JP2012198460A - Projector and control method of projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector which properly adjusts its projection state according to a state of ambient light and to provide a control method thereof.SOLUTION: A projector 100 includes: a light source 140; a liquid crystal panel 130 which modulates light emitted from the light source 140; a projection optical system 150 which projects the modulated light on a screen SC; an imaging unit 180 which captures the screen SC; an ambient light detection unit 122 which performs detection of ambient light on the screen SC based on the captured image data; a light amount adjustment unit 123 which performs, based on a result of the detection, adjustment of an amount of light reaching the screen SC from the light source 140; and a correction control unit 124 which controls, after the adjustment by the light amount adjustment unit 123, at least either the liquid crystal panel 130 or the projection optical system 150 based on the captured image data captured by the imaging unit 180, so as to correct a projection image.

Description

  The present invention relates to a projector that projects an image on a projection surface, and a projector control method.

  Conventionally, in a projector that projects an image on a projection surface, a technique that includes an imaging unit that captures the projection surface and automatically corrects a change in the projection image based on a captured image obtained by capturing the projection surface has been proposed (for example, Patent Document 1). The projector described in Patent Document 1 performs trapezoidal distortion correction based on a captured image. In addition to trapezoidal distortion correction, examples of performing focus adjustment and color correction are known.

JP 2004-260785 A

By the way, the visibility of the image projected by the projector is greatly affected by the ambient light (sunlight or illumination). For example, even if the above-described trapezoidal distortion correction, focus adjustment, or color tone correction is performed, if the state of this adjustment does not match the state of the ambient light, it will be felt that the display quality is not improved. On the other hand, ambient light varies depending on the structure of the building, lighting environment, light-shielding environment, and usage time, so it is difficult to make the projector's operating environment constant so as not to be affected by ambient light. . For this reason, when trying to project an image on a projection surface in a place that is susceptible to ambient light, the image is manually adjusted according to the ambient light or repeatedly adjusted so that the projection state is suitable for ambient light. Sometimes it was cumbersome.
The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a projector capable of appropriately adjusting the projection state according to the state of ambient light, and a control method thereof.

In order to achieve the above object, the present invention provides a light source, a modulation unit that modulates light emitted from the light source, a projection unit that projects light modulated by the modulation unit onto a projection surface, and the projection surface. From the light source based on the detection result of the imaging means for imaging, the ambient light detection means for detecting the ambient light that illuminates the projection surface based on the captured image data captured by the imaging means, and the detection result of the ambient light detection means A light amount adjusting unit that adjusts the amount of light that reaches the projection surface, and at least one of the modulating unit and the projecting unit based on the captured image data captured by the image capturing unit after adjustment by the light amount adjusting unit. Correction means for controlling and correcting the projected image.
According to the present invention, the ambient light that illuminates the projection surface is detected from the captured image obtained by capturing the projection surface, and the amount of light reaching the projection surface from the light source is adjusted based on the ambient light, and then the image captured by the imaging unit. Based on the image, the projection image is corrected. Thereby, ambient light can be detected from the captured image, and the brightness of the light source can be adjusted according to the brightness of the ambient light. Further, since the projection image is corrected after the light amount adjustment, the projection image can be reliably corrected in accordance with the projection environment. Therefore, without using an illuminance sensor or the like, the amount of light projected on the projection surface is corrected corresponding to the ambient light, and the projection image can be reliably corrected to reflect the response to the ambient light, so the adjustment is repeated. And good image quality can be obtained quickly.

According to the present invention, in the projector described above, at the time of starting the projector, the start control that blocks the light emitted from the light source by the modulation means for a predetermined time from when the light source starts energization until the brightness of the light source is stabilized. And the ambient light detection means illuminates the projection surface based on the captured image data captured by the imaging means while the light emitted from the light source is blocked by the control of the activation control means. It is characterized by detecting ambient light.
According to the present invention, since ambient light is detected while the light from the light source is blocked, it is possible to more accurately detect ambient light that illuminates the projection surface. In addition, the amount of light can be adjusted using the waiting time at the time of activation, which is efficient.

In the projector according to the aspect of the invention, the correction unit may perform correction based on captured image data captured by the imaging unit in a state where a predetermined correction pattern is projected on the projection surface by the modulation unit. It is characterized by that.
According to the present invention, it is possible to correct a projection image promptly and reliably in accordance with the projection environment.

In the projector according to the aspect of the invention, the correction unit may perform at least one of correction of a shape of a projection image formed on the projection surface, correction of a tone of the projection image, and optical correction including focus. It is characterized by doing.
According to the present invention, an optical change including a change in the shape of a projected image, a change in color tone, and a focus shift can be corrected corresponding to the projection environment.

In the projector according to the aspect of the invention, the light amount adjusting unit may include a luminance adjusting unit that adjusts luminance of the light source by changing power supplied to the light source, or one unit of light emitted from the light source. It is characterized by comprising dimming means for adjusting the amount of light by blocking.
According to the present invention, the amount of light projected on the projection surface can be appropriately corrected according to the ambient light by changing the power supplied to the light source or blocking part of the light emitted from the light source.

