JP2006023400A - Projector device and focal point adjustment method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform a correct adjustment using a small-scale circuit so as to acquire an optimum focal distance. <P>SOLUTION: The projector device 1 projects a test pattern which is a predetermined image onto a screen 3, causes a camera 12 to image the test pattern projected on the screen 3, and causes a control section 11 to measure the brightness of each of pixels adjacent to one another. When the absolute value of a difference between the adjacent pixels is greater than a threshold, the control section 11 counts pixels having the brightness determined to be greater than a prescribed value, and adjusts the focal point so that the number of pixels subjected to counting becomes maximum. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projector device that projects an image on a screen and a focus adjustment method for the projector device.

  In the field of presentation or video projection, a projector device is used that acquires image data from a personal computer or a video playback device and projects an image based on the acquired image data onto an external screen. The projector device forms an image based on image data on a projection device such as a liquid crystal panel or DMD (Digital Micromirror Device), and projects the image on the projection device onto an external screen by light from an internal light source. In addition, the projector device projects color images by combining R (red), G (green), and B (blue) colors, or by projecting R, G, and B color images in a time-sharing manner. Images can be projected onto the screen.

  Unless the screen and the projector device are both fixed as in a theater or the like, the relative position between the screen and the projector device is usually variable. Therefore, the projector device needs to adjust the projection range, projection shape, focal length, and the like of the image so that an appropriate image is projected onto the screen. A conventional technique for adjusting the projector device is disclosed in Patent Document 1, for example. The projector device projects a predetermined image (hereinafter referred to as a test pattern) on a screen, and images the test pattern projected on the screen with a camera. The projector device adjusts the projection range of the image so that the size of the captured test pattern falls within an appropriate range on the screen, and the projected shape of the image so that the captured test pattern has a predetermined shape Adjust.

  Further, the projector device can adjust the focal length using the test pattern. FIG. 4 is a schematic diagram illustrating an example of a test pattern for adjusting the focal length. FIG. 4 shows an example of a test pattern composed of a plurality of vertical straight lines. The project apparatus adjusts the focal length based on, for example, a change in the image signal intensity indicating the brightness of each pixel constituting the captured test pattern in the horizontal direction (direction orthogonal to the vertical straight line of the test pattern). . Specifically, while controlling the operation of the focus motor to control the position of the projection lens and changing the focal length, the difference in image signal intensity between the bright and dark portions of the captured test pattern Since the distance becomes larger as the distance approaches the optimum value, the focal distance at which the amplitude of the change in the image signal intensity is maximum, that is, the focal distance at which the sum of squares of the amplitude of the change in the image signal intensity is maximized is set as the optimum value. The projector device realizes an autofocus function.

As described above, the conventional project apparatus can automatically adjust the projection range, projection shape, focal length, and the like of the image by projecting the test pattern.
JP 2002-303780 A

  However, as described above, in order to calculate the sum of squares for the amplitude of the change in image signal intensity between adjacent pixels for a predetermined test pattern, the scale of the arithmetic circuit becomes relatively large, and the projector device can be downsized. There is a problem that it is difficult to reduce the weight. In general, in order to reduce the scale of the arithmetic circuit, it is desirable to reduce the multiplication process and to configure the circuit so as to perform the calculation using the addition / subtraction process as much as possible.

  Further, when the imaging means of the projector device captures a test pattern, the screen is not necessarily a flat surface, and the image may be distorted. There is also a possibility that the optimum focal length cannot be specified only by the sum of squares calculated with respect to the amplitude of the change in the image signal intensity between adjacent pixels.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a projector apparatus and a projector apparatus that can be accurately adjusted to an optimum focal length using a small-scale circuit. It is to provide a focus adjustment method.

