JP4010304B2 - Projector and pattern image display method - Google Patents

Description

  The present invention relates to a projector that displays an image by projecting projection light onto a projection object such as a screen, and in particular, a zoom lens capable of changing the size of a projection light range onto which projection light is projected, The present invention relates to a projector including an imaging unit that captures an image of a projection target.

  In recent projectors, a zoom lens is provided in a projection lens, the zoom lens is driven, and the zoom position of the zoom lens is changed to freely change the size of the projection light range formed on the screen. Things are known.

  When such a projector is installed in front of the screen, zoom adjustment and keystone correction are performed in advance in the projector so that an image is appropriately displayed on the screen by the projection light projected from the projector onto the screen. Various adjustments such as focus adjustment are required.

  However, in the case of a portable projector, the relative position with respect to the screen may change every time the projector is installed. Therefore, the user must make various adjustments as described above. It was complicated.

  Therefore, conventionally, as described in, for example, Patent Document 1 below, when a projector is provided with a monitor camera and the projector is installed in front of the screen, first, the projector is operated on the liquid crystal light valve. The adjustment pattern image formed on the screen is enlarged and projected on the screen, and the screen on which the pattern image is displayed is photographed by a monitor camera, the photographed image is analyzed, and the above-described various types of images are analyzed. Adjustments were made automatically.

  In general, a monitor camera includes a CCD (Charge Coupled Device) that converts incident light into an electrical signal, and the like, in order to set the overall brightness of a captured image to a preset value (exposure target value). It has a function (automatic exposure) for changing the shutter speed, gain (sensitivity), aperture, and the like.

FIG. 6 is an explanatory diagram for explaining the effect of automatic exposure of a conventional monitor camera. In FIG. 6, the upper part shows a screen on which the adjustment pattern image is displayed, the middle part shows a photographed image obtained by photographing the screen with a monitor camera, and the bottom part shows a central horizontal line ( A value representing the brightness of each pixel arranged along the broken line) is shown. (A) shows the normal state of the projector, and (B) shows the state when the projector is set to low brightness.
A value representing the brightness of each pixel in the captured image is hereinafter referred to as a gradation value. Such a gradation value is a value obtained from the image signal of the captured image output from the monitor camera (CCD module).

  In FIG. 6, the adjustment pattern image formed on the liquid crystal light valve is a white image on the entire surface, and as shown in the upper part, the area where the pattern image is displayed on the screen, that is, the range of the white portion is as described above. This is the projection light range.

  Further, the captured image obtained by capturing with the monitor camera is as shown in the middle row.

  In the lower part, the horizontal axis corresponds to the position of each pixel on the central horizontal line of the captured image, and the vertical axis represents the gradation value of each pixel.

  In the projector, when the light source lamp is set to a low luminance setting, the luminance of the projection light projected from the projector is lower than in the normal case. Therefore, as shown in FIG. 6B, the brightness of the pattern image displayed on the screen is also darker than in the normal case of FIG. However, when the pattern image is taken with a monitor camera with automatic exposure, the shutter speed, gain, aperture, etc. are adjusted so that the overall brightness of the shot image is appropriate even when the subject is dark. Then, as shown in FIG. 8B, the brightness of the pattern image is not different from the normal time of (A). Accordingly, in the photographed image, the black portion (that is, the portion outside the projection light range) is so dark that it can be ignored. Therefore, the gradation value of each pixel in the black portion can be regarded as 0, whereas the white portion (that is, the pattern image) The gradation value of each pixel in (part) remains almost the same as the desired gradation value Lt.

  In this way, by operating the automatic exposure function in the monitor camera, even if the brightness of the light source lamp is set low in the projector and the brightness of the pattern image displayed on the screen becomes dark, the white portion ( That is, the gradation value of each pixel in the pattern image portion) can be substantially maintained at the desired gradation value Lt as in the normal case. This is not limited to the low luminance setting, and the same applies to the case where the luminance of the light source lamp deteriorates with age and the luminance decreases.

JP 2000-241874 A

  However, in such a projector having a zoom lens and a monitor camera, when the zoom lens zoom position is changed to change the size of the projection light range on the screen, the monitor camera is automatically exposed. There were the following problems.

  FIG. 7 is an explanatory diagram for explaining a problem caused by automatic exposure of the monitor camera when the zoom position in the related art is changed. In FIG. 7, as in FIG. 6, the upper part shows the screen on which the adjustment pattern image is displayed, the middle part shows the captured image of the screen, and the lower part shows the gradation value of the pixel in the captured image. (A) shows the state when the zoom position of the zoom lens is set to the intermediate position, (B) shows the state when the zoom position is set to the wide side, and (C) shows the zoom position. The state when the position is set to the tele side is shown.

