JP2005114902A - Projection type video display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projection type video display device capable of automatically adjusting the size of a projected video to size in accordance with screen size. <P>SOLUTION: The projection type video display device is equipped with a line sensor for measuring luminance and an adjusting means for automatically adjusting the size of the projected video to the size fit to the screen size based on a detection signal from the line sensor. Every time the projected video is zoomed up by an amount equivalent to prescribed steps, the adjusting means detects luminance on the inside and the outside of the contour of the projected video in the vicinity of the contour of the projected video from the detection signal from the line sensor, discriminates whether or not the projected video sticks out from the screen based on the difference of the detected luminance, and zooms down the projected video by the amount equivalent to the prescribed steps in discriminating that the projected video sticks out from the screen. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

  Some liquid crystal projectors have a zoom function for changing the size of a projected image. When the image projected on the screen is too large or too small for the screen size, the user operates the operation unit such as a remote control to zoom in (enlarge) the entire image or zoom down ( The size of the projected image is adjusted to a size corresponding to the screen size.

  Since such an operation is troublesome, it is convenient if the size of the projected image can be automatically adjusted to a size corresponding to the screen size.

  An object of the present invention is to provide a projection-type image display apparatus that can automatically adjust the size of a projected image to a size corresponding to a screen size.

  According to the first aspect of the present invention, when the projected image is in the screen based on the line sensor for measuring the luminance and the detection signal of the line sensor, the size of the projected image is determined on the screen. Adjusting means for automatically adjusting to a size suitable for the size, and the adjusting means adjusts the brightness inside and outside the contour of the projected image in the vicinity of the contour of the projected image projected on the screen. The first means for detecting the difference between the detected luminances from the detection signal of the line sensor, calculating the difference between the two detected luminances, and holding the obtained difference as a reference value, zooming up the projected image by a predetermined step and zooming in By means of second means and second means for detecting the brightness inside and outside the contour of the projected video in the vicinity of the contour of the projected video from the detection signal of the line sensor and calculating the difference between the detected brightnesses. The third means for determining whether or not the difference between the brightness difference calculated in step 1 and the reference value exceeds a predetermined value, and the third means if the difference between the brightness difference calculated by the second means and the reference value exceeds a predetermined value. Until the determination is made by the means, the fourth means for executing the processing by the second means and the processing by the third means again, and the difference between the luminance difference calculated by the second means and the reference value exceeds a predetermined value. If it is determined by the third means, a fifth means for zooming down the projected image by the predetermined step and holding the zoom ratio after the zoom-down as a zoom ratio according to the screen size is provided. It is characterized by.

According to a second aspect of the present invention, when the projected image is in the screen based on the line sensor for measuring the luminance and the detection signal of the line sensor, the size of the projected image is determined on the screen. Adjusting means for automatically adjusting to a size suitable for the size, and the adjusting means adjusts the brightness inside and outside the contour of the projected image in the vicinity of the contour of the projected image projected on the screen. A first means that detects from the detection signal of the line sensor, calculates a difference between the detected luminances, and holds the obtained difference as a first reference value, and zooms up the projected image by m steps larger than one step In addition, the brightness of the inside and outside of the contour of the projected image is detected from the detection signal of the line sensor near the contour of the zoomed-up projected image, and the difference between both detected luminances is calculated. Second means, third means for determining whether or not a difference between the luminance difference calculated by the second means and the first reference value exceeds a predetermined value, and the luminance difference calculated by the second means and the first reference value The fourth means for executing again the processing by the second means and the processing by the third means until the difference by the third means is determined to exceed the predetermined value, and the luminance difference calculated by the second means and the above When the third means determines that the difference from the first reference value exceeds a predetermined value, the brightness difference calculated by the second means is held as the second reference value, and the projected image is smaller than m steps. The zoom is reduced by n steps, and the brightness inside and outside the projected video contour is detected from the detection signal of the line sensor near the contour of the zoomed-down projected video, and the difference between the detected brightnesses is calculated. Means, sixth means for the luminance difference calculated by the fifth means, the difference between the second reference value, it is determined whether or not exceeds a predetermined value,
Until the difference between the brightness difference calculated by the fifth means and the second reference value exceeds a predetermined value, the processing by the fifth means and the processing by the sixth means are executed again until it is determined by the sixth means. When the third means determines that the difference between the luminance difference calculated by the seventh means and the fifth means and the second reference value exceeds a predetermined value, the zoom ratio at that time is determined according to the screen size. Eighth means for maintaining the zoom ratio is provided.

