JP2005143043A - Projector and focus detecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector capable of carrying out focusing of a projected image accurately in the case that the distance up to a screen is short, and in a short time in the case that the distance up to the screen is long. <P>SOLUTION: A projector 2 uses at least one of a first line type passive range finder 30 and a second line type passive range finder 40 to find a range from the projector 2 up to the screen 1. The projector 2 optically sets a step width being the movement range of a projection lens optical system 8 and the sampling interval of sensor data outputted from a light receiving sensor 21 on the basis of the obtained range finding data. Then the projector 2 moves the projection lens optical system 8 at the set step width and the set sampling interval to measure a contrast value of the image projected on the screen 1, thereby particularizing a focal position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a projector apparatus that focuses an image projected on a screen and a focus detection method thereof.

  In a projector device, it is desired to accurately focus an image projected on a screen in order to improve the convenience of the projector device.

  Focusing on the fact that the contrast value of the image signal corresponds to the definition of the reproduced image as one method of focusing the image, the position of the projection lens matches the in-focus position so that the contrast value is maximized An automatic focusing method is known.

  The automatic focus adjustment method disclosed in the imaging apparatus of Patent Document 1 will be described below. As shown in FIG. 16, the imaging apparatus of Patent Document 1 includes a main lens 101, a focus lens 102, a diaphragm shutter 103, a focus motor 104, a reset switch 105, a photoelectric conversion element 106, and an imaging circuit 107. An arithmetic circuit 108, a CPU 109, and a mode switch 110.

  The focus lens 102 that forms the subject image on the photoelectric conversion element 106 is moved so that the focal length continuously changes. The subject image formed on the photoelectric conversion element 106 by the focus lens 102 is converted into an electric signal by the photoelectric conversion element 106, and the electric signal is converted into a luminance signal suitable for the arithmetic circuit 108 in the subsequent stage by the imaging circuit 107. The luminance signal is input to the arithmetic circuit 108, and a focus evaluation value is obtained. The focus evaluation value represents the magnitude of contrast, and the higher the focus evaluation value, the higher the definition of the image.

Japanese Patent Application Laid-Open No. 8-1866752.

  In general, since the projection lens has a depth of focus (a range in which an image can be clearly seen even if the focus is slightly shifted), the depth of focus increases as the distance between the projector device and the screen increases, that is, the in-focus range. Becomes wider. Conversely, when the distance between the projector device and the screen is shortened, the depth of focus is shallow, that is, the in-focus range is narrowed. As a result, when the distance to the screen is long, the projected image is focused even if the projection lens position is slightly shifted from the peak position of the contrast value. Conversely, when the distance to the screen is short, the projection lens If the position is slightly deviated from the peak position of the contrast value, the projected image is not focused.

  Therefore, in the prior art, even if the focal length of the projection lens is continuously changed for focusing, an interval for moving the projection lens (hereinafter referred to as a step width) and light reception for receiving reflected light from the screen. If the interval for acquiring sensor data from the element (hereinafter referred to as sampling interval) is not set appropriately according to the distance to the screen, the peak position of the contrast value cannot be detected accurately, or the time to detect the peak position The problem of taking too much arises.

  The present invention has been made in view of the above circumstances, and can perform projection image focusing accurately when the distance to the screen is short, and in a short time when the distance to the screen is long. An object is to provide an apparatus.

  In order to achieve this object, the projector device according to claim 1 receives reflected light of an image projected on a screen by a light receiving element while moving the projection lens optical system at a predetermined movement interval, and outputs the light from the light receiving element. A projector apparatus that performs a focus detection process for acquiring a signal at a predetermined acquisition interval and specifying a position where a focus of the projection lens optical system is aligned with the screen based on the output signal, Based on the distance measurement data, at least one of the movement interval and the acquisition interval is set, the focus detection process is performed at the set interval, and the in-focus position where the focal point of the projection lens optical system matches the screen is specified. It has a control means.

  According to the first aspect of the present invention, at least one of the movement interval of the projection lens optical system and the interval for obtaining the output signal of the light receiving element is set based on the distance measurement data up to the screen, and the focus is set at the set interval. A detection process is performed to identify the in-focus position where the projection lens optical system is focused on the screen. The depth of focus, that is, the range in which the projected image is in focus, varies depending on the distance to the screen on which the image is projected. Therefore, by changing at least one of the movement interval and the acquisition interval according to the distance to the screen, it is possible to efficiently specify the in-focus position where the projection lens optical system is focused on the screen.

  The projector device according to claim 2, the reflected light of the image projected on the screen is received by the light receiving element while moving the projection lens optical system at the predetermined movement interval, and the output signal of the light receiving element is received at the predetermined acquisition interval. A projector device that performs a focus detection process for acquiring and determining a position where the focal point of the projection lens optical system matches the screen based on the output signal, and based on distance measurement data up to the distance-measured screen, At least one of the movement interval and the acquisition interval is set, the projection lens optical system is moved within a predetermined range before and after the in-focus point specified by the focus detection processing, the focus detection processing is performed again, and the projection It has a control means for specifying a position where the focal point of the lens optical system matches the screen.

  According to the second aspect of the invention, the focus detection process is performed again by moving the projection lens optical system within a predetermined range before and after the in-focus point specified by the focus detection process. At this time, at least one of the movement interval of the projection lens optical system and the interval for acquiring the output signal of the light receiving element is set based on the distance measurement data. Since the depth of focus, that is, the range in which the projected image is focused, changes depending on the distance to the screen on which the image is projected, setting at least one of the movement interval and the acquisition interval to a value corresponding to the distance measurement data The focal position can be identified efficiently. In addition, the approximate position of the in-focus position is obtained in the first focus detection process, and the second detailed focus detection process is performed only within a predetermined range before and after the in-focus position, thereby detecting the in-focus position detection accuracy. As well as the time required for the second detailed focus detection process.