  In the projector, when the zoom position of the zoom lens is set to the wide side, the area of the projection light range on the screen is wider than the intermediate position of (A) as shown in the upper part of FIG. . Here, since the adjustment pattern image formed on the liquid crystal light valve is constant, when the area of the projection light range on the screen is increased, the pattern image displayed on the screen is enlarged accordingly. Therefore, when the pattern image is photographed by the monitor camera, the area of the white portion (that is, the pattern image portion) in the photographed image is at an intermediate position of (A) as shown in the middle part of FIG. The area of the black part (that is, the part outside the projection light range) becomes narrower.

  At this time, if the shooting is performed with automatic exposure, the overall brightness of the shot image is calculated as the exposure calculation value, and the shutter speed and gain are set so that the exposure calculation value becomes equal to the preset exposure target value. And aperture are controlled. Here, the overall brightness of the photographed image is also the sum of the amount of light detected by each pixel in the CCD converted into an electric signal, and the value is the gradation value of each pixel in the photographed image. It is proportional to the average value of. Therefore, normally, the average value of the gradation values of all the pixels in the captured image is used as the exposure calculation value.

  On the other hand, since the exposure target value is a preset constant value, as shown in FIG. 7A, when the zoom position is the intermediate position, the calculated exposure value matches the exposure target value. As described above, when the zoom position is set to the wide side and the area of the white portion in the photographed image is widened, the average value of the gradation values of all pixels, that is, the exposure calculation, is equivalent to the spread of the area. The value rises above the exposure target value. As a result, if the shutter speed, gain, aperture, etc. are changed so that the automatic exposure works and the calculated exposure value becomes equal to the exposure target value, the average value of the gradation values of all the pixels in the captured image will decrease. . As described above, in the photographed image, the black portion is so dark that it can be ignored, and the gradation value of each pixel in the black portion can be regarded as 0. Therefore, the average value of the gradation values of all the pixels decreases. As shown in the lower part of B), the gradation value of each pixel in the white portion is none other than the desired gradation value Lt.

  On the contrary, when the zoom position of the zoom lens is set to the tele side, the area of the projection light range on the screen is narrower than the intermediate position of (A) as shown in the upper part of FIG. . Here, as described above, since the pattern image formed on the liquid crystal light valve is constant, when the area of the projection light range on the screen is reduced, the pattern image displayed on the screen is reduced accordingly. . Therefore, when the pattern image is photographed by the monitor camera, the area of the white portion (that is, the pattern image portion) in the photographed image is at an intermediate position of (A) as shown in the middle part of FIG. In comparison, the area becomes narrower and the area of the black portion (that is, the portion outside the projection light range) becomes wider.

  As described above, when the area of the white portion in the photographed image is narrowed, the average value of the gradation values of all the pixels, that is, the calculated exposure value is lower than the exposure target value by the narrowness of the area. . As a result, if the shutter speed, gain, aperture, etc. are changed so that the automatic exposure works and the calculated exposure value is equal to the exposure target value, the average value of the gradation values of all the pixels in the captured image increases, and as a result As shown in the lower part of FIG. 7C, the gradation value of each pixel in the white portion is higher than the desired gradation value Lt.

  As described above, conventionally, when the zoom position of the zoom lens is set to the wide side and the area of the projection light range on the screen is widened, in the captured image due to the automatic exposure of the monitor camera. When the gradation value of each pixel in the white portion falls below the desired gradation value Lt, and conversely, when the area of the projection light range becomes narrower on the tele side, the gradation value of each pixel in the white portion In this case, the average value of the gradation values in the white portion cannot be maintained at the desired gradation value Lt.

  Accordingly, when the average value of the gradation values of the white portion in the photographed image deviates from the desired gradation value Lt due to the change in the zoom position of the zoom lens, the photographed image is thereafter changed as described above. When analysis is performed and various adjustments are automatically performed based on the analysis results, there is a problem that appropriate adjustment cannot be performed depending on the content of the adjustment.

  Such a problem is not limited to the case where the adjustment pattern image is entirely white, but is also a case where the adjustment pattern image is a specific color other than white (for example, green) or a part of the adjustment pattern image. Can also occur.

  Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, and even if the zoom position of the zoom lens changes, the average gradation value of the specific color portion represented by the specific color in the captured image An object of the present invention is to provide a technique capable of maintaining a value substantially at a desired gradation value.

