art Today, data projectors are widely used as image projection apparatuses that project a screen of a personal computer, a video image, an image based on image data stored in a memory card or the like onto a screen. This projector focuses light emitted from a light source on a micromirror display element called DMD (digital micromirror device) or a liquid crystal plate, and displays a color image on a screen.

  With the spread of video equipment such as personal computers and DVD players, projectors are used in different environments from business presentations to home use.

  Therefore, Patent Document 1 shown below discloses a projector that can remove discomfort to the eyes caused by uneven brightness and external light on the screen.

JP 2004-304479 A

  In the projector shown in Patent Document 1, brightness control is performed by feeding back projection image information, and brightness unevenness of the projection image due to the projection distance, size, angle, and optical characteristics of the display device is suppressed.

  However, for example, the ambient light changes due to the state of the curtain or the lighting state of the lighting fixture during the projection of the projector, and the brightness changes in a part of the room. The brightness on the screen may change in brightness, and the state of the screen reflected light of the projected light may change fluidly.

  The projector disclosed in Patent Document 1 acquires luminance information of the entire screen from the projection image information projected on the screen and reduces luminance unevenness on the screen, but accurate luminance adjustment in consideration of fluctuations in ambient light I couldn't.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a projector that adjusts the luminance in consideration of the brightness change of the ambient light on the screen surface.

  The projector according to the present invention is a projector that projects an image onto a projection object, and includes an illuminance sensor that measures the reflected light of the projection object, a light source device, a display element, and a light source control unit that controls the light source device. The display element control unit for controlling the display element and the first measurement timing are set at one first timing of the emission switching timing of each color in one frame, and the emission switching timing of each color in the one frame is set. Measurement timing setting means for setting a second measurement timing at one second time, and the light source control unit or the display element control unit performs a first operation on the projection object at the first measurement timing. The light source device or the display element is controlled so that light is emitted at a gradation of the light source, and the light source control unit or the display element control unit applies to the projection object at the second measurement timing. The light source device or the display element is controlled so that light is emitted at a second gradation different from the first gradation, and the illuminance sensor is at the first measurement timing and the second measurement timing. The apparatus includes a control unit that measures reflected light of the projection object and controls brightness of a projection image based on measurement values obtained by the illuminance sensor at the first measurement timing and the second measurement timing.

  The projector control method according to the present invention includes an illuminance sensor that measures reflected light of a projection object, a light source device, a display element, a light source control unit that controls the light source device, and a control of the display element. In the projection control method of the projector having the display element control unit for projecting the image onto the projection object, the first measurement timing is set at one first timing of the light emission switching timing of each color in one frame. In addition, a second measurement timing is set at one second timing of the light emission switching timing of each color in the one frame, and the light source control unit or the display element control unit is configured to perform the projection at the first measurement timing. The light source device or the display element is controlled so that light is emitted at a first gradation, and the light source control unit or the display element control unit is configured to project the projection at the second measurement timing. The light source device or the display element is controlled so that light is emitted at a second gradation different from the first gradation, and the illuminance sensor is configured to detect the first measurement timing and the second gradation. The reflected light of the projection object is measured at the measurement timing, and the brightness of the projection image is controlled based on the measurement values obtained by the illuminance sensor at the first measurement timing and the second measurement timing.

  Furthermore, a projector control program according to the present invention includes a light source control unit that controls a light source device, a display element control unit that controls a display element, and an illuminance sensor that measures reflected light from a screen. The first measurement timing is set at one first timing of the light emission switching timing of each color in one frame, and the second one of the light emission switching timings of each color in the one frame. A second measurement timing is set at the time of the above, and the light source control unit or the display element control unit is configured to irradiate the projection object with light at a first gradation at the first measurement timing. The light source device or the display element is controlled, and the light source control unit or the display element control unit is different from the first gradation with respect to the projection object at the second measurement timing. The light source device or the display element is controlled so that light is emitted with two gradations, and the illuminance sensor measures reflected light of the projection object at the first measurement timing and the second measurement timing. The brightness of the projected image is controlled based on the measurement values obtained by the illuminance sensor at the first measurement timing and the second measurement timing.

  According to the present invention, it is possible to provide a projector, a projection control method, and a projection control program that perform brightness adjustment in consideration of a change in brightness of ambient light.

1 is a perspective view of a projector according to an embodiment of the invention. FIG. 3 is a plan view of the projector according to the embodiment of the present invention with the top panel removed. It is a functional block diagram of the projector which concerns on embodiment of this invention. It is explanatory drawing regarding the directivity of the illumination intensity sensor which concerns on embodiment of this invention. It is explanatory drawing regarding the measurement range of the illumination intensity sensor on the screen of the projector which concerns on embodiment of this invention. It is a time chart of the brightness | luminance measurement at the time of starting of the projector which concerns on embodiment of this invention. It is a time chart when performing a brightness | luminance measurement by projecting a white pattern during the image projection of the projector which concerns on embodiment of this invention. 6 is a time chart when luminance measurement is performed by projecting a complementary color pattern during image projection of the projector according to the embodiment of the present invention. It is a time chart when performing the brightness | luminance measurement during the image projection of the projector by the lamp type light source which concerns on embodiment of this invention. It is a flowchart of the brightness | luminance measurement at the time of starting of the projector which concerns on embodiment of this invention. It is a flowchart of the brightness | luminance measurement during the image projection of the projector which concerns on embodiment of this invention. It is a flowchart regarding control of the brightness | luminance of the projection image of the projector which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an external perspective view of the projector 10. In the present embodiment, the left and right in the projector 10 indicate the left and right direction with respect to the projection direction, and the front and rear indicate the screen side direction as the projection object of the projector 10 and the front and back direction with respect to the traveling direction of the light bundle. Indicates.

  As shown in FIG. 1, the projector 10 has a substantially rectangular parallelepiped shape, and has a lens cover 19 that covers the projection port on the side of the front panel 12 that is a front side plate of the projector housing. The panel 12 is provided with a plurality of intake holes 18. Further, although not shown, an Ir receiver for receiving a control signal from the remote controller is provided.

  In addition, a key / indicator unit 37 is provided on the top panel 11 of the housing. The key / indicator unit 37 switches a power switch key, a power indicator for notifying power on / off, and switching on / off of projection. Keys and indicators such as an overheat indicator for notifying when a projection switch key, a light source unit, a display element, a control circuit, etc. are overheated are arranged.

  In addition, an input / output connector portion provided with a D-SUB terminal, an S terminal, an RCA terminal, an audio output terminal, and the like for inputting a video signal to which a USB terminal or an analog RGB video signal is input on the rear panel is provided on the back of the housing Various terminals 20 such as a power adapter plug are provided. In addition, a plurality of intake holes are formed in the back panel. A plurality of exhaust holes 17 are formed in each of the right panel, which is a side plate of the housing (not shown), and the left panel 15, which is the side plate shown in FIG. An intake hole 18 is also formed at a corner near the back panel of the left panel 15.