  According to a third aspect of the present invention, in the projector device according to the first or second aspect, the control means compares the distance measurement data with a threshold value, and the distance measurement data is larger than the threshold value. Sets at least one of the movement interval and the acquisition interval to be longer than a reference value, and if the distance measurement data is smaller than the threshold value, sets at least one of the movement interval and the acquisition interval. It is characterized in that it is set shorter than the reference value.

  According to a third aspect of the present invention, when a threshold value is provided and the distance measurement data is larger than the threshold value, at least a movement interval of the projection lens optical system and an interval at which the output signal of the light receiving element is acquired. One is set longer than the reference value. When the threshold is larger than the distance measurement data, at least one of the movement interval and the acquisition interval is made shorter than the reference value. When the distance to the screen is long, the depth of focus becomes deep and the range in which the projected image is focused becomes wide. For this reason, even if at least one of the movement interval and the acquisition interval is set longer than the reference value, the problem that the in-focus point cannot be detected does not occur. In addition, since the movement interval and the acquisition interval are set to be long, it is possible to shorten the time for detecting the in-focus point. On the contrary, when the distance to the screen is short, the depth of focus becomes shallow and the range in which the projected image is focused becomes narrow. For this reason, by setting at least one of the movement interval and the acquisition interval to be shorter than the reference value, it is possible to perform detailed detection and accurately detect the focal point.

  The focus detection method according to claim 4, wherein reflected light of an image projected on a screen is received by a light receiving element while moving the projection lens optical system at a predetermined movement interval, and the output signal is acquired at a predetermined acquisition interval. A focus detection method for identifying a position where the focus of the projection lens optical system is aligned with the screen based on the output signal, wherein at least one of the movement interval and the acquisition interval is a distance from the measured screen to the screen. The interval is set based on the distance measurement data.

  According to a fourth aspect of the present invention, at least one of the movement interval of the projection lens optical system and the interval at which the output signal of the light receiving element is acquired is set based on the distance measurement data up to the screen, and the projection lens optical system The position where the focus is on the screen is specified. The depth of focus, that is, the range in which the projected image is in focus, varies depending on the distance to the screen on which the image is projected. Therefore, by changing at least one of the movement interval and the acquisition interval according to the distance to the screen, it is possible to efficiently specify the in-focus position where the projection lens optical system is focused on the screen.

  The focus detection method according to claim 5, wherein reflected light of an image projected on a screen is received by a light receiving element while moving the projection lens optical system at a predetermined movement interval, and an output signal of the light receiving element is received at a predetermined acquisition interval. And a first focus detection step for identifying a position where the focus of the projection lens optical system is aligned with the screen based on the output signal, and the movement based on the distance measurement data up to the distanced screen. At least one of an interval and the acquisition interval is set, the projection lens optical system is moved within a predetermined range before and after the in-focus point specified by the focus detection process, the focus detection process is performed again, and the projection lens optical And a second focus detection step for specifying a position where the focus of the system is aligned with the screen.

  The invention according to claim 5 performs the second focus detection step by moving the projection lens optical system within a predetermined range before and after the in-focus point specified in the first focus detection step. At this time, at least one of the movement interval of the projection lens optical system and the interval for acquiring the output signal of the light receiving element is set based on the distance measurement data. Since the depth of focus, that is, the in-focus range of the projected image also changes depending on the distance to the screen onto which the image is projected, focusing is achieved by changing at least one of the movement interval and the acquisition interval according to the distance to the screen. The position can be identified efficiently. In addition, an approximate position of the in-focus point is obtained in the first focus detection step, and the second focus detection step is executed only within a predetermined range before and after the in-focus position, thereby detecting the focus position detection accuracy. As well as the time required for the second focus detection step.

  The focus detection method according to claim 6 is the focus detection method according to claim 4 or 5, wherein when the distance measurement data is larger than the threshold value, at least one of the movement interval and the acquisition interval is used as a reference. When the distance measurement data is smaller than the threshold value, at least one of the movement interval and the acquisition interval is set shorter than the reference value.

  According to the sixth aspect of the present invention, when the distance measurement data is larger than the threshold value, at least one of the movement interval of the projection lens optical system and the interval of acquiring the output signal of the light receiving element is set longer than the reference value To do. When the threshold is larger than the distance measurement data, at least one of the movement interval and the acquisition interval is made shorter than the reference value. When the distance to the screen is long, the depth of focus becomes deep and the range in which the projected image is focused becomes wide. For this reason, even if at least one of the movement interval and the acquisition interval is set longer than the reference value, there is no problem that the focal point cannot be detected. In addition, since the movement interval and the acquisition interval are set to be long, it is possible to shorten the time for detecting the in-focus point. On the contrary, when the distance to the screen is short, the depth of focus becomes shallow and the range in which the projected image is focused becomes narrow. For this reason, by setting at least one of the movement interval and the acquisition interval to be shorter than the reference value, it is possible to perform detailed detection and accurately detect the focal point.

  According to the present invention, it is possible to provide a projector apparatus that can accurately perform projection image focusing when the distance to the screen is short and in a short time when the distance to the screen is long.

  Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  First, the configuration of the projector device 2 according to the present embodiment will be described with reference to FIG. As shown in FIG. 1, the projector device 2 of the present embodiment receives the reflected light of the image projected on the screen 1 by the projection lens optical system 8 and determines the contrast value for determining the focal position of the projected image. An automatic focus detection device 20 that calculates the distance, a first line type passive distance measuring device 30 that measures the distance from the projector device 2 to the screen 1 at a plurality of points in the left-right direction (horizontal direction) of the screen 1, and a projector device. An image is input from a second line type passive distance measuring device 40 that measures the distance from 2 to the screen 1 at a plurality of points in the vertical direction (vertical direction) of the screen 1 and a personal computer (not shown). A projection image generation unit 6 that outputs display data to be projected onto the display 1 and a display drive unit that outputs display data to the projection lens optical system 8 A projection lens optical system 8 that projects the display data output by the display drive unit 7 onto the screen 1, and a projection lens optical system 8 along the optical axis in order to change the focal length of the projection lens optical system 8. An optical system drive unit 9 composed of a stepping motor or the like for moving the projector, a memory unit 10 storing data and commands necessary for the configuration of the projector device 2, and a control circuit 5 for controlling these units.

  The automatic focus detection device 20 performs an operation on a light receiving sensor 21 that receives reflected light of an image projected on the screen 1 by the projection lens optical system 8 and an electric signal (sensor data) output from the light receiving sensor 21. And an arithmetic unit 22 for calculating the contrast value of the image. In this embodiment, a CCD line sensor is applied as the light receiving sensor 21.

  The calculation unit 22 of the automatic focus detection apparatus 20 will be described with reference to FIG. As shown in FIG. 2, the calculation unit 22 includes a high-pass filter (HPF) 22 a that extracts a high-frequency component from the electrical signal (sensor data) input from the light-receiving sensor 21, and amplitude detection of the luminance signal that includes only the high-frequency component. A detector 22b for performing A / D conversion, an A / D converter 22c for A / D converting the detection output of the detector 22b and converting it to a digital signal, and an integrator for integrating the digital signal output from the A / D converter 22c 22d. The integrator 22d outputs the contrast value of the image signal as shown in FIG.

  As shown in FIG. 3, the contrast value appearing in the high-frequency component of the image signal has a characteristic that the contrast value becomes maximum at the in-focus position and decreases as the position deviates from the in-focus position. . Using this characteristic, the position (focus position) of the projection lens optical system 8 when an image photographed by the projection lens optical system 8 forms an image on the screen 1 is obtained (hereinafter, this method is hill-climbed and autofocused). Called).

  FIG. 4 shows a configuration diagram of the projector device 2 shown in FIG. 1 as viewed from the front. A projection lens is provided in front of the projector device 2. The projection lens is included in a projection lens optical system (which may include a condenser lens) 8, and an image is projected onto the screen 1 through the projection lens.

  As shown in FIG. 4, the first line type passive distance measuring device 30 includes a pair of lenses 31 a and 31 b that are spaced apart by a base line length a in the horizontal direction on the plane that forms the front of the projector device 2. It has an imaging unit 31 provided. Similarly, the second line type passive distance measuring device 40 includes a pair of lenses 41a and a pair of lenses 41a arranged on the plane constituting the front surface of the projector device 2 as shown in FIG. It has an imaging unit 41 provided with 41b. In this embodiment, as shown in FIG. 4, the direction parallel to the base line length a of the imaging unit 31 is referred to as the first reference direction of the projector device 2. A direction parallel to the base line length b of the imaging unit 41 is referred to as a second reference direction of the projector device 2. As shown in FIG. 5A, the first line type passive distance measuring device 30 calculates the tilt angle θ1 of the screen 1 with respect to the first reference direction (the horizontal direction of the projector device 2). Measure the distance to multiple ranging positions. As shown in FIG. 5B, the second line type passive distance measuring device 40 calculates the tilt angle θ2 of the screen 1 with respect to the second reference direction (vertical direction of the projector device 2). Measure the distance to multiple ranging positions. 5A shows a top view of the projector device 2 and the screen 1 as viewed from above, and FIG. 5B shows a side view of the projector device 2 and the screen 1 as viewed from the side. It is shown.

  The configuration of the imaging unit 31 will be described with reference to FIG. A line sensor 31c is disposed below the lens 31a that receives light incident from the outside and is separated by a focal length f. A line sensor 31d is disposed below the lens 31b by a focal distance f. These line sensors 31c and 31d are composed of a pair of line CCDs having a plurality of photodetecting elements arranged in a straight line or other line type image pickup elements. For the image formed on the line sensors 31c and 31d via the lenses 31a and 31b, the imaging unit 31 serially outputs an electrical signal corresponding to the light amount of the image via an output unit (not shown). Note that the configuration of the imaging unit 41 is the same as that of the imaging unit 31, and thus the description thereof is omitted.

  The calculation unit 32 calculates a correlation value while sequentially shifting at least one of the pair of image signals output from the line sensors 31c and 31d over a predetermined shift range. Similarly, the calculation unit 42 calculates a correlation value while sequentially shifting at least one of the pair of image signals output from the line sensors 41c and 41d over a predetermined shift range, and calculates the correlation value. Based on this, the distance to the measurement object is calculated.

  The control circuit 5 receives the contrast value of the output projection image from the automatic focus detection device 20, and specifies the position (focus position) where the projection lens optical system 8 is focused on the screen. Further, based on the distance calculation result of the first line type passive distance measuring device 30, the tilt angle of the screen 1 with respect to the first reference direction of the projector device 2 is calculated. Similarly, the inclination angle of the screen 1 with respect to the second reference direction of the projector device 2 is calculated based on the distance calculation result of the second line type passive distance measuring device 40. Based on the tilt angle information, the shape of the trapezoidal distortion is obtained, and a control signal for generating a trapezoidal distortion opposite to the image projected on the screen 1 is notified to the projected image generation unit 6.