In order to achieve at least a part of the above object, a projector according to the present invention is a projector that projects projection light onto a projection object and displays an image,
An image forming unit capable of forming a predetermined pattern image to be displayed on the projection object;
A zoom lens capable of changing the size of the projection light range onto which the projection light is projected;
A control unit;
An imaging unit for imaging the projection object;
An exposure calculation value is calculated from a captured image captured by the imaging unit, and exposure adjustment is performed in the imaging unit so that the calculated exposure calculation value is substantially equal to an exposure target value set by the control unit. An imaging control unit;
With
The control unit obtains a photographed image photographed by the photographing unit, and a parameter related to the area of a specific color portion represented by a specific color in the obtained photographed image is a preset target parameter. The gist is to change the area of the specific color portion in the pattern image formed in the image forming section so as to be substantially equal.

  As described above, in the projector of the present invention, the area of the specific color portion in the pattern image formed in the image forming unit is changed so that the parameter related to the area of the specific color portion in the photographed image is substantially equal to the target parameter. I am letting. Since the area of the specific color portion in the captured image has a correlation with the area of the specific color portion in the pattern image formed in the image forming unit, the area of the specific color portion in the pattern image formed in the image forming unit is changed. Thus, the parameter related to the area of the specific color portion in the captured image can be changed. On the other hand, the area of the specific color portion in the captured image is uniquely determined when the average value of the gradation values of the specific color portion is determined. Therefore, for example, as the target parameter, the value of a parameter related to the area of the specific color portion in the photographed image when the average value of the gradation value of the specific color portion in the photographed image matches the desired gradation value is set. If the zoom position of the zoom lens is changed, the average value of the gradation value of the specific color portion in the captured image deviates from the desired gradation value, and the parameter related to the area of the specific color portion deviates from the target parameter. However, by changing the area of the specific color portion in the pattern image formed on the image forming unit so as to be substantially equal to the target parameter, the average value of the gradation values of the specific color portion in the photographed image can be obtained. It can be made almost equal to the key value.

  Therefore, according to the projector of the present invention, even if the zoom position of the zoom lens changes, the average value of the gradation values of the specific color portion in the photographed image can be substantially maintained at the desired gradation value.

  In the claims and the specification, the parameters related to the area of the specific color portion in the photographed image include the number of pixels constituting the specific color portion and the shape constituting the specific color portion in addition to the area itself. The length (for example, if the specific color portion is a rectangle, the length of one side thereof) is included. Correspondingly, the target parameter includes a target area, a target pixel number, a target length, and the like.

  In the projector according to the aspect of the invention, the specific color may be white. Moreover, other specific colors other than white, for example, green, gray, etc., may be used.

  Note that the present invention is not limited to the above-described aspects of the apparatus invention such as the projector, but can be realized in an aspect as a method invention such as a method of displaying a predetermined pattern image on the projection target in the projector. .

Hereinafter, embodiments of the present invention will be described based on examples in the following order.
1. Projector configuration:
2. Image projection operation:
3. Exposure target value setting operation:
4). Concrete example:
5). Effects of the embodiment:
6). Variation:
6-1. Modification 1:
6-2. Modification 2:
6-3. Modification 3:
6-4. Modification 4:

1. Projector configuration:
FIG. 1 is a block diagram showing a configuration of a projector as an embodiment of the present invention. This projector 100 is a portable projector, and as shown in FIG. 1, an A / D conversion unit 102, an imaging unit 104, an imaging control unit 105, a captured image memory 106, and a pattern image memory 107. An image processing unit 108, a liquid crystal light valve driving unit 110, an illumination optical system 112, a liquid crystal light valve 114, a projection optical system 118 including a zoom lens 116, a CPU 120, a zoom lens driving unit 124, and a remote controller. A control unit 126 and a remote control 128 are provided.

  In FIG. 1, the CPU 120 is connected to the imaging control unit 105, the captured image memory 106, the pattern image memory 107, the image processing unit 108, the liquid crystal light valve driving unit 110, the zoom lens driving unit 124, and the remote control unit via a bus. Although it is drawn so as to be connected only to 126, it is actually connected to other components. The imaging unit 104 includes a CCD, and the imaging unit 104 and the imaging control unit 105 constitute a CCD module 130 as a monitor camera.

  Further, in this embodiment, the imaging unit 104 shown in FIG. 1 is the imaging unit described in the claims, the imaging control unit 105 is the imaging control unit described in the claims, and the liquid crystal light valve 114 is the image described in the claims. In the forming unit, the zoom lens 116 corresponds to the zoom lens described in the claims, and the CPU 120 corresponds to the control unit in the claims.

