JP2000180779A - Projector device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector device capable of correcting the trapezoidal direction of a projected image and making the number of display pixels per unit area nearly uniform. SOLUTION: This device is constituted to display an image by scanning light from a light source 1 and obliquely projecting the light to a screen. In such a case, the device is provided with a rectangular area segmenting means 12 for segmenting a rectangular image display area in a scanning area and a light emission control means 21 which inhibits light emission of the light source 1 for a specified pixel so that the number of display pixels per unit area in the rectangular image display area is nearly uniform, and controlling the light emission timing of the light source 1, so that the display position of the pixel is moved by a specified amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projector for projecting an image obliquely onto a screen, and more particularly to a projector capable of correcting trapezoidal distortion of a projected image.

[0002]

2. Description of the Related Art Conventionally, when an image is projected obliquely to a screen, a trapezoidal distortion occurs in the projected image on the screen. Producing projector devices have been proposed.

For example, JP-A-8-9306 and JP-A-8-79669 disclose a method of thinning out (or overwriting) a predetermined number of pixels of each horizontal line of a video signal in advance, and Discloses a technique for correcting a trapezoidal distortion by forming an image to be displayed on the image so as to cancel the trapezoidal distortion due to oblique projection.

[0004] That is, for example, when an image is projected on the screen from obliquely above, as shown in FIG.
The number of pixels in one horizontal line is reduced toward the lower side of the image, and a trapezoidal image having a shorter lower side is displayed on the liquid crystal panel. By projecting the display image of the liquid crystal panel on the screen, it is possible to obtain a projection image in which the lengths of the upper and lower sides are uniform, as shown in FIG.

[0005]

However, in the above-mentioned conventional projector device, the number of pixels in each horizontal line is variable, so that the projected image on the screen is, as shown in FIG. The upper line has a smaller number of display pixels and a partially different resolution, resulting in an unnatural image.

The present invention has been made in view of the above points, and provides a projector device capable of correcting trapezoidal distortion of a projected image and making the number of display pixels per unit area substantially uniform. The purpose is to do.

[0007]

According to a first aspect of the present invention, there is provided a projector apparatus for displaying an image by scanning light from a light source and projecting the light obliquely on a screen. A rectangular area cutout means for cutting out a rectangular image display area in the scanning area; and light emission for inhibiting light emission of the light source for predetermined pixels so that the number of display pixels per unit area in the rectangular image display area is substantially uniform. Control means.

Thus, a trapezoidal distortion of the projected image can be corrected to obtain a rectangular display image, and a predetermined number of pixels can be reduced in a portion having a high pixel density in the rectangular image display area. By prohibiting the light source from emitting light to the pixels, the number of display pixels per unit area can be made substantially uniform, and a natural projected image can be obtained with a simple configuration.

According to a second aspect of the present invention, there is provided a projector device for displaying an image by scanning light from a light source and projecting the light obliquely on a screen. A rectangular area cutout means for cutting out a display area, so that the number of display pixels per unit area in the rectangular image display area is substantially uniform,
A light emission control unit that controls light emission timing of the light source so as to prohibit light emission of the light source for a predetermined pixel and move a display position of the pixel by a predetermined amount is provided.

This makes it possible to obtain a rectangular display image by correcting the trapezoidal distortion of the projection image, and to reduce the number of display pixels in a portion where the pixel density is high in the rectangular image display area. By prohibiting light emission of the light source for the pixel and shifting the light emission timing of the light source for the pixel so as to shift the position of the display pixel by a predetermined amount, the number of display pixels per unit area can be made substantially uniform, It is possible to obtain a more natural projected image.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the projector device of the present invention will be described with reference to FIGS. Here, FIG. 1 is an explanatory diagram showing a schematic configuration of the projector device of the present embodiment, FIG. 2 is an explanatory diagram showing a relationship between a scanning region and a rectangular image display region in the projector device of the present embodiment, and FIG. FIG. 4 is a block diagram showing a trapezoidal distortion correction circuit in the projector device according to the embodiment.

FIG. 4 is an explanatory diagram showing scanning lines in a rectangular image display area in the projector of this embodiment. FIG. 5 is a diagram showing scanning positions in the rectangular image display area and pixels of an original image in the projector of this embodiment. FIG. 6 is an explanatory diagram showing a relationship with a position, and FIG. 6 is an explanatory diagram showing a display pixel position in a rectangular image display area in the projector device of the present embodiment.

As shown in FIG. 1, the projector device of this embodiment includes a point light source 1 such as an LED or a laser that emits light in accordance with an input video signal, a lens 2 that converges the light from the point light source 1, The polygon mirror 3 scans the light emitted from the lens 2 in the vertical direction (Y direction), and the reflected light from the polygon mirror 3 is reflected by the mirror 4 and then reflected in the horizontal direction (X direction).
(A direction).