  The projection image generation unit 6 receives image data output from an image data output unit such as an external personal computer, converts the input image data into display data, and outputs the display data to the display drive unit 7.

  The display drive unit 7 functions as an image distortion correction unit, and based on the tilt angles with respect to the first reference direction and the second reference direction calculated by the control circuit 5, a projection lens optical system including a condenser lens as a projection lens (not shown) 8 is adjusted to correct the trapezoidal distortion of the projected image. The display driving unit 7 functions as an autofocus unit that automatically adjusts the focus of a projection lens (not shown). The projection lens optical system 8 projects predetermined image light on the screen 1.

  Next, the operation principle of the first passive distance measuring device (external light triangular distance measuring method) 30 will be described with reference to FIG. FIG. 6 is a diagram illustrating a state in which the distance to the screen 1 is measured by the first line type passive distance measuring device 30. Note that the operation principle of the second line type passive distance measuring device 40 is the same as that of the first line type passive distance measuring device 30, and thus the description thereof is omitted.

  In FIG. 6A, a pair of lenses 31 a and 31 b are arranged apart from each other by a predetermined baseline length “a” extending in the horizontal direction on a plane constituting the front surface of the projector device 2. A pair of line sensors 31c and 31d that are spaced apart from the pair of lenses 31a and 31b by their focal lengths f and extend in the direction of the baseline length a are disposed below the plane that forms the front surface of the projector device 2. Yes. The line sensors 31c and 31d are arranged so that the central portions thereof are substantially located on the optical axes 31ax and 31bx of the lenses 31a and 31b, respectively. On these line sensors 31c and 31d, an image T at a certain position on the screen 1 for distance measurement (ranging) is formed via the corresponding lenses 31a and 31b. In FIG. 6A, the measurement position T on the screen 1 is imaged on the line sensors 31c and 31d through the optical paths A and B in different directions and the respective lenses 31a and 31b. .

  Assuming that the measurement position T exists at an infinite position, the measurement position T is located on the line sensors 31c and 31d at the focal length f from the pair of lenses 31a and 31b, and the optical axes 31ax of the lenses 31a and 31b. And 31bx are imaged at reference positions 31cx and 31dx. When the measurement position T approaches from the infinity position along the direction A on the optical axis 31ax of the lens 31a and reaches the position LC in FIG. 6A, that is, the distance LC from the lens 31a to the screen 2, the measurement position Although T is imaged on the reference position 31cx on the line sensor 31c, it is imaged on the line sensor 31d at a position shifted by a phase difference (deviation amount) α from the reference position 31dx by the lens 31b. Is done.

  At this time, the distance LC from the principle of triangulation to the measurement position T is obtained by LC = af / α. Here, the base line length a and the focal length f are known values known in advance, and the distance LC can be measured by detecting the phase difference (shift amount) α from the reference position 31dx on the line sensor 31d. That is, the distance to the screen 1 can be detected. This is the operating principle of a passive line sensor distance measuring device for external light triangulation. The detection of the phase difference (shift amount) α and the calculation of LC = af / α are executed by the calculation unit 32 shown in FIG.

  Detection of the phase difference (shift amount) α from the reference position 31dx of the line sensor 31d is performed by detecting the partial image data group iLm extracted from the pair of image data signal sequences IL and IR output from the pair of line sensors 31c and 31d, respectively. iRn is detected by the calculation unit 32 performing a correlation calculation.

  An outline of the correlation calculation will be described. As shown in FIG. 6B, the correlation calculation is performed by using the line sensors 31c and 31d as the line sensors 31c and 31d for the regions where the degree of coincidence is highest when the partial image data groups iLm and iRn are superimposed on each other. This is a calculation that is detected while relatively shifting. In FIG. 6B, the partial image data group iLm from one line sensor 31c is fixed at the reference position 31cx and used as a reference portion. The partial image data group iRn from the other line sensor 31d is shifted one pixel at a time as a reference portion, and the partial image data group iRn having the highest degree of coincidence with the reference portion is searched. The interval between the position on the line sensor 31d that generates the partial image data group iRn having the highest degree of coincidence and the reference position 31dx of the line sensor 31d is the phase difference (deviation amount) α.

  Since each of the line sensors 31c and 31d is composed of a pair of line CCDs in which a predetermined number of photodetecting elements (pixels) are arranged on a straight line having a predetermined length, the phase difference (shift amount) α is the partial image data. It can be easily obtained from the pixel position and pixel pitch in the image data signal sequence IR of the group iRn. In this way, the distance LC to the measurement position T in the same direction A as the optical axis 31ax of the lens 31a can be measured by detecting the phase difference (deviation amount) α.

  The projector device 2 according to the present embodiment specifies a focus position where the projection lens optical system 8 is focused on the screen by hill-climbing autofocus. However, the projection lens has a property that, as the distance from the projector device 2 to the screen 1 becomes shorter, the depth of focus becomes shallower as the distance from the projector device 2 to the screen 1 becomes longer, and the depth of focus becomes deeper as the distance becomes longer.

  Accordingly, in the hill-climbing autofocus, the calculation unit 22 acquires the sensor data of the light receiving sensor 21 to calculate the contrast value (hereinafter referred to as the sampling interval), or moves the projection lens optical system 8 in the optical axis direction. If the movement interval (hereinafter referred to as “step width”) is not set appropriately in accordance with the distance to the screen, there arises a problem that the detection time of the in-focus position becomes long or the in-focus position cannot be detected accurately. For example, when the distance to the screen 1 is short, the depth of focus is shallow as shown in FIG. 7A. Therefore, if the step width for moving the projection lens optical system 8 is wide, the peak position of the contrast value is accurately detected. I can't. Also, when the distance to the screen 1 is long, the depth of focus is deep as shown in FIG. 7B, so that the peak position of the contrast value can be easily detected without reducing the step width and shortening the measurement interval. can do. Therefore, if the contrast value is measured with the step width kept small, there is a problem that a useless measurement time is generated and the measurement time becomes long.

