JP2004205684A - Projection device and its focusing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize accurate and automatic focusing even when a strong diffused external light exists around a screen in a projection device such as a liquid crystal projector. <P>SOLUTION: The projection device 100 equipped with a projection lens 20 which can be adjusted to be focused and zoomed and projecting an image on a screen S through the lens 20, is constituted by being equipped with a focus pattern generation part 44 projecting a focus pattern on the screen S through the lens 20, a camera 30 picking up the image of the focus pattern projected to the screen S, a focus area setting part (mask circuit 31 and focus area generation part 45) for setting a focus area on the picked-up image by the camera 30, and an autofocus control part 41 automatically focusing the lens 20 while analyzing the focus area part of the picked-up image. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a projection device such as a liquid crystal projector that projects an image on a screen via a projection lens, and more particularly, to a projection device that can automatically perform focus adjustment of a projection lens and a focus adjustment method thereof.
[0002]
[Prior art]
2. Description of the Related Art In recent years, a projection apparatus and a focus adjustment method for automatically adjusting the focus of a projection lens while capturing an image of a focus pattern projected on a screen with a camera and analyzing the captured image have been proposed. Reference 1).
[0003]
The focus adjustment method disclosed in Patent Literature 1 utilizes that a predetermined signal component of the captured image changes according to a focus state of a focus pattern on a screen. For example, a high-frequency component of the captured image is used. By adjusting the focus of the projection lens such that the high-frequency component is maximized while detecting the focus pattern, the focus pattern on the screen is focused.
[0004]
The camera is provided with an image sensor such as a CCD or a CMOS. When capturing a focus pattern projected on a screen, an accumulation time adjustment corresponding to a shutter speed adjustment of a silver halide camera is performed. That is, the brightness (image level) of the image captured by the camera changes according to the length of the accumulation time. If the time is too short, the image becomes black, and if the time is too long, the image becomes saturated and becomes white. It is necessary to detect the image level of the image and adjust the accumulation time so that the image level becomes a predetermined level.
[0005]
[Patent Document 1]
JP-A-2000-28901 (page 5, FIG. 3)
[0006]
[Problems to be solved by the invention]
By the way, since projection devices such as liquid crystal projectors are used in various places, it is conceivable that a lighting fixture that generates strong light or a mirror that reflects strong light exists near the screen. When the above-described automatic focus adjustment is performed in such a place, the camera may capture 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 relatively decreases, the accuracy of the automatic focus adjustment decreases, and in the worst case, the automatic focus adjustment cannot be performed.
[0007]
In addition, since the projection device is usually provided with a zoom adjustment mechanism for adjusting the size of the projection screen, in a situation where the zoom ratio is reduced and projection is performed on the screen, as shown in FIG. In addition, there is a problem that the imaging range of the camera becomes relatively wide, and the camera is easily affected by disturbance light.
Further, as shown in FIGS. 6A and 6B, when the zoom adjustment of the projection device is performed, the size of the focus pattern captured by the camera relatively changes, so that the characteristic of the predetermined signal component changes. However, the accuracy of the automatic focus adjustment may be reduced.
[0008]
The present invention has been made in view of the above circumstances, and is to automatically focus the projection lens while capturing a focus pattern projected on a screen with a camera and analyzing the captured image. By setting a focus area on a captured image of a camera and performing focus adjustment while analyzing only this focus area portion, a projection device capable of performing highly accurate focus adjustment without being affected by strong disturbance light and An object of the present invention is to provide a focus adjustment method.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a projection device of the present invention includes a projection lens capable of focus adjustment and zoom adjustment, and is a projection device that projects an image on a screen via the projection lens. Through, a focus pattern projection unit that projects a focus pattern on the screen, a camera that captures a focus pattern projected on the screen, and a focus area setting unit that sets a focus area on an image captured by 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 is provided.
[0010]
With this configuration of the projection device, a focus area is set on the image captured by the camera, and focus adjustment is performed while analyzing only the focus area portion. Focus adjustment of the projection lens can be performed without being affected by light.
Thus, it is possible to solve the problems that the accuracy of the automatic focus adjustment is reduced or the automatic focus adjustment cannot be performed due to the influence of strong disturbance light included in the captured image.