The light from the point light source 1 is two-dimensionally scanned by two scanning optical systems 6 comprising a polygon mirror 3 and a galvanometer mirror 5, projected on a screen obliquely, and an image is displayed on the screen. Here, since the axis perpendicular to the screen surface is greatly inclined with respect to the projection optical axis,
The image display frame 7 on the screen, which is a scanning area, has a trapezoidal shape.

Therefore, as shown in FIG. 2, only the largest rectangular area included in the trapezoidal image display frame (scanning area) 7 is cut out and used as the rectangular image display area 8 to obtain the projected image. To prevent trapezoidal distortion. Further, by controlling the light emission of the point light source 1 so that the number of display pixels per unit area in the rectangular image display area 8 becomes substantially uniform, a natural projection image is obtained.

That is, in the projector device of the present embodiment, as shown in FIG. 3, the number of display pixels per unit area in the rectangular image display area 8 is made substantially uniform based on the input video signal. Light emission control unit 11 that generates a control signal for controlling light emission / non-light emission of point light source 1
Is provided.

Further, based on a synchronization signal for synchronizing the point light source 1 and the scanning optical system 6 output from the light emission control section 11, the scanning range (scanning start position, scanning end position, Position) is detected, and the rectangular image display area 8 is detected.
A rectangular image display area cut-out unit 12 for outputting a control signal for scanning to the scanning optical system 6 is provided.

Next, a method for displaying an image having a substantially uniform pixel density by using the rectangular image display area 8 cut out by the rectangular image display area cut-out section 12 will be described in detail. Here, in order to simplify the description, the ratio of the upper base to the lower base of the trapezoidal image display frame (scanning area) 7 is 1: 1.
2. Assume that the number of scanning lines scanning in the X direction is 33, and the number of scanning lines scanning in the Y direction is 22.

At this time, X in the rectangular image display area 8
As shown in FIG. 4, the number of scanning lines in the direction is 33 in the direction closest to the scanning optical system 6 and 17 in the direction farthest from the scanning optical system 6.
It becomes a book. Therefore, the resolution of the display image in the rectangular image display area 8 is adjusted to the number of scanning lines farthest from the scanning optical system 6.

As described above, when the resolution of a display image in the rectangular image display area 8 is unified to the number of scanning lines farthest from the scanning optical system 6, as shown in FIG. And the scanning position on the screen. Therefore, as shown in FIG. 6, the light emission / non-emission of the point light source 1 is controlled so that only the pixel on the scanning line closest to the pixel position shown in FIG. 5 is displayed and other pixels are not displayed.

Therefore, the light emission / non-light emission of the point light source 1
In a portion where the pixel density is high (a portion close to the scanning optical system 6) in the rectangular image display area 8, the number of display pixels decreases, and the number of pixels of the original image shown in FIG. 5 and the number of display pixels shown in FIG. Are the same. That is, the number of display pixels per unit area in the rectangular image display area 8 can be made substantially uniform, and a natural projection image can be obtained with a simple configuration.

In FIG. 6, for the sake of simplicity, the positions of the display pixels are shown under the condition that the number of scanning lines is small and the number of light emitted by the point light source 1 is small. Is noticeable, but by increasing the number of scanning lines and the number of light emitted by the point light source 1, the distortion of the displayed image becomes less noticeable.

In this embodiment, as shown in FIG. 6, the display pixel position on the scanning line in the X direction is fixed, and only the pixel to be displayed on the scanning line in the Y direction is selected. Yes, the processing amount can be reduced and the configuration can be simplified.

Furthermore, by shifting the light emission timing of the point light source 1, the position of the display pixel can be moved on the scanning line in the X direction so as to approach the pixel position of the original image shown in FIG. This will be described as a second embodiment of the projector device of the present invention with reference to FIGS. 7 and 8, but the same parts as those in the first embodiment will be denoted by the same reference numerals, and description thereof will be omitted.

FIG. 7 is a block diagram showing a trapezoidal distortion correction circuit in the projector of this embodiment, and FIG.
FIG. 3 is an explanatory diagram showing display pixel positions in a rectangular image display area in the projector device of the present embodiment.

As shown in FIG. 7, the projector device of the present embodiment is designed so that the number of display pixels per unit area in the rectangular image display area 8 cut out by the rectangular image display area cutout unit 12 becomes substantially uniform. And a light emission control unit 21 for controlling the light emission timing of the point light source 1 so as to prohibit the light emission of the point light source 1 for a predetermined pixel and to move the display position of the pixel by a predetermined amount.

That is, in this embodiment, as shown in FIG. 8, only the pixels on the scanning line closest to the pixel position of the original image shown in FIG. 5 are displayed, and the display position of the pixel is changed to the original image. The light emission timing of the point light source 1 is controlled so that the point light source 1 is moved on a scanning line that scans in the X direction so as to approach the pixel position.