  According to a third aspect of the present invention, when the projected image is in a state of protruding outside the screen based on the line sensor for measuring the luminance and the detection signal of the line sensor, the size of the projected image is determined. Adjusting means for automatically adjusting to a size suitable for the screen size, and the adjusting means includes brightness on the inside and outside of the contour of the projected image in the vicinity of the contour of the projected image projected on the screen. Is detected from the detection signal of the line sensor, the difference between the two detected luminances is calculated, the first means for holding the obtained difference as a reference value, and the projected image is zoomed down by a predetermined step and is zoomed down. A second means for detecting the brightness inside and outside the contour of the projected video near the contour of the projected video from the detection signal of the line sensor, and calculating a difference between the detected brightnesses; The third means for determining whether or not the difference between the luminance difference calculated by the above and the reference value exceeds a predetermined value, and the third means if the difference between the luminance difference calculated by the second means and the reference value exceeds the predetermined value. Until the determination is made by the means, the fourth means for executing the processing by the second means and the processing by the third means again, and the difference between the luminance difference calculated by the second means and the reference value exceeds a predetermined value. In the case where the third means determines that the zoom ratio is at that time, the zoom ratio according to the screen size is maintained as a fifth means.

  According to the fourth aspect of the present invention, when the projected image is in a state of protruding outside the screen based on the line sensor for measuring the luminance and the detection signal of the line sensor, the size of the projected image is determined. Adjusting means for automatically adjusting to a size suitable for the screen size, and the adjusting means includes brightness on the inside and outside of the contour of the projected image in the vicinity of the contour of the projected image projected on the screen. Is detected from the detection signal of the line sensor, the difference between the detected luminances is calculated, the first means for holding the obtained difference as a first reference value, and the projected image is zoomed by m steps larger than one step. The brightness of the inside and outside of the projected image contour is detected from the detection signal of the line sensor near the contour of the projected image that has been zoomed down, and the difference between the detected brightnesses is detected. The second means for outputting, the third means for determining whether or not the difference between the luminance difference calculated by the second means and the first reference value exceeds a predetermined value, the luminance difference calculated by the second means and the first The luminance difference calculated by the fourth means and the second means for executing again the processing by the second means and the processing by the third means until the third means determines that the difference from the reference value exceeds the predetermined value. When the third means determines that the difference between the first reference value and the first reference value exceeds a predetermined value, the brightness difference calculated by the second means is held as the second reference value, and the projected image is displayed for m steps. While zooming in by smaller n steps, near the contour of the projected image that has been zoomed in, the brightness inside and outside the contour of the projected image is detected from the detection signal of the line sensor, and the difference between both detected luminances is calculated. The fifth means, the sixth means for determining whether or not the difference between the luminance difference calculated by the fifth means and the second reference value exceeds a predetermined value, the luminance difference calculated by the fifth means and the second The luminance calculated by the seventh means and the fifth means for executing again the processing by the fifth means and the processing by the sixth means until the sixth means determines that the difference from the reference value exceeds the predetermined value. When the third means determines that the difference between the difference and the second reference value exceeds a predetermined value, the projected image is zoomed down by the n steps, and the zoom ratio after the zoom-down is set to the screen size. Eighth means for holding the corresponding zoom ratio is provided.