  In the vicinity of the lens cover 19 of the front panel 12 of the housing, a daylighting window 16 is formed as a transparent window for daylighting in order to detect the brightness of the projected part on the screen by an illuminance sensor described later.

  Next, the internal structure of the projector 10 will be described. FIG. 2 is a schematic plan view showing the internal structure of the projector 10. The projector 10 includes a control circuit board 241 in the vicinity of the right panel 14 as shown in FIG. The control circuit board 241 includes a power circuit block, a light source control block, and the like. In addition, the projector 10 includes a light source unit 60 on the side of the control circuit board 241, that is, at a substantially central portion of the projector housing. Further, the projector 10 includes an optical system unit 160 between the light source unit 60 and the left panel 15.

  The projector 10 is provided with an illuminance sensor 61 for detecting the brightness of the screen, that is, the brightness of both the ambient light and the projected image, on the inner side of the lighting window 16 toward the screen that displays the projected image. .

  The light source unit 60 is located on the optical axis of the light beam emitted from the excitation light irradiation device 70 and the excitation light irradiation device 70 disposed in the vicinity of the rear panel 13 at a substantially central portion in the left-right direction of the projector housing. The green light source device 80 by the fluorescent light emitting device 100 disposed in the vicinity of the front panel 12 and the blue light source device disposed in the vicinity of the front panel 12 so as to be parallel to the light bundle emitted from the fluorescent light emitting device 100 300, the red light source device 120 disposed between the excitation light irradiation device 70 and the fluorescent light emitting device 100, the emitted light from the fluorescent light emitting device 100, the emitted light from the red light source device 120, the blue light source device 300 A light guide optical system 140 that converts the optical axes of the emitted light so as to be the same optical axis and collects each color light at the entrance of the light tunnel 175 that is a predetermined surface.

  The excitation light irradiation device 70 in the green light source device 80 includes an excitation light source 71 by a semiconductor light emitting element arranged so that the optical axis is parallel to the rear panel 13, and an optical axis of light emitted from the excitation light source 71 in the direction of the front panel 12 A reflecting mirror group 75 that converts the light to 90 degrees, a condenser lens 78 that condenses the light emitted from the excitation light source 71 reflected by the reflection mirror group 75, and a heat sink disposed between the excitation light source 71 and the right panel 14. 81.

  In the excitation light source 71, blue laser diodes, which are a total of 24 semiconductor light emitting elements in 3 rows and 8 columns, are arranged in a matrix, and light emitted from each blue laser diode is placed on the optical axis of each blue laser diode. Collimator lenses 73 that are condensing lenses that convert the light into parallel light are respectively disposed. The reflection mirror group 75 includes a plurality of reflection mirrors arranged in a stepped manner, and reduces the cross-sectional area of the light beam emitted from the excitation light source 71 in one direction and emits it to the condensing lens 78.

  A cooling fan 261 is disposed between the heat sink 81 and the back panel 13, and the excitation light source 71 is cooled by the cooling fan 261 and the heat sink 81. Further, a cooling fan 261 is also disposed between the reflection mirror group 75 and the back panel 13, and the reflection mirror group 75 and the condenser lens 78 are cooled by the cooling fan 261.

  The fluorescent light emitting device 100 in the green light source device 80 includes a fluorescent wheel 101 disposed so as to be parallel to the front panel 12, that is, orthogonal to the optical axis of the light emitted from the excitation light irradiation device 70, and the fluorescent light A wheel motor 110 that rotationally drives the wheel 101 and a condensing lens group 111 that condenses the light bundle emitted from the fluorescent wheel 101 toward the rear panel 13 are provided.

  The fluorescent wheel 101 is a disk-shaped metal substrate, and an annular fluorescent light emitting region that emits fluorescent light in the green wavelength band using the light emitted from the excitation light source 71 as excitation light is formed as a recess, and the excitation light And functions as a fluorescent plate that emits fluorescence. In addition, the surface of the fluorescent light wheel 101 including the fluorescent light emitting region on the side of the excitation light source 71 is mirror-processed by silver deposition or the like to form a reflective surface that reflects light, and a green phosphor layer is formed on the reflective surface. It is laid.

  The light emitted from the excitation light irradiating device 70 applied to the green phosphor layer of the fluorescent wheel 101 excites the green phosphor in the green phosphor layer, and the light bundle is emitted in all directions from the green phosphor. Is emitted directly to the excitation light source 71 side or after being reflected by the reflection surface of the fluorescent wheel 101 to the excitation light source 71 side. Moreover, the excitation light irradiated to the metal substrate without being absorbed by the phosphor of the phosphor layer is reflected by the reflecting surface and is incident on the phosphor layer again to excite the phosphor. Therefore, by using the surface of the concave portion of the fluorescent wheel 101 as a reflective surface, the utilization efficiency of the excitation light emitted from the excitation light source 71, which is a green light source, can be increased and light can be emitted more brightly.

  In the excitation light reflected on the phosphor layer side by the reflecting surface of the fluorescent wheel 101, the excitation light emitted to the excitation light source 71 side without being absorbed by the phosphor passes through a first dichroic mirror 141 described later. Since the fluorescent light is reflected by the first dichroic mirror 141, the excitation light is not emitted to the outside. A cooling fan 261 is disposed between the wheel motor 110 and the front panel 12, and the fluorescent wheel 101 is cooled by the cooling fan 261.

  The red light source device 120 includes a red light source 121 disposed so that the optical axis is parallel to the excitation light source 71, and a condensing lens group 125 that condenses the light emitted from the red light source 121. The red light source device 120 is disposed so that the optical axis intersects the light emitted from the excitation light irradiation device 70 and the green wavelength band light emitted from the fluorescent wheel 101. The red light source 121 is a red light emitting diode as a semiconductor light emitting element that emits red wavelength band light. Furthermore, the red light source device 120 includes a heat sink 130 disposed on the right panel 14 side of the red light source 121. A cooling fan 261 is disposed between the heat sink 130 and the front panel 12, and the red light source 121 is cooled by the cooling fan 261.

  The blue light source device 300 includes a blue light source 301 disposed so as to be parallel to the optical axis of the light emitted from the fluorescent light emitting device 100, and a condenser lens group 305 that collects the light emitted from the blue light source 301. Prepare. The blue light source device 300 is arranged so that the light emitted from the red light source device 120 and the optical axis intersect. The blue light source 301 is a blue light emitting diode as a semiconductor light emitting element that emits light in a blue wavelength band. Furthermore, the blue light source device 300 includes a heat sink 310 disposed on the front panel 12 side of the blue light source 301. A cooling fan 261 is disposed between the heat sink 310 and the front panel 12, and the blue light source 301 is cooled by the cooling fan 261.