2. Image projection operation:
First, an image projection operation that is a normal operation in the projector 100 will be briefly described.

  In FIG. 1, when the user instructs the start of image projection using the remote control 128, the remote control 128 transmits the input instruction to the remote control control unit 126 by wireless communication. The remote controller control unit 126 transmits an instruction from the remote controller 128 to the CPU 120 via the bus. Based on these instructions, the CPU 120 controls each component including the image processing unit 108 to perform an image projection operation.

  First, the A / D conversion unit 102 inputs an image signal output from a video player, a television, a DVD player, or the like, or an image signal output from a personal computer or the like, and converts these analog image signals into digital image signals. And output to the image processing unit 108. The image processing unit 108 adjusts the input digital image signal so that the display state of the image (for example, luminance, contrast, synchronization, tracking, color density, hue, etc.) is in a desired state, and the liquid crystal light Output to the valve drive unit 110.

  The liquid crystal light valve driving unit 110 drives the liquid crystal light valve 114 based on the input digital image signal to form an image on the liquid crystal light valve 114. Thereby, the liquid crystal panel 114 modulates the illumination light emitted from the illumination optical system 112 according to the formed image. The projection optical system 118 is attached to the front surface of the housing of the projector 100 and projects the projection light modulated by the liquid crystal light valve 114 onto a screen (not shown). Thereby, an image is projected and displayed on the screen.

3. Pattern image variable operation:
Now, the pattern image variable operation that is a characteristic part of the present invention in the projector 100 will be described in detail.

  Conventionally, as described above, the adjustment pattern image formed on the liquid crystal light valve is constant, but in this embodiment, the area of the white portion in the photographed image is substantially equal to the target area. Even if the zoom position of the zoom lens 116 is changed by changing the area of the white portion in the adjustment pattern image formed on the liquid crystal light valve, the average value of the gradation values of the white portion in the captured image is The desired gradation value set in advance is substantially maintained.

  Therefore, when the user installs the projector 100 at a desired position in front of the screen and then turns on the power of the projector 100, the projector 100 projects and displays an adjustment pattern image on the screen in order to perform various adjustments. Let

  Specifically, when the CPU 120 generates an adjustment pattern image, writes it as a digital image signal in the pattern image memory 107, and instructs the image processing unit 108, the liquid crystal light valve driving unit 110, etc. to project an image, the image processing unit 108 reads the written digital image signal and outputs it to the liquid crystal light valve driving unit 110. The liquid crystal light valve driving unit 110 drives the liquid crystal light valve 114 based on the input digital image signal, and forms an adjustment pattern image as described later on the liquid crystal light valve 114. The liquid crystal light valve 114 modulates the illumination light emitted from the illumination optical system 112 according to the formed pattern image. The projection optical system 118 projects the projection light modulated by the liquid crystal light valve 114 onto the screen via the zoom lens 116 and the like. As a result, the adjustment pattern image is displayed on the screen. On the screen, the range in which the adjustment pattern image is displayed becomes the projection light range.

  In the present embodiment, as the adjustment pattern image, for example, an image divided into upper and lower two colors in which the upper portion is black and the lower portion is white in the vertical direction is used. Therefore, the projection light range on the screen is also divided into upper and lower two colors, with the upper part being black and the lower part being white.

  After the pattern image is displayed on the screen in this way, the user then operates a zoom button (not shown) of the remote control 128 to adjust the size of the projection light range on the screen, and the zoom position. The remote control 128 transmits the input instruction to the remote control unit 126 by wireless communication. The remote controller control unit 126 transmits an instruction from the remote controller 128 to the CPU 120 via the bus. Based on the instruction, the CPU 120 controls the zoom lens driving unit 124 to drive the zoom lens 116 included in the projection optical system 118 and move the zoom position of the zoom lens 116. After that, when the projection light range on the screen reaches a desired size, when the user operates the zoom button of the remote control 128 to instruct the stop of the zoom position movement, the CPU 120 performs the zoom lens based on the instruction. The drive unit 124 is controlled to stop the movement of the zoom position of the zoom lens 116.

  Further, the CPU 120 reads and executes a pattern image variable processing program from a memory (not shown). Specifically, the CPU 120 controls each component including the pattern image memory 107 according to the processing procedure shown in FIG.

  FIG. 2 is a flowchart showing a processing procedure of pattern image variable processing in the projector of FIG.