In order to achieve the above object, the present invention provides a projector control method for projecting onto a projection surface, wherein light emitted from a light source is modulated and projected onto the projection surface to photograph the projection surface. Detecting the ambient light that illuminates the projection surface based on the captured image data, adjusting the amount of light reaching the projection surface from the light source based on the detection result of the ambient light, and after adjusting the light amount, The projection surface is photographed, and the projection image is corrected based on the photographed image data.
By executing the control method of the present invention, the projector detects ambient light that illuminates the projection surface from a captured image obtained by photographing the projection surface, and adjusts the amount of light reaching the projection surface from the light source based on the ambient light. Since the image is taken and the projection image is corrected based on the taken image, the ambient light can be detected from the taken image, and the luminance of the light source can be adjusted according to the brightness of the ambient light. Further, since the projection image is corrected based on the captured image data captured after the light amount adjustment, the projection image can be reliably corrected in accordance with the projection environment. Therefore, without using an illuminance sensor or the like, the amount of light projected on the projection surface is corrected corresponding to the ambient light, and the projection image can be reliably corrected to reflect the response to the ambient light, so the adjustment is repeated. And good image quality can be obtained quickly.

  According to the present invention, the amount of light projected on the projection surface can be corrected in accordance with the ambient light, and the projection image can be reliably corrected to reflect the response to the ambient light. Image quality can be obtained.

It is a block diagram which shows the structure of the projector which concerns on embodiment to which this invention is applied. It is a flowchart which shows operation | movement of a projector. It is a flowchart which shows in detail the light quantity adjustment process which a projector performs. It is a flowchart which shows the trapezoid distortion correction process which a projector performs in detail.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram illustrating an overall configuration of a projector 100 according to the embodiment. The projector 100 receives image signals from an image source (not shown) stored in a built-in storage device or an external image supply device (not shown) such as a personal computer or various video players. The projector 100 projects light modulated based on an input image signal onto a projection surface such as a screen SC, and forms a projection image on the screen SC. In this embodiment, the screen SC is almost upright, and the screen surface is rectangular. The image input to the projector 100 may be either a moving image (video) or a still image, and the projector 100 can project the video on the screen SC or continue to project the still image on the screen SC. In the following embodiments, a case where an image is projected based on an analog input signal input from an external image supply device via a cable 200 will be described as an example.

  The projector 100 (projector) is roughly divided into an optical system that forms an optical image and an image processing system that controls the operation of the entire projector 100 and electrically processes an image signal. The optical system that functions as a projection unit includes a light source 140, a liquid crystal panel 130 that is a modulation means, and a projection optical system 150. The light source 140 (light source) is a xenon lamp, an ultra-high pressure mercury lamp, an LED (Light Emitting Diode), or the like. A reflector for guiding the light emitted from the light source 140 to the liquid crystal panel 130 and an auxiliary reflector may be provided. Moreover, you may provide the light control element (not shown) etc. which light-reduce the light which the light source 140 emitted on the path | route which reaches the liquid crystal panel 130. FIG.

  The liquid crystal panel 130 receives a signal from an image processing system, which will be described later, and forms an image on the panel surface. The liquid crystal panel 130 includes three liquid crystal panels corresponding to the three primary colors RGB in order to perform color projection. The light from the light source 140 is separated into three color lights of RGB, and the light of each color enters each corresponding liquid crystal panel. The color light modulated by passing through each liquid crystal panel is combined by a combining optical system such as a cross dichroic prism and emitted to the projection optical system 150.

  The projection optical system 150 (projection unit) includes a zoom lens 151 that performs enlargement / reduction and focus adjustment of an image to be projected, a zoom adjustment motor 152 that adjusts the degree of zoom, and a focus adjustment motor 153 that performs focus adjustment. Is provided. The projection optical system 150 receives light modulated by the liquid crystal panel 130 and forms a projected image on the screen SC using the zoom lens 151. The zoom lens 151 is adjusted by a zoom adjustment motor 152 and a focus adjustment motor 153 to adjust the position of the lens, and zoom adjustment for enlarging / reducing the projected image on the screen SC, and a projected image on the screen SC. Adjust the focus for proper image formation.

  The image processing system is configured around a CPU 120 and an image processor 131 that control the entire projector 100 in an integrated manner, and includes an A / D conversion unit 110, a modulation means driving unit 134, a light source driving unit 141, a lens driving unit 154, A RAM 160, a ROM 170 including an image storage unit 171 and a threshold storage unit 172, an imaging unit 180 including a CCD camera 181, a captured image memory 182, a remote controller control unit 190, a remote controller 191, an operation unit 195, and the like are provided. These elements constituting the image processing system are connected to each other via a bus 102.

  The A / D conversion unit 110 is a device that performs A / D conversion on an analog input signal input from the above-described external image supply apparatus via the cable 200, and outputs the converted digital signal to the image processor 131. .

  The CPU 120 performs image processing and luminance adjustment processing in the projector 100 together with the image processor 131. The CPU 120 includes an activation control unit 121, an ambient light detection unit 122, a light amount adjustment unit 123, a correction control unit 124, a zoom ratio calculation unit 125, a focal length calculation unit 126, a three-dimensional surveying unit 127, and a projection. And an angle calculation unit 128. Each of these units is realized by the CPU 120 executing a specific program stored in the ROM 170 in advance.

