Projector and control method for the projector

A projector includes a projecting unit including a projection optical system and configured to project an image on a screen SC, a lens driving unit configured to perform focus adjustment for the projection optical system, a trapezoidal-distortion correcting unit configured to perform distortion correction processing for correcting distortion of the image projected by the projecting unit, and a projection control unit configured to cause the trapezoidal-distortion correcting unit to execute the distortion correction processing until a completion condition for the distortion correction processing holds after a start condition for the distortion correction processing holds and restrict the execution of the focus adjustment by the lens driving unit while the projection control unit causes the trapezoidal-distortion correcting unit to execute the distortion correction processing.

CROSS REFERENCE TO RELATED APPLICATIONS

The entire disclosure of Japanese Patent Application No. 2012-050118, filed Mar. 7, 2012 is expressly incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a projector that projects an image on a projection surface and a control method for the projector.

BACKGROUND ART

There has been known a projector that projects an image on a projection surface, the projector projecting an image for adjustment on the projection surface to photograph the projection surface and performing distortion correction on the basis of a projection state of the image for adjustment. The projector of this type is likely to be unable to accurately detect an image if the image for adjustment is unclear. Therefore, the projector executes focus adjustment prior to the distortion correction (see, for example, PLT 1). For example, an apparatus described in PLT 1 is configured to project an image for focus adjustment and execute a focus on the basis of a projection state of the image. The apparatus uses an image for focus adjustment that can be more promptly detected.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In general, focus adjustment of a projector is performed by moving an optical system including a lens. Therefore, for an increase in speed, it is necessary to improve a physical mechanism. It is not easy to increase speed. On the other hand, in order to realize improvement of convenience of the projector, it is desired to perform, in a shorter time, a series of processing for correcting distortion.

Solution to Problem

An advantage of some aspects of the invention is to provide a projector that can execute, in a shorter time, processing for correcting distortion of a projected image on a projection surface and a control method for the projector. An aspect of the invention is directed to a projector including: a projecting unit including a projection optical system and configured to project an image on a projection surface; a focus adjusting unit configured to perform focus adjustment for the projection optical system; a correcting unit configured to perform distortion correction processing for correcting distortion of the image projected by the projecting unit; a correction control unit configured to cause the correcting unit to execute the distortion correction processing until a completion condition for the distortion correction processing holds after a start condition for the distortion correction processing holds; and a focus control unit configured to restrict the execution of the focus adjustment by the focus adjusting unit while the correction control unit causes the correcting unit to execute the distortion correction processing.

According to the aspect of the invention, the execution of the focus adjustment that consumes time for, for example, driving of a lens is restricted while the distortion correction for the image projected on the projection surface is performed. Therefore, it is possible to promptly complete the distortion correction.

In the projector of the aspect of the invention, the focus control unit may cause the focus adjusting unit to execute the focus adjustment for the projection optical system when the start condition for the distortion correction processing holds and the correction control unit causes the correcting unit to start the distortion correction processing.

According to this configuration, the distortion correction is executed in a state in which the focus is adjusted and a clear image is projected. Therefore, it is possible to surely and promptly perform the distortion correction.

The projector of the aspect of the invention may include a focus-adjustment-value calculating unit configured to calculate a focus adjustment value for the projection optical system on the basis of a projection condition. The focus adjusting unit may be configured to execute the focus adjustment according to the set focus adjustment value. When the focus adjustment value calculated by the focus-adjustment-value calculating unit when the distortion correction processing is started by the correcting unit and a focus adjustment value already set in the focus adjusting unit have a difference equal to or larger than a predetermined difference, the focus control unit may set, as a new focus adjustment value, the focus adjustment value calculated by the focus-adjustment-value calculating unit in the focus adjusting unit and cause the focus adjusting unit to execute the focus adjustment.

According to this configuration, the distortion correction is performed after the focus adjustment is performed when necessary. Therefore, it is possible to surely and more promptly execute the distortion correction in a state in which a clear image is projected.