  When the processing shown in FIG. 2 is started, the CPU 120 generates a predetermined initial image as an adjustment pattern image, writes it as a digital image signal in the pattern image memory 107 (step S102), and the image processing unit 108. Then, the liquid crystal light valve driving unit 110 is instructed to project an image (step S104). As the initial image, for example, an image similar to the above, which is divided into black and white at the top and bottom, and an area ratio of the black portion and the white portion with respect to the entire image is 50% each is used. Shall. As a result, a pattern image that is divided in half in black and white is formed on the liquid crystal light valve 114, and the pattern image is enlarged and projected on the screen.

  Note that, when the adjustment pattern image itself generated by the CPU 120 is such an initial image after the projector 100 is turned on as described above, these steps S102 and S104 can be omitted. Further, as the initial image, it is sufficient that at least a white portion exists in the image, and the size and shape of the white portion may be arbitrary.

  Next, the CPU 120 instructs the imaging control unit 105 to perform shooting (step S106). Thereby, the imaging control unit 105 controls the imaging unit 104 to start imaging. The imaging unit 104 captures a screen on which a pattern image is displayed. At this time, the imaging control unit 105 calculates an average value Lccd of gradation values of all pixels from the captured image captured by the imaging unit 104 as an exposure calculation value, and the exposure calculation value is set in advance. The automatic exposure is performed by controlling the shutter speed, gain, aperture, and the like in the imaging unit 104 so as to be equal to the exposure target value R.

  Thus, when the image capturing unit 104 captures the screen on which the pattern image is displayed, the image capturing unit 104 outputs the captured image to the image processing unit 108 as a digital image signal. The image processing unit 108 performs desired processing on the input digital image signal, and then writes it in the captured image memory 106.

  Next, the CPU 120 reads out a digital image signal from the photographed image memory 106 and applies a binarization process to obtain a monochrome binary photographed image. Then, the acquired captured image is analyzed to derive the area of the white portion in the captured image (step S108). Since the area of the white portion is proportional to the number of pixels of the white pixel, the CPU 120 can derive the area of the white portion by counting the number of pixels of the white pixel from the monochrome binary captured image.

  FIG. 3 is an explanatory view showing an adjustment pattern image formed on the liquid crystal light valve 114 and a photographed image photographed by the CCD module 130. 3A is an adjustment pattern image formed on the liquid crystal light valve 114, and FIG. 3B is an enlarged projection image of the adjustment pattern image displayed on the screen, and the displayed screen is displayed on the CCD. 3 is a photographed image photographed by the module 130. As described above, since the range in which the adjustment pattern image is displayed is the projection light range on the screen, the portion of the projection light range also corresponds to the adjustment pattern image in the captured image.

  In this embodiment, as shown in FIG. 3 (A), as an adjustment pattern image, an upper part is black and a lower part is white. As shown in (2), in the photographed image, in the projected light range, the upper part is a black part and the lower part is a white part. Further, the portion outside the projection light range is a black portion. In the initial image, the upper black portion and the lower white portion are halved.

Now, as shown in FIG. 3B, in the captured image, the area of the white portion (that is, the portion below the projection light range) is Sp, the average value of the gradation values of the white portion is L, and the entire captured image is Assuming that the area is Sccd and the average value of the gradation values of all the pixels in the captured image is Lccd, the relationship between the average value of the gradation value and the area is as shown in Expression (1).
Lccd / L = Sp / Sccd (1)

Therefore, the area Sp of the white portion in the captured image is expressed by Expression (2).
Sp = (Lccd × Sccd) / L (2)
This is because, in the photographed image, the black portion (that is, the portion above the projection light range and the portion outside the projection light range) is so dark that it can be ignored, and the gradation value of each pixel in the black portion can be regarded as zero.
Note that, for example, in a captured image, a pixel whose gradation value is not 0, but is a certain threshold value or less, it is determined that the portion is above the projection light range or outside the projection light range, and that portion. The gradation value of the pixel at may be calculated by replacing it with 0.

By the way, in the automatic exposure, as described above, the average value Lccd of the gradation values of all the pixels in the photographed image is used as the exposure calculation value, and the exposure calculation value Lccd is equal to the target exposure value R. Shutter speed, gain, aperture, etc. are controlled. Therefore, by substituting R for Lccd in equation (2), equation (2) becomes equation (3).
Sp = (R × Sccd) / L (3)

  Here, since the exposure target value R is a constant and the area Sccd of the entire captured image is also a constant, if the average value L of the gradation values of the white portion in the captured image is determined from Equation (3), It can be seen that the area Sp of the white portion is uniquely determined.