  For this reason, the projector device 2 of the present embodiment measures the distance from the projector device 2 to the screen 1 by at least one of the first line type passive distance measuring device 30 and the second line type passive distance measuring device 40. Based on the obtained distance measurement data, that is, the distance to the screen 1, the step width, which is the movement interval of the projection lens optical system 8, and the sampling interval of the sensor data output from the light receiving sensor 21 are set to optimum values. Thus, the focal point is detected more efficiently.

  Next, the operation procedure of this embodiment will be described with reference to the flowchart shown in FIG. In this procedure, the case where the step width of the projection lens optical system 8 is adjusted according to the distance measurement data will be described. However, even if the sampling interval of the sensor data is adjusted, the same procedure can be used. it can. First, the distance from the projector device 2 to the screen 1 is measured by one or both of the first line type passive distance measuring device 30 and the second line type passive distance measuring device 40 (step S1). In this embodiment, the first line-type passive distance measuring device 30 and the second line-type passive distance measuring device 40 for correcting the trapezoidal distortion by obtaining the tilt of the screen 1 are used as the distance measuring device. A passive or active distance measuring device may be provided separately.

  Next, when the distance to the screen 1 is measured by the distance measuring device, the control circuit 5 compares the distance measurement data with a preset reference value (step S2). When the distance measurement data is larger than the reference value (step S2 / YES), the step width of the next hill-climbing autofocus to be performed is set to A. If the distance measurement data is smaller than the reference value (step S2 / NO), the hill-climbing autofocus step width is set to B (step S4). Since the step width A is set larger than the step width B, when the distance to the screen is short, detailed measurement can be performed by shortening the movement interval of the projection lens optical system 8. Further, when the distance to the screen is long, the movement time of the projection lens optical system 8 can be increased to shorten the measurement time.

  An image is projected on the screen 1 while moving the projection lens optical system 8 with the set step width, and hill-climbing autofocus is performed (step S5). Details of the hill-climbing autofocus will be described with reference to the flowchart shown in FIG. In hill-climbing autofocus, an image pattern is projected onto the screen 1 while moving the projection lens optical system 8 from the initial position shown in FIG. This is a focus detection method in which the reflected light of this image pattern is received by the light receiving sensor 21 to obtain a contrast value, the measured contrast value is compared, and the projection lens optical system 8 is moved to a position (Max_cont) having the largest value. . The initial position is a position where the focal length of the projection lens optical system 8 is infinity, and the nearest position is a position where the focal length of the projection lens optical system 8 is closest.

  First, the projection lens optical system 8 is driven to the initial position by the optical system drive unit 9, and the area of the memory unit 10 that stores the measurement result is initialized (step S10). Information to be initialized includes a contrast value (cont) calculated by the automatic focus detection device 20, a contrast value (Max_cont) having the maximum value among the calculated contrast values, and from the initial position to the Max_cont position. Information on the number of steps.

  Next, an image pattern for autofocus suitable for automatic focus adjustment stored in advance in the projector 2 is projected onto the screen 1 by the projection lens optical system 8 (step S11).

  Next, the projection lens optical system 8 is moved from the initial position (position where the focal length is infinite) by the optical system driving unit 9 such as a stepping motor by the step width set in step S3 or S4 (start of feeding). At the same time, the light receiving sensor 21 receives the reflected light of the image pattern projected on the screen 1 (step S12). The light receiving sensor 21 outputs an electrical signal (sensor data) corresponding to the received reflected light amount to the calculation unit 22 at the subsequent stage (step S13). The electric signal (sensor data) from the light receiving sensor 21 is subjected to filter processing, A / D conversion processing, integration processing, and the like by the calculation unit 22 (step S14), and the contrast value (cont) of the image is calculated (step S15). ). The calculated contrast value (cont) is output to the control circuit 5.

  The control circuit 5 determines whether or not the contrast value (cont) calculated by the calculation unit 22 is larger than the maximum contrast value (Max_cont). The maximum contrast value (Max_cont) is the maximum value among the contrast values obtained before the calculated contrast value. If the calculated contrast value (cont) is larger than the maximum contrast value (Max_cont) (step S16 / YES), the contrast value (cont) is replaced as the maximum contrast value (Max_cont), and the number of steps up to this position (initial value) (When the position is counted as 0) is registered in the memory unit 10 (step S17). If the calculated contrast value is smaller than the maximum contrast value (Max_cont) (step S16 / NO), processing for this contrast value is performed. Exit.

  Next, the control circuit 5 checks whether or not the number of steps for driving the stepping motor has reached a preset number of steps (step S18). Since the number of steps for driving the projection lens optical system 8 from the initial position to the nearest position is determined in advance, it is determined whether or not the current number of driving steps has reached the number of steps up to this nearest position. If not reached (step S18 / NO), the contrast value is calculated from the electrical signal corresponding to the reflected light intensity output from the light receiving sensor 21, and the procedure of comparing with the maximum contrast value (Max_cont) is repeated.

  When the current number of driving steps reaches the number of steps up to the nearest position (step S18 / YES), the measurement of the contrast value is finished, and control is performed to move the projection lens optical system 8 to the detected Max_cont position. (Step S19).