In the projector of the aspect of the invention, the correction control unit may cause the correcting unit to execute the distortion correction processing a plurality of times until the completion condition for the distortion correction processing holds after the start condition for the distortion correction processing holds.

According to this configuration, the distortion correction is performed a plurality of times until the completion condition holds. Therefore, it is possible to execute the distortion correction following a change in projection conditions such as a projection distance and a projection angle. By restricting the focus adjustment in this period, it is possible to promptly execute the distortion correction every time and promptly follow a change in the projection conditions.

In the projector of the aspect of the invention, the correction control unit may cause the projecting unit to project an image for correction until the completion condition for the distortion correction processing holds after the start condition for the distortion correction processing holds. The correcting unit may correct distortion of the image projected by the projecting unit on the basis of a state of the image for correction projected by the projecting unit.

According to this configuration, it is possible to promptly execute the distortion correction on the basis of the image for correction clearly projected by performing the focus adjustment.

In the projector of the aspect of the invention, the correction control unit may determine, on the basis of the movement of the projector, whether the start condition for the distortion correction processing holds and whether the completion condition for the distortion correction processing holds.

According to this configuration, when the distortion correction is necessary, it is possible to promptly execute the correction according to the movement of the projector.

Another aspect of the invention is directed to a control method for a projector, the control method including: controlling a projector including a projecting unit including a projection optical system, which projects an image on a projection surface, and configured to project the image on the projection surface and a focus adjusting unit configured to perform focus adjustment for the projection optical system; and executing distortion correction processing for correcting distortion of the image projected by the projecting unit until a completion condition for the distortion correction processing holds after a start condition for the distortion correction processing holds and restricting the execution of the focus adjustment for the projection optical system while the distortion correction processing is executed.

According to the aspect of the invention, the execution of the focus adjustment that consumes time for, for example, driving of a lens is restricted while the distortion correction for the image projected on the projection surface is performed. Therefore, it is possible to promptly complete the distortion correction.

Advantageous Effects of Invention

According to the aspects of the invention, it is possible to restrict the execution of the focus adjustment that consumes time for, for example, driving of a lens and promptly complete the distortion correction.

DESCRIPTION OF EMBODIMENTS

An embodiment to which the invention is applied is explained below with reference to the drawings.

FIG. 1is a block diagram showing an overall configuration of a projector100according to the embodiment. The projector100projects an image on a screen SC on the basis of an image stored in an image storing unit171incorporated therein or image data input from an external image supply apparatus (not shown in the figure) such as a personal computer or various video players. In this embodiment, the screen SC stands substantially upright. A screen surface is formed in a rectangular shape.

The image data input to the projector100may be either data of a moving image (a video) or data of a still image. The projector100can project the video on the screen SC and can continue to project the still image on the screen SC. In an example explained in the embodiment explained below, an image is projected on the basis of an analog image signal input from the external image supply apparatus via a cable200.

The projector100roughly includes a projecting unit101(projecting means) that performs formation of an optical image and an image processing system that controls the operation of the entire projector100and electrically processes an image signal. The projecting unit101includes a light source140, a light modulation device130, and a projection optical system150. As the light source140, a Xenon lamp, an extra-high pressure mercury lamp, an LED (Light Emitting Diode), a laser light source, or the like can be used. The light source140may include a reflector and an auxiliary reflector that guide light emitted by the light source140to the light modulation device130and a dimming device (not shown in the figure) that reduces the light emitted by the light source140on a path leading to the light modulation device130.

The light modulation device130receives a signal from the image processing system explained below and modulates the light emitted by the light source140into image light. Examples of a specific configuration of the light modulation device130include a system in which three transmissive or reflective liquid crystal light valves corresponding to the respective colors of RGB are used. In this case, the light emitted by the light source140is separated in to respective color lights of R, G, and B by a dichroic mirror or the like and made incident on the light modulation device130. The respective color lights are modulated by liquid crystal panels for the respective colors included in the light modulation device130. Thereafter, the respective color lights are combined by a cross-dichroic prism and guided to the projection optical system150. In this embodiment, the light modulation device130includes a transmissive liquid crystal panel. The light modulation device130is driven by a light-modulation-device driving unit134explained below. The light modulation device130changes the transmittance of light in respective pixels arranged in a matrix shape to thereby form an image.