Therefore, if the area Sp of the white portion in the captured image when the average value L of the gradation values of the white portion in the captured image matches the desired gradation value Lt, the target area Spt is: From equation (3), it can be derived as shown in equation (4).
Spt = (R × Sccd) / Lt (4)

  Therefore, regardless of the change in the zoom position of the zoom lens 116, the average value L of the gradation values of the white portion in the captured image can be maintained substantially at the desired gradation value Lt regardless of the change in the zoom position. The area Sp of the white portion in the captured image may be set to the target area Spt.

On the other hand, as described above, in the captured image, the portion of the projection light range corresponds to the pattern image displayed on the screen, in other words, the pattern image formed on the liquid crystal light valve 114. Therefore, as shown in FIG. 3B, the area of the projection light range in the photographed image is Sz, and as shown in FIG. 3A, the area of the entire pattern image formed on the liquid crystal light valve 114 is Slv. When the area of the white portion in the pattern image (hereinafter abbreviated as the light valve white area) is Sq, the ratio (area ratio) of the area Sp of the white portion to the area Sz of the projection light range in the photographed image is The ratio (area ratio) of the light valve white area Sq to the area Slv of the entire pattern image on the liquid crystal light valve 114 coincides as shown in Expression (5).
Sp / Sz = Sq / Slv (5)

Accordingly, the area Sp of the white portion in the captured image is expressed by Expression (6).
Sp = (Sq × Sz) / Slv (6)

  In Expression (6), the area Slv of the entire pattern image on the liquid crystal light valve 114 is a constant. Further, as described above, since the movement of the zoom position of the zoom lens 116 is stopped at the present time, the size of the projection light range on the screen does not change. Therefore, the area of the projection light range in the photographed image is not changed. Sz is also constant. Therefore, it can be seen from Equation (6) that if the light valve white area Sq is changed, the area Sp of the white portion in the captured image changes.

  From the above, if the light valve white area Sq is changed so that the area Sp of the white portion in the captured image becomes substantially equal to the target area Spt regardless of the change in the zoom position of the zoom lens 116, the zoom can be performed. Regardless of the change in position, the average value L of the gradation values of the white portion in the photographed image can be substantially maintained at the desired gradation value Lt.

  Therefore, the target area Spt is set in advance and stored in a memory (not shown). Returning to FIG. 2, the CPU 120 reads the target area Spt from the memory, and compares the area Sp of the white portion derived in step 108 with the target area Spt (step S110). As a result of comparison, if the area Sp of the white portion is not equal to the target area Spt, the CPU 120 changes the light valve white area Sq so that they are equal.

  FIG. 4 is an explanatory diagram showing how the area of the white portion in the pattern image formed on the liquid crystal light valve 114 changes. In FIG. 4, (B) is the above-mentioned initial image, (A) shows the case where the light valve white area Sq is increased with respect to the initial image, and (C) is the case where Sq is reduced on the contrary. Is shown. As described above, in the present embodiment, in the pattern image formed on the liquid crystal light valve 114, the light valve white area Sq is reduced by changing the length of the vertical side while maintaining the length of the horizontal side of the white portion. It is changing.

  Therefore, as a result of the comparison in step S110 of FIG. 2, for example, when the area Sp of the white portion is larger than the target area Spt, in order to reduce the area Sp of the white portion, the CPU 120 selects FIG. The adjustment pattern image is modified so that the light valve white area Sq is reduced as shown in FIG. 6 and the contents of the pattern image memory 107 are rewritten (step S112), and then the image processing unit 108 and the liquid crystal light valve driving unit 110 are rewritten. And so on (step S114). As a result, a pattern image modified to reduce the light valve white area Sq is formed on the liquid crystal light valve 114, and the modified pattern image is enlarged and projected on the screen. Then, the CPU 120 again acquires a captured image from the captured image memory 106, and derives the area Sp of the white portion in the captured image (step S108). At this time, since the light valve white area Sq is reduced, the area Sp of the white portion in the photographed image is also reduced, and thus approaches the target area Spt.

  On the contrary, when the area Sp of the white part is smaller than the target area Spt, the CPU 120 increases the light valve white area Sq as shown in FIG. 4A in order to increase the area Sp of the white part. Then, after correcting the pattern image for adjustment and rewriting the contents of the pattern image memory 107 (step S116), the image processing unit 108, the liquid crystal light valve driving unit 110, and the like are similarly instructed to project an image (step S116). Step S118). As a result, a pattern image modified to increase the light valve white area Sq is formed on the liquid crystal light valve 114, and the modified pattern image is enlarged and projected on the screen. The CPU 120 acquires a captured image from the captured image memory 106, and derives the area Sp of the white portion in the captured image (step S108). At this time, since the light valve white area Sq is increased, the area Sp of the white portion in the captured image is also increased, and thus approaches the target area Spt.

