JP3859590B2 - Projection apparatus and focus adjustment method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a projection apparatus such as a liquid crystal projector that projects an image on a screen via a projection lens, and more particularly to a projection apparatus that can automatically adjust the focus of a projection lens and a focus adjustment method thereof.
[0002]
[Prior art]
In recent years, there has been proposed a projection apparatus and a focus adjustment method for automatically adjusting the focus of a projection lens while capturing a focus pattern projected on a screen with a camera and analyzing the captured image (for example, patents). Reference 1).
[0003]
The focus adjustment method disclosed in Patent Document 1 utilizes that the predetermined signal component of the captured image changes according to the focus state of the focus pattern on the screen. For example, the high-frequency component of the captured image The focus pattern on the screen is focused by adjusting the focus of the projection lens so that this high frequency component is maximized.
[0004]
The camera includes an image sensor such as a CCD or CMOS, and when a focus pattern projected on the screen is imaged, an accumulation time adjustment corresponding to the shutter speed adjustment of the silver salt camera is performed. In other words, the image taken by the camera changes in brightness (image level) according to the length of the accumulation time, and if this time is too short, it becomes black, and if it is too long, it becomes saturated and white. It is necessary to detect the image level of the image and adjust the accumulation time so that it becomes a predetermined level.
[0005]
[Patent Document 1]
JP 2000-28901 A (page 5, FIG. 3)
[0006]
[Problems to be solved by the invention]
By the way, since projection apparatuses, such as a liquid crystal projector, are used in various places, it is assumed that the lighting fixture which generate | occur | produces strong light and the mirror which reflects strong light exist in the vicinity of a screen. When the automatic focus adjustment described above is executed in such a place, the camera may detect strong disturbance light and the accumulation time may be adjusted based on the brightness. In such a situation, since the image level of the focus pattern is relatively lowered, the accuracy of the automatic focus adjustment is lowered, and in the worst case, the automatic focus adjustment cannot be performed.
[0007]
In addition, since the projection apparatus normally includes a zoom adjustment mechanism for adjusting the size of the projection screen, the imaging range of the camera is relatively wide in a situation where the zoom ratio is reduced and projected onto the screen. Therefore, there is a problem that it is easily affected by ambient light.
Further, when the zoom adjustment of the projection apparatus is performed, the size of the focus pattern captured by the camera also changes relatively, so that the characteristics of the predetermined signal component described above may change, and the accuracy of automatic focus adjustment may be reduced.
[0008]
The present invention has been considered in view of the above circumstances, and while the focus pattern projected on the screen is imaged by the camera and the captured image is analyzed, the focus adjustment of the projection lens is automatically performed. A projection device capable of performing high-precision focus adjustment without being affected by strong disturbance light by setting a focus area on a captured image of a camera and performing focus adjustment while analyzing only the focus area portion, and An object is to provide a method for adjusting the focus.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a projection apparatus of the present invention is provided with a projection lens capable of focus adjustment and zoom adjustment, and projects an image on a screen through the projection lens. A focus pattern projection unit that projects a focus pattern on the screen, a camera that captures the focus pattern projected on the screen, and an image captured by the camera regardless of the zoom adjustment position of the projection lens. An auto focus adjustment unit that automatically adjusts the focus of the projection lens while analyzing only the focus area portion of the captured image, and a focus area setting unit that surrounds only the focus pattern portion of the image and sets a focus area on the captured image of the camera And a focus control unit.
[0010]
If the projector is configured in this way, a focus area is set in the captured image of the camera so as to surround only the focus pattern portion of the captured image, and the focus adjustment is performed while analyzing only the focus area portion, thereby capturing the image. The focus adjustment of the projection lens can be performed without being affected by strong disturbance light such as a lighting fixture or a mirror included in the image.
As a result, it is possible to solve the problem that the accuracy of the automatic focus adjustment is reduced or the automatic focus adjustment cannot be performed due to the strong disturbance light included in the captured image.
[0011]
Further, since the focus area can be set so as to include only the focus pattern regardless of the zoom adjustment of the projection lens, it is possible to reliably eliminate strong disturbance light included in the imaging data.