  According to the present invention, the size of the projected image can be automatically adjusted to a size corresponding to the screen size.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the configuration of a liquid crystal projector.

  The input video signal is sent to the video signal processing circuit 2 via the A / D converter 1. The video signal processing circuit 2 includes a frame memory 3. The signal obtained by the video signal processing circuit 2 is sent to a display panel (not shown).

  This liquid crystal projector is controlled by the CPU 10. The CPU 10 includes a ROM and a RAM (not shown). This liquid crystal projector has a function of automatically adjusting the size of a projected image to a size corresponding to the screen size (referred to as an image size automatic adjustment function). The liquid crystal projector is provided with a monochromatic line sensor 12 used for realizing an image size automatic adjustment function. The monochromatic line sensor 12 is connected to the CPU 10.

  As shown in FIG. 2, the monochromatic line sensor 12 is provided on the front surface of the projector body so as to face forward. As shown in FIG. 3, a wide-angle lens 13 is provided on the front side of the monochromatic line sensor 12 to increase the detection width.

  As shown in FIG. 3, the monochromatic line sensor 12 can detect the luminance within the range inside the width of the screen 20 and can measure the luminance within the range exceeding the width of the screen 20. .

  In this liquid crystal projector, an image size automatic adjustment mode is prepared as an operation mode, and when the image size automatic adjustment mode is set, an image size automatic adjustment process is performed. The image size automatic adjustment process will be described below.

[1] Description of First Example of Automatic Image Size Adjustment Processing FIG. 4 shows the procedure of automatic image size adjustment processing.

  The image size automatic adjustment processing according to the first embodiment is based on the assumption that the projected video 30 is inside the screen 20 as shown in FIG. 3 at the start of the image size automatic adjustment processing.

  When the image size automatic adjustment mode is set while the image is being projected, the CPU 10, based on the detection signal of the monochrome line sensor 12, near the one side end of the projected image (inside the one side end ( The luminance (video inner luminance) A inside the video and indicated by the symbol Pa in FIG. 3 and the luminance (video video) outside the one end (the location outside the video and indicated by the symbol Pb in FIG. 3). (Outside luminance) B is detected (step 1). Since the luminance inside the video is much larger than the luminance outside the video, it is possible to detect the luminance A inside the one side end of the projected video and the luminance B outside.

  The absolute value α (= | A−B |) of the difference between the extracted video inner luminance A and video outer luminance B is calculated and held (step 2). Next, the projected image is zoomed up (enlarged) by a predetermined step (one step in this example) (step 3). That is, the video signal is enlarged by a predetermined step (one step in this example).

  Then, in the same manner as in step 1, near the one side edge of the projected image, the brightness inside the one side edge (video inside brightness) A and the brightness outside the one side edge (video outside brightness) B are detected. (Step 4). The absolute value β (= | A−B |) of the difference between the extracted video inner luminance A and video outer luminance B is calculated and held (step 5).

  Then, it is determined whether or not the absolute value (| α−β |) of the difference between α and β is larger than a predetermined threshold value X (step 6). If the absolute value of the difference between β and α is within the threshold value X, it is determined that the projected image is inside the screen 20, and the process returns to step 3. In this way, the processing from step 3 to step 6 is repeated.

  Since the projected image is zoomed up in this way, if the projected image protrudes outside the screen, the brightness on the screen and the brightness on the outside of the screen are different, so the absolute value of the difference between α and β ( | Α−β |) becomes larger than the predetermined threshold value X, and YES is determined in Step 6, so that the projected image is zoomed down (reduced) by the predetermined step (one step in this example) (Step 7). Then, the zoom rate after the zoom-down is held as a zoom rate corresponding to the screen size (step 8). Then, the current image size automatic adjustment mode ends. Thereafter, the input video is enlarged and displayed at the zoom rate obtained in step 8.

[2] Description of Second Example of Image Size Automatic Adjustment Processing FIG. 5 shows the procedure of image size automatic adjustment processing.

