JP2015175856A - Image projection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image projection device configured to detect a degree of degradation in each of colors projected, without projecting a specific pattern image.SOLUTION: An image projection device according to the present invention includes an image forming section, an imaging section, a first control section, a calculation section, and a second control section. The image forming section modulates light from a light source that changes color sequentially, to form an image to be projected on a projection surface. The imaging section images the projection surface. The first control section causes the imaging section to perform imaging, in synchronization with projection of light of multiple kinds of single colors. The calculation section calculates a ratio of brightness of each of the colors in the light projected on the projection surface, on the basis of a captured image obtained by imaging of the imaging section. The second control section controls the image forming section so that the ratio may be equal to a prescribed value.

Description

  The present invention relates to an image projection apparatus.

  Conventionally, high-pressure mercury lamps have been used as light sources for projectors. However, in recent years, a projector using a semiconductor laser (LD) or a light emitting diode (LED) has been developed because of the advantages such as mercury-free, long life, and wide color reproduction range. In a projector that uses an LD or LED as a light source, a different light source is used for each color. Therefore, when the projector is used for a long time, the brightness decreases at a different rate. For this reason, there is a problem that the balance of each color is lost when the usage time elapses, and the color changes from the design value.

  In order to prevent this problem, there is already a method in which the brightness of each light source is measured by a sensor to detect the degree of deterioration of each light source (the degree of deterioration of each projected color) and control is performed so that the color does not change. Are known. For example, in Patent Document 1, the entire screen is monochromatic by a projector for the purpose of suppressing deterioration in the lifetime of the entire projector due to continuous use when the optical component is deteriorated by detecting the deterioration state of the optical component. A configuration is disclosed in which a deterioration state of each optical component is detected based on an image captured by an imaging unit mounted on the projector when a pattern image (test image) to be displayed is projected.

  However, in the technique disclosed in Patent Document 1, since it is necessary to project a specific pattern image in order to detect the degree of deterioration of each projected color, the user does not use the projector during this detection period. Cannot be used. For this reason, there exists a problem that a user's convenience is low.

  The present invention has been made in view of the above, and an object of the present invention is to provide an image projection apparatus capable of detecting the degree of deterioration of each projected color without projecting a specific pattern image.

  In order to solve the above-described problems and achieve the object, the present invention modulates light from a light source that sequentially switches colors to form an image for projection onto a projection plane, and the projection An imaging unit that captures a surface; a first control unit that causes the imaging unit to perform imaging in accordance with a timing at which a plurality of types of monochromatic light are projected; and a captured image obtained by imaging by the imaging unit Based on the calculation unit that calculates the ratio of the brightness of the light projected on the projection plane of each of the plurality of types of single colors, and controls the image forming unit so that the ratio becomes a predetermined value. And a second control unit.

  According to the present invention, it is possible to detect the degree of deterioration of each projected color without projecting a specific pattern image.

FIG. 1 is an overall view illustrating an example of an image projection system according to an embodiment. FIG. 2 is a diagram illustrating an internal configuration of hardware of the image projection apparatus according to the embodiment. FIG. 3 is a diagram illustrating an example of a functional configuration of the image projection apparatus according to the embodiment. FIG. 4 is a schematic diagram showing the relationship between the rotation period of the color wheel and the shutter / exposure timing of the camera unit. FIG. 5 is a diagram illustrating an example of the configuration of the color wheel. FIG. 6 is a flowchart illustrating an example of processing by the image projection apparatus. FIG. 7 is a diagram illustrating an example of a variation of the camera unit installation method.

  Hereinafter, embodiments of an image projection apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an overall view showing an example of an image projection system of the present embodiment. The image projection apparatus 10 is connected to an external PC (not shown), and projects image data (projection target image data) such as a still image and a moving image input from the external PC onto the screen 20 that is a projection plane. . A camera unit 30 is connected to the image projection apparatus 10. The camera unit 30 may be provided as external hardware, or may be built in the image projection apparatus 10. The camera unit 30 can be considered to correspond to the “imaging unit” in the claims.

  FIG. 2 is a diagram illustrating an example of an internal configuration of hardware of the image projection apparatus 10. As shown in FIG. 2, the image projection apparatus 10 includes an illumination unit 3a and a projection unit 3b. The illumination unit 3a includes a color wheel 5, a light tunnel 6, a relay lens 7, a plane mirror 8, and a convex mirror 9. Each of these members is provided in the main body of the image projector 10. In addition, the image projector 10 is provided with an image forming unit 2. In this example, the image forming unit 2 includes a DMD element that is an example of a light modulation element that forms an image.