In addition, since the relative size of the focus pattern in the focus area is constant regardless of the zoom adjustment position, it is possible to always obtain appropriate high-frequency component characteristics and perform automatic focus adjustment with high accuracy.
[0012]
Also, with this configuration, it is possible to perform a focus area setting with extremely high accuracy, such as changing the focus area steplessly in accordance with zoom adjustment.
[0013]
In the projection device of the present invention, the autofocus control unit adjusts the accumulation time of the camera based on the image level of the focus area portion in the captured image.
If the projection device is configured in this way, even when the camera captures strong disturbance light, it is possible to perform appropriate accumulation time adjustment without using the brightness as a reference. As a result, erroneous accumulation time adjustment can be avoided, and highly accurate automatic focus adjustment can be performed.
[0014]
In the projection apparatus of the present invention, the autofocus control unit adjusts the focus of the projection lens so that the high frequency component of the focus area portion in the captured image is maximized.
By configuring the projection device in this way, even if the camera captures strong disturbance light, the maximum value of the high-frequency component can be detected without being affected, so the accuracy of automatic focus adjustment is improved. Is possible.
[0015]
In the projection apparatus of the present invention, the focus area setting unit has a plurality of focus area data , surrounds only the focus pattern portion of the captured image, regardless of the zoom adjustment position of the projection lens, The zoom focus area data is selected.
If the projection apparatus is configured in this way, the focus area setting process can be simplified as compared with the case where the focus area data is generated in accordance with the zoom adjustment.
[0016]
In the projection apparatus of the present invention, the autofocus control unit prohibits zoom adjustment of the projection lens during focus adjustment of the projection lens.
If the projection apparatus is configured in this way, even if the zoom adjustment operation is mistakenly performed during the automatic focus adjustment, the automatic focus adjustment can be continued without any problem.
[0017]
Further, in order to achieve the above object, the focus adjustment method of the projection apparatus according to the present invention includes a projection lens capable of focus adjustment and zoom adjustment, and the focus of the projection apparatus that projects an image on the screen via the projection lens. An adjustment method, wherein a focus pattern is projected on the screen via the projection lens, and the focus pattern projected on the screen is imaged by a camera, regardless of the zoom adjustment position of the projection lens. A method of automatically adjusting the focus of the projection lens while enclosing only a focus pattern portion of a captured image captured by a camera, setting a focus area on the captured image of the camera, and analyzing the focus area portion of the captured image It is as.
If the focus adjustment method of the projection device is set to such a method, focus adjustment can be performed while analyzing only the focus area portion of the captured image, so that accurate focus adjustment is not affected by strong disturbance light. It becomes possible to do.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
First, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view of a projection device and a screen in the first embodiment, and FIG. 2 is a block diagram showing a configuration of the projection device in the first embodiment.
As shown in these drawings, the projection apparatus 100 includes a projection circuit 10, a projection lens 20, a camera 30, a control unit 40, and the like.
[0019]
The projection circuit 10 inputs an external projection signal or focus pattern data stored in the image memory 11 via the switching circuit 12. The projection signal from the outside is an RGB signal or a video signal output from a personal computer or the like, and the focus pattern data is image data written in the image memory 11 by the control unit 40. The projection circuit 10 forms an image of the input projection signal or focus pattern data on an image forming device such as a liquid crystal panel, and this is projected onto the screen S via the projection lens 20.
[0020]
The projection lens 20 includes a focus adjustment mechanism and a zoom adjustment mechanism. A focus lens drive motor 21 constituting a focus adjustment mechanism is driven by a focus lens drive circuit 22 and moves a focus lens (not shown) of the projection lens 20. Further, the movement position of the focus lens is detected by the focus lens position sensor 23 and is input to the control unit 40 via the focus lens position detection circuit 24.
[0021]
On the other hand, the zoom lens drive motor 25 constituting the zoom adjustment mechanism is driven by the zoom lens drive circuit 26 and moves the zoom lens (not shown) of the projection lens 20. The movement position of the zoom lens is detected by the zoom lens position sensor 27 and is input to the control unit 40 via the zoom lens position detection circuit 28.
[0022]
The camera 30 includes an image sensor such as a CCD or a CMOS, and images the focus pattern projected on the screen S in accordance with an imaging instruction signal from the control unit 40. At that time, the camera 30 forms a captured image based on the accumulation time designated by the control unit 40.