  The light guide optical system 140 is a condensing lens that condenses the light bundles in the red, green, and blue wavelength bands, a dichroic mirror that converts the optical axes of the light bundles in the respective color wavelength bands into the same optical axis, etc. Consists of. Specifically, the optical axis of the blue wavelength band light emitted from the excitation light irradiation device 70 and the green wavelength band light emitted from the fluorescent wheel 101, and the optical axis of the red wavelength band light emitted from the red light source device 120 The first dichroic mirror 141 that transmits the blue and red wavelength band light, reflects the green wavelength band light, and converts the optical axis of the green light by 90 degrees toward the left panel 15 is disposed at the position where ing.

  Further, the blue wavelength band light is transmitted at a position where the optical axis of the blue wavelength band light emitted from the blue light source device 300 and the optical axis of the red wavelength band light emitted from the red light source device 120 intersect, A second dichroic mirror 148 that reflects green and red wavelength band light and converts the optical axes of the green and red light in the direction of the rear panel 13 by 90 degrees is disposed. A condensing lens is disposed between the first dichroic mirror 141 and the second dichroic mirror 148. Further, in the vicinity of the light tunnel 175, a condenser lens 173 that condenses the light source light at the entrance of the light tunnel 175 is disposed.

  The optical system unit 160 includes an illumination side block 161 located on the left side of the excitation light irradiation device 70, an image generation block 165 located near a position where the back panel 13 and the left panel 15 intersect, and a light guide optical system. The projection-side block 168 located between the 140 and the left panel 15 is configured in a substantially U-shape.

  The illumination side block 161 includes a part of the light source side optical system 170 that guides the light source light emitted from the light source unit 60 to the display element 51 provided in the image generation block 165. The light source side optical system 170 included in the illumination side block 161 includes a light tunnel 175 that uses a light beam emitted from the light source unit 60 as a light flux having a uniform intensity distribution, and a light collecting unit that collects light emitted from the light tunnel 175. There are an optical lens 178, an optical axis conversion mirror 181 that converts the optical axis of the light beam emitted from the light tunnel 175 in the direction of the image generation block 165, and the like.

  As the light source side optical system 170, the image generation block 165 includes a condenser lens 183 that condenses the light source light reflected by the optical axis conversion mirror 181 on the display element 51, and a light beam that has passed through the condenser lens 183 as a display element. And an irradiation mirror 185 that irradiates 51 at a predetermined angle. Further, the image generation block 165 includes a DMD serving as the display element 51, and a heat sink 190 for cooling the display element 51 is disposed between the display element 51 and the rear panel 13. Element 51 is cooled. Further, a condenser lens 195 as the projection-side optical system 220 is disposed near the front surface of the display element 51.

  The projection-side block 168 has a lens group of the projection-side optical system 220 that emits ON light reflected by the display element 51 to the screen. The projection-side optical system 220 includes a fixed lens group 225 built in a fixed lens barrel and a movable lens group 235 built in a movable lens barrel, and is a variable focus lens having a zoom function, and is movable by a lens motor. Zoom adjustment and focus adjustment can be performed by moving the lens group 235.

  Next, projector control means of the projector 10 will be described with reference to the functional block diagram of FIG. The projector control means includes a control unit 38, an input / output interface 22, an image conversion unit 23, a display encoder 24, a display drive unit 26, and the like. The control unit 38 controls the operation of each circuit in the projector 10, and includes a CPU such as a microprocessor, a ROM that stores operation programs such as various settings in a fixed manner, and a RAM that is used as a work memory. It is comprised by.

  Then, the image signal of various standards input from the input / output connector unit 21 by the projector control means is in a predetermined format suitable for display by the image conversion unit 23 via the input / output interface 22 and the system bus (SB). After being converted so as to be unified into an image signal, it is output to the display encoder 24.

  The display encoder 24 develops and stores the input image signal in the video RAM 25, generates a video signal from the stored contents of the video RAM 25, and outputs the video signal to the display drive unit 26.

  The display drive unit 26 functions as a display element control unit, and each mirror of the display element 51 which is a spatial light modulation element (SOM) at an appropriate frame rate corresponding to the image signal output from the display encoder 24. Is turned on or off to drive the light emitted from the light source to be reflected or unreflected, and the light beam emitted from the light source unit 60 is applied to the display element 51 via the light source side optical system 170 described above. As a result, an optical image is formed by the reflected light of the display element 51, and an image is projected and displayed on a screen (not shown) via the projection-side optical system 220 described above. The movable lens group 235 of the projection side optical system 220 is driven by the lens motor 45 for zoom adjustment and focus adjustment.

  The image compression / decompression unit 31 performs a recording process in which the luminance signal and the color difference signal of the image signal are data-compressed by a process such as ADCT and Huffman coding, and sequentially written in a memory card 32 that is a detachable recording medium. Further, the image compression / decompression unit 31 reads the image data recorded on the memory card 32 in the reproduction mode, decompresses individual image data constituting a series of moving images in units of one frame, and converts the image data into the image conversion unit 23. Is output to the display encoder 24 and the processing for enabling the display of a moving image or the like based on the image data stored in the memory card 32 is performed.

  Then, an operation signal of a key / indicator unit 37 composed of a main key and an indicator provided on the top panel 11 of the housing is directly sent to the control unit 38, and a key operation signal from the remote controller is received by Ir. The code signal received by the unit 35 and demodulated by the Ir processing unit 36 is output to the control unit 38.

  Note that an audio processing unit 47 is connected to the control unit 38 via a system bus (SB). The sound processing unit 47 includes a sound source circuit such as a PCM sound source, converts the sound data into analog in the projection mode and the playback mode, and drives the speaker 48 to emit loud sounds.

  Further, the control unit 38 controls a light source control circuit 41 as a light source control unit, and the light source control circuit 41 is configured so that light of a predetermined wavelength band required at the time of image generation is emitted from the light source unit 60. The light emission timings of the red light source device 120, the green light source device 80, and the blue light source device 300 of the light source unit 60 are individually controlled.

  Further, an illuminance sensor 61 is connected to the control unit 38 via an AD converter 62 in order to detect the brightness of the screen during projection and the screen during non-projection, and is detected by the illuminance sensor 61. The projection brightness of the image is adjusted according to the brightness to make the image easy to see for the user.

  Specifically, the control unit 38 sets the first measurement timing at one first timing of the light emission switching timing of each color in one frame, and one first light emission switching timing of each color in this one frame. Set the second measurement timing at the second time.

  Then, the control unit 38 controls the display element control unit so that no light is projected onto the screen at the first measurement timing. That is, the display element is controlled so that all the light guided to the display element is turned off.

  The control unit 38 controls the light source control unit at the second measurement timing to turn on the light source device with a predetermined brightness, and all the light guided from the light source device to the display element is projected onto the screen. The display element 51 is controlled as described above. That is, the display element is controlled so that all light guided to the display element is turned on.

  In the present embodiment, the display element is controlled at the first measurement timing so that no light is projected onto the screen. However, the present invention is not limited to this, and the light source control unit controls the display element from the light source device at the first measurement timing. Control may be performed so that light is not irradiated so that no light is projected onto the screen.