  The disc-shaped color wheel 5 has a plurality of color regions (not shown) arranged in the circumferential direction, and converts white light from the light source 4 into light in which the color of each region (segment) repeats every unit time. Then, the light is emitted toward the light tunnel 6. In other words, the color wheel 5 can be regarded as emitting light from the light source 4 whose colors are sequentially switched toward the light tunnel 6.

  The light tunnel 6 is formed in a cylindrical shape by laminating plate glasses, and guides light emitted from the color wheel 5 (light from the light source 4 whose colors are sequentially switched) to the relay lens 7. The relay lens 7 is configured by combining two lenses, and collects light while correcting axial chromatic aberration of light emitted from the light tunnel 6. The plane mirror 8 and the convex mirror 9 reflect the light emitted from the relay lens 7 and guide it to the image forming unit 2 to collect it.

  The image forming unit 2 modulates light from the light source 4 whose colors are sequentially switched to form an image to be projected on the projection surface. More specifically, the image forming unit 2 has a rectangular mirror surface composed of a plurality of micromirrors (DMD elements), and on / off of each micromirror based on an input signal (video or image data). By switching OFF (whether or not to project light to the projection unit 3b side), light directed to the projection unit 3b side is selectively output.

  Moreover, as the light source 4, LD, LED, etc. are used, for example. The light source 4 emits white light toward the illumination unit 3a. The white light emitted from the light source 4 passes through the color wheel 5 and then is condensed on the image forming unit 2 through the light tunnel 6, the relay lens 7, the plane mirror 8, and the concave mirror 9. The image forming unit 2 forms an image based on the input signal, and the projection unit 3b enlarges and projects the image formed by the image forming unit 2.

  In addition, an OFF light plate that receives unnecessary light that is not used as projection light among light incident on the image forming unit 2 is vertically above the image forming unit 2 illustrated in FIG. Is provided. When light enters the image forming unit 2, a plurality of micromirrors are operated based on the input signal in a time-sharing manner by the action of the DMD element, and the light used by the micromirrors is reflected to the projection lens, and the light to be discarded is OFF. Reflected to the light plate. In the image forming unit 2, the light used for the projection image is reflected to the projection unit 3 b and enlarged through a plurality of projection lenses, and the enlarged image light is enlarged and projected.

  FIG. 3 is a block diagram illustrating an example of a functional configuration of the image projection apparatus 10. The image projection apparatus 10 controls the input of the video signal so that the projection of light and the drive of the image forming unit 2 are synchronized. As shown in FIG. 3, the image projection apparatus 10 includes a projection video signal input processing unit 11, a video processing unit 12, a device drive control unit 13, an image forming unit 2, a lamp power supply 14, a light source 4, a color wheel 5, and a camera. Unit 30, camera video signal input processing unit 15, calculation unit 16, and illuminance ratio recording unit 40.

  First, a digital signal such as HDMI (registered trademark) or an analog signal such as VGA or a component signal is input to the projection video signal input processing unit 11 of the image projection apparatus 10 from an external PC. The projection video signal input processing unit 11 performs processing for processing video into RGB, YPbPr signals, and the like according to the input signals. When the input video signal is a digital signal, the projection video signal input processing unit 11 converts it into a bit format defined by the video processing unit 12 according to the number of bits of the input signal. Further, when the input video signal is an analog signal input, the projection video signal input processing unit 11 performs a DAC process for digitally sampling the analog signal and inputs an RGB or YPbPr format signal to the video processing unit 12. .

  The video processing unit 12 performs digital image processing or the like according to the input signal. Specifically, appropriate image processing is performed according to the scaler function such as contrast, brightness, saturation, hue, RGB gain, sharpness, enlargement / reduction, or the like, or the characteristics of the device drive control unit 13. The input signal after the digital image processing is passed to the device drive control unit 13. In addition, the video processing unit 12 can generate an image signal of an arbitrarily designated or registered layout.

  The device drive control unit 13 determines the drive condition of the lamp power source 14 that controls the drive current of the color wheel 5, the image forming unit 2, and the light source 4, and drives the color wheel 5, the image forming unit 2, and the lamp power source 14. Give instructions. The device drive control unit 13 controls the color wheel 5 to sequentially switch the color of the projection light.