Therefore, since the display pixel position can be moved in the X direction to be closer to the original image pixel position shown in FIG. 5, the number of display pixels per unit area in the rectangular image display area 7 can be increased. It can be made substantially uniform.

In the projector apparatuses of the first and second embodiments, the point light source 1 such as an LED or a laser is used as a light source. However, as shown in FIG. An array light source 31 arranged one-dimensionally may be used. In this case, the scanning optical system can be composed of only the galvanometer mirror 5 that scans the light emitted from the lens 2 in the horizontal direction (X direction).

That is, the array light source 31 in which the point light sources are arranged one-dimensionally can be considered as one scanning line in the vertical direction (Y direction). For example, the number of the point light sources is 33, and the trapezoidal image display frame is provided. (Scanning Area) When the ratio of the upper base to the lower base is 1: 2, the number of scanning lines in the X direction in the rectangular image display area 8 is the closest to the scanning optical system 6 as shown in FIG. 33, and 17 farthest from the scanning optical system 6.

Therefore, by adjusting the resolution of the display image in the rectangular image display area 8 to the number of scanning lines farthest from the scanning optical system 6, an array light source is provided in the same manner as in the first and second embodiments. The display pixels shown in FIGS. 6 and 8 can be obtained by selectively controlling light emission / non-light emission of the point light sources included in 31 and shifting the light emission timing of the point light sources by a predetermined amount.

[0032]

The projector device according to the first aspect of the present invention is configured as described above, so that trapezoidal distortion of a projected image can be corrected to obtain a rectangular display image, and a rectangular display image can be obtained. By prohibiting the light source from emitting light to predetermined pixels so as to reduce the number of display pixels in a portion where the pixel density is high in the image display area, the number of display pixels per unit area can be made substantially uniform, thus simplifying the operation. With a simple configuration, a natural projection image can be obtained.

The projector device according to the second aspect of the present invention can obtain a rectangular display image by correcting trapezoidal distortion of a projected image, and can obtain a rectangular display image in a portion having a high pixel density in a rectangular image display area. Light emission of the light source for a predetermined pixel is prohibited so as to reduce the number of display pixels, and the light emission timing of the light source for the pixel is shifted so that the display position of the pixel is moved by a predetermined amount, thereby displaying per unit area. The number of pixels can be made substantially uniform, and a more natural projected image can be obtained.

[Brief description of the drawings]

FIG. 1A is a top view and FIG. 1B is a side view showing a schematic configuration of a first embodiment of a projector device of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a scanning area and a rectangular image display area in the first embodiment of the projector device of the present invention.

FIG. 3 is a block diagram showing a trapezoidal distortion correction circuit in the first embodiment of the projector device of the present invention.

FIG. 4 is an explanatory diagram showing scanning lines in a rectangular image display area in the first embodiment of the projector device of the present invention.

FIG. 5 is an explanatory diagram showing a relationship between a scanning position in a rectangular image display area and a pixel position of an original image in the first embodiment of the projector device of the present invention.

FIG. 6 is an explanatory diagram showing display pixel positions in a rectangular image display area in the first embodiment of the projector device of the present invention.

FIG. 7 is a block diagram illustrating a trapezoidal distortion correction circuit according to a second embodiment of the projector device of the present invention.

FIG. 8 is an explanatory diagram showing display pixel positions within a rectangular image display area in a second embodiment of the projector device of the present invention.

9A is a top view and FIG. 9B is a side view showing a schematic configuration of another embodiment of the projector device of the present invention.

FIG. 10 is an explanatory diagram showing (a) a display image on a liquid crystal panel and (b) a projection image on a screen in a conventional projector device.

[Explanation of symbols]

 1 point light source 2 lens 3 polygon mirror 4 mirror 5 galvanometer mirror 6 scanning optical system 7 image display frame 8 rectangular image display area 11 light emission control unit 12 rectangular image display area cutout unit 21 light emission control unit 31 array light source

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G09G 3/34 G09G 3/34 J H04N 5/74 H04N 5/74 D

Claims (2)

[Claims] 1. A projector device for displaying an image by scanning light from a light source and projecting the light obliquely on a screen, wherein: a rectangular area cutout means for cutting out a rectangular image display area in a scanning area; A projector apparatus, comprising: light emission control means for prohibiting light emission of the light source for predetermined pixels so that the number of display pixels per unit area in an image display area is substantially uniform. 2. A projector device for displaying an image by scanning light from a light source and projecting the light obliquely on a screen, wherein: a rectangular area cutout means for cutting out a rectangular image display area in a scanning area; The light emission timing of the light source is so controlled that the light emission of the light source for a predetermined pixel is prohibited and the display position of the pixel is moved by a predetermined amount so that the number of display pixels per unit area in the image display area is substantially uniform. And a light emission control means for controlling the light emission.