  The activation control unit 121 (activation control unit) controls the modulation unit driving unit 134 for a predetermined time (hereinafter referred to as luminance stabilization period) until the luminance of the light source 140 is stabilized when the projector 100 is activated. 130 is set to a non-transmissive state (black), and the light from the light source 140 to the screen SC is blocked.

The environment light detection unit 122 (environment light detection means) is based on the captured image captured by the imaging unit 180 while the light from the light source 140 to the screen SC is blocked by the activation control unit 121. Detect ambient light that illuminates.
Specifically, the ambient light detection unit 122 detects the brightness of the ambient light that illuminates the screen SC by performing a process of analyzing the brightness distribution (brightness analysis process) on the captured image captured by the imaging unit 180.

The light amount adjustment unit 123 (light amount adjustment unit) adjusts the amount of light reaching the liquid crystal panel 130 from the light source 140, that is, the amount of light reaching the screen SC from the light source 140, based on the ambient light detected by the ambient light detection unit 122.
Specifically, the light amount adjusting unit 123 is configured to capture the imaging unit 180 (CCD camera 181) until the luminance of the ambient light detected from the captured image is substantially equal to a predetermined target luminance (hereinafter referred to as target luminance). The brightness according to the ISO sensitivity and the shutter speed when the target brightness is reached, that is, the brightness of the ambient light, and the predetermined brightness stored in the threshold storage unit 172 of the ROM 170 are changed. Is compared with a threshold value representing.

  For example, in a projection environment where sunlight is incident on the screen SC, the light from the light source 140 is neutralized by the ambient light, so that the amount of light is insufficient. Therefore, it is not necessary to suppress the luminance of the light source 140. On the other hand, there is nothing that neutralizes the light from the light source 140 in a projection environment where illumination is reduced at night or in a room where outside light is blocked. For this reason, although the amount of light can be secured, there may be an excessive amount of light supply, in which case it is desirable to suppress the luminance of the light source 140.

  Therefore, in the projector 100 according to the present embodiment, the ambient light suppresses the light from the light source 140 by comparing the ISO sensitivity, the shutter speed, and the threshold when the target brightness is reached by the function of the light amount adjustment unit 123. It is determined whether or not it should be in a state. That is, instead of directly measuring the illuminance of the ambient light incident on the screen SC, the ISO sensitivity and the shutter speed when the ISO sensitivity and the shutter speed are automatically adjusted so that the amount of light received by the CCD camera 181 becomes the target value. The shutter speed is used as an index representing the intensity of the influence of ambient light. Since ISO sensitivity and shutter speed have different dimensions, the actual threshold value is a value calculated by combining ISO sensitivity and shutter speed, or another value determined by the correlation between ISO sensitivity and shutter speed. May be. If the shutter speed is slow (long) under the same ISO sensitivity, the ambient light is weak (low). Therefore, it is preferable to reduce the amount of light in the projected image, and the faster (short) the shutter light, the stronger the ambient light. Therefore, the amount of light in the projected image should be increased. Under the same shutter speed, it can be said that the ambient light is strong when the ISO sensitivity is low, and the ambient light is weak when the ISO sensitivity is high.

  As the threshold value, a value set based on the ISO sensitivity and shutter speed of the imaging unit 180 measured under ambient light in which the projector 100 is assumed to be used can be used. As a specific example, the ISO sensitivity and the shutter speed of the imaging unit 180 when the brightness is changed to the target luminance under the ambient light that the user who sees the projection image feels dazzling during the projection of the projector 100. Is set as a threshold value. That is, the projected image looks bright when the periphery of the screen SC is dark and the external light hitting the screen SC is weak. In this case, the ISO sensitivity and the shutter speed that can be seen without suppressing the light from the light source 140 are set as threshold values. If the projected image on the screen SC looks brighter than in this case, it can be said that the light from the light source 140 should be suppressed. Since there are individual differences in the ISO sensitivity and the shutter speed of the image capturing unit 180, it is preferable to individually adjust at the time of shipment from the factory and set a threshold corresponding to the characteristics of each individual image capturing unit 180.

  As a result of comparing the brightness of the ambient light with the threshold value, the light amount adjusting unit 123 determines that the brightness of the ambient light is brighter than the threshold value, and sends an instruction signal to the light source driving unit 141 to set the brightness of the light source 140 to a low level. By outputting, the amount of light reaching the screen SC is suppressed. When it is determined that the brightness of the ambient light is equal to or less than the threshold value, an instruction signal for increasing the luminance of the light source 140 is output to the light source driving unit 141 so that the amount of light reaching the screen SC is maximized. For example, assuming that the ISO sensitivity of the imaging unit 180 is “400” and the shutter speed “1/10” is a threshold value, if the shutter speed when shooting ambient light of the target luminance is longer than 1/10, It is determined that the influence of ambient light is small, and the luminance of the light source 140 is set to low luminance. If the shutter speed when shooting ambient light with the target brightness is 1/10 or less, it is determined that the influence of the ambient light is large, and the brightness of the light source 140 is set high.