  The device drive control unit 13 has a function of controlling imaging by the camera unit 30 and issues an imaging instruction to the camera unit 30. The timing of imaging by the camera unit 30 (imaging timing) will be described later. In this specification, “imaging” refers to converting an image of a subject formed by an optical system such as a lens into an electrical signal.

  The camera unit 30 images the entire screen 20 in accordance with an instruction from the device drive control unit 13. In the following description, an image obtained by imaging with the camera unit 30 may be referred to as a “captured image”. As an imaging method of the camera unit 30, there are a global shutter method and a rolling shutter method. In the global shutter method, all pixels are simultaneously exposed to light, and each pixel requires a more complicated circuit than the rolling shutter method. However, the advantage is that all pixels can be exposed and imaged at once. is there. In the rolling shutter system, progressive scanning type photosensitivity is performed, which can be implemented with a simple circuit and can be imaged in a scanning manner. However, since the imaging timing is different for each pixel, distortion or the like may occur when an object that moves at high speed is imaged.

  Here, the imaging timing of the camera unit 30 will be described. In the present embodiment, the device drive control unit 13 causes the camera unit 30 to perform imaging in accordance with the timing at which a plurality of types of monochromatic light are respectively projected. Specific contents will be described below. In this example, it can be considered that the device drive control unit 13 corresponds to a “first control unit” in the claims.

  FIG. 4 is a schematic diagram showing the relationship between the rotation period of the color wheel 5 and the shutter / exposure timing of the camera unit 30. In the example of FIG. 4, the color wheel 5 repeats rotation with four periods of A period, B period, C period, and D period as one unit. Here, for example, in the period A, only “red (one color)” light (light having a wavelength corresponding to red) out of the light incident from the light source 4 passes through the color wheel 5. That is, it can be considered that red light is projected on the screen 20 in the period A. For example, in the period B, only “green” light (light having a wavelength corresponding to green) passes through the color wheel 5. That is, it can be considered that green light is projected on the screen 20 in the period B. For example, in the period C, only “blue” light (light having a wavelength corresponding to blue) passes through the color wheel 5. That is, it can be considered that “blue” light is projected onto the screen 20 during the period C.

  In the example of FIG. 4, the camera unit 30 rotates at a cycle of 30 Hz, and the camera unit 30 can capture an image every time the color wheel 5 rotates four times. Here, by shifting the synchronization of the imaging timing of the color wheel 5 and the camera unit 30, for example, the screen 20 when red light is projected, the screen 20 when green light is projected, and the like, The screen 20 when monochromatic light is projected can be captured by the camera unit 30. In the example of FIG. 4, the device drive control unit 13 determines the timing (a, b, and c shown in FIG. 4) at which red, green, and blue light are projected on the screen 20 as the imaging timing of the camera unit 30. To do. Even when the number of segments of the color wheel 5 increases or decreases, similarly to the above, the imaging timing of the camera unit 30 is determined in accordance with the timing at which a plurality of types of monochromatic light are respectively projected on the screen 20. be able to. Note that the device drive control unit 13 can also control the camera unit 30 so that a plurality of captured images corresponding to a plurality of types of single colors are obtained within a certain period. Thereby, the below-mentioned illuminance ratio corresponding to each single color can be accurately obtained.

  FIG. 5 is a diagram illustrating a configuration example of the color wheel 5 of the present embodiment. In the example of FIG. 5, the color wheel rotates in accordance with the driving of the motor 51, and the color wheel 5 itself is provided with a black seal 52 that serves as an index for detecting the rotation. A sensor 53 for detecting the black seal 52 is provided. The drive of the motor 51 is controlled by the device drive control unit 13. In addition, the device drive control unit 13 acquires a signal indicating the timing at which the black seal 52 is detected (in the following description, it may be referred to as “synchronization signal”) from the sensor 53, and the acquired synchronization signal is included in the acquired synchronization signal. Based on this, the imaging timing of the camera unit 30 described above is determined (set), and an imaging instruction is issued to the camera unit 30 so that imaging by the camera unit 30 is executed at the determined imaging timing.

  Returning to FIG. 3, the description will be continued. A captured image from the camera unit 30 is input to the camera video signal input processing unit 15. Based on the captured image input to the camera video signal input unit 15, the calculation unit 16 calculates the ratio of the brightness of light projected on each of a plurality of arbitrary types (three in this example) of single-color screens 20 ( (Illuminance ratio) is calculated. In this example, the calculation unit 16 corrects the brightness (illuminance) of the captured image based on information indicating the operation of the image forming unit 2 when the captured image is obtained, and calculates the illumination ratio based on the correction result. calculate. More specifically, it is as follows.