  Then, the control unit 38 controls the illuminance sensor 61 to measure the reflected light of the screen at each of the first measurement timing and the second measurement timing, and each measurement value at the first measurement timing and the second measurement timing. To control the brightness of the projected image.

  For example, the control unit 38 calculates a difference value between the measurement values of the reflected light at the first measurement timing and the second measurement timing, and corrects the brightness of the projection image based on the difference value.

  Then, the memory including the ROM of the projector 10 is based on a table in which the correspondence between the difference between the measurement values of the reflected light at the first measurement timing and the second measurement timing and the luminance of the projection image is shown in advance. Table data is stored, and the control unit 38 refers to the table data to obtain a correction value for the brightness of the projection image.

  Further, the control unit 38 causes the cooling fan drive control circuit 43 to perform temperature detection using a plurality of temperature sensors provided in the light source unit 60 and the like, and controls the rotation speed of the cooling fan from the result of the temperature detection. Further, the control unit 38 causes the cooling fan drive control circuit 43 to keep the cooling fan rotating even after the projector body is turned off by a timer or the like, or to turn off the projector body depending on the result of temperature detection by the temperature sensor. Control is also performed.

  Next, the directivity of the illuminance sensor 61 in the present embodiment will be described with reference to the drawings. FIG. 4 is an explanatory diagram regarding the directivity in the vertical direction and the horizontal direction of the illuminance sensor 61.

  The illuminance sensor 61 is installed approximately in the center of the front of the apparatus, and detects the brightness on the screen side through the daylighting window 16 of the front panel 12. The illuminance sensor 61 detects the brightness of the substantially central portion of the screen through the daylighting window 16 from the inside of the apparatus.

  For example, the output characteristics of a general illuminance sensor 61 can be obtained by arranging the output characteristics of directivity as shown in FIGS. 4A and 4B at the front position with respect to the screen positioned in front. Assuming that the output is 1, the output is attenuated by about 10% when the angle is inclined 30 degrees vertically and horizontally.

  Based on these characteristics, the illuminance sensor 61 is provided with masking or the like in front of the daylighting window 16 or the internal sensor so as to be within the light receiving range inside the angle of view of the projected image.

  Specifically, the light receiving range of the illuminance sensor 61 includes the vicinity of the center with respect to the projection image of the wide-side angle of view of the horizontally long rectangular zoom function irradiated toward the screen as shown in FIG. The circular shape is such that the upper side and the lower side are in contact with each other so that the maximum area can be obtained, and the reflected light from the projection light can be appropriately measured.

  Next, regarding the control of the brightness of the projected image of the projector 10, two patterns of light and dark are projected on the screen during the projection, and the ambient light and the screen reflected light of the projected light are obtained from the pattern, and the projected image is obtained. An operation for controlling the brightness of the image will be described with reference to the drawings. FIG. 6 is a time chart regarding the measurement of the reflected light at the first measurement timing and the reflected light at the second measurement timing when the projector 10 is activated. FIG. 7 is a time chart when the brightness measurement is performed by projecting a white pattern during the image projection of the projector 10. FIG. 8 is a time chart when luminance measurement is performed by projecting a complementary color pattern during image projection of the projector 10.

  The projector 10 has a luminance automatic control mode in which the luminance is automatically changed with respect to a change in external light as a projection mode. In the automatic brightness control mode, two patterns of light (reflected light at the second measurement timing) and dark (reflected light at the first measurement timing) are projected onto the screen at startup and during projection, and ambient light is projected from the pattern. The brightness of the projected image is controlled by obtaining two light reflected from the screen.

  When the projector is set to the automatic brightness control mode and the projection start operation is further performed by the user, the control unit 38 first rotates the fluorescent wheel 101 as shown in FIG. Let

  Then, the control unit 38 measures the reflected light at the first measurement timing, which is the reflected light on the screen indicating the external light that is the ambient light, before turning on the light source. At timing 1 (T1), which is one measurement timing, the illuminance sensor 61 is energized and AD conversion is performed by the AD converter 62 to measure the reflected light at the first measurement timing. The control unit 38 stops energization of the illuminance sensor 61 when the outside light is measured for a predetermined time.

  Next, the control unit 38 controls the light source control unit, and when the rotation speed of the fluorescent wheel 101 is stabilized, for example, as shown in FIG. Test pattern projection before image projection is performed in combination with lighting. In FIG. 6, the blue light source 301 and the red light source 121 which are turned off are turned on to perform test pattern projection before image projection, or the excitation light source 71, the blue light source 301 and the red light source 121 are turned on, and the blue light and red light are turned on. In some cases, a non-image white projection before image projection may be performed using three colors of green light based on excitation light.

  Then, the control unit 38 controls the display element control unit so as to form the timing 2 (T2) which is the second measurement timing shown in FIG. 6 at the switching time when the DMD mirror is originally turned off. At this timing, all the mirrors of the DMD are turned on, and the projection light is irradiated onto the irradiation range of the screen. Then, in order to measure the reflected light at the second measurement timing, which is reflected light on the screen being projected, the control unit 38 energizes the illuminance sensor 61 again and performs AD conversion by the AD converter 62 to perform second conversion. Measure the reflected light at the measurement timing. When the control unit 38 measures the reflected light on the screen during projection for a predetermined time, the illuminance sensor 61 is turned off again.

  Then, the control unit 38 determines the measurement result of the reflected light at the first measurement timing of the ambient light due to the stop of irradiation and the reflected light at the second measurement timing that is the reflected light on the screen during projection to which the ambient light is added. Based on this, the brightness of the projected image is controlled.

  Specifically, at the time of startup, the control unit 38 calculates a difference value between the reflected light at the first measurement timing and the reflected light at the second measurement timing, and the brightness value due to the ambient light due to the stop of irradiation. In this relationship, table data defined by a table showing the correspondence relationship in brightness of the projected image is stored in advance in the memory, and the correction value of the brightness of the projected image is obtained by referring to the table data.

  Then, the control unit 38 obtains a correction value of the brightness of the projected image at the time of activation, thereby correcting the image data of each color and projecting a predetermined projected image under the control of the display element control unit.

  Further, since the projector 10 performs brightness correction as needed in accordance with changes in outside light even during projection in the brightness automatic control mode, the sensing point is continuously detected at the emission switching timing (C) of each color for each frame. Is provided, and two patterns of light and dark are projected onto the sensing point on the sensing point, and the brightness of the projected image is controlled by obtaining two of the ambient light and the screen reflected light of the projected light from the pattern.

  That is, in order to measure the reflected light on the screen indicating the ambient light that is the ambient light during the projection, the control unit 38 senses at the emission switching timing (C) of each color in one frame as shown in FIG. The display element control unit is controlled to drive the display element (DMD) 51 so as to provide points.