  The projector device according to the present invention includes a projecting unit that projects an image onto an external screen, and an image capturing unit that captures an image projected on the screen, and performs focus adjustment based on a predetermined image captured by the image capturing unit. In the projector apparatus that performs the above, a measuring unit that measures the brightness in units of pixels for the pixels included in the predetermined image captured by the imaging unit, and a measurement result by the measuring unit, between adjacent pixels in units of pixels. Comparing means for comparing the absolute value of the brightness difference with the threshold value, and from the comparison result by the comparing means, the number of pixels in which the absolute value of the brightness difference between adjacent pixels in pixel units is larger than the threshold value. A counting means for counting, and a focus position setting hand for performing focus adjustment with a focus position corresponding to the largest value among the count values counted by the counting means at a plurality of focus positions as an optimum focus position Characterized in that it comprises and.

  In the projector device according to the present invention, a predetermined image projected on the screen is captured, the number of pixels in which the brightness difference between adjacent pixels of the captured image is greater than a threshold value is counted, and the brightness of the adjacent pixels is determined. The focal position is adjusted so that the number of pixels with the difference larger than the threshold value is maximized. Accordingly, a subtraction circuit that calculates the difference in brightness between adjacent pixels, a comparison circuit that compares whether the difference in brightness between adjacent pixels is greater than a threshold, and the difference in brightness between adjacent pixels from the threshold. Since an addition circuit that counts a large number of pixels can be used and a multiplication circuit that increases the circuit scale is not used, the arithmetic circuit can be reduced in size, and the projector device can be reduced in size or weight. It becomes possible. In addition, even if there is some distortion, distortion, etc. on the screen, and the captured image is distorted, the focus position where the number of pixels whose brightness difference is greater than the threshold is the maximum is the optimal focus position As a result, it is possible to adjust the focus.

  In the projector device according to the present invention, the predetermined image is a test pattern in which a bright part and a dark part are combined.

  In the projector device according to the present invention, the test pattern projected on the screen is imaged, and the number of pixels in which the brightness difference between adjacent pixels is greater than the threshold is counted for the captured test pattern so that the number of pixels is maximized. Adjust the focus position. As a result, the number of pixels in which the difference in brightness between adjacent pixels is greater than the threshold can be counted based on a clear and dark image, and the focus adjustment can be performed with higher accuracy with a simple circuit configuration. .

  The projector according to the present invention is characterized in that the measuring unit is configured to measure brightness in units of pixels in a direction crossing a boundary between a bright part and a dark part of the test pattern.

  In the projector device according to the present invention, the brightness of pixels adjacent in the direction crossing the boundary between the bright part and the dark part in the captured test pattern is measured in units of pixels. As a result, the number of pixels in which the difference in brightness between adjacent pixels in a clear and dark direction is greater than the threshold can be counted, and the focus adjustment can be performed more accurately with a simple circuit configuration.

  According to another aspect of the present invention, there is provided a focus adjustment method for a projector device, the focus adjustment method for a projector device projecting an image to an external screen, capturing a predetermined image projected on the screen, The brightness of each pixel included is measured, and the absolute value of the difference in brightness between adjacent pixels is compared with the threshold value from the measurement result, and the threshold value is compared with the comparison result. The number of pixels whose absolute value of the brightness difference between the two is larger than the threshold is counted, and the focus position corresponding to the largest value among the counted values counted at a plurality of focus positions is set as the optimum focus position. It is characterized by performing.

  In the focus adjustment method of the projector device according to the present invention, a predetermined image projected on the screen is captured, the number of pixels in which the brightness difference between adjacent pixels of the captured image is greater than a threshold value is counted, and the adjacent pixels The focal position is adjusted so that the number of pixels in which the brightness difference is greater than the threshold value is maximized. Accordingly, a subtraction circuit that calculates the difference in brightness between adjacent pixels, a comparison circuit that compares whether the difference in brightness between adjacent pixels is greater than a threshold, and the difference in brightness between adjacent pixels from the threshold. Since an addition circuit that counts a large number of pixels can be used and a multiplication circuit that increases the circuit scale is not used, the arithmetic circuit can be reduced in size, and the projector device can be reduced in size or weight. It becomes possible. In addition, even if there is some distortion, distortion, etc. on the screen, and the captured image is distorted, the focus position where the number of pixels whose brightness difference is greater than the threshold is the maximum is the optimal focus position As a result, it is possible to adjust the focus.