The captured image data captured here is output to the mask circuit 31 (a part of the focus area setting unit), where it is masked. That is, the mask circuit 31 sets the focus area on the captured image based on the focus area signal input from the control unit 40, and sets the image signal level outside the focus area to 0.
[0023]
The captured image data output from the mask circuit 31 is input to the control unit 40 via the image level detection circuit 32 or the high frequency component detection circuit 33. The switching is performed by the control unit 40 switching the switching circuit 34.
The image level detection circuit 32 detects the image level of the captured image data, and the detection signal is used for adjusting the accumulation time of the camera 30.
The high frequency component detection circuit 33 detects a high frequency component of the imaged image data, and the detection signal is used for automatic focus adjustment of the projection lens 20. That is, the high-frequency component included in the captured image changes according to the focus state of the focus pattern on the screen S, and automatic focus adjustment described later is performed based on this.
[0024]
The control unit 40 includes a CPU, ROM, RAM, and the like as hardware, and an autofocus control unit 41, switching units 42 and 43, a focus pattern generation unit (focus pattern projection unit) 44, and a program written in the ROM. A focus area generation unit (part of the focus area setting unit) 45 and the like are configured.
[0025]
The autofocus control unit 41 outputs an autofocus mode signal to the switching circuit 12, the switching units 42 and 43, the focus pattern generation unit 44, the focus area generation unit 45, and the like in response to an autofocus start signal from a personal computer or a remote controller. At the same time, the accumulation time of the camera 30 is adjusted based on the image level signal from the image level detection circuit 32, and then the focus adjustment of the projection lens 20 is automatically performed while analyzing the high frequency component signal from the high frequency component detection circuit 33. Do it.
[0026]
The switching unit 42 is a part that switches an output signal to the focus lens driving circuit 22. In the normal mode, the switching unit 42 outputs a focus lens driving signal from a personal computer or a remote controller to the focus lens driving circuit 22. The switching operation is performed so that the focus lens drive signal from the control unit 41 is output to the focus lens drive circuit 22.
[0027]
The switching unit 43 is a part for turning on / off the signal output to the zoom lens driving circuit 26. In the normal mode, the switching unit 43 outputs a zoom lens driving signal from a personal computer or a remote controller to the zoom lens driving circuit 26, and in the auto focus mode. It is switched to prohibit it.
[0028]
The focus pattern generation unit 44 is a part that generates focus pattern data to be projected onto the screen S during automatic focus adjustment. The focus pattern data generated here is written into the image memory 11.
[0029]
The focus area generation unit 45 is a part that sets focus area data in accordance with the output of the zoom lens position detection circuit 28 and outputs this to the mask circuit 31. At this time, the focus area is set so as to surround only the focus pattern portion of the captured image regardless of the zoom adjustment position of the projection lens 20.
Thus, the accumulation time of the camera 30 is adjusted without being affected by strong disturbance light such as a lighting fixture or a mirror included in the captured image, and the automatic focus adjustment of the projection lens 20 is performed based on the captured image of an appropriate level. It becomes possible.
In addition, since the relative size of the focus pattern in the focus area is constant regardless of the zoom adjustment position, it is possible to always obtain appropriate high-frequency component characteristics and perform automatic focus adjustment with high accuracy.
[0030]
Next, the operation of the projection apparatus 100 will be described with reference to FIGS.
FIG. 3 is a flowchart showing operation steps (autofocus mode) of the projection apparatus in the first embodiment, and FIG. 4 is an explanatory diagram showing a captured image in the projection apparatus of the first embodiment.
[0031]
When an autofocus start signal is input from the outside, the control unit 40 enters the autofocus mode, and the autofocus adjustment of the projection lens 20 is executed by the operation steps shown in FIG. As shown in FIG. 3, the operation steps of the autofocus mode include an autofocus start processing step (S101), a step of projecting a focus pattern onto the screen S (S102), and a focus pattern projected onto the screen S. The camera 30 (S103), the step of setting the focus area in the captured image (S104), the step of reading the image level of the focus area portion in the captured image (S105), and the camera based on the image level. A step of performing 30 accumulation time adjustment (S106), a step of determining the end of the accumulation time adjustment (S107), a step of switching the switching circuit 34 and reading a high-frequency component signal of a focus area portion in a captured image (S108); , Throw A step (S109) for setting the focus lens of the lens 20 to a position where the high-frequency component signal is maximum, a step (S110) for determining the end of focus adjustment, and a step (S111) for performing an autofocus end process. . Hereinafter, each step will be described along the configuration of FIG.