  Then, for example, the control unit 38 sets the illuminance while turning off all the mirrors of the DMD at the timing 1 (T1) which is the first measurement timing in the red and blue light emission switching timing (C) in one frame during projection. The sensor 61 is energized, and AD conversion is performed by the AD converter 62 to measure reflected light of only external light. The control unit 38 stops energization of the illuminance sensor 61 when the external light due to the irradiation stop is measured for a predetermined time.

  Next, the control unit 38 measures, for example, white light as reflected light at the second measurement timing, at the second measurement timing of the emission switching timing (C) when switching between green and red shown in FIG. At a certain timing 2 (T2), each light source is turned on, white light is formed and turned on, all DMD mirrors are turned on, the illuminance sensor 61 is energized, and AD conversion is performed by the AD converter 62. And measure the reflected light. When the control unit 38 measures the reflected light of the screen on which white light is projected in addition to the brightness of external light for a predetermined time, the illuminance sensor 61 is de-energized.

  Then, the control unit 38 controls the brightness of the projected image based on the measurement results of the reflected light on the screen onto which the white light is projected and the reflected light of the environmental light due to the stop of irradiation.

  In FIG. 7 and the like, the DMD is displayed in the ON state in all the color projection periods of the red, green, and blue wavelength band lights, but during the projection period of each color according to the color of the image projected on the screen. Needless to say, the ON state time of the DMD is controlled to be appropriately short.

  Further, the control unit 38 calculates the value of the reflected light at the first measurement timing and the reflected light at the second measurement timing during the projection as well as the start-up, and calculates the difference value and the brightness by the ambient light due to the irradiation stop. In this relationship, table data defined by a table showing the correspondence relationship in brightness of the projected image is stored in advance in the memory, and the correction value of the brightness of the projected image is obtained by referring to the table data. Then, the control unit 38 continuously obtains the correction value of the brightness of the projection image even during the projection, thereby correcting the image data of each color, and causes the predetermined projection image to be projected by controlling the display element control unit.

  Note that the control unit 38 is not limited to controlling the light source control unit to turn on white light as reflected light at the second measurement timing and measure the reflected light, for example, the three primary colors of red, blue, and green light sources. As shown in FIG. 8, among the light sources, the red and green light sources are turned on to form yellow light which is a complementary color, and all the DMD mirrors are turned on, and the illuminance sensor 61 is turned on. Energize and perform AD conversion by the AD converter 62 to measure the reflected light at the second measurement timing, or turn on only one of the light sources and turn on the monochromatic light of the three primary colors of red, blue and green light sources You may make it measure reflected light by.

  Further, in the present embodiment shown in FIG. 2, as a light source device that emits light in the wavelength band of three light sources: a green light source device 80 using an excitation light source 71 and a fluorescent wheel 101, a red light source device 120 using a light emitting diode, and a blue light source device 300. However, even with a projector 10 provided with a light source that emits complementary wavelength band light by adding, for example, a yellow light emitting diode, only the complementary color light source is turned on, or the complementary color and other light sources are turned on. The reflected light can also be measured.

  The projector 10 is not limited to a light source device composed of a plurality of light sources. For example, one projector that forms three colors of red, green, and blue using a white lamp light source and a color wheel that converts a predetermined color. The present invention can also be applied to the projector 10 in a light source device including a light source.

  In this case, in the projector 10 using a lamp using a color wheel as a light source, the display element 51 is controlled using the spoke period (S) generated at the emission switching timing (C) of each color in one frame as shown in FIG. And a light source control unit for controlling the light source of one white halogen lamp.

  Then, in the predetermined spoke period (S), the illuminance sensor 61 causes the illuminance sensor 61 to turn on all rays by the DMD at timing 2 (T2) which is the second measurement timing in the predetermined spoke period (S). 10 is emitted from the screen to measure the reflected light at the second measurement timing from the screen, and in one frame, all off-lights are emitted by the DMD during the spoke period (S) different from the predetermined spoke period (S). As described above, the control unit 38 measures the second reflected light from the screen by the ambient light at timing 1 (T1) which is the first measurement timing, and the control unit 38 reflects the reflected light at the first measurement timing and the reflected light at the second measurement timing. The brightness of the projected image may be controlled based on the measurement result.

  Next, the control of the brightness of the projected image when the projector 10 is activated and projected will be described in detail using a flowchart. 10 to 12 are flowcharts relating to the brightness control of a series of projected images of the projector 10.

  First, when the main body power is turned on by the user and the brightness automatic control mode is set and the projection start operation is performed, at the time of startup as shown in the flowchart of FIG. As a confirmation, if the light source device is composed of a plurality of light sources, the rotation of the fluorescent wheel 101 is performed, or if the light source device is composed of one white lamp light source, a wheel rotation start process of rotating the color wheel (step S101). Execute.

  Next, in order to measure the reflected light on the screen showing the ambient light that is the ambient light before turning on the light source, the control unit 38 at the timing 1 (T1) that is the first measurement timing shown in FIG. Then, the first reflected light measurement process (step S105) is performed in which the illuminance sensor 61 is energized and AD conversion is performed by the AD converter 62 to measure the reflected light. Then, the control unit 38 stops energization of the illuminance sensor 61 when the external light is measured for a predetermined time.

  Subsequently, when the rotation speed of the fluorescent wheel 101 or the color wheel is stabilized, the control unit 38 executes a light source lighting process (step S110) for controlling the light source control unit to turn on the light source.

  Then, when the control unit 38 turns on the light source for irradiation of the startup screen at startup, the control unit 38 controls the display element control unit at a timing 2 (T2) that is the second measurement timing shown in FIG. At this time, all the mirrors are turned on to turn on all the dots of the DMD, and the display element control process (step S115) for irradiating the irradiation range of the screen with the projection light is executed.

  Then, the control unit 38 energizes the illuminance sensor 61 again and performs AD conversion by the AD converter 62 in order to measure the reflected light at the second measurement timing, which is reflected light on the screen in the irradiated start screen. Then, a second reflected light measurement process (step S120) for measuring the reflected light at the second measurement timing is executed.

  When the control unit 38 measures the reflected light on the screen on the irradiated start screen for a predetermined time, it again turns off the illuminance sensor 61 and turns off all the mirrors to turn off all the dots of the DMD. An irradiation stop process (step S125) for stopping the projection light irradiation to the irradiation range of the screen is executed.

  In the startup process, the control unit 38 calculates a difference value between the measurement results based on the measurement results of the reflected light on the screen on the irradiated startup screen and the reflected light of the environmental light due to the irradiation stop. Based on this value, a correction value for correcting the brightness of the projected image is determined, and a startup correction process (step S130) for controlling the brightness of the projected image is executed.

  When the control unit 38 completes a series of activation processes and starts projecting an image to be projected on the screen while controlling the luminance of the projection image based on the correction value at the time of activation, the control unit 38 also performs the projection as shown in FIGS. The correction action is continued in the flow of the flowchart shown in FIG.