  The image size automatic adjustment processing according to the second embodiment is based on the assumption that the projected video 30 is inside the screen 20 as shown in FIG. 3 at the start of the image size automatic adjustment processing.

  When the image size automatic adjustment mode is set while the image is being projected, the CPU 10, based on the detection signal of the monochrome line sensor 12, near the one side end of the projected image (inside the one side end ( The luminance (video inner luminance) A inside the video and indicated by the symbol Pa in FIG. 3 and the luminance (video video) outside the one end (the location outside the video and indicated by the symbol Pb in FIG. 3). (Outside luminance) B is detected (step 11).

  The absolute value α (= | A−B |) of the difference between the extracted video inner luminance A and video outer luminance B is calculated and held (step 12). Next, the projected image is zoomed up (enlarged) by m steps (m> 1) (step 13). That is, the video signal is enlarged by n steps.

  Then, in the same manner as in step 11, near the one side end of the projected image, a luminance inside the one side end (video inside luminance) A and a luminance outside the one side end (video outside luminance) B are detected. (Step 14). The absolute value β (= | A−B |) of the difference between the extracted video inner luminance A and video outer luminance B is calculated (step 15).

  Then, it is determined whether or not the absolute value (| α−β |) of the difference between α and β is larger than a predetermined threshold value X (step 16). If the absolute value of the difference between β and α is within the threshold value X, it is determined that the projected image is inside the screen 20, and the process returns to step 13. In this way, the processing from step 13 to step 16 is repeated.

  Since the projected image is zoomed up in this way, if the projected image protrudes outside the screen, the brightness on the screen and the brightness on the outside of the screen are different, so the absolute value of the difference between α and β ( | Α−β |) becomes larger than the predetermined threshold value X, and YES is determined in the step 16.

  If YES in step 16, the projected image is zoomed down (reduced) by n steps (n <m) smaller than m steps (step 17). Then, in the same manner as in step 11, near the one side end of the projected image, a luminance inside the one side end (video inside luminance) A and a luminance outside the one side end (video outside luminance) B are detected. (Step 18). The absolute value γ (= | A−B |) of the difference between the extracted video inner luminance A and video outer luminance B is calculated (step 19).

  Then, it is determined whether or not the absolute value (| β−γ |) of the difference between β last calculated in step 15 and γ calculated in step 19 is larger than a predetermined threshold Y (step 20). ). If the absolute value of the difference between β and γ is within the threshold Y, it is determined that the projected image is outside the screen 20 and the process returns to step 17. In this way, the processing from step 17 to step 20 is repeated.

  Since the projected image is zoomed down in this way, when the projected image enters the inside of the screen, the brightness on the screen is different from the brightness on the outside of the screen, so the absolute value of the difference between β and γ ( | Β−γ |) is larger than the predetermined threshold Y, and YES is obtained in Step 20. If YES in step 20, the current zoom rate is held as a zoom rate corresponding to the screen size (step 21). Then, the current image size automatic adjustment mode ends. Thereafter, the input video is enlarged and displayed at the zoom rate obtained in step 21.

[3] Description of Third Example of Automatic Image Size Adjustment Processing FIG. 6 shows the procedure of automatic image size adjustment processing.

  The image size automatic adjustment processing according to the third embodiment is based on the assumption that the projected video 30 protrudes from the screen 20 as shown in FIG. 7 at the start of the image size automatic adjustment processing.

  When the image size automatic adjustment mode is set while the image is being projected, the CPU 10, based on the detection signal of the monochrome line sensor 12, near the one side end of the projected image (inside the one side end ( The luminance (video inner luminance) A inside the video (position indicated by symbol Pa in FIG. 7) and the luminance (video outside the video and indicated by symbol Pb in FIG. 7) outside the one side end (video). (Outside luminance) B is detected (step 31).

