JP4475929B2 - Projection display device - Google Patents

Description

  The present invention relates to a projection display apparatus such as a liquid crystal projector.

Adjustment contents of the setting at the time of projection of the projection display apparatus include focus adjustment of the projected image and keystone distortion correction (see Patent Document 1).
JP 2003-78842 A

  By the way, in order to perform the focus adjustment and the trapezoidal distortion correction described above, the projection display apparatus projects a stripe image in which white lines and black lines are alternately arranged as an adjustment image, and this stripe image is applied to the image sensor. It is conceivable to obtain an output signal of the image sensor corresponding to the white line position and the black line position. In this case, in order for focus adjustment and trapezoidal distortion correction to be performed accurately, it is necessary that the image for adjustment has no distortion, but the image distortion is completely eliminated due to the lens distortion existing in the projection lens. It is difficult to lose.

  In view of the above circumstances, an object of the present invention is to provide a projection display apparatus that can accurately perform focus adjustment and trapezoidal distortion correction even when an adjustment image is distorted.

In order to solve the above-described problem, the projection display apparatus according to the present invention is a projection display apparatus that modulates light emitted from a light source with a light modulation element and enlarges and projects an image with a projection lens. A sensor unit including an image sensor that captures the enlarged image, and means for performing focus adjustment and / or trapezoidal distortion correction based on the output of the sensor unit, and the center of the light modulation element is projected The position is shifted with respect to the optical axis of the lens, and the image pickup device picks up an image at a position deviated from the center of the image to be enlarged and projected.

  In general, a projection lens often has lens distortion in a donut shape range between the center and the periphery of the projection lens. In the configuration in which the center of the light valve is displaced with respect to the optical axis of the projection lens, the influence of the lens distortion is present. This tends to occur at the center of the adjustment video. In the projection display apparatus having the above-described configuration, the line-shaped image sensor is attached so that the line to be imaged deviates from the center of the projected image. Adjustment and trapezoidal distortion correction can be performed accurately.

  As described above, according to the present invention, the line-shaped imaging device is attached so that the imaging target line deviates from the center of the projected image, so that it is possible to avoid imaging of a distorted image portion and focus. There is an effect that adjustment and keystone distortion correction can be performed accurately.

  A liquid crystal projector according to an embodiment of the present invention will be described below with reference to FIGS.

  FIG. 1 is a view showing a three-plate liquid crystal projector 30 of this embodiment. The light emitting part in the light source 1 is composed of an ultra-high pressure mercury lamp, a metal halide lamp, a xenon lamp or the like, and the irradiation light is emitted as parallel light by a parabolic reflector and guided to the integrator lens 4.

  The integrator lens 4 is composed of a pair of lens groups (fly eye lenses) 4a and 4b, and each lens portion guides light emitted from the light source 1 to the entire surface of a liquid crystal light valve to be described later. The partial luminance unevenness existing in the light source 1 is averaged, and the light amount difference between the center of the screen and the peripheral portion is reduced. The light passing through the integrator lens 4 is guided to the first dichroic mirror 7 after passing through the polarization conversion device 5 and the condenser lens 6.

  The polarization conversion device 5 is configured by a polarization beam splitter array (hereinafter referred to as a PBS array). The PBS array includes a polarization separation film and a phase difference plate (1 / 2λ plate). Each polarization separation film of the PBS array passes, for example, P-polarized light out of the light from the integrator lens 4 and changes the optical path of S-polarized light by 90 °. The optically polarized S-polarized light is reflected by the adjacent polarization separation film and emitted as it is. On the other hand, the P-polarized light transmitted through the polarization separation film is converted into S-polarized light by the retardation plate provided on the front side (light emitting side) and emitted. That is, in this case, almost all light is converted to S-polarized light.

  The first dichroic mirror 7 transmits light in the red wavelength band and reflects light in the cyan (green + blue) wavelength band. The light in the red wavelength band that has passed through the first dichroic mirror 7 is reflected by the reflection mirror 8 to change the optical path. The red light reflected by the reflection mirror 8 is light-modulated by passing through a lens 9 and a transmissive liquid crystal light valve 31 for red light. On the other hand, the light in the cyan wavelength band reflected by the first dichroic mirror 7 is guided to the second dichroic mirror 10.