[0011]
In the projection device according to the aspect of the invention, the autofocus control unit may adjust the accumulation time of the camera based on an image level of a focus area portion in the captured image.
With this configuration of the projection device, even if 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, incorrect accumulation time adjustment can be avoided, and highly accurate automatic focus adjustment can be performed.
[0012]
In the projection device according to the aspect of the invention, the autofocus control unit may perform focus adjustment of the projection lens such that a high-frequency component of a focus area portion in the captured image is maximized.
With this configuration of the projection device, even if the camera captures strong disturbance light, the maximum value of the high-frequency component can be detected without being affected by the disturbance light, thereby improving the accuracy of the automatic focus adjustment. Becomes possible.
[0013]
In the projection device according to the aspect of the invention, the focus area setting unit may set a focus area on the captured image according to a zoom adjustment position of the projection lens.
With this configuration of the projection device, the focus area can be set so as to include only the focus pattern regardless of the zoom adjustment of the projection lens, so that strong disturbance light included in the image data is reliably eliminated. 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, an appropriate high-frequency component characteristic is always obtained, and highly accurate automatic focus adjustment can be performed.
[0014]
In the projection device according to the aspect of the invention, the focus area setting unit may generate focus area data suitable for a zoom adjustment position of the projection lens.
With this configuration of the projection device, it is possible to set a very accurate focus area, for example, by changing the focus area in a stepless manner in accordance with the zoom adjustment.
[0015]
In the projection device according to the aspect of the invention, the focus area setting unit may include a plurality of focus area data, and select focus area data suitable for a zoom adjustment position of the projection lens from the plurality of focus area data.
With this configuration of the projection device, the focus area setting process can be simplified as compared with a case where focus area data is generated according to zoom adjustment.
[0016]
In the projection device according to the aspect of the invention, the autofocus control unit may prohibit a zoom adjustment of the projection lens when adjusting a focus of the projection lens.
With this configuration of the projection device, even if the zoom adjustment operation is performed by mistake during the automatic focus adjustment, the automatic focus adjustment can be continued without any problem.
[0017]
In order to achieve the above object, a method of adjusting the focus of a projection device according to the present invention includes a projection lens capable of performing focus adjustment and zoom adjustment, and the focus of the projection device that projects an image on a screen via the projection lens. An adjustment method, via the projection lens, project a focus pattern on the screen, capture a focus pattern projected on the screen with a camera, set a focus area on the captured image of the camera, This is a method of automatically adjusting the focus of the projection lens while analyzing a focus area portion of the captured image.
If the focus adjustment method of the projection device is set to such a method, the focus adjustment can be performed while analyzing only the focus area portion of the captured image, so that the focus adjustment can be performed with high accuracy without being affected by strong disturbance light. It is possible to do.
[0018]
BEST MODE FOR CARRYING OUT 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 according to the first embodiment, and FIG. 2 is a block diagram illustrating a configuration of the projection device according to the first embodiment.
As shown in these drawings, the projection device 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 receives an external projection signal or focus pattern data stored in the image memory 11 via a switching circuit 12. The external projection signal 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 to the image memory 11 by the control unit 40. Then, 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 on 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 to move a focus lens (not shown) of the projection lens 20. The moving position of the focus lens is detected by the focus lens position sensor 23 and input to the control unit 40 via the focus lens position detection circuit 24.
[0021]
On the other hand, a zoom lens drive motor 25 constituting a zoom adjustment mechanism is driven by a zoom lens drive circuit 26 to move a zoom lens (not shown) of the projection lens 20. The moving position of the zoom lens is detected by the zoom lens position sensor 27 and input to the control unit 40 via the zoom lens position detecting circuit 28.
[0022]
The camera 30 includes an image sensor such as a CCD or a CMOS, and captures an image of the focus pattern projected on the screen S in response to a capture instruction signal from the control unit 40. At this time, the camera 30 forms a captured image based on the accumulation time specified by the control unit 40.
The captured image data captured here is output to the mask circuit 31 (part of the focus area setting unit), where the mask processing is performed. 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 captured 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 based on this, the automatic focus adjustment described later is performed.