  In the present invention, a predetermined image projected on the screen is captured, the number of pixels in which the brightness difference between adjacent pixels of the captured image is greater than a threshold value is counted, and the brightness difference between adjacent pixels is calculated. Focus adjustment is performed so that the number of pixels larger than the threshold is maximized. Therefore, a subtraction circuit that calculates the difference in brightness between adjacent pixels, a comparison circuit that compares whether the brightness difference between adjacent pixels is greater than a threshold, and the difference in brightness between adjacent pixels is greater than the threshold. Since an adder circuit that counts the number of pixels can be used and a multiplication circuit that increases the circuit scale is not used, the arithmetic circuit can be reduced in size, and the projector device can be reduced in size or weight. Is possible.

  In addition, even when some distortion, distortion, or the like is present on the screen and the captured image is distorted, it is possible to obtain a focal position where the number of pixels having a large difference in brightness is maximized. The present invention has excellent effects.

  Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof. FIG. 1 is a block diagram showing the internal configuration of the projector apparatus of the present invention. Arrows in the figure indicate data, and white arrows indicate light. The projector apparatus 1 includes a light source 18 such as a xenon lamp or an ultra-high pressure mercury lamp, a condensing optical system 17 that condenses light from the light source 18, a projection device 14 that forms an image, and an image on the projection device 14. And a projection optical system 13 for enlarging and projecting to an external screen 3.

  The projector device 1 irradiates the projection device 14 with light from the light source 18 through the condensing optical system 17, and projects the light reflected on the projection device 14 that formed the image through the projection optical system 13, thereby projecting the projection device. 14 is projected onto the screen 3. In addition, it is good also as a structure which projects an image by making the light from the light source 18 permeate | transmit instead of reflecting on the projection device 14. FIG.

  The condensing optical system 17 includes a color filter, a lens, a prism, or the like, and performs condensing / polarization / color separation of light from the light source. The projection device 14 includes one or a plurality of liquid crystal panels or DMDs, and forms R, G, and B color images. The projection optical system 13 includes a projection lens, a motor for adjusting the position of the projection lens, a drive circuit for driving the motor, and the like. The projection optical system 13 may have a configuration including a color synthesis optical system that synthesizes R, G, and B color images.

  Further, the project device 1 receives image data transmitted from an external transmission device 2 such as a personal computer or a video reproduction device, processes the image data received by the communication unit 16, and based on the image data An image processing unit 15 that forms an image on the projection device 14. Accordingly, an image based on the image data transmitted from the transmission device 2 is projected onto the screen 3.

  The projector device 1 also includes a camera 12 that captures an image projected on the screen 3. The camera 12 includes a CCD that captures an image, an AD conversion unit that converts an image signal indicating an image captured by the CCD into a digital image signal, and the like.

  Furthermore, the projector device 1 includes a control unit 11 that controls the operation of the entire projector device 1. The control unit 11 includes a CPU that performs calculations, a flash memory that stores programs, and the like. The camera 12 outputs an image signal indicating the captured image to the control unit 11, and the control unit 11 controls the projection optical system 13 and the image processing unit 15 based on the image signal input from the camera 12. The control unit 11 controls the rotation of the focus motor by controlling the operation of the drive circuit of the projection optical system 13, and controls the projection range, focal length, and the like of the image projected by the projector device 1. In addition, the control unit 11 controls the processing of causing the projection device 14 to form an image by the image processing unit 15, thereby controlling the content of the image to be projected, the shape of the image, the hue, the projection luminous intensity of the image, and the like.

  Next, the focus adjustment method of the projector apparatus 1 of the present invention will be described. FIG. 2 is a flowchart illustrating a procedure of counting processing for the number of pixels in which the absolute value of the brightness difference between adjacent pixels is greater than a threshold value, which is performed by the projector device 1 of the present invention. The control unit 11 instructs the image processing unit 15 to cause the projection device 14 to form a test pattern, thereby projecting the test pattern from the projector device 1 onto the screen 3 (S11). The test pattern is not limited to a test pattern composed of a plurality of vertical straight lines as shown in FIG. 4, and any test pattern can be used as long as it can distinguish between light and dark.