  The second dichroic mirror 10 transmits light in the blue wavelength band and reflects light in the green wavelength band. The light in the green wavelength band reflected by the second dichroic mirror 10 is guided to the transmissive liquid crystal light valve 32 for green light through the lens 11 and is modulated by being transmitted therethrough. The light in the blue wavelength band that has passed through the second dichroic mirror 10 is guided to the blue-light transmissive liquid crystal light valve 33 through the total reflection mirror 12, total reflection mirror 13, and lens 14, and is transmitted therethrough. It is optically modulated.

  Each of the liquid crystal light valves 31, 32, 33 includes a panel portion 31b, in which liquid crystal is sealed between an incident-side polarizing plate 31a, 32a, 33a and a pair of glass substrates (with pixel electrodes and alignment films formed). 32b, 33b and output side polarizing plates 31c, 32c, 33c.

  The modulated light (each color video light) modulated by passing through the liquid crystal light valves 31, 32, 33 is synthesized by the cross dichroic prism 15 to become color video light. The color image light is enlarged and projected by the projection lens 16 and displayed on the screen 40 (see FIG. 4).

  The projection lens 16 includes a focus motor (lens driving motor) 22 for focus adjustment. When a feed direction drive signal is given to the focus motor 22 from a microcomputer 25 (described later), the lens moves in the feed direction, and when a pull direction drive signal is given to the focus motor 22, the lens is driven in the draw direction. The

  FIG. 2 is a block diagram showing an outline of the signal processing system of the liquid crystal projector 30. The video signal processing circuit 23 inputs a video signal and performs processing such as resolution conversion and image enlargement / reduction, and also executes image processing for trapezoidal distortion correction based on a command from the microcomputer 25. Each of the panel drivers 24R, 24G, and 24B supplies (drives) a video signal (video data) to the liquid crystal light valve.

  The operation unit (or remote control transmitter) 27 is provided with keys for various operations. In this embodiment, an adjustment instruction key for instructing focus adjustment and trapezoidal distortion correction is provided as the key.

  An OSD (On Screen Display) circuit 28 generates video data based on character information and graphic information instructed to be output from the microcomputer 25, and writes this video data in the image memory 21. The OSD circuit 29 can project an image created on the device side other than the input image.

  The sensor 29 includes a first sensor unit 29A and a second sensor unit 29B. As shown in FIG. 3, each sensor unit 29A (29B) includes two lens units 29a and a CCD line sensor 29b provided corresponding to each lens unit 29a. The CCD line sensor 29b is formed long in the direction in which the lens portions 29a are arranged. As such a sensor part 29A (29B), the sensor currently disclosed by Unexamined-Japanese-Patent No. 2002-213946 or Unexamined-Japanese-Patent No. 2003-57531 can be utilized.

  The first sensor unit 29A is arranged so that the lens units 29a and 29a are arranged in the vertical direction, and the second sensor unit 29B is arranged so that the lens units 29a and 29a are arranged in the horizontal direction.

  The microcomputer 25 samples the imaging signal of the sensor 29 to generate imaging data, and calculates contrast data and angle data. The contrast data is a signal indicating the degree of the high frequency component on the image pickup signal output from the CCD line sensor 29b. The higher the high frequency component is obtained on the image pickup signal, the more the focus state is indicated. The angle data includes first angle data θ1 (see FIG. 4A) indicating the degree of vertical trapezoidal distortion obtained by the first sensor unit 29A, and lateral trapezoidal distortion obtained by the second sensor unit 29B. There is second angle data θ2 (see FIG. 4B) indicating the degree of.