[0024]
The control unit 40 includes a CPU, a ROM, a RAM, and the like as hardware, and executes an autofocus control unit 41, switching units 42 and 43, a focus pattern generation unit (focus pattern projection unit) 44, 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 adjusted while analyzing the high frequency component signal from the high frequency component detection circuit 33. Do it.
[0026]
The switching section 42 is a section for switching an output signal to the focus lens drive circuit 22. In the normal mode, the switch section 42 outputs a focus lens drive signal from a personal computer or a remote controller to the focus lens drive circuit 22, and in the auto focus mode, the auto focus mode. The switching operation is performed so as to output the focus lens drive signal from the control unit 41 to the focus lens drive circuit 22.
[0027]
The switching unit 43 is a part for turning on / off a 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. The switching operation is performed so as to prohibit it.
[0028]
The focus pattern generation unit 44 is a unit that generates data of a focus pattern to be projected on the screen S at the time of automatic focus adjustment, and the generated focus pattern data is written to the image memory 11.
[0029]
The focus area generation unit 45 is a part that sets the data of the focus area according to the output of the zoom lens position detection circuit 28 and outputs the data 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.
Thereby, the accumulation time of the camera 30 is adjusted without being affected by strong disturbance light such as a lighting device and 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.
Further, 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 highly accurate automatic focus adjustment.
[0030]
Next, the operation of the projection device 100 will be described with reference to FIGS.
FIG. 3 is a flowchart illustrating operation steps (autofocus mode) of the projection device according to the first embodiment. FIG. 4 is an explanatory diagram illustrating an image captured when the zoom ratio is changed in the projection device according to the first embodiment. is there.
[0031]
When an autofocus start signal is input from the outside, the control unit 40 enters the autofocus mode, and the automatic focus adjustment of the projection lens 20 is executed by the operation steps shown in FIG. As shown in FIG. 3, the operation steps in the autofocus mode include a step of performing an autofocus start process (S101), a step of projecting a focus pattern on a screen S (S102), and a step of projecting a focus pattern on the screen S. (S103), setting a focus area on the captured image (S104), reading the image level of the focus area portion in the captured image (S105), and setting the camera based on the image level. 30 (S106), a step of determining the end of the accumulation time adjustment (S107), and a step of switching the switching circuit 34 to read the high-frequency component signal of the focus area portion in the captured image (S108). , Throw It comprises a step (S109) of setting the focus lens of the lens 20 to a position where the high-frequency component signal is maximized, a step (S110) of determining the end of the focus adjustment, and a step (S111) of performing an autofocus end process. . Hereinafter, each step will be described with reference to the configuration of FIG.
[0032]
First, an autofocus mode signal is output from the autofocus control unit 41, and the switching circuits 12, 34 and the switching units 42, 43 are switched. Thereby, the focus adjustment by the auto focus control unit 41 is prioritized, and the zoom adjustment by the external signal is prohibited. (S101)
[0033]
Next, the focus pattern generation unit 44 is operated by the auto focus mode signal, and the focus pattern data is written into the image memory 11.
By switching the switching circuit 12, focus pattern data of the image memory 11 is output to the projection circuit 10, and this focus pattern is projected on the screen S via the projection lens 20. (S102)
[0034]
When the focus pattern is projected on the screen S, the auto focus control unit 41 outputs an imaging instruction signal. The camera 30 captures an image of the focus pattern projected on the screen S in response to the capturing 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 and sets the image level outside the focus area to 0 in cooperation with the focus area generation unit 45. (S104)
Accordingly, the captured image includes only the focus pattern regardless of the zoom adjustment position, as shown in FIG.
[0036]
The autofocus control unit 41 updates the accumulation time setting of the camera 30 so that the image level signal of the captured image is input to the predetermined level while inputting the image level signal of the captured image from the image level detection circuit 32, 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 a direction in which the high frequency component is maximized, and the focus lens is finally adjusted to a position where the high frequency component is maximized. In the meantime, the auto focus 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 the focus adjustment is determined (S110), the output of the autofocus mode signal from the autofocus control unit 41 is stopped, so that the switching circuit 12 and the switching units 42 and 43 are switched to the normal mode side and the autofocus is performed. An end signal is output to end the auto focus mode. (S111)
[0039]
According to the projection device 100 of the first embodiment configured as described above, the focus pattern projected on the screen S is captured 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 on the image picked up by the camera 30 and the focus is adjusted while analyzing only the focus area portion, so that strong disturbance light such as lighting fixtures and mirrors included in the imaged image is obtained. Focus adjustment of the projection lens 20 can be performed without being affected by
Thus, it is possible to solve the problems that the accuracy of the automatic focus adjustment is reduced or the automatic focus adjustment cannot be performed due to the influence of strong disturbance light included in the captured image.