  The control unit 11 causes the camera 12 to capture an image of the test pattern projected on the screen 3 (S12). The camera 12 generates an image signal indicating a captured image obtained by capturing the test pattern and outputs the image signal to the control unit 11, and the control unit 11 receives the image signal input from the camera 12 (S13). The image signal includes a signal indicating the brightness of each pixel constituting the captured image, and specifically includes a luminance signal indicating the brightness at each pixel or an RGB signal indicating the brightness of each color at each pixel. .

  Next, the control unit 11 measures the brightness of the received image signal (S14). The control unit 11 measures the brightness in units of pixels in a direction crossing the boundary between the bright part and the dark part of the test pattern. Thereby, it is possible to count the number of pixels in which the difference in brightness between adjacent pixels in a clear direction of brightness is greater than the threshold value. At this time, the control unit 11 may measure the brightness of all the pixels constituting the captured image, or may measure the brightness of some of the selected pixels.

  The control unit 11 calculates the absolute value of the difference in brightness between adjacent pixels based on the measured brightness (S15), and whether or not the calculated absolute value of the difference in brightness is larger than a predetermined threshold value. Is determined (S16). If the absolute value of the calculated brightness difference is larger than the threshold value (S16: YES), the controller 11 can determine that there is a high possibility that it is a straight line boundary in a test pattern including a plurality of vertical straight lines. Then, the number of pixels whose absolute value of the calculated brightness difference is equal to or greater than a predetermined threshold is counted (S17). If the absolute value of the calculated brightness difference is smaller than the threshold (S16: NO), the number of pixels is not counted.

  The above processing is executed for all the pixels included in the received image signal (S18), and the counted number of pixels is stored in a flash memory or the like (S19).

  FIG. 3 is a flowchart showing a procedure of focus adjustment processing for obtaining an optimum focus position performed by the projector device 1 of the present invention. The control unit 11 repeats the pixel count counting process described above while changing the focal length F for each unit distance by driving a focus motor that moves the projection optical system 13. Specifically, the control unit 11 performs the processing shown in FIG. 2 at the initial value F1 of the focal length F, and counts the number of pixels whose absolute value of the brightness difference is equal to or greater than a predetermined threshold value. (S21), the counted number of pixels is stored (S22). Then, the control unit 11 outputs an instruction signal to the focus motor so that the initial value F1 of the focal length F is increased (shortened) by the unit distance ΔF (S23). After the focal length fluctuates by unit distance due to the rotation of the focus motor, that is, when the focal length F = F1 + ΔF, the control unit 11 returns the process to S11 in FIG. A counting process for a larger number of pixels is executed.

  When the process of S19 in FIG. 2 is completed, the control unit 11 determines whether or not the counted number of pixels is larger than the stored number of pixels (S24). When the control unit 11 determines that the counted number of pixels is larger than the stored number of pixels (S24: YES), the control unit 11 causes the focus motor to make the focal length F longer (shorter) than the unit distance ΔF. The instruction signal is output to (S25), and the process of FIG. 2 is repeatedly executed.

  When the control unit 11 determines that the counted number of pixels is smaller than the stored number of pixels (S24: NO), the control unit 11 determines that the counted number of pixels is the maximum value, and determines the focal length F at this time. The optimum focal length is specified (S26).

  After the above-described image focus adjustment processing is completed, the projector device 1 adjusts the projection range, projection shape, projection intensity, and the like of the image using the test pattern, and after all adjustments are completed, the communication is performed. The unit 16 projects an image based on the received image data.