  In the present embodiment, the calculation unit 16 includes a projection video area detection unit 17, a gradation value output unit 18, and an illuminance value correction processing unit 19. The projected video area detection unit 17 detects a region in which light from the image projection device 10 is projected from the captured image input to the camera video signal input processing unit 15, and displays information indicating the detection result as an illuminance value. Output to the correction processing unit 19. Further, the gradation value output unit 18 is based on the value of the input signal input to the projection video signal input processing unit 11, and the gradation value at each position when a captured image is obtained by imaging with the camera unit 30. (Tone values of a plurality of pixels included in the image data (input signal) input to the projection video signal input processing unit 11), that is, information indicating the on / off ratio of each DMD element (captured image was obtained) Information indicating the operation of the image forming unit 2 at that time) is output to the illuminance value correction processing unit 19.

  The illuminance value correction processing unit 19 corrects the value of the illuminance (brightness) of the captured image based on the information input from the projection video area detection unit 17 and the information input from the gradation value output unit 18. . The illuminance value correction processing unit 19 performs the above correction processing for each of a plurality of captured images corresponding to any one of a plurality of types (three in this example) and one to one, and for each of a plurality of types of single colors. The illuminance value of the light projected on the screen 20 is calculated. Then, the illuminance ratio is calculated using a plurality of illuminance values corresponding to a plurality of types of single colors, and the calculated illuminance ratio is recorded in the illuminance ratio recording unit 40.

  The video processing unit 12 compares the illuminance ratio recorded in the illuminance ratio recording unit 40 with a predetermined illuminance ratio, and is input to the projection video signal input processing unit 11 so as to obtain a specified illuminance ratio. Image processing (correction processing) is performed on the input signal (image data). Then, the device drive control unit 13 determines the drive condition of the image forming unit 2 according to the corrected input signal. In other words, it can be considered that the device drive control unit 13 controls the image forming unit 2 so that the illuminance ratio recorded in the illuminance ratio recording unit 40 becomes a predetermined value. The device drive control unit 13 can be considered to correspond to the “second control unit” in the claims. Further, for example, it can be considered that a combination of the video processing unit 12 and the device drive control unit 13 corresponds to a “second control unit” in the claims.

  For example, the device drive control unit 13 may execute the control with an interval of a certain time or more when executing the control. Thereby, since a user can suppress that a color tint changes frequently while using the image projection apparatus 10, it can prevent the said user from feeling uncomfortable.

  Further, for example, the video processing unit 12 may be configured not to perform the input signal correction process when the contrast indicating the difference between the brightest part and the darkest part of the captured image is equal to or less than a threshold value. That is, when the contrast of the captured image is equal to or less than the threshold, the device drive control unit 13 performs the above control (control of the image forming unit 2 to set the illuminance ratio recorded in the illuminance ratio recording unit 40 to a predetermined value. ) May not be executed. Accordingly, it is possible to prevent the projection image from being corrected based on the illuminance ratio obtained under inappropriate conditions, for example, when the surrounding environment is very bright.

  Next, an example of processing by the image projection apparatus 10 of the present embodiment will be described using FIG. As shown in FIG. 6, first, the device drive control unit 13 receives (acquires) a synchronization signal from the color wheel 5 (step S1). Next, the device drive control unit 13 controls the camera unit 30 so that the screen 20 is imaged at a timing when any one of a plurality of types of single colors is projected (step S2). Next, as described above, the calculation unit 16 is information indicating the operation of the image forming unit 2 when a captured image is obtained by imaging by the camera unit 30 (in this example, information indicating the on / off ratio of each DMD element). ) To correct the brightness of the captured image (step S3), and based on the correction result (corrected captured image), the color projected on the screen 20 during imaging by the camera unit 30 in step S2 described above The illuminance value corresponding to (monochrome) is calculated and recorded (step S4). The processes in steps S1 to S4 described above are performed until all the illuminance values corresponding to any of a plurality of types (three in this example) of single colors are recorded (step S5).