  In this embodiment, a case where both the ISO sensitivity and the shutter speed are changed will be described as an example. However, any one of the shooting conditions may be changed. In this embodiment, the luminance of the light source 140 is set to two levels of low luminance and high luminance. However, the present invention is not limited to this, and a mode in which the luminance can be switched to three or more levels by providing a plurality of threshold values. Good. In the present embodiment, the light amount reaching the screen SC is adjusted by switching the luminance of the light source 140. However, the present invention is not limited to this, and the light control element disposed between the light source 140 and the liquid crystal panel 130 is used. The amount of light reaching the screen SC may be adjusted by controlling (not shown).

  The correction control unit 124 (correction unit) controls the image processor 131 and the lens driving unit 154 to control the execution timing of trapezoidal distortion correction, optical adjustment, and image quality adjustment. After the light amount is adjusted by the light amount adjusting unit 123, the light from the light source 140 to the screen SC is released by waiting until the luminance stabilization period elapses under the control of the activation control unit 121. Thereafter, the correction control unit 124 controls the image processor 131 and the lens driving unit 154 to sequentially perform trapezoidal distortion correction, optical adjustment, and image quality adjustment.

  In addition, the correction control unit 124 displays the distortion detection image stored in the image storage unit 171 of the ROM 170 on the liquid crystal panel 130 in the above trapezoidal distortion correction and optical adjustment, and the distortion detection image is projected onto the screen SC. In this state, the projected image is captured by the imaging unit 180. Then, the correction control unit 124 performs the projection angle and the projection angle by the functions of the processing units of the zoom ratio calculation unit 125, the focal length calculation unit 126, the three-dimensional surveying unit 127, and the projection angle calculation unit 128, which will be described later, based on the captured image. When the projection distance is calculated, a signal corresponding to the projection angle is output to the image processor 131, and a signal corresponding to the projection distance is output to the lens driving unit 154.

  Further, in the image quality adjustment, the correction control unit 124 defines the values of the setting items such as brightness and color tone as image quality parameters in accordance with the brightness of the ambient light detected by the light amount adjustment unit 123, and the image processor 131. Output to. Here, the image quality parameter is composed of parameter set data such as “brightness”, “contrast”, “sharpness”, and “hue” which are detailed items of image quality. The order of performing the trapezoidal distortion correction process, the optical adjustment process, and the image quality adjustment process is not particularly limited.

  The processing units of the zoom ratio calculation unit 125, the focal length calculation unit 126, the three-dimensional surveying unit 127, and the projection angle calculation unit 128 are controlled by the correction control unit 124, and the relative distances between the projector 100 and the screen SC (hereinafter, referred to as the relative distances). A process necessary for calculating a projection angle that is an inclination of the optical axis of the projection light projected from the projector 100 with respect to the plane of the screen SC and the plane of the screen SC is performed.

  The image processor 131 performs processing for adjusting the display state of the image such as luminance, contrast, color density, hue, and projected image shape on the digital signal input from the A / D conversion unit 110. The processed image signal is output to the modulation means driving unit 134. The image processor 131 is provided with a trapezoidal distortion correcting unit 132 that corrects keystone distortion and an image quality adjusting unit 133 that adjusts the image quality of the input image such as brightness, contrast, and hue as digital processing units. The image processor 131 can be configured using a general-purpose processor sold as a DSP (digital signal processor) for correcting trapezoidal distortion or adjusting image quality, or can be configured as a dedicated ASIC. .

  When a signal corresponding to the projection angle is input from the CPU 120 (correction control unit 124), the trapezoidal distortion correction unit 132 performs trapezoidal distortion correction based on this signal. When the projection angle, which is the angle formed by the optical axis of the optical system of the projector 100 and the screen SC, is specified, it is possible to determine how to distort the image. With the function of the trapezoidal distortion correction unit 132, the image displayed on the liquid crystal panel 130 is deformed so as to correct the trapezoidal distortion.

  When a signal corresponding to an image quality parameter (parameter set) is input from the CPU 120 (correction control unit 124), the image quality adjustment unit 133 adjusts brightness, contrast, sharpness, hue, and the like based on the image quality parameter represented by the signal. And multiple types of image quality adjustment such as gamma correction. The function of the trapezoidal distortion correcting unit 132 adjusts the image quality of the image displayed on the liquid crystal panel 130.

  The drive unit 134 drives the liquid crystal panel 130 based on the image signal input from the image processor 131. As a result, an image corresponding to the image signal input to the A / D converter 110 is formed on the liquid crystal panel 130, and this image is formed as a projected image on the screen SC via the projection optical system 150.

  The light source driving unit 141 switches the voltage value applied to the light source 140 in accordance with an instruction signal input from the CPU 120. Thereby, the luminance of the light source 140 is switched between low luminance and high luminance in accordance with the voltage value applied by the light source driving unit 141.

  When a signal representing the projection distance is input from the CPU 120, the lens driving unit 154 drives the focus adjustment motor 153 based on this signal to perform focus adjustment (optical adjustment). In order to perform focus adjustment, the zoom ratio of the zoom lens 151 is necessary. This zoom ratio may be calculated from, for example, the driving amount of the zoom lens 151 by the zoom adjustment motor 152, or may be calculated from a photographed image by the imaging unit 180.