  Next, a second embodiment of the present invention will be described with reference to the accompanying drawings. In the above embodiment, the distance to the screen 1 is first measured using the passive distance measuring device. However, when the projection lens optical system 8 is not focused on the screen 1, the distance measurement data of the passive distance measuring device. Therefore, the accuracy of adjusting the step width based on the distance measurement data may be reduced. In this embodiment, first, the projection lens optical system 8 is moved from the initial position where the focal length of the lens is infinite to the nearest position where the focal length is the closest, and the first hill-climbing autofocus is performed. This hill-climbing autofocus uses a preset value for the step width and sampling interval to specify a rough focus position. Next, the distance to the screen 1 is measured using the first line type passive distance measuring device 30 or the second line type passive distance measuring device 40. The distance measurement data obtained by the distance measuring apparatus is compared with a reference value. If the distance measurement data is larger than the reference value, the step width of the next detailed detection to be performed is set to A. If the distance measurement data is smaller than the reference value, the step width of the next detail detection to be performed is set to B. The values of A and B are set such that A> B as in the first embodiment described above.

  Further, in the detailed detection performed at the second time, as shown in FIG. 10, the projection lens optics is used within a predetermined range before and after the in-focus position with the in-focus position roughly specified by the first hill-climbing autofocus as a reference point. The system 8 is moved again to make a detailed measurement. When there is a distance to the screen (the distance measurement data is larger than the reference value), the setting value A that is set larger (or longer) than the step width and sampling interval used during the first hill-climbing autofocus is set. use. In addition, when the distance to the screen 1 is short (the distance measurement data is smaller than the reference value), the value is set smaller (or shorter) than the step width and sampling interval used in the first hill-climbing autofocus. Set value B is used. When the distance to the screen 1 is long, the depth of focus becomes deep and the range in which the projected image is focused is widened. Therefore, there is no problem that the focused point cannot be detected even if the set value A is used. On the contrary, when the distance to the screen 1 is short, the depth of focus becomes shallow, and the range in which the projected image is focused becomes narrow. Therefore, detailed focus detection is performed using the setting value B. The direction in which the projection lens optical system 8 is returned from the in-focus position to the initial position side is referred to as the retraction direction, and the direction in which the projection lens optical system 8 is advanced from the in-focus position to the closest position is referred to as the extension direction (see FIG. 10).

  As described above, in this embodiment, the approximate position of the in-focus point is obtained by the first hill-climbing autofocus, and the second detail detection is executed only within a predetermined range before and after the in-focus position. Therefore, it is possible to improve the detection accuracy of the in-focus position and reduce the time required for the second detailed detection. Further, since rough hill-climbing autofocus is performed prior to passive distance measurement, distance measurement data with higher accuracy can be obtained, and the step width can be set with higher accuracy than in the above-described embodiment.

  Next, the operation procedure of this embodiment will be described with reference to the flowchart shown in FIG. First, the projection lens optical system 8 is driven from the initial position to the nearest position, and a rough focus position is obtained by hill-climbing autofocus (step S20). Details of the hill-climbing autofocus have already been described in the first embodiment, and a description thereof will be omitted. Next, the distance from the projector device 2 to the screen 1 is measured using at least one of the first line type passive distance measuring device 30 and the second line type passive distance measuring device 40 (step S21). The control circuit 5 compares the distance measurement data from the distance measuring device with a preset reference value, and determines the step width of detail detection to be performed next (step 22). When the distance measurement data is larger than the reference value (step S22 / YES), the step width of the detailed detection is set to A. If the distance measurement data is smaller than the reference value (step S22 / NO), the detail detection step width is set to B (step S24).

  Next, the projection lens optical system 8 is moved by the determined step width to perform detailed detection (step 25). The detailed detection procedure will be described with reference to the flowchart shown in FIG. When the driving from the initial position to the nearest position is completed in the first hill-climbing autofocus (step S20), the projection lens optical system 8 determines the Max_cont position where the contrast value is maximum (determined as the focal point in the first hill-climbing autofocus Position). Using the Max_cont position as a reference point, the projection lens optical system 8 is moved to a feeding direction and a predetermined range in the feeding direction to perform detailed detection.

  First, from the Max_cont position detected by the first hill-climbing autofocus, the projection lens optical system 8 is advanced toward the nearest position by a predetermined number of steps (Ni_max). Then, when the projection lens optical system 8 is extended, the contrast data is measured again (step S30). The maximum contrast value detected by the detailed detection in the feeding direction is referred to as Max_contI. Further, the number of steps from the Max_cont position to the position where Max_contI is measured is defined as a Nip step.

  Similarly, from the Max_cont position, the projection lens optical system 8 is moved toward the infinity focal position by a predetermined number of steps (Nr_max). Then, when the projection lens optical system 8 is retracted, contrast data is measured again (step S31). The maximum contrast value detected by the detailed detection in the retraction direction is referred to as Max_contR. Further, the number of steps from the Max_cont position to the position where Max_contR is measured is defined as an Nrp step.

  The maximum contrast value (Max_contI) detected by the detailed detection in the feeding direction is compared with the maximum contrast value (Max_contR) detected by the detailed detection in the feeding direction (step S32), and a larger contrast value is projected to the measured position. The lens optical system 8 is moved (Nip step extension or Nrp step extension) (step S33 or step S34).

  Next, details of the above-described feeding direction detail detection (step S30) will be described with reference to the flowchart shown in FIG. First, initialization is performed, and Max_contI, cont, NiP, and n recorded in the memory unit 10 are set to zero (step S41). Max_contI is a detailed measurement in the feeding direction shown in FIG. 10 and records the maximum contrast value. “cont” records the contrast value calculated by the detailed measurement in the feeding direction, and “NiP” records the number of steps when the contrast value is maximum. N is a counter value of a counter that counts the number of steps for driving the stepping motor.