  When the illuminance values corresponding to all the single colors are recorded (step S5: Yes), the calculation unit 16 (illuminance value correction processing unit 19) uses the illuminance values corresponding to a plurality of types of single colors and the illuminance values. The ratio is calculated, and the calculated illuminance ratio is recorded in the illuminance ratio recording unit 40 (step S6). Next, the video processing unit 12 compares the illuminance ratio recorded in the illuminance ratio recording unit 40 with a predetermined illuminance ratio (step S7), and determines whether or not the difference between the two is within a threshold value. (Step S8). If the difference is within the threshold (step S8: Yes), the process is terminated as it is. On the other hand, when the difference exceeds the threshold value (step S8: No), the device drive control unit 13 calculates a control value (in this example, the on / off ratio of each DMD element) for setting the recorded illuminance ratio to a specified value. (Step S9). The device drive control unit 13 controls the image forming unit 2 using the control value calculated in step S9 (step S10). And the process after the above-mentioned step S1 is repeated.

  As described above, in the present embodiment, the camera unit 30 performs imaging in accordance with the timings at which a plurality of types of single-color light are projected, and based on the captured image obtained by imaging by the camera unit 30. Then, the brightness ratio (illuminance ratio) of the light projected on each of the plurality of types of single-color screens 20 is calculated, and the image forming unit 2 is controlled so that the calculated illumination ratio becomes a predetermined value. doing. Thereby, it is possible to detect the degree of deterioration of each projected color without projecting a specific pattern image. Further, according to the present embodiment, it is possible to control the color in real time.

  As mentioned above, although embodiment of this invention was described, the above-mentioned embodiment is shown as an example and is not intending limiting the range of invention. The present invention is not limited to the above-described embodiments as they are, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some components may be deleted from all the components shown in the embodiment.

  For example, the above-described camera unit 30 does not need to be built in the image projection apparatus 10 and, as shown in FIG. 7, (a) an external system, (b) a built-in system, (c) an external connection system, etc. Can be provided in a desired manner.

  Note that the program executed by the image projection apparatus 10 of the present embodiment is provided by being incorporated in advance in a ROM or the like. A program executed by the image projection apparatus 10 according to the present embodiment is a file in an installable format or an executable format, and is a computer such as a CD-ROM, a flexible disk (FD), a CD-R, or a DVD (Digital Versatile Disk). The information may be provided by being recorded on a recording medium that can be read by the user.

  Furthermore, the program executed by the image projection apparatus 10 of the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Further, the program executed by the image projection apparatus 10 of the present embodiment may be configured to be provided or distributed via a network such as the Internet.

  Furthermore, the program executed by the image projection apparatus 10 of the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Further, the program executed by the image projection apparatus 10 of the present embodiment may be configured to be provided or distributed via a network such as the Internet.

  The program executed by the image projection apparatus 10 according to the present embodiment has a module configuration including the above-described units. As actual hardware, the CPU (processor) reads the program from the ROM and executes the program. Each unit is loaded on the main storage device, and each unit is generated on the main storage device. Each unit in the image projection apparatus 10 may be realized as software by a program, or may be realized as hardware by a combination of predetermined electronic circuits.

DESCRIPTION OF SYMBOLS 10 Image projector 11 Projection video signal input process part 12 Video process part 13 Device drive control part 14 Lamp power supply 15 Camera video signal input process part 16 Calculation part 17 Projection video area detection part 18 Tonal value output part 19 Illuminance value correction process Unit 20 screen 30 camera unit 40 illuminance ratio recording unit 51 motor 52 black seal 53 sensor

JP 2012-113217 A

Claims (5)

An image forming unit that modulates light from a light source that sequentially switches colors and forms an image to be projected onto a projection surface;
An imaging unit for imaging the projection plane;
A first control unit that causes the imaging unit to perform imaging in accordance with a timing at which a plurality of types of monochromatic light are respectively projected;
A calculation unit that calculates a ratio of brightness of light projected on the projection plane of each of the plurality of types of single colors based on a captured image obtained by imaging by the imaging unit;
A second control unit that controls the image forming unit so that the ratio becomes a predetermined value.
Image projection device. The calculation unit corrects the brightness of the captured image based on information indicating the operation of the image forming unit when the captured image is obtained, and calculates the ratio based on the correction result.
The image projection apparatus according to claim 1. The first control unit controls the imaging unit so that a plurality of the captured images corresponding to the plurality of types of single colors are obtained within a certain period.
The image projection apparatus according to claim 1 or 2. The second control unit, when executing the control, executes the control with an interval of a certain time or more,
The image projection device according to claim 1. The second control unit does not execute the control when the contrast indicating the difference between the brightest part and the darkest part of the captured image is equal to or less than a threshold value.
The image projection device according to claim 1.

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