  The absolute value α (= | A−B |) of the difference between the extracted video inner luminance A and video outer luminance B is calculated and held (step 32). Next, the projected image is zoomed down (reduced) by a predetermined step (one step in this example) (step 33). That is, the video signal is reduced by a predetermined step (one step in this example).

  Then, in the same manner as in step 31, near the one side end of the projected image, a luminance inside the one side end (video inside luminance) A and a luminance outside the one side end (video outside luminance) B are detected. (Step 34). An absolute value β (= | A−B |) of a difference between the extracted video inner luminance A and video outer luminance B is calculated (step 35).

  Then, it is determined whether or not the absolute value (| α−β |) of the difference between α and β is larger than a predetermined threshold value X (step 36). If the absolute value of the difference between β and α is within the threshold value X, it is determined that the projected image is outside the screen 20, and the process returns to step 33. In this way, the processing from step 33 to step 36 is repeated.

  Since the projected image is zoomed down in this way, when the projected image enters the inside of the screen, the brightness on the screen and the brightness on the outside of the screen are different, so the absolute value of the difference between α and β ( | Α−β |) becomes larger than the predetermined threshold value X, and YES is determined in the step 36. If YES in step 36, the current zoom rate is held as a zoom rate corresponding to the screen size (step 37). Then, the current image size automatic adjustment mode ends. Thereafter, the input video is enlarged and displayed at the zoom rate obtained in step 37.

[4] Description of Fourth Embodiment of Automatic Image Size Adjustment Processing FIG. 8 shows the procedure of automatic image size adjustment processing.

  The image size automatic adjustment process according to the fourth embodiment is based on the assumption that the projected video 30 protrudes from the screen 20 as shown in FIG. 7 at the start of the image size automatic adjustment process.

  When the image size automatic adjustment mode is set while the image is being projected, the CPU 10, based on the detection signal of the monochrome line sensor 12, near the one side end of the projected image (inside the one side end ( The luminance (video inner luminance) A inside the video (position indicated by symbol Pa in FIG. 7) and the luminance (video outside the video and indicated by symbol Pb in FIG. 7) outside the one side end (video). (Outside luminance) B is detected (step 41).

  The absolute value α (= | A−B |) of the difference between the extracted video inner luminance A and video outer luminance B is calculated and held (step 42). Next, the projected image is zoomed down (reduced) by m steps (m> 1) (step 43). That is, the video signal is reduced by m steps.

  Then, in the same manner as in step 41, near the one side edge of the projected image, the brightness inside the one side edge (video inside brightness) A and the brightness outside the one side edge (video outside brightness) B are detected. (Step 44). The absolute value β (= | A−B |) of the difference between the extracted video inner luminance A and video outer luminance B is calculated (step 45).

  Then, it is determined whether or not the absolute value (| α−β |) of the difference between α and β is larger than a predetermined threshold value X (step 46). If the absolute value of the difference between β and α is within the threshold value X, it is determined that the projected image is outside the screen 20, and the process returns to step 43. In this way, the processing from step 43 to step 46 is repeated.

  Since the projected image is zoomed down in this way, when the projected image enters the inside of the screen, the brightness on the screen and the brightness on the outside of the screen are different, so the absolute value of the difference between α and β ( | Α−β |) becomes larger than the predetermined threshold value X, and YES is determined in the step 46.

  If YES in step 46, the projection image is zoomed up (enlarged) by n steps (n <m) smaller than m steps (step 47). Then, in the same manner as in step 41, near the one side edge of the projected image, the brightness inside the one side edge (video inside brightness) A and the brightness outside the one side edge (video outside brightness) B are detected. (Step 48). The absolute value γ (= | A−B |) of the difference between the extracted video inner luminance A and video outer luminance B is calculated (step 49).

  Then, it is determined whether or not the absolute value (| β−γ |) of the difference between β finally calculated in step 45 and γ calculated in step 49 is larger than a predetermined threshold Y (step 50). ). If the absolute value of the difference between β and γ is within the threshold Y, it is determined that the projected image is inside the screen 20, and the process returns to step 47. In this way, the processing from step 47 to step 50 is repeated.