  The RAM 160 forms a work area for temporarily storing programs executed by the CPU 120 and data. The image processor 131 includes, as a built-in RAM, a work area necessary for executing each process such as an image display state adjustment process performed by itself.

The ROM 170 stores a program executed by the CPU 120 to realize each processing unit described above, data related to the program, and the like. In addition, the ROM 170 stores, in the image storage unit 171, trapezoidal distortion correction image data used for trapezoidal distortion correction, image quality adjustment image data used for image quality adjustment, optical adjustment image data used for optical adjustment, and the like. ing.
The distortion detection image is, for example, a lattice pattern in which four quadrangles are arranged in the vertical and horizontal directions, or a dot pattern in which a plurality of feature points (dots) are arranged in the vertical and horizontal directions. The image quality adjustment image is a color pattern (color bar) or the like. The optical adjustment image has the same pattern as the distortion detection image. In addition, the ROM 170 stores threshold value data used by the light amount adjustment unit 123 for comparison with ambient light in the threshold value storage unit 172.

  The imaging unit 180 (imaging means) includes a CCD camera 181 using a CCD that is a well-known image sensor. The imaging unit 180 is provided at a position where the CCD camera 181 can image the front surface of the projector 100, that is, the direction in which the projection optical system 150 projects an image toward the screen SC. In the imaging unit 180, the camera direction and the angle of view of the CCD camera 181 are set so that the entire projected image on the screen SC falls within the imaging range at the recommended projection distance. In addition to the CCD, the CCD camera 181 includes a single focus lens that forms an image on the CCD, a mechanism such as auto iris that adjusts the amount of light incident on the CCD, and a control circuit that reads an image signal from the CCD. The CCD camera 181 switches between ISO sensitivity and shutter speed according to the control of the correction control unit 124.

The auto iris mechanism provided in the CCD camera is provided in the single focus lens so that a signal corresponding to the accumulated value of the brightness of the image from the CCD camera 181 is received from the control circuit, and the accumulated value of the brightness falls within a predetermined range. The iris (aperture) is adjusted automatically.
The image whose brightness has been adjusted by auto iris is output from the imaging unit 180 to the captured image memory 182 and repeatedly written in a predetermined area of the captured image memory 182. When the captured image memory 182 completes writing of an image for one screen, the flag of a predetermined area is sequentially reversed. Therefore, the CPU 120 refers to this flag to determine whether imaging using the imaging unit 180 is completed. You can know whether or not. The CPU 120 accesses the captured image memory 182 while referring to this flag, and acquires a necessary captured image.

Remote control control unit 190 receives a radio signal transmitted from remote control 191 outside projector 100. The remote controller 191 includes an operation element (not shown) operated by a user, and transmits an operation signal corresponding to an operation on the operation element as an infrared signal or a wireless signal using a radio wave of a predetermined frequency. The remote control unit 190 includes a light receiving unit (not shown) that receives an infrared signal and a receiving circuit (not shown) that receives a radio signal. The remote control unit 190 receives a signal transmitted from the remote control 191, analyzes it, and operates by a user. Is generated and output to the CPU 120.
The operation unit 195 includes an operation element (not shown), and outputs an operation signal corresponding to an operation on the operation element to the CPU 120. Examples of the operation element include a switch for instructing power ON / OFF, a switch for instructing start of trapezoidal distortion correction, and a switch for instructing start of recorrection processing described later.

Next, the operation of the projector 100 will be described.
2, 3 and 4 are flowcharts showing the operation of the projector 100, and FIG. 2 shows the overall operation. 3 shows in detail the light amount adjustment process shown in step S13 of FIG. 2, and FIG. 4 shows the trapezoidal distortion correction process shown in step S16 of FIG. 2 in detail.
When the power supply of the projector 100 is turned on, the CPU 120 causes the light source driving unit 141 to start supplying voltage to the light source 140 to cause the light source 140 to emit light (step S11). Subsequently, the CPU 120 controls the modulation means driving unit 134 by the function of the activation control unit 121 and sets the liquid crystal panel 130 in a non-transmissive state (black), thereby blocking light from the light source 140 to the screen SC (step). S12).

  Next, while the light to the screen SC is blocked, the CPU 120 executes light amount adjustment processing for adjusting the light amount emitted from the light source 140 by the functions of the ambient light detection unit 122 and the light amount adjustment unit 123 (step S13). ). By this light amount adjustment processing, the light amount emitted from the light source 140 is adjusted to a value corresponding to the ambient light.

Here, the light amount adjustment processing will be described with reference to FIG.
As illustrated in FIG. 3, the CPU 120 starts photographing with the imaging unit 180 and causes the imaging unit 180 to photograph the screen SC (step S <b> 21). The captured image is stored in the captured image memory 182 under the control of the CPU 120. Note that the ISO sensitivity and shutter speed of the imaging unit 180 at this time are not particularly limited.