  Hereinafter, the same processing is repeated until the area Sp of the white portion in the captured image becomes equal to the target area Spt. As a result of the comparison in step S110, if the area Sp of the white portion finally becomes equal to the target area Spt, the CPU 120 Then, the imaging control unit 105 is instructed to perform imaging (step S120), and the pattern image variable process shown in FIG.

  Since the imaging unit 104 is already shooting, the imaging control unit 105 causes the imaging unit 104 to continue shooting. In addition, the imaging control unit 105 calculates an exposure calculation value from an image captured by the imaging unit 104, and controls a shutter speed, a gain, an aperture, and the like in the imaging unit 104 so that the exposure calculation value becomes equal to the exposure target value R. Then, auto exposure is performed.

  The imaging unit 104 outputs the captured image as a digital image signal to the image processing unit 108. The image processing unit 108 performs desired processing on the digital image signal, and then writes the digital image signal in the captured image memory 106. Will be updated.

  Thereafter, the CPU 120 reads out a digital image signal from the captured image memory 106, acquires a captured image, and analyzes the captured image. Then, various adjustments are performed based on the analysis result.

4). Concrete example:
Here, the operation when the area Sp of the white portion in the captured image is not equal to the target area Spt will be described more specifically with reference to the drawings.

  FIG. 5 is an explanatory diagram showing a photographed image and the gradation value of each pixel of the photographed image. In FIG. 5, the upper part shows a photographed image photographed by the CCD module 130, and the lower part shows the photographed image. The gradation value of each pixel arranged along the predetermined horizontal line shown with a broken line is shown.

  For example, as shown in FIG. 5B, when the average value L of the gradation values of the white portion in the photographed image matches the desired gradation value Lt, the area Sp of the white portion in the photographed image is “ If it is 120,000 ", the above-mentioned target area Spt is" 120,000 ". Therefore, as shown in the lower part of FIG. 5A, the average value L of the gradation values of the white portion in the photographed image is only half of the desired gradation value Lt, and the area Sp of the white portion is as shown in FIG. As shown in the upper part, when there is “240,000” which is twice the target area Spt, the CPU 120 reduces the light valve white area Sq in order to reduce the area Sp of the white portion. Reduce the length of the vertical side of the white part. Then, as shown in the upper part of FIG. 5B, when the area Sp of the white portion in the captured image becomes equal to the target area Spt (“120,000”), the average value L of the gradation values of the white portion. However, as shown in the lower part of FIG. 5 (B), it becomes equal to the desired gradation value Lt.

  Further, as shown in the lower part of FIG. 5C, the average value L of the gradation values of the white portion in the photographed image is twice the desired gradation value Lt, and the area Sp of the white portion is half of the target area Sp. When there is only “60,000”, the CPU 120 increases the length of the vertical side of the white portion so as to increase the light valve white area Sq in order to increase the target area Sp of the white portion. Then, as described above, when the area Sp of the white portion in the photographed image becomes equal to the target area Spt (“120,000”) (upper part of FIG. 5B), the average value of the gradation values of the white portion L coincides with the desired gradation value Lt (lower part of FIG. 5B).

5). Effects of the embodiment:
As described above, in the present embodiment, even if the area Sp of the white portion in the captured image deviates from the target area Spt due to the change in the zoom position of the zoom lens, the liquid crystal light is set to be substantially equal to the target area Spt. By changing the area of the white part in the adjustment pattern image formed on the valve, the average value L of the gradation values of the white part in the photographed image is made substantially equal to the desired gradation value Lt. Therefore, even if the zoom position of the zoom lens 116 changes, the average value L of the white portion gradation values in the captured image can be substantially maintained at the desired gradation value Lt.

6). Variation:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the scope of the invention.

6-1. Modification 1:
In the above-described embodiments, the adjustment pattern image is an image divided into upper and lower two colors in which the upper portion is black and the lower portion is white in the vertical direction. However, the present invention is not limited to this. Is not to be done. Therefore, an appropriate pattern image can be used as the adjustment pattern image in accordance with the content of adjustment performed later.

  Further, in the adjustment pattern image formed on the liquid crystal light valve 114, the light valve white area Sq is changed by changing the length of the vertical side while maintaining the length of the horizontal side of the white portion. However, the present invention is not limited to this, and it is only necessary to change the light valve white area Sq, and the shape of the white portion may be any shape.

  Furthermore, for example, as the adjustment pattern image, other specific colors such as green and gray may be used instead of the above-described white.