  Since the projected image is zoomed up in this way, when the projected image protrudes outside the screen, the brightness on the screen and the brightness on the outside of the screen are different, so the absolute value of the difference between β and γ ( | Β−γ |) is greater than the predetermined threshold Y, and YES is obtained in step 50. If YES in step 50, the projected image is zoomed down (reduced) by n steps (step 51), and the zoom rate after this zoom down is held as a zoom rate corresponding to the screen size (step 51). 52). Then, the current image size automatic adjustment mode ends. Thereafter, the input video is enlarged and displayed at the zoom rate obtained in step 52.

It is a block diagram which shows the electric constitution of a liquid crystal projector. It is a front view of a liquid-crystal projector main body. It is a schematic diagram which shows the image projected on the screen, and the detection range of the monochrome line sensor 12. It is a flowchart which shows the procedure of the image size automatic adjustment process by 1st Example. It is a flowchart which shows the procedure of the image size automatic adjustment process by 2nd Example. It is a flowchart which shows the procedure of the image size automatic adjustment process by 3rd Example. FIG. 6 is a schematic diagram showing that a projected image 30 protrudes from a screen 20 at the start of automatic image size adjustment processing. It is a flowchart which shows the procedure of the image size automatic adjustment process by 4th Example.

Explanation of symbols

1 A / D converter 2 Video signal processing circuit 3 Frame memory 10 CPU
12 Monochromatic line sensor

Claims (4)