  First, the projection lens optical system 8 is advanced toward the focal position by one step, and 1 is added to n (step S42). Next, the reflected light of the image projected on the screen 1 from the projection lens optical system 8 is received by the light receiving sensor 21, and an electrical signal (sensor data) corresponding to the received light amount of the received reflected light is output (step). S43). This electrical signal is sent to the calculation unit 22, and subjected to filter processing, A / D conversion processing, integration processing, and the like (step S44), and the contrast value of the image is calculated (step S45).

  The control circuit 5 inputs the contrast value calculated by the calculation unit 22, and compares this contrast value (cont) with Max_contI (step S46). Max_contI is a record of the contrast value having the maximum value among the previously measured contrast values. If cont is larger (step S46 / YES), cont is substituted for Max_contI and n is substituted for NiP (step S47).

  Then, it is determined whether n has reached the Ni_max value (step S48). Ni_max defines the width of detail detection in the feeding direction.

  If cont is smaller than Max_contI (step S46 / NO), it is determined whether n has reached the maximum number of feeding steps Ni_max without performing processing for the held cont (step S48).

  When the n value has reached the maximum extension step number Ni_max (step S48 / YES), the projection lens optical system 8 is returned to the initial position direction by Ni_max, and the contrast value is maximized by the first hill-climbing autofocus. Return to the Max_cont position (step S49).

  Next, details of the above-described retraction direction detail detection (step S31) will be described with reference to the flowchart shown in FIG. First, initialization is performed, and Max_contR, cont, NrP, and n recorded in the memory unit 10 are set to zero (step S51). Max_contR is a detailed measurement in the retraction direction shown in FIG. 3 and records the maximum contrast value. “cont” records the contrast value calculated by the detailed measurement in the retraction direction, and “NrP” records the number of steps when the contrast value is maximum. N is a counter value of a counter that counts the number of steps for driving the stepping motor.

  First, the projection lens optical system 8 is moved in the initial position direction by one step, and 1 is added to n (step S52). Next, the reflected light of the image projected on the screen 1 from the projection lens optical system 8 is received by the light receiving sensor 21, and an electrical signal (sensor data) corresponding to the received light amount of the received reflected light is output (step). S53). This electrical signal (sensor data) is sent to the calculation unit 22, subjected to filter processing, A / D conversion processing, integration processing, and the like (step S54), and the contrast value of the image is calculated (step S55).

  The control circuit 5 inputs the contrast value calculated by the calculation unit 22, and compares this contrast value (cont) with Max_contR (step S56). Max_contR is a record of the contrast value having the maximum value among the previously measured contrast values. If cont is larger (step S56 / YES), cont is substituted for Max_contR and n is substituted for NrP (step S57).

  Then, it is determined whether n has reached Nr_max (step S58). Nr_max defines the width of detail detection in the retraction direction.

  If cont is smaller than Max_contR (step S56 / NO), it is determined whether or not n has reached the maximum number of retraction steps Nr_max without performing processing for the held cont (step S58).

  When n has reached the maximum number of retraction steps Nr_max (step S58 / YES), the projection lens optical system 8 is returned to the closest focus position direction by Nr_max, and the contrast value is maximized by the first hill-climbing autofocus. Return to the Max_cont position (step S59).

  The contrast value of the detailed measurement in the feeding direction calculated in this way is compared with the contrast value of the detailed measurement in the feeding direction. As a result of comparison, the projection lens optical system 8 is moved to this focal position, with the one having the larger contrast value as the true focal position.

  In the first and second embodiments described above, the automatic focus detection device 20 that outputs a contrast value for determining the focus position of the projection lens optical system 8 and the relative inclination angle of the screen 1 with respect to the projector 2. Are separately provided with the first and second line-type passive distance measuring devices 30 and 40 that accurately measure in the horizontal plane and the vertical plane.

  In this embodiment, as shown in FIG. 15, one of the first and second line type passive distance measuring devices 30 and 40 has the function of the automatic focus detection device 20 of the first embodiment and the second embodiment. It is Since the line sensors are used for the imaging units 31 and 41 of the first and second line-type passive distance measuring devices 30 and 40, the calculation unit 32 or 42 calculates the output of any one of the line sensors. The image contrast value is output. The control circuit 5 detects the position where the contrast value is maximized based on the contrast value output from one of the first and second line-type passive distance measuring devices 30 and 40, and outputs the position from the projection lens optical system 8. Alignment is performed so that the image is projected onto the screen 1. In addition, the position where the contrast value is maximized is detected from the contrast value output from one of the first and second line type passive distance measuring devices 30 and 40 also in the detailed measurement.

  As described above, in this embodiment, the focus detection function for detecting the focus position of the projection light is provided in the distance measuring device, so that the number of components can be reduced and the configuration of the projector can be simplified.

  The above-described embodiment is a preferred embodiment of the present invention. However, the present invention is not limited to this, and various modifications can be made without departing from the scope of the present invention.

  For example, in the second embodiment described above, the projection lens optical system 8 is driven from the initial position to the nearest position, hill-climbing autofocusing is performed, and the in-focus position is roughly specified, and then the second detail detection is performed. The rough focus position may be specified based on distance measurement data measured by the distance measuring device. In this case, the distance to the screen is measured by a phase difference detection method by a pair of line sensors mounted on the first line type passive distance measuring device 30 and the second line type passive distance measuring device 40. Based on the obtained distance measurement data, the projection lens optical system 8 is moved in the optical axis direction so that the focal length of the projection lens optical system 8 becomes the distance measured. Even if the in-focus position is specified by such a procedure, the same effect as the above-described embodiment can be obtained. Note that the phase difference detection method using a pair of line sensors has already been described in the first embodiment, and will not be described.