[0040]
Further, the auto focus 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. Therefore, even if the camera 30 captures strong disturbance light, It is possible to perform appropriate accumulation time adjustment without performing. As a result, incorrect accumulation time adjustment can be avoided, and highly accurate automatic focus adjustment can be performed.
[0041]
In addition, 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. Therefore, even if the camera captures strong disturbance light, the effect is affected. Without detecting the maximum value of the high-frequency component, the accuracy of the 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, it is necessary to set the focus area to include only the focus pattern regardless of the zoom adjustment of the projection lens 20. Therefore, strong disturbance light included in the imaging data can be reliably eliminated.
In addition, since the relative size of the focus pattern in the focus area is constant regardless of the zoom adjustment position, an appropriate high-frequency component characteristic is always obtained, and highly accurate automatic focus adjustment can be performed.
[0043]
[Second embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. However, portions common to the first embodiment are denoted by the same reference numerals, and the description of the first embodiment is referred to.
FIG. 5 is a block diagram illustrating a configuration of the projection device according to the second embodiment.
As shown in this figure, the projection device 100 of the second embodiment is different from the first embodiment in that a focus area selection unit 46, an area data unit 47, and a switching unit 48 are provided instead of the focus area generation unit 45. I do.
[0044]
The area data section 47 stores N 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 out the focus area data corresponding to the area selection signal from the area data unit 47 and writes it into the image memory 11. Thereby, substantially the same effects as in 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 focus adjustment of the projection lens is automatically performed while analyzing the captured image. By setting a focus area on an image and performing focus adjustment while analyzing only this focus area portion, highly accurate focus adjustment can be performed without being affected by strong disturbance light.
[Brief description of the drawings]
FIG. 1 is a perspective view of a projection device and a screen according to a first embodiment.
FIG. 2 is a block diagram illustrating a configuration of a projection device according to the first embodiment.
FIG. 3 is a flowchart illustrating operation steps (autofocus mode) of the projection device according to the first embodiment.
FIG. 4 is an explanatory diagram showing a captured image when the zoom ratio is changed in the projection device of the first embodiment.
FIG. 5 is a block diagram illustrating a configuration of a projection device according to a second embodiment.
FIG. 6 is an explanatory diagram showing a captured image when a zoom ratio is changed in a conventional projection device.
[Explanation of symbols]
REFERENCE SIGNS LIST 100 Projection device 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 unit 41 Autofocus Control unit 44 Focus pattern generation unit 45 Focus area generation unit 46 Focus area selection unit S screen

Claims (8)

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,
Through the projection lens, a focus pattern projection unit that projects a focus pattern on the screen,
A camera for imaging a focus pattern projected on the screen,
A focus area setting unit that sets a focus area on an image captured by 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. 2. The projection device 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 device according to claim 1, wherein the autofocus control unit adjusts a focus of the projection lens such that a high-frequency component of a focus area in the captured image is maximized. The projection apparatus according to claim 1, wherein the focus area setting unit sets a focus area on the captured image according to a zoom adjustment position of the projection lens. The projection device according to claim 1, wherein the focus area setting unit generates focus area data suitable for a zoom adjustment position of the projection lens. The said focus area setting part has a some focus area data, and selects the focus area data suitable for the zoom adjustment position of the said projection lens from among them, The Claim 1 characterized by the above-mentioned. Projection equipment. The projection device according to claim 1, wherein the autofocus control unit prohibits zoom adjustment of the projection lens when adjusting the focus of the projection lens. A focus adjustment method for 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,
Through the projection lens, project a focus pattern on the screen,
The focus pattern projected on the screen is imaged by a camera,
Setting a focus area on the captured image of the camera,
A focus adjustment method for a projection device, wherein a focus adjustment of the projection lens is automatically performed while analyzing a focus area portion of the captured image.

Images