When the CPU 120 obtains a photographed image from the photographed image memory 182, the function of the ambient light detection unit 122 converts the photographed image into luminance data by performing luminance analysis processing. From the luminance distribution obtained by this conversion, the screen The brightness of the ambient light that illuminates the SC is detected (step S22).
Subsequently, the CPU 120 compares the brightness of the ambient light detected in step S22 with the target brightness by using the function of the light amount adjustment unit 123 (step S23), and determines whether or not both brightnesses are equal (step S24). . When it is determined that the two luminances are not equal (step S24; No), the CPU 120 changes the shooting condition by changing the ISO sensitivity and the shutter speed of the imaging unit 180 (step S25). And by returning to step S21 again, the process of step S21-> S25 is repeated until the brightness | luminance detected by step S23 converges equally with target brightness | luminance.
If it is determined in step S24 that both luminances are equal (step S24; Yes), the CPU 120 reads the current ISO sensitivity and shutter speed of the imaging unit 180, and the threshold value stored in the threshold value storage unit 172 of the ROM 170. Compare (step S26).

When it is determined that the brightness of the ambient light according to the ISO sensitivity and the shutter speed of the imaging unit 180 is equal to or less than the threshold value (step S27; No), the CPU 120 transmits an instruction signal for setting the luminance of the light source 140 to a low luminance. 141 (step S28), and this light amount adjustment processing is terminated.
If it is determined that the brightness of the ambient light according to the ISO sensitivity and the shutter speed of the imaging unit 180 exceeds the threshold (step S27; Yes), an instruction signal for increasing the brightness of the light source 140 is used as the light source. This is output to the drive unit 141 (step S29), and this light amount adjustment process is terminated. Thus, in the light source driving unit 141, the light source driving unit 141 supplies voltage to the light source 140 according to the ambient light.

  After performing the light amount adjustment process of FIG. 3, the CPU 120 waits until a luminance stabilization period in which the luminance of the light source 140 is stable has elapsed (step S <b> 14 in FIG. 2). When the luminance stabilization period elapses (step S14; Yes), the CPU 120 controls the modulation means driving unit 134 by using the function of the activation control unit 121 and sets the liquid crystal panel 130 to the transmissive state, so that the light source 140 changes to the screen SC. Light is irradiated (step S15). Next, the CPU 120 executes trapezoidal distortion correction processing by the function of the correction control unit 124 (step S16). By this trapezoidal distortion correction processing, the projection image projected on the screen SC is corrected for deformation due to the projection angle of the projector 100, and becomes almost the original shape.

Here, the trapezoidal distortion correction processing will be described with reference to FIG.
As shown in FIG. 4, the CPU 120 reads the trapezoidal distortion correction image data stored in the image storage unit 171 of the ROM 170, outputs it together with the command to the image processor 131, displays it on the liquid crystal panel 130, and displays the screen SC. (Step S31).
Next, the CPU 120 causes the imaging unit 180 to capture a projected image in a state where the trapezoidal distortion correction image is projected on the screen SC (step S32). The captured image is stored in the captured image memory 182 under the control of the CPU 120.

The CPU 120 acquires a captured image captured during the projection of the adjustment image from the captured image memory 182, and calculates parameters for correcting the trapezoidal distortion by the trapezoidal distortion correction unit 132 based on the captured image (step). S33).
In step S <b> 33, the CPU 120 executes a three-dimensional survey process using the function of the three-dimensional survey unit 127. This three-dimensional surveying process is a process for detecting the three-dimensional state of a plane including the screen SC in a three-dimensional coordinate system (hereinafter also referred to as “lens coordinate system”) having the origin of the zoom lens 151 of the projector 100 as an origin. is there. That is, the three-dimensional inclination of the screen SC with respect to the optical axis of the projection optical system 150 in the projector 100 is detected. For example, when the trapezoidal distortion correction image is the lattice pattern described above, in this process, the captured image acquired from the captured image memory 182 is discretized, and the centers of 16 squares included in the captured image are obtained as measurement points. Subsequently, the CPU 120 selects three points that can define a plane from the measurement points, and detects three-dimensional coordinates in the lens coordinate system of the selected three measurement points. The CPU 120 calculates an approximate plane that approximates the plane including the screen SC based on the detected three-dimensional coordinates of the three measurement points. Subsequently, the CPU 120 uses the function of the projection angle calculation unit 128 to project the projection angle that is an angle between the approximate plane of the screen plane detected by the three-dimensional surveying process and the optical axis of the projection light projected from the projector 100, and the screen plane. A projection distance that is a distance between the approximate plane and the projector 100 is calculated. Next, the CPU 120 obtains the corrected image shape in the displayable area of the liquid crystal panel 130 based on the calculated projection angle. Then, the CPU 120 calculates a conversion coefficient (parameter) for converting the uncorrected image shape in the displayable area of the liquid crystal panel 130 into the corrected image shape.
This conversion coefficient is a coefficient used when three-dimensional vector calculation is performed on pixel position information (coordinates) of the image signal input to the image processor 131.

The CPU 120 sets the obtained parameter in the trapezoidal distortion correction unit 132, and causes the trapezoidal distortion correction unit 132 to execute the trapezoidal distortion correction (step S34).
The trapezoidal distortion correction unit 132 converts the input digital signal using the set parameters, and outputs the converted result to the modulation means driving unit 134. That is, the trapezoidal distortion correction unit 132 repeats vector calculation for the coordinates of each pixel with respect to the digital signal input from the A / D conversion unit 110, and corrects the trapezoidal distortion of the image displayed on the liquid crystal panel 130 To deform. During the trapezoidal distortion correction, an image deformed based on the above parameters so as to correct the deformation of the projected image on the screen SC is displayed in the displayable range of the liquid crystal panel 130 which is usually rectangular.
After starting the trapezoidal distortion correction process, the CPU 120 starts projecting an image input from the A / D conversion unit 110 to the image processor 131 (step S35), and sets the correction parameters necessary for the trapezoidal distortion correction process. Calculation / setting ends.