  In the first and second embodiments described above, the procedure for adjusting the step width of the projection lens optical system 8 according to the distance to the screen 1 has been described. However, sensor data output from the light receiving sensor 21 is described. The same effect can be obtained even if the sampling interval for acquiring the is set.

  In the above-described embodiment, a stepping motor is used as the optical system driving unit 9 and the step width is adjusted according to the distance to the screen 1. However, a DC motor may be used as the optical system driving unit 9. In this case, if the projection lens optical system 8 is driven at a constant speed and the energization time of the DC motor is adjusted according to the distance to the screen 1, the same effect as in the above embodiment can be obtained.

  In the above-described embodiment, the projection lens optical system 8 is driven from the infinity position (initial position) to the nearest position during hill-climbing autofocus. However, the projection position may be driven to the infinity position using the nearest position as the initial position. .

  In the above-described embodiment, only one reference value is provided and compared with distance measurement data. However, a plurality of reference values are provided to compare distance measurement data with these reference values. Also good. In this case, since the step width or the sampling interval can be set in more detail according to the value of the distance measurement data, a highly accurate autofocus function can be realized.

It is a block diagram which shows the structure of the projector apparatus 2 of 1st Example. 2 is a diagram illustrating a configuration of an automatic focus detection device 20. FIG. It is a figure for demonstrating hill-climbing autofocus. It is a figure which shows the structure which looked at the projector apparatus from the front. (A) is a figure for demonstrating the inclination angle with respect to the horizontal direction of the screen 1, (B) is a figure for demonstrating the inclination angle with respect to the vertical direction of the screen 1. FIG. It is the figure which showed a mode that a screen distance-measures with a passive ranging device. It is a figure for demonstrating a depth of focus. It is a flowchart which shows the operation | movement procedure of 1st Example. It is a flowchart which shows the operation | movement procedure of hill-climbing autofocus. It is a figure which shows the outline of operation | movement of the projector apparatus of 2nd Example. It is a flowchart which shows the operation | movement procedure of 2nd Example. It is a flowchart which shows the processing procedure of detail detection. It is a flowchart which shows the procedure of the detailed detection of a feeding direction. It is a flowchart which shows the procedure of the detailed detection of a retraction | saving direction. It is a block diagram which shows the structure of the projector apparatus of 3rd Example. It is a figure which shows the structure of the conventional imaging device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Screen 2 Projector apparatus 5 Control circuit 6 Projection image generation part 7 Display drive part 8 Projection lens optical system 9 Optical system drive part 10 Memory part 20 Automatic focus detection apparatus 21 Light reception sensor 22 Calculation part 30 1st line type passive ranging device 31 Imaging unit 40 Second line type passive distance measuring device 41 Imaging unit

Claims (6)

The reflected light of the image projected on the screen is received by the light receiving element while moving the projection lens optical system at a predetermined movement interval, and the output signal of the light receiving element is acquired at the predetermined acquisition interval, and based on the output signal A projector apparatus that performs a focus detection process for specifying a position where a focus of the projection lens optical system is aligned with the screen;
Based on distance measurement data up to the screen that has been measured, at least one of the movement interval and the acquisition interval is set, the focus detection process is performed at the set interval, and the focus of the projection lens optical system is applied to the screen. A projector device comprising control means for specifying an in-focus position. The reflected light of the image projected on the screen is received by the light receiving element while moving the projection lens optical system at a predetermined movement interval, and the output signal of the light receiving element is acquired at the predetermined acquisition interval, and based on the output signal A projector apparatus that performs a focus detection process for specifying a position where a focus of the projection lens optical system is aligned with the screen;
The projection lens optical system is set within a predetermined range before and after the in-focus point specified by the focus detection process by setting at least one of the movement interval and the acquisition interval based on the distance measurement data up to the screen. And a control means for specifying the position where the focal point of the projection lens optical system matches the screen. The control means compares the distance measurement data with a threshold value, and if the distance measurement data is larger than the threshold value, at least one of the movement interval and the acquisition interval is set longer than a reference value. And
3. The projector device according to claim 1, wherein when the distance measurement data is smaller than the threshold value, at least one of the movement interval and the acquisition interval is set shorter than the reference value. . The reflected light of the image projected on the screen is received by the light receiving element while moving the projection lens optical system at a predetermined movement interval, and the output signal of the light receiving element is acquired at the predetermined acquisition interval, and based on the output signal A focus detection method for specifying a position where a focus of the projection lens optical system is aligned with the screen,
At least one of the movement interval and the acquisition interval is an interval set based on distance measurement data up to the screen that has been measured. The reflected light of the image projected on the screen is received by the light receiving element while moving the projection lens optical system at a predetermined movement interval, and the output signal of the light receiving element is acquired at the predetermined acquisition interval, and based on the output signal A first focus detection step for specifying a position where the projection lens optical system is focused on the screen;
The projection lens optical system is set within a predetermined range before and after the in-focus point specified by the focus detection process by setting at least one of the movement interval and the acquisition interval based on the distance measurement data up to the screen. And a second focus detection step of performing a focus detection process again to specify a position where the focus of the projection lens optical system matches the screen. If the distance measurement data is larger than the threshold value, set at least one of the movement interval and the acquisition interval longer than a reference value,
6. The focus according to claim 4, wherein when the distance measurement data is smaller than the threshold value, at least one of the movement interval and the acquisition interval is set shorter than the reference value. Detection method.

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