Based on the line sensor for measuring the brightness and the detection signal of the line sensor, when the projected image is in the screen, the size of the projected image is automatically adjusted to the size suitable for the screen size. And adjusting means for adjusting to
Adjustment means
Near the contour of the projected image projected on the screen, the brightness inside and outside the contour of the projected image is detected from the detection signal of the line sensor, the difference between both detected luminances is calculated, and the difference obtained is used as a reference A first means of holding as a value,
The projected image is zoomed up by a predetermined number of steps, and the brightness inside and outside the contour of the projected image is detected from the detection signal of the line sensor near the contour of the zoomed-up projected image, and the difference between both detected brightnesses is detected. A second means for calculating,
Third means for determining whether or not a difference between the luminance difference calculated by the second means and the reference value exceeds a predetermined value;
A fourth process for executing the process by the second means and the process by the third means again until the third means determines that the difference between the luminance difference calculated by the second means and the reference value exceeds a predetermined value. When the third means determines that the difference between the brightness difference calculated by the means and the second means and the reference value exceeds a predetermined value, the projected image is zoomed down by the predetermined step, and this zoom down Fifth means for holding the subsequent zoom rate as a zoom rate according to the screen size;
A projection-type image display device. Based on the line sensor for measuring the brightness and the detection signal of the line sensor, when the projected image is in the screen, the size of the projected image is automatically adjusted to the size suitable for the screen size. And adjusting means for adjusting to
Adjustment means
In the vicinity of the contour of the projected image projected on the screen, the brightness inside and outside the contour of the projected image is detected from the detection signal of the line sensor, the difference between both detected luminances is calculated, and the obtained difference is 1st means holding as 1 standard value,
The projected image is zoomed up by m steps larger than one step, and the brightness inside and outside the projected image contour is detected from the detection signal of the line sensor in the vicinity of the contour of the zoomed-up projected image. A second means for calculating the difference between the two luminances;
Third means for determining whether or not the difference between the luminance difference calculated by the second means and the first reference value exceeds a predetermined value;
The processing by the second means and the processing by the third means are executed again until the third means determines that the difference between the luminance difference calculated by the second means and the first reference value exceeds a predetermined value. 4th means,
If the third means determines that the difference between the brightness difference calculated by the second means and the first reference value exceeds a predetermined value, the brightness difference calculated by the second means is held as the second reference value. The projection image is zoomed down by n steps smaller than m steps, and the brightness of the inside and outside of the projection image outline is detected from the detection signal of the line sensor in the vicinity of the contour of the zoomed-down projection image, A fifth means for calculating a difference between the detected luminances;
Sixth means for determining whether or not a difference between the luminance difference calculated by the fifth means and the second reference value exceeds a predetermined value;
Until the difference between the brightness difference calculated by the fifth means and the second reference value exceeds a predetermined value, the processing by the fifth means and the processing by the sixth means are executed again until it is determined by the sixth means. If the third means determines that the difference between the luminance difference calculated by the seventh means and the fifth means and the second reference value exceeds a predetermined value, the zoom ratio at that time is determined according to the screen size. An eighth means for holding the zoom rate;
A projection-type image display device. Based on the line sensor for measuring brightness and the detection signal of the line sensor, when the projected image is outside the screen, the size of the projected image is automatically adjusted to the size suitable for the screen size. Adjusting means for adjusting automatically,
Adjustment means
Near the contour of the projected image projected on the screen, the brightness inside and outside the contour of the projected image is detected from the detection signal of the line sensor, the difference between both detected luminances is calculated, and the difference obtained is used as a reference A first means of holding as a value,
The projected image is zoomed down by a predetermined number of steps, and the brightness inside and outside the contour of the projected image is detected from the detection signal of the line sensor near the contour of the zoomed-down projected image, and the difference between the detected brightnesses is detected. A second means for calculating,
Third means for determining whether or not a difference between the luminance difference calculated by the second means and the reference value exceeds a predetermined value;
A fourth process for executing the process by the second means and the process by the third means again until the third means determines that the difference between the luminance difference calculated by the second means and the reference value exceeds a predetermined value. When the third means determines that the difference between the brightness difference calculated by the means and the second means and the reference value exceeds a predetermined value, the zoom ratio at that time is held as a zoom ratio corresponding to the screen size. 5th means to let
A projection-type image display device. Based on the line sensor for measuring brightness and the detection signal of the line sensor, when the projected image is outside the screen, the size of the projected image is automatically adjusted to the size suitable for the screen size. Adjusting means for adjusting automatically,
Adjustment means
In the vicinity of the contour of the projected image projected on the screen, the brightness inside and outside the contour of the projected image is detected from the detection signal of the line sensor, the difference between both detected luminances is calculated, and the obtained difference is 1st means holding as 1 standard value,
The projected image is zoomed down by m steps larger than one step, and the brightness inside and outside the projected image outline is detected from the detection signal of the line sensor near the contour of the zoomed-down projected image. A second means for calculating the difference between the two luminances;
Third means for determining whether or not the difference between the luminance difference calculated by the second means and the first reference value exceeds a predetermined value;
The processing by the second means and the processing by the third means are executed again until the third means determines that the difference between the luminance difference calculated by the second means and the first reference value exceeds a predetermined value. 4th means,
If the third means determines that the difference between the brightness difference calculated by the second means and the first reference value exceeds a predetermined value, the brightness difference calculated by the second means is held as the second reference value. And zooming up the projection image by n steps smaller than m steps, and detecting the brightness inside and outside the outline of the projection image in the vicinity of the contour of the zoomed-up projection image from the detection signal of the line sensor, A fifth means for calculating a difference between the detected luminances;
Sixth means for determining whether or not a difference between the luminance difference calculated by the fifth means and the second reference value exceeds a predetermined value;
Until the difference between the brightness difference calculated by the fifth means and the second reference value exceeds a predetermined value, the processing by the fifth means and the processing by the sixth means are executed again until it is determined by the sixth means. If the third means determines that the difference between the luminance difference calculated by the seventh means and the fifth means and the second reference value exceeds a predetermined value, the projected image is zoomed down by the n steps. , An eighth means for holding the zoom rate after the zoom-down as a zoom rate according to the screen size;
A projection-type image display device.

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