  After performing the trapezoidal distortion correction processing of FIG. 4, when the CPU 120 sets the image quality parameter according to the brightness of the ambient light by the function of the correction control unit 124, the CPU 120 outputs the set image quality parameter to the image quality adjustment unit 133. Then, the image quality adjustment unit 133 executes image quality adjustment processing for adjusting image quality such as brightness, contrast, sharpness, hue, and gamma correction (step S17). In the image quality adjustment process in step S17, the image quality adjustment image stored in the image storage unit 171 of the ROM 170 is projected onto the screen SC, and the brightness is determined based on the captured image of the image quality adjustment image captured by the imaging unit 180. The image quality adjustment such as the adjustment of the contrast, the sharpness, and the hue, and the gamma correction may be performed.

Next, the CPU 120 causes the lens driving unit 154 to drive the focus adjustment motor 153 by outputting the projection distance calculated during the trapezoidal distortion correction process to the lens driving unit 154 by the function of the correction control unit 124. Then, an optical adjustment process for adjusting the focus is executed (step S18). Thereafter, normal projector projection processing is performed.
In the focus adjustment in step S17, the optical adjustment image stored in the image storage unit 171 of the ROM 170 is projected onto the screen SC, and the focus adjustment or the focus adjustment is performed based on the captured image of the optical adjustment image captured by the imaging unit 180. An optical adjustment such as zoom adjustment may be performed. In the present embodiment, all of the trapezoidal distortion correction process, the image quality adjustment process, and the optical adjustment process are performed. However, the present invention is not limited to this, and any one of the trapezoidal distortion correction process, the image quality adjustment process, and the optical adjustment process is performed. It is good.

  As described above, according to projector 100 according to the present embodiment, light source 140, liquid crystal panel 130 that modulates light emitted from light source 140, and light modulated by liquid crystal panel 130 are projected onto screen SC. The projection optical system 150, the imaging unit 180 that captures the screen SC, the ambient light detection unit 122 that detects the ambient light of the screen SC based on the captured image data captured by the imaging unit 180, and the ambient light detection unit 122 Based on the detection result, the light amount adjusting unit 123 that adjusts the amount of light reaching the screen SC from the light source 140, and the liquid crystal panel based on the captured image data captured by the imaging unit 180 after adjustment by the light amount adjusting unit 123 And a correction control unit 124 that controls at least one of 130 and the projection optical system 150 to correct the projection image. So detecting the ambient light illuminating the screen SC from the captured image data by the imaging unit 180 is taken, you can adjust the brightness of the light source 140 to emit the amount of light reaching from the light source 140 on the screen SC on the basis of the ambient light. And since a projection image is correct | amended after light quantity adjustment, the change of a projection image can be correct | amended reliably corresponding to a projection environment. Therefore, without using an illuminance sensor or the like, the amount of light projected on the projection surface is corrected corresponding to the ambient light, and the projection image can be reliably corrected to reflect the response to the ambient light, so the adjustment is repeated. Therefore, good image quality can be obtained promptly, and improvement in convenience can be expected.

In addition, the projector 100 includes an activation control unit 121 that blocks light emitted from the light source 140 by the liquid crystal panel 130 for a predetermined time from when the light source 140 starts energization at the time of activation until the luminance of the light source 140 becomes stable. 100 indicates the environment of the screen SC based on the captured image data captured by the imaging unit 180 while the light emitted from the light source 140 is blocked by the control of the activation control unit 121 by the function of the ambient light detection unit 122. Detect light. For this reason, since the ambient light is detected while the light from the light source 140 is blocked, the ambient light incident on the screen SC can be detected more accurately. In addition, the amount of light can be adjusted using the waiting time at the time of activation, which is efficient.
Further, the projector 100 performs correction based on the captured image data captured by the imaging unit 180 in a state where a predetermined correction pattern is projected onto the screen SC by the liquid crystal panel 130 by the function of the correction control unit 124. Corresponding to the projection environment, changes in the projected image can be corrected quickly and reliably.
Further, the projector 100 executes at least one of correction of trapezoidal distortion of the projected image formed on the screen SC, correction of the color tone of the projected image, and optical correction including focus by the function of the correction control unit 124. As a result, a high-quality image can be projected by correcting optical changes including trapezoidal distortion, color tone change, and focus shift of the projected image.
Further, the projector 100 blocks a part of the light emitted from the light source 140 or the light source driving unit 141 that adjusts the luminance of the light source 140 by changing the power supplied to the light source 140 by the function of the light amount adjusting unit 123. Therefore, the light control element (not shown) for adjusting the amount of light is controlled, so that the amount of light projected on the screen SC can be reduced by changing the power supplied to the light source 140 or blocking part of the light emitted from the light source 140. Can be corrected appropriately according to ambient light.