[0032]
First, an autofocus mode signal is output from the autofocus control unit 41 and the switching circuits 12 and 34 and the switching units 42 and 43 are switched. Accordingly, priority is given to focus adjustment by the autofocus control unit 41 and zoom adjustment by an external signal is prohibited. (S101)
[0033]
Next, the focus pattern generation unit 44 is operated by the autofocus mode signal, and the focus pattern data is written in the image memory 11.
By switching the switching circuit 12, the focus pattern data in the image memory 11 is output to the projection circuit 10, and this focus pattern is projected onto the screen S via the projection lens 20. (S102)
[0034]
When the focus pattern is projected onto the screen S, the autofocus control unit 41 outputs an imaging instruction signal. The camera 30 images the focus pattern projected on the screen S according to the imaging instruction signal, and outputs the captured image data to the mask circuit 31. (S103)
[0035]
The mask circuit 31 sets a focus area corresponding to the zoom adjustment position of the projection lens 20 on the captured image in cooperation with the focus area generation unit 45, and sets the image level outside the focus area to zero. (S104)
Thereby, as shown in FIG. 4, the captured image includes only the focus pattern regardless of the zoom adjustment position.
[0036]
The autofocus control unit 41 inputs the image level signal of the captured image from the image level detection circuit 32 (S105), updates the accumulation time setting of the camera 30 so that it becomes a predetermined level, and adjusts the accumulation time. (S106). This accumulation time adjustment is determined to end when the image level signal reaches a predetermined level. (S107)
[0037]
Next, the autofocus control unit 41 switches the switching circuit 34 and inputs the high frequency component signal of the focus area portion in the captured image from the high frequency component detection circuit 33 (S108).
Then, the focus lens is moved in the direction in which the high frequency component is maximized, and finally the focus lens is adjusted to the position where the high frequency component is maximized. Meanwhile, the autofocus control unit 41 controls the movement of the focus lens while monitoring the output of the focus lens position detection circuit 24. (S109)
[0038]
When the end of focus adjustment is determined (S110), the switching of the switching circuit 12 and the switching units 42 and 43 to the normal mode side is stopped by stopping the output of the autofocus mode signal from the autofocus control unit 41, and the autofocus. Outputs the end signal and ends the autofocus mode. (S111)
[0039]
According to the projection apparatus 100 of the first embodiment configured as described above, the focus pattern projected on the screen S is imaged by the camera 30, and the focus adjustment of the projection lens 20 is automatically performed while analyzing the captured image. The focus area is set in the captured image of the camera 30 and the focus adjustment is performed while analyzing only the focus area portion, so that strong disturbance light such as a lighting fixture or a mirror included in the captured image is performed. Thus, the focus adjustment of the projection lens 20 can be performed without being affected by the above.
As a result, it is possible to solve the problem that the accuracy of the automatic focus adjustment is reduced or the automatic focus adjustment cannot be performed due to the strong disturbance light included in the captured image.
[0040]
Further, since the autofocus control unit 41 adjusts the accumulation time of the camera 30 based on the image level of the focus area portion in the captured image, even if the camera 30 captures strong disturbance light, the brightness is used as a reference. Therefore, it is possible to adjust the appropriate accumulation time without doing so. As a result, erroneous accumulation time adjustment can be avoided, and highly accurate automatic focus adjustment can be performed.
[0041]
Further, since the autofocus control unit 41 adjusts the focus of the projection lens 20 so that the high frequency component of the focus area portion in the captured image is maximized, even if the camera captures strong disturbance light, it is affected. Therefore, the maximum value of the high frequency component can be detected, and as a result, the accuracy of automatic focus adjustment can be improved.
[0042]
In addition, since the focus area is set on the captured image according to the zoom adjustment position of the projection lens 20, the focus area should be set to include only the focus pattern regardless of the zoom adjustment of the projection lens 20. Therefore, it is possible to reliably eliminate strong disturbance light included in the imaging data.