  When the control unit 38 starts projecting the projection image on the screen, the control unit 38 measures the first reflected light and the second reflected light, for example, every second, and performs this measurement a total of five times.

  The control unit 38 executes 1-second elapsed determination (step S201) for determining whether 1 second has elapsed.

  Next, when 1 second has elapsed in the determination of 1 second elapse (step S201), the control unit 38 next performs timing 1 (1) at the light emission switching timing (C) at the time of switching between red and blue in one frame shown in FIG. T1 determination (step S205) is performed to determine whether or not T1) has been reached.

  In T1 determination (step S205), when the timing 1 (T1) shown in FIG. 7 is reached, the control unit 38 energizes the illuminance sensor 61 and performs AD conversion by the AD converter 62 to measure reflected light. The reflected light measurement process (step S210) is executed.

  Next, the control unit 38 determines whether or not the timing 2 (T2) in the light emission switching timing (C) at the time of switching between green and red in one frame shown in FIG. Step S215) is executed.

  When the control unit 38 determines that the timing 2 (T2) has been reached in the T2 determination (step S215), the control unit 38 controls the light source control unit to turn on the predetermined light source, and controls the display element control unit. A display element control process (step S220) is performed in which all the mirrors are turned on to turn on all the dots of the DMD and the projection light is irradiated onto the irradiation range of the screen.

  Then, in order to measure the reflected light at timing 2 (T2), the control unit 38 energizes the illuminance sensor 61 again, performs AD conversion by the AD converter 62, and measures the reflected light. (Step S210) is executed.

  When the control unit 38 measures the reflected light on the screen on the irradiated start screen for a predetermined time, it again turns off the illuminance sensor 61 and turns off all the mirrors to turn off all the dots of the DMD. An irradiation stop process (step S230) for stopping the projection light irradiation to the irradiation range of the screen is executed.

  The control unit 38 continues the projection by controlling the DMD based on the image data except for the first reflected light measurement process (step S210) and the first reflected light measurement process (step S210). The measurement determination (step S235) is performed five times by using a counter or the like to determine whether or not the reflected light and the second reflected light are measured five times.

  In the five measurement determination (step S235), if the measurement is not performed five times, the process returns to step S201, and if the measurement is performed five times, the process proceeds to step S301.

  That is, when the control unit 38 measures the first reflected light and the second reflected light five times, the existing measured value (first measured value) obtained by calculating the current set value based on the latest measurement result. Is compared with the measurement value (second measurement value) which is the latest measurement result (step S301), and a determination is made as to whether or not there is a difference based on whether or not the difference between the two measurement values is equal to or less than a threshold value (step S305). It is determined whether a projection correction process for controlling the brightness of the projected image is necessary.

  Then, if there is no difference between the latest measured value and the existing measured value, the process ends without changing the brightness adjustment of the projected image, and if the difference exceeds the threshold, the first reflected light and the first measured light Measurement that calculates the value of the difference between the first reflected light and the second reflected light based on the average value of the five measurement results with the second reflected light, and calculates the current set value that is the existing measured value The value is compared with the newly calculated average value (third measured value) (step S310), and whether or not there is a difference based on whether the difference between the average value and the base value is equal to or less than a threshold value (step S315) is determined. Do.

  If the difference between the average value and the base value is equal to or less than the threshold value, the process ends without changing the brightness adjustment of the projected image. If the difference exceeds the threshold value, the correction value is calculated based on the calculated average value. Is extracted, and the averaged projection correction process (step S320) is performed in which the luminance of the projected image is corrected based on the correction value to control the luminance of the projected image. And it returns to step S201 again and the control part 38 performs the correction process during projection continuously.

  In this way, the latest measurement result is compared with the measurement value based on the current setting, and it is determined whether or not to perform correction based on the latest measurement value, and correction processing is performed only when correction is to be performed. When a large processing load is not applied to the projector 10 and the latest measured value becomes an abnormal value due to a disturbance, the abnormal value can be removed and corrected by calculating an average value. Note that step 310 and step 315 may be omitted, and the latest measurement value may be used as it is, compared with the current measurement value, and correction may be performed using the latest measurement value.

  As a result, the projector 10 continuously controls the brightness of the projected image according to the change of the external light with a simple configuration, and the projector 10 projects by changing the brightness of a part of the room, particularly the room light on the screen. The hue of the image and the sharpness of the image change, and it is possible to remove discomfort to the eyes caused by uneven brightness and external light.

  As described above, according to the present embodiment, two patterns of light and dark are projected on the screen during projection, and the brightness adjustment is performed by obtaining two of the reflected light of the ambient light and the projected light from the pattern. 10 can be offered.

  In addition, according to the present embodiment, since the light source is turned on during the light emission switching period of each color, a bright pattern is projected onto the screen and the reflected light is measured, the brightness difference is clarified without affecting the projected image. be able to.

  Furthermore, according to the present embodiment, the light source that emits light in the red, green, and blue emission wavelength bands is provided, and the reflected light can be measured by projecting an arbitrary color as a bright pattern during the emission switching period of each color. It is possible to perform measurement simply by turning on only one light source.

  Further, according to the present embodiment, if a light source that emits light of complementary colors other than the red, green, and blue emission wavelength bands is provided, the complementary color light is projected as a bright pattern during the light emission switching period, and a projected image is obtained. By detecting a luminance difference based on a color close to, realistic luminance adjustment can be achieved.

  Furthermore, according to the present embodiment, white projection is performed during the light emission switching period and measurement is performed by the illuminance sensor 61. Therefore, the brightness difference becomes clear without changing the hue of the projected image, which is effective for brightness adjustment. is there.

  Further, according to the present embodiment, since all of the plurality of light sources are turned on in a predetermined light emission switching period to set a high-intensity white projection period, this white light can be used to increase the luminance of the projection image. .

  Furthermore, according to the present embodiment, if a laser diode or a light emitting diode is used as a light source, each color with high luminance can be formed.

  Further, according to the present embodiment, it is possible to provide the projector 10 that performs luminance adjustment with an inexpensive configuration.

  And according to this embodiment, the brightness value of the projected image is clearly calculated by calculating the value of the difference between the bright reflected light and the dark reflected light, and correcting the brightness of the projected image based on the difference value. Can be controlled.

  Furthermore, according to the present embodiment, it is possible to perform optimum adjustment by obtaining a correction value of the brightness of the projected image with reference to a table showing the correspondence between the value of the brightness difference and the brightness of the projected image. be able to.

  In this embodiment, the display element control unit is controlled so that all are turned off by the display element 51 at the first measurement timing and all are turned on by the display element 51 at the second measurement timing. For example, at the first measurement timing, all of the DMD mirrors are not turned off, and a part thereof is turned on, and only a predetermined ratio is turned on by the display element 51, that is, the screen is illuminated with the first gradation. The display element control unit controls the display element 51 so that a part of the DMD mirror is not turned on but turned off at the second measurement timing. Is turned off, that is, light is emitted at a second gradation different from the first gradation, and control is performed so as to project on-light with brightness (gradation) different from the first measurement timing. All right .