  The above-described embodiment is merely an example of a specific mode to which the present invention is applied, and the present invention is not limited. The present invention can be applied as a mode different from the above-described embodiment. For example, in the above-described embodiment, when the projector 100 is activated, the operation (steps S12 to S18) illustrated in FIG. 2 is performed. However, the present invention is not limited thereto, and any operation may be performed according to the operation of the remote controller 191 or the operation unit 195. The operation of FIG. 2 may be executed at the timing.

  Further, in the above-described embodiment, the configuration in which one light source 140 is provided as a light emitter and the amount of light of the entire projection light is adjusted by adjusting the luminance of the light source 140 has been described as an example. For example, a light emitter may be prepared for each color, and the light emission amount of each color may be adjusted by adjusting the luminance of each light emitter. In this case, the same effect as AWB (Auto White Balance) can be obtained. For example, green tends to be strong under an environmental light source using a Bayer color sensor and a fluorescent lamp. In such a case, increasing the amount of red and blue light emission among the three primary colors of red, blue, and green suppresses the range for correcting the tendency of green to be strengthened by digital color correction processing. Data saturation can be avoided.

In the above embodiment, the imaging unit 180 is described as having a CCD camera 181 including a CCD image sensor. However, the present invention is not limited to this, and a CMOS sensor is used as the image sensor of the imaging unit 180. It may be used.
Further, in the above embodiment, a configuration using three transmissive or reflective liquid crystal panels 130 corresponding to each color of RGB as an example of a modulation device (modulation unit) that modulates light emitted from a light source is given as an example. As described above, the present invention is not limited to this. For example, a system using a single liquid crystal panel and a color wheel, a system using three digital mirror devices (DMD), and a single digital mirror You may comprise by the system etc. which combined the device and the color wheel. Here, when only one liquid crystal panel or DMD is used as the display unit, a member corresponding to a synthetic optical system such as a cross dichroic prism is unnecessary. In addition to the liquid crystal panel and the DMD, any configuration that can modulate the light emitted from the light source can be used without any problem.
Further, each functional unit illustrated in FIG. 1 indicates a functional configuration of the projector 100, and a specific mounting form is not particularly limited. That is, it is not always necessary to mount hardware corresponding to each function unit individually, and it is of course possible to adopt a configuration in which the functions of a plurality of function units are realized by one processor executing a program. In addition, in the above embodiment, a part of the function realized by software may be realized by hardware, or a part of the function realized by hardware may be realized by software.

  DESCRIPTION OF SYMBOLS 100 ... Projector, 120 ... CPU, 121 ... Startup control part (startup control means), 122 ... Ambient light detection part (ambient light detection means), 123 ... Light quantity adjustment part (light quantity adjustment means), 124 ... Correction control part (Correction) Means ..., 130 ... liquid crystal panel (modulation means), 131 ... image processor, 132 ... trapezoidal distortion correction section, 133 ... image quality adjustment section, 134 ... modulation means drive section, 140 ... light source, 150 ... projection optical system (projection means) 172, Threshold value storage unit, 180 ... Imaging unit (imaging means), 181 ... CCD camera, 182 ... Captured image memory, SC ... Screen (projection surface).

Claims (6)

A light source;
Modulation means for modulating light emitted from the light source;
Projection means for projecting the light modulated by the modulation unit onto a projection surface;
Imaging means for photographing the projection surface;
Based on captured image data captured by the imaging unit, ambient light detection means for detecting ambient light that illuminates the projection surface;
A light amount adjusting means for adjusting a light amount reaching the projection surface from the light source based on a detection result of the ambient light detection unit;
A correction unit that controls the at least one of the modulation unit and the projection unit to correct the projection image based on the captured image data captured by the imaging unit after the adjustment by the light amount adjustment unit;
A projector comprising: When the projector is activated, the apparatus includes a startup control unit that blocks light emitted from the light source by the modulation unit for a predetermined time from when the light source starts energization to when the luminance of the light source becomes stable.
The ambient light detection means detects ambient light that illuminates the projection surface based on photographed image data taken by the imaging means while light emitted from the light source is blocked by the control of the activation control means. The projector according to claim 1, wherein:   The correction means executes correction based on photographed image data photographed by the imaging means in a state where a predetermined correction pattern is projected onto the projection surface by the modulation means. The projector described.   The correction means executes at least one of correction of a shape of a projection image formed on the projection surface, correction of a tone of the projection image, and optical correction including focus. 4. The projector according to any one of 3.   The light amount adjusting unit is a luminance adjusting unit that adjusts the luminance of the light source by changing power supplied to the light source, or a light adjusting unit that adjusts the light amount by blocking a part of the light emitted from the light source. The projector according to claim 1, comprising: A method of controlling a projector that projects onto a projection surface,
The light emitted from the light source is modulated and projected onto the projection surface, and the projection surface is photographed.
Based on the captured image data, the ambient light that illuminates the projection surface is detected,
Based on the detection result of ambient light, adjust the amount of light reaching the projection surface from the light source,
Photographing the projection surface after adjusting the amount of light, and correcting the projection image based on the photographed image data;
A projector control method characterized by the above.

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