In addition, since the relative size of the focus pattern in the focus area is constant regardless of the zoom adjustment position, it is possible to always obtain appropriate high-frequency component characteristics and perform automatic focus adjustment with high accuracy.
[0043]
[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. However, the part which is common in 1st embodiment attaches the same code | symbol, and uses description of 1st embodiment.
FIG. 5 is a block diagram showing the configuration of the projection apparatus in the second embodiment.
As shown in this figure, the projection apparatus 100 of the second embodiment is different from the first embodiment in that it includes a focus area selection unit 46, an area data unit 47, and a switching unit 48 instead of the focus area generation unit 45. To do.
[0044]
The area data unit 47 stores N pieces of focus area data having different sizes. The focus area selection unit 46 selects focus area data according to the zoom adjustment position of the projection lens 20 and outputs an area selection signal to the switching unit 48. The switching unit 48 reads the focus area data corresponding to the area selection signal from the area data unit 47 and writes it in the image memory 11. Thereby, substantially the same effect as the first embodiment can be obtained.
[0045]
【The invention's effect】
As described above, according to the present invention, the focus pattern projected on the screen is captured by the camera, and the captured image is analyzed while the focus adjustment of the projection lens is automatically performed. A focus area is set in the captured image of the camera so as to surround only the focus pattern part, and focus adjustment is performed while analyzing only the focus area part, so that it is not affected by strong disturbance light and is highly accurate. It can be performed.
[Brief description of the drawings]
FIG. 1 is a perspective view of a projection device and a screen in a first embodiment.
FIG. 2 is a block diagram showing a configuration of a projection device in the first embodiment.
FIG. 3 is a flowchart showing operation steps (autofocus mode) of the projection apparatus in the first embodiment.
FIG. 4 is an explanatory diagram showing a captured image in the projection apparatus of the first embodiment.
FIG. 5 is a block diagram showing a configuration of a projection apparatus according to a second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Projector 10 Projection circuit 20 Projection lens 21 Focus lens drive motor 23 Focus lens position sensor 25 Zoom lens drive motor 27 Zoom lens position sensor 30 Camera 31 Mask circuit 32 Image level detection circuit 33 High frequency component detection circuit 40 Control part 41 Autofocus Control unit 44 Focus pattern generation unit 45 Focus area generation unit 46 Focus area selection unit S Screen

Claims (6)

A projection device that includes a projection lens capable of focus adjustment and zoom adjustment, and projects an image on a screen via the projection lens,
A focus pattern projection unit for projecting a focus pattern onto the screen via the projection lens;
A camera for imaging a focus pattern projected on the screen;
Regardless of the zoom adjustment position of the projection lens, a focus area setting unit that surrounds only a focus pattern portion of a captured image captured by the camera and sets a focus area on the captured image of the camera;
An autofocus control unit that automatically adjusts the focus of the projection lens while analyzing a focus area portion of the captured image.   The projection apparatus according to claim 1, wherein the autofocus control unit adjusts the accumulation time of the camera based on an image level of a focus area portion in the captured image.   The projection apparatus according to claim 1, wherein the autofocus control unit adjusts the focus of the projection lens so that a high frequency component of a focus area portion in the captured image is maximized. The focus area setting unit has a plurality of focus area data, and surrounds only a focus pattern portion of a captured image regardless of a zoom adjustment position of the projection lens, and selects the focus area data. The projection apparatus in any one of 1-3.   The projection apparatus according to claim 1, wherein the autofocus control unit prohibits zoom adjustment of the projection lens during focus adjustment of the projection lens. A focus adjustment method for a projection apparatus including a projection lens capable of focus adjustment and zoom adjustment, and projecting an image on a screen via the projection lens,
A focus pattern is projected onto the screen via the projection lens,
Capture the focus pattern projected on the screen with a camera,
Regardless of the zoom adjustment position of the projection lens, only the focus pattern portion of the captured image captured by the camera is enclosed, and a focus area is set on the captured image of the camera.
A focus adjustment method for a projection apparatus, wherein the focus adjustment of the projection lens is automatically performed while analyzing a focus area portion of the captured image.

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