  The angle data can be obtained by a calculation process based on a distance measurement result from the sensor 29 to the adjustment projection image (screen 40). The distance measurement is performed by so-called triangulation, and is obtained from the relative shift (phase difference) of the captured image on each CCD line sensor 29b of the sensor unit 29A (29B), the lens focal length, and the inter-lens distance. Can do. The distance measurement can be performed for each of a plurality of areas in the imaging range of the adjustment projection image. That is, it is possible to divide the field angle range of the CCD line sensor 29b into a plurality of areas and calculate a distance measurement result for each distance measurement area. For example, distance measurement is performed for each of the uppermost area and the lowermost area (the leftmost area and the rightmost area) of the adjustment projection image. The difference in distance measurement between the top and bottom areas (the left and right areas) is a large value corresponding to the non-verticality between the projection optical axis and the screen. The angle data (θ1, θ2) can be calculated by obtaining the arctangent from the difference between the distance between the areas (the leftmost area and the rightmost area) and the distance measurement value.

  The microcomputer 25 performs overall control in the liquid crystal projector 30. In particular, as control according to the present invention, adjustment control of the setting at the time of projection shown below is performed.

  After the power is turned on, the user waits for the light source to enter a sufficient light emitting state, and then presses the adjustment instruction key on the operation unit 27. When the microcomputer 25 detects that the adjustment instruction key is pressed, the OSD circuit 28 executes a drawing process of the first adjustment projection video (image data writing to the image memory 21). As shown in FIG. 5A, the first adjustment projection image is a stripe image in which white horizontal line regions and black horizontal line regions are alternately formed.

  Further, the microcomputer 25 gives a feeding direction drive signal to the focus motor 22 and samples the image pickup signal of the sensor 29 to generate contrast data. When starting the sampling, the microcomputer 25 starts a timer, generates contrast data at a constant time interval, and stores it in a memory (not shown). The microcomputer 25 determines the best contrast data, and acquires time information (focusing lens position information) when the contrast data is obtained. The microcomputer 25 gives a pull-in direction drive signal to the focus motor 22 for a time obtained by subtracting the time information from the total time when the feed-out direction drive signal is given to the focus motor 22. Thereby, focus adjustment is realized.

  Further, the microcomputer 25 performs trapezoidal distortion correction based on the image data of the sensor 29. The trapezoidal distortion includes a vertical trapezoidal distortion and a horizontal trapezoidal distortion. First, in the first adjustment projection image shown in FIG. 5A, the acquisition processing of the angle data θ1 for correcting the vertical trapezoidal distortion is performed. Do. That is, the microcomputer 25 employs the output of the first sensor unit 29A, performs distance measurement for each of the uppermost area and the lowermost area of the adjustment projection image, and calculates the distance between the uppermost area and the lowermost area and the distance measurement value. The angle data θ1 is calculated from the difference. Next, the microcomputer 25 executes a drawing process of the second adjustment projection image by the OSD circuit 28. As shown in FIG. 5B, the second adjustment projection image is a stripe image in which white vertical line areas and black vertical line areas are alternately formed.

  The microcomputer 25 employs the output of the second sensor unit 29B, performs distance measurement for each of the leftmost area and the rightmost area of the adjustment projection image, and calculates the distance between the leftmost area and the rightmost area and the distance measurement value. Angle data θ2 is calculated from the difference.

  The microcomputer 25 performs trapezoidal distortion correction based on the first angle data θ1 and the second angle data θ2. The angle and the degree of trapezoidal distortion are in a proportional relationship. If the angle is known, it can be determined how much correction should be performed on the image. For example, the video signal processing circuit 23 receives the angle data from the microcomputer 25 and performs pixel interpolation of the input video data so as to have a trapezoidal distortion that is opposite to the trapezoidal distortion that is assumed to be generated by projection at the angle. / Execute pixel thinning processing.

  Here, the relationship among the liquid crystal light valve (31, 32, 33), the projection lens 16, and the projected image is shown in FIG. In the projection display apparatus 30, the center of the light valve (31, 32, 33) is shifted from the optical axis of the projection lens 16, and the relationship between the area that can be displayed by the projection lens 16 and the display area is as follows: As shown in FIG. In general, the projection lens 16 often has lens distortion in a donut shape range between its center and periphery. For this reason, the influence of the lens distortion tends to occur on the center side of the adjustment image. The sensor 29 is attached to a front cover (not shown), and the center axis of the imaging is designed to be parallel to the optical axis of the projection lens 16 by design, and the attachment surface of the sensor 29 is formed so as to ensure this parallelism. The In this embodiment, a spacer is interposed between the second sensor 29B and the mounting surface on the front cover, and the second sensor 29B is inclined downward with respect to the mounting surface by this spacer. Due to this downward inclination, the imaging target position (stagnation direction) of the second sensor 29B is below the center of the projected image.