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

The invention described in the scope of the first claim of the present application will be added below.
[1] In a projector that projects an image onto a projection object,
An illuminance sensor for measuring the reflected light of the projection object;
A light source device;
A display element;
A light source control unit for controlling the light source device;
A display element control unit for controlling the display element;
The first measurement timing is set at one first timing of the light emission switching timing of each color in one frame, and the second measurement timing is set at one second timing of the light emission switching timing of each color in the one frame. Measuring timing setting means to
The light source control unit or the display element control unit controls the light source device or the display element so that the projection object is irradiated with light at a first gradation at the first measurement timing,
The light source control unit or the display element control unit is configured to irradiate the projection object with light at a second gradation different from the first gradation at the second measurement timing. Or controlling the display element,
The illuminance sensor measures reflected light of the projection object at the first measurement timing and the second measurement timing,
A projector comprising: a control unit that controls brightness of a projected image based on measurement values obtained by the illuminance sensor at the first measurement timing and the second measurement timing.
[2] The light source control unit or the display element control unit controls the light source device or the display element so that no light is irradiated to the projection object at the first measurement timing. The projector according to [1] above.
[3] The light source control unit turns on the light source device at a predetermined brightness at the second measurement timing, and at this time, the display element control unit transmits light guided from the light source device to the display element. The projector according to the above [1] or [2], wherein the display element is controlled such that all the light is projected onto the projection object.
[4] The light source device has at least three light sources having different emission wavelength bands,
The projector according to any one of [1] to [3], wherein the light source control unit lights one of the at least three light sources at the second measurement timing.
[5] The projector according to [4], wherein the light source device emits light in a red, green, or blue emission wavelength band at the second measurement timing.
[6] The projector according to [4], wherein the light source device emits complementary color light other than red, green, or blue emission wavelength band at the second measurement timing.
[7] The above [1] to [6], wherein the light source control unit turns on at least three of the light sources to form white light at the second measurement timing. Projector.
[8] The projector according to any one of [1] to [7], wherein the light source device includes a laser diode or a light emitting diode.
[9] The light source device includes a color wheel, further includes a color wheel control unit that controls the color wheel, and the emission switching timing of each color in one frame is a spoke period of the color wheel. The projector according to any one of [1] to [3].
[10] The projector according to [9], wherein the light source device uses a halogen lamp as a light source.
[11] The control unit calculates a difference value between the measurement values of the reflected light at the first measurement timing and the second measurement timing, and corrects the brightness of the projection image based on the difference value. The projector according to any one of [1] to [10] above.
[12] The control unit according to [11], wherein the control unit obtains a correction value of the luminance of the projection image with reference to a table showing a correspondence relationship between the difference value and the luminance of the projection image. Projector.
[13] The control unit calculates a difference value between the measurement values of the reflected light of the projection object between the first measurement timing and the second measurement timing, thereby calculating a difference value between the first measurement values. And correcting the brightness of the projection device based on the first difference value, and then again measuring the reflected light of the projection object at the first measurement timing and the second measurement timing. A difference value between the first measurement value and the second measurement value is obtained by calculating a difference value between the first measurement value and the second measurement value. If the difference between the first measured value and the second measured value is equal to or smaller than a predetermined threshold value, the process is terminated without correcting the brightness of the projection device, and the difference between the first measured value and the second measured value exceeds the threshold value. The brightness of the projection device is corrected based on the second measurement value, the above [11] or [[ The projector according to 2].
[14] The control unit calculates a difference value between the measurement values of the reflected light of the projection object between the first measurement timing and the second measurement timing, thereby calculating a difference value between the first measurement values. And correcting the brightness of the projection device based on the first difference value, and then again measuring the reflected light of the projection object at the first measurement timing and the second measurement timing. The difference between the plurality of measurement values is calculated a plurality of times, and the average of the differences between the plurality of measurement values is obtained to obtain the third measurement value difference value, and the first measurement value and the third measurement value are obtained. In comparison, if the difference between the first measurement value and the third measurement value is less than or equal to a predetermined threshold value, the process ends without correcting the brightness of the projection device, and the first measurement value If the difference between the third measurement values exceeds the threshold, the brightness of the projection device is calculated based on the third measurement value. The projector according to the above [11] or [12] above, wherein the positive to.
[15] An illuminance sensor that measures the reflected light of the projection object, a light source device, a display element, a light source control unit that controls the light source device, and a display element control unit that controls the display element. In a projection control method for a projector that projects an image onto the projection object,
The first measurement timing is set at one first timing of the light emission switching timing of each color in one frame, and the second measurement timing is set at one second timing of the light emission switching timing of each color in the one frame. And
The light source control unit or the display element control unit controls the light source device or the display element so that the projection object is irradiated with light at a first gradation at the first measurement timing,
The light source control unit or the display element control unit is configured to irradiate the projection object with light at a second gradation different from the first gradation at the second measurement timing. Or controlling the display element,
The illuminance sensor measures reflected light of the projection object at the first measurement timing and the second measurement timing,
A projection control method for a projector, comprising: controlling brightness of a projection image based on measurement values obtained by the illuminance sensor at the first measurement timing and the second measurement timing.
[16] A program for controlling a light source control unit for controlling a light source device, a display element control unit for controlling a display element, and an illuminance sensor for measuring reflected light of a screen by a control unit of the projector,
The first measurement timing is set at one first timing of the light emission switching timing of each color in one frame, and the second measurement timing is set at one second timing of the light emission switching timing of each color in the one frame. And
The light source control unit or the display element control unit controls the light source device or the display element so that the projection object is irradiated with light at a first gradation at the first measurement timing,
The light source control unit or the display element control unit is configured to irradiate the projection object with light at a second gradation different from the first gradation at the second measurement timing. Or controlling the display element,
The illuminance sensor measures reflected light of the projection object at the first measurement timing and the second measurement timing,
A computer-readable projection control program for a projector, wherein brightness of a projection image is controlled based on measurement values obtained by the illuminance sensor at the first measurement timing and the second measurement timing.