6-2. Modification 2:
In the above-described embodiments, the area Sp of the white portion in the captured image is controlled to be equal to the target area Spt. However, the present invention is not limited to such an area Sp of the white portion. Even if it is not itself, it may be a value related to the area Sp of the white portion. That is, instead of the area Sp of the white portion, for example, the ratio (area ratio) of the area Sp of the white portion to the area Sz of the projection light range in the photographed image, the length of the horizontal side and / or the length of the vertical side of the white portion You may make it use length and the number of the pixels which comprise a white part. Furthermore, you may make it use the number of the pixels which comprise the area of the black part of a picked-up image, and the black part in a projection light range.

  When such a change is made instead of the area Sq of the white portion, the target area Spt needs to be changed to a corresponding value accordingly.

6-3. Modification 3:
In the above-described embodiment, the imaging control unit 105 controls the shutter speed, gain, aperture, and the like in the imaging unit 104 to perform automatic exposure. However, the present invention is not limited to this, and the shutter speed is not limited to this. , Gain and aperture may be controlled to perform automatic exposure, or two or more may be combined and controlled to perform automatic exposure.

6-4. Modification 4:
Although the liquid crystal light valve 114 is used as an electro-optical device in the projector 100, the present invention is not limited to this, and an image is formed based on an image signal, and light modulated in accordance with the formed image is generated. Various devices for injection can be used. For example, a DMD (digital micromirror device) (trademark of TI) may be used, or a CRT or a plasma display panel may be used.

It is a block diagram which shows the structure of the projector as one Example of this invention. It is a flowchart which shows the process sequence of the pattern image variable process in the projector of FIG. FIG. 6 is an explanatory diagram showing an adjustment pattern image formed on the liquid crystal light valve 114 and a photographed image photographed by the CCD module 130. It is explanatory drawing which shows a mode that the area of the white part in the pattern image formed on the liquid crystal light valve 114 changes. It is explanatory drawing which shows the gradation value of each pixel of a picked-up image and a picked-up image. It is explanatory drawing for demonstrating the effect by the automatic exposure of the monitor camera in the past. It is explanatory drawing for demonstrating the problem by the automatic exposure of a monitor camera at the time of changing the zoom position in the past.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Projector 102 ... A / D conversion part 104 ... Imaging part 105 ... Imaging control part 106 ... Captured image memory 107 ... Pattern image memory 108 ... Image processing part 110. .. Liquid crystal light valve drive unit 112 ... Illumination optical system 114 ... Liquid crystal light valve 116 ... Zoom lens 118 ... Projection optical system 120 ... CPU
124 ... Zoom lens drive unit 126 ... Remote control unit 128 ... Remote control 130 ... CCD module

Claims (4)

A projector that projects projection light onto a projection object to display an image,
An image forming unit capable of forming a predetermined pattern image to be displayed on the projection object;
A zoom lens capable of changing the size of the projection light range onto which the projection light is projected;
A control unit;
An imaging unit for imaging the projection object;
An exposure calculation value is calculated from a captured image captured by the imaging unit, and exposure adjustment is performed in the imaging unit so that the calculated exposure calculation value is substantially equal to an exposure target value set by the control unit. An imaging control unit;
With
The control unit obtains a photographed image photographed by the photographing unit, and a parameter related to the area of a specific color portion represented by a specific color in the obtained photographed image is a preset target parameter. A projector that changes an area of a specific color portion in the pattern image formed in the image forming unit so as to be substantially equal. The projector according to claim 1, wherein
The projector according to claim 1, wherein the specific color is white. A zoom lens capable of projecting projection light onto a projection object to display an image and changing the size of a projection light range onto which the projection light is projected, and an imaging unit for photographing the projection object Calculating an exposure calculation value from a captured image captured by the imaging unit, and adjusting the exposure in the imaging unit so that the calculated exposure calculation value is substantially equal to an exposure target value set by the control unit. In a projector comprising an imaging control unit that performs the following, a method for displaying a predetermined pattern image on the projection object,
(A) forming the pattern image having a specific color portion represented by a specific color;
(B) displaying the formed pattern image on the projection object via the zoom lens;
(C) photographing the projection object on which the pattern image is displayed by the photographing unit;
(D) obtaining a photographed image photographed by the photographing unit;
(E) changing the area of the specific color portion in the formed pattern image so that a parameter related to the specific color portion in the acquired captured image is substantially equal to a preset target parameter;
A pattern image display method comprising: The pattern image display method according to claim 3,
The pattern image display method, wherein the specific color is white.

Images