  As described above, the influence of lens distortion tends to occur on the center side of the adjustment image. However, the imaging target position (stagnation direction) of the second sensor 29B is lower (upper case) than the center of the adjustment projection image. In other words, it is possible to avoid image capturing of a distorted video portion, and to accurately perform focus adjustment and trapezoidal distortion correction even when the adjustment video is distorted.

  In the above example, the central axis of imaging of the second sensor 29B is designed to be parallel to the optical axis of the projection lens 16, and a spacer is interposed between the second sensor 29B and the mounting surface on the front cover. . Here, in the trial of determining the thickness of the spacer, first, the projection of the adjustment image and the correction of the trapezoidal distortion are attempted without the spacer. Then, the second sensor 29B is tilted downward or upward little by little to grasp the tilt when the best correction result or sensor output is obtained, and the thickness of the spacer matching this tilt is determined. In the mass production shipment stage of the same model of the projection type image display device 30, the sensor inclination is not adjusted for each of the projection type image display devices 30, but the second sensor 29 </ b> B is applied by uniformly applying the determined thickness spacer. Attach to 30.

  The spacer is not limited to setting the inclination of the second sensor 29B. By forming the sensor mounting surface so that the central axis of imaging of the second sensor 29B is non-parallel to the optical axis of the projection lens 16 by design, the imaging direction (stagnation direction) of the second sensor 29B is for adjustment. It may be located below or above the center of the projected image. Also, the focus adjustment and trapezoidal distortion correction methods described above are not limited in any way, and any method may be used. Further, although a transmissive liquid crystal projector has been shown as a projection display apparatus, a reflective liquid crystal projector may be used, and the present invention is not limited to a liquid crystal projector. It is good also as a type | mold video display apparatus. In this embodiment, the microcomputer 25 that performs overall control in the liquid crystal projector 30 performs adjustment control of the above-described setting during projection. However, a dedicated microcomputer is provided in the sensor 29, and focus adjustment and The microcomputer 25 may perform processing such as calculation of angle data, and the microcomputer 25 may allocate processing capacity for other processing. Further, the present invention is not limited to displaying the first adjustment video and the second adjustment video separately.

1 is a configuration diagram showing an optical system of a liquid crystal projector of an embodiment of the present invention. It is the block diagram which showed the signal processing system of the liquid crystal projector. It is a schematic block diagram of a sensor. FIG. 4A is an explanatory diagram showing how vertical trapezoidal distortion occurs, and FIG. 5B is an explanatory diagram showing how horizontal trapezoidal distortion occurs. FIG. 4A is an explanatory diagram showing that vertical trapezoidal distortion has occurred in the first adjustment projection image projected on the screen, and FIG. 4B shows the second image projected on the screen. It is explanatory drawing which showed that the horizontal trapezoid distortion had arisen in the projection image for adjustment. FIG. 4A is an explanatory diagram showing the relationship between the liquid crystal light valve, the projection lens, and the projected image, and FIG. 4B shows the relationship between the displayable area and the display area by the projection lens. It is explanatory drawing.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 16 Projection lens 22 Focus motor 23 Video signal processing circuit 25 Microcomputer (microcomputer)
28 On-screen display circuit (OSD circuit)
29 Sensor 30 Liquid crystal projector 31, 32, 33 Liquid crystal light valve

Claims (1)

In a projection display apparatus that modulates light emitted from a light source with a light modulation element and enlarges and projects an image with a projection lens,
A sensor unit having a that IMAGING element to image the image is enlarged and projected,
Means for performing focus adjustment and / or trapezoidal distortion correction based on the output of the sensor unit,
Projection center of the optical modulator is offset position with respect to the optical axis of the projection lens, before Symbol IMAGING element, wherein the position of the imaging to Turkey off the center of the image to be magnified and projected Type image display device.

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