DESCRIPTION OF SYMBOLS 10 Projector 11 Top panel 12 Front panel 13 Rear panel 14 Right side panel 15 Left side panel 16 Daylighting window 17 Exhaust hole 18 Intake hole 19 Lens cover 20 Various terminals 21 Input / output connector part 22 Input / output interface 23 Image conversion part 24 Display encoder 25 Video RAM
26 Display Drive Unit 31 Image Compression / Expansion Unit 32 Memory Card 35 Ir Reception Unit 36 Ir Processing Unit 37 Key / Indicator Unit 38 Control Unit
DESCRIPTION OF SYMBOLS 41 Light source control circuit 61 Illuminance sensor 43 Cooling fan drive control circuit 45 Lens motor 47 Audio | voice processing part 48 Speaker 51 Display element 60 Light source unit 61 Illuminance sensor 62 AD converter 70 Excitation light irradiation apparatus 71 Excitation light source 73 Collimator lens 75 Reflective mirror group 78 Condensing lens 80 Green light source device 81 Heat sink 100 Fluorescent light emitting device 101 Fluorescent wheel 110 Wheel motor 111 Condensing lens group 120 Red light source device 121 Red light source 125 Condensing lens group 130 Heat sink 140 Light guide optical system 141 First dichroic mirror 148 First Two-dichroic mirror 160 Optical system unit 161 Illumination side block 165 Image generation block 168 Projection side block 170 Light source side optical system 173 Condensing lens 175 Lightton 178 Condensing lens 181 Optical axis conversion mirror 183 Condensing lens 185 Irradiation mirror 190 Heat sink 195 Condenser lens 220 Projection side optical system 225 Fixed lens group 235 Movable lens group 241 Control circuit board 261 Cooling fan 300 Blue light source device 301 Blue light source 305 Condensing lens group 310 Heat sink

Claims (16)

In a projector that projects an image onto a projection object,
An illuminance sensor for measuring the reflected light of the projection object;
A light source device;
A display element;
A light source control unit for controlling the light source device;
A display element control unit for controlling the display element;
The first measurement timing is set at one first timing of the light emission switching timing of each color in one frame, and the second measurement timing is set at one second timing of the light emission switching timing of each color in the one frame. Measuring timing setting means to
The light source control unit or the display element control unit controls the light source device or the display element so that the projection object is irradiated with light at a first gradation at the first measurement timing,
The light source control unit or the display element control unit is configured to irradiate the projection object with light at a second gradation different from the first gradation at the second measurement timing. Or controlling the display element,
The illuminance sensor measures reflected light of the projection object at the first measurement timing and the second measurement timing,
A projector comprising: a control unit that controls brightness of a projected image based on measurement values obtained by the illuminance sensor at the first measurement timing and the second measurement timing.   The light source control unit or the display element control unit controls the light source device or the display element so that no light is irradiated to the projection object at the first measurement timing. Projector.   The light source control unit turns on the light source device at a predetermined brightness at the second measurement timing, and at this time, the display element control unit receives light guided from the light source device to the display element. The projector according to claim 1, wherein the display element is controlled so as to be projected onto the projection object. The light source device has at least three types of light sources having different emission wavelength bands,
4. The projector according to claim 1, wherein the light source controller turns on one of the at least three light sources at the second measurement timing. 5.   The projector according to claim 4, wherein the light source device emits light in a red, green, or blue emission wavelength band at the second measurement timing.   The projector according to claim 4, wherein the light source device emits complementary color light other than red, green, or blue light emission wavelength band at the second measurement timing.   The projector according to any one of claims 1 to 6, wherein the light source control unit turns on at least three of the light sources to form white light at the second measurement timing.   The projector according to claim 1, wherein the light source device includes a laser diode or a light emitting diode.   The light source device includes a color wheel, further includes a color wheel control unit that controls the color wheel, and the emission switching timing of each color in one frame is a spoke period of the color wheel. The projector according to claim 1.   The projector according to claim 9, wherein the light source device uses a halogen lamp as a light source.   The control unit calculates a difference value between the measurement values of the reflected light at the first measurement timing and the second measurement timing, and corrects the luminance of the projection image based on the difference value. The projector according to any one of claims 1 to 10.   The projector according to claim 11, wherein the control unit obtains a correction value of the luminance of the projection image with reference to a table showing a correspondence relationship between the difference value and the luminance of the projection image. .   The control unit calculates a difference value between the measurement values of the reflected light of the projection object between the first measurement timing and the second measurement timing to obtain a difference value between the first measurement values. , After correcting the brightness of the projection device based on the first difference value, again the difference in the measurement value of the reflected light of the projection object between the first measurement timing and the second measurement timing. Calculating a value to obtain a difference value of the second measurement value, comparing the first measurement value and the second measurement value, and calculating the first measurement value and the second measurement value; If the difference between the first measured value and the second measured value is less than a predetermined threshold value, the process ends without correcting the brightness of the projection device, and the difference between the first measured value and the second measured value exceeds the threshold value. 13. The brightness of the projection device is corrected based on the second measurement value. The projector according.   The control unit calculates a difference value between the measurement values of the reflected light of the projection object between the first measurement timing and the second measurement timing to obtain a difference value between the first measurement values. Then, after correcting the brightness of the projection device based on the first difference value, the difference in the measured value of the reflected light of the projection object is again measured between the first measurement timing and the second measurement timing. Calculate multiple times, obtain the difference value of the third measurement value by calculating the average of the difference of the plurality of measurement values, compare the first measurement value and the third measurement value If the difference between the first measurement value and the third measurement value is less than or equal to a predetermined threshold value, the process is terminated without correcting the brightness of the projection device, and the first measurement value and the third measurement value are terminated. If the difference between the measured values exceeds the threshold, the brightness of the projection device is corrected based on the third measured value. The projector according to claim 11 or claim 12, characterized in that. An illuminance sensor that measures the reflected light of the projection object, a light source device, a display element, a light source control unit that controls the light source device, a display element control unit that controls the display element, and the image In a projection control method for a projector that projects onto a projection object,
The first measurement timing is set at one first timing of the light emission switching timing of each color in one frame, and the second measurement timing is set at one second timing of the light emission switching timing of each color in the one frame. And
The light source control unit or the display element control unit controls the light source device or the display element so that the projection object is irradiated with light at a first gradation at the first measurement timing,
The light source control unit or the display element control unit is configured to irradiate the projection object with light at a second gradation different from the first gradation at the second measurement timing. Or controlling the display element,
The illuminance sensor measures reflected light of the projection object at the first measurement timing and the second measurement timing,
A projection control method for a projector, comprising: controlling brightness of a projection image based on measurement values obtained by the illuminance sensor at the first measurement timing and the second measurement timing. A program for controlling a light source control unit for controlling a light source device, a display element control unit for controlling a display element, and an illuminance sensor for measuring reflected light of a screen by a control unit of the projector,
The first measurement timing is set at one first timing of the light emission switching timing of each color in one frame, and the second measurement timing is set at one second timing of the light emission switching timing of each color in the one frame. And
The light source control unit or the display element control unit controls the light source device or the display element so that the projection object is irradiated with light at a first gradation at the first measurement timing,
The light source control unit or the display element control unit is configured to irradiate the projection object with light at a second gradation different from the first gradation at the second measurement timing. Or controlling the display element,
The illuminance sensor measures reflected light of the projection object at the first measurement timing and the second measurement timing,
A computer-readable projection control program for a projector, wherein brightness of a projection image is controlled based on measurement values obtained by the illuminance sensor at the first measurement timing and the second measurement timing.

Images