  As described above in detail, in the present invention, the test pattern projected on the screen 3 is captured by the camera 12, and the number of pixels in which the absolute value of the brightness difference between adjacent pixels in the captured image is greater than the threshold value is counted. The focus adjustment is performed so that the number of pixels in which the brightness difference between adjacent pixels is greater than the threshold value is maximized. Accordingly, a subtracting circuit that calculates the absolute value of the difference in brightness between adjacent pixels, a comparison circuit that compares whether the absolute value of the brightness difference between adjacent pixels is greater than a threshold, and the brightness of the adjacent pixels Since the addition circuit that counts the number of pixels in which the absolute value of the difference in difference is larger than the threshold value is used, a multiplication circuit that increases the circuit scale is not used, and the arithmetic circuit can be downsized. It is possible to reduce the size or weight of the device.

  In addition, even when some distortion or distortion is present on the screen and the captured image is distorted or the like, the focal length at which the number of pixels whose absolute value of the brightness difference is greater than the threshold value is maximized is obtained. It becomes possible.

  In the present embodiment, the projector apparatus 1 performs focus adjustment by controlling the operation of the focus motor that drives the projection optical system 13, but the present invention is not limited to this, and the condensing optical system 17 is provided. The form which adjusts the projection light intensity of an image using other methods, such as reducing the light quantity radiated | emitted from the projection optical system 13, may be sufficient.

  In the present embodiment, the projector device 1 is configured to perform focus adjustment when a test pattern is projected. However, the present invention is not limited to this, and an image based on image data received by the communication unit 16 is used. In this case, the focus adjustment may be performed when the projection is performed. In the present embodiment, the projector apparatus 1 is configured to perform focus adjustment on the entire projected image, but may be configured to perform focus adjustment on a pixel basis of the projected image.

  In the present embodiment, the projector device 1 is configured to project an image based on the image data received by the communication unit 16, but is not limited thereto, and is recorded on a recording medium such as a DVD or a hard disk. The image data reading means may be provided inside, and an image based on the read image data may be projected.

It is a block diagram which shows the internal structure of the projector apparatus of this invention. It is a flowchart which shows the procedure of the count process of the pixel number with which the absolute value of the brightness difference of the adjacent pixel which the projector apparatus of this invention is larger than a threshold value. It is a flowchart which shows the procedure of the focus adjustment process which calculates | requires the optimal focus position which the projector apparatus of this invention performs. It is a schematic diagram which shows the example of the test pattern for adjusting a focal distance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projector apparatus 3 Screen 11 Control part 12 Camera 13 Projection optical system 14 Projection device 15 Image processing part

Claims (4)

In a projector apparatus that includes a projecting unit that projects an image onto an external screen and an imaging unit that captures an image projected on the screen, and performs focus adjustment based on a predetermined image captured by the imaging unit.
Measuring means for measuring brightness in pixel units for pixels included in the predetermined image captured by the imaging means;
Comparison means for comparing the absolute value of the difference in brightness between adjacent pixels in pixel units with a threshold value from the measurement result by the measurement means;
Counting means for counting the number of pixels in which the absolute value of the difference in brightness between adjacent pixels in a pixel unit is larger than a threshold value from the comparison result by the comparing means;
A projector apparatus comprising: a focus position setting unit that performs focus adjustment with a focus position corresponding to the largest value among count values counted at a plurality of focus positions as an optimum focus position.   The projector device according to claim 1, wherein the predetermined image is a test pattern in which a bright part and a dark part are combined.   3. The projector apparatus according to claim 2, wherein the measuring unit is configured to measure brightness in units of pixels in a direction crossing a boundary between a bright part and a dark part of the test pattern. In a focus adjustment method of a projector device that projects an image to an external screen,
Capture a predetermined image projected on the screen,
Measure the brightness in pixel units for the pixels included in the captured image
From the measurement results, compare the absolute value of the difference in brightness between adjacent pixels in pixel units and the threshold,
From the comparison result, the number of pixels in which the absolute value of the difference in brightness between adjacent pixels is greater than the threshold is counted in units of pixels.
A focus adjustment method for a projector apparatus, characterized in that focus adjustment is performed with a focus position corresponding to the largest value among count values counted at a plurality of focus positions as an optimum focus position.

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