The projection optical system150includes a zoom lens151that performs expansion and reduction of an image to be projected and adjustment of a focus, a motor for zoom adjustment152that adjusts a degree of zoom, and a motor for focus adjustment153that performs adjustment of a focus. Light modulated by the light modulating device130is made incident on the projection optical system150. The light is projected on the screen SC through the zoom lens151to focus a projected image. The zoom lens151includes a lens group including a plurality of lenses. A lens driving unit154drives the motor for zoom adjustment152and the motor for focus adjustment153to execute adjustment of the projection optical system150according to the control by the CPU120. Specifically, the lens driving unit154controls the motor for zoom adjustment152to drive the zoom lens151and performs, for example, position adjustment for the lenses to perform zoom adjustment for expanding and reducing the projected image on the screen SC. The lens driving unit154functions as a focus adjusting means, controls the motor for focus adjustment153to drive the zoom lens151, and performs focus adjustment for properly focusing the projected image on the screen SC.

The image processing system mainly includes a CPU120that collectively controls the entire projector100and a processor for images131. The image processing system includes an A/D conversion unit110, a light-modulation-device driving unit134, a light-source driving unit141, a lens driving unit154, a RAM160, a ROM170including an image storing unit171and a correction-pattern storing unit172, an image pickup unit180including a CCD camera181, a photographed image memory182, a motion detecting unit185, a remote-controller control unit190, a remote controller191, and an operation unit195. The components included in the image processing system are connected to one another via a bus102.

The A/D conversion unit110is a device that subjects an analog input signal, which is input from the external image supply apparatus via the cable200, to A/D conversion. The A/D conversion unit110outputs a digital signal after the conversion to the processor for images131.

The CPU120performs image processing in the projector100in cooperation with the processor for images131. The CPU120includes, besides a projection control unit121that performs control related to projection by the projector100, a correction control unit122, a zoom-ratio calculating unit123, a three-dimensional measurement unit124, a projection-angle calculating unit125, and a focus-adjustment-value calculating unit126. The units are realized by the CPU120executing a program stored in the ROM170in advance. The CPU120functions as a controlling means. In particular the function of the projection control unit121is equivalent to the controlling means.

The processor for images131includes a trapezoidal-distortion correcting unit132and a superimposition processing unit133. The processor for images131processes, according to the control by the CPU120, image data input from the A/D conversion unit110, generates an image signal for rendering a projected image using the light modulation device130, and outputs the generated image signal to a light-modulation-device driving unit134. The processor for images131can be configured using a general-purpose processor sold as a DSP (digital signal processor) for trapezoidal distortion correction and image processing and can be configured as a dedicated ASIC. When the projector100projects image data stored in the image storing unit171, the processor for images131applies the processing explained above to the image data.

The light-modulation-device driving unit134drives the light modulation device130on the basis of an image signal input from the processor for images131. Consequently, an image corresponding to the image signal input to the A/D conversion unit110is formed in an image forming region of the light modulation device130. The image is formed on the screen SC as a projected image via the projection optical system150.

The light-source driving unit141applies a voltage to the light source141and lights or extinguishes the light source140according to an instruction signal input from the CPU120. The lens driving unit154drives the motor for zoom adjustment152and the motor for focus adjustment153to perform zoom adjustment and focus adjustment according to the control by the CPU120.

The RAM160forms a work area for temporarily storing programs and data executed by the CPU120and the processor for images131. The processor for images131may include, as a built-in RAM, a work area necessary for execution of various kinds of processing such as adjustment processing for a display state of an image performed by the processor for images131.

The ROM170stores a program executed by the CPU120in order to realize the processing units and data and the like related to the program. The ROM170includes an image storing unit171that stores an image projected by the projecting unit101and a correction-pattern storing unit172that stores a correction pattern used for the distortion correction processing.

The image pickup unit180includes a CCD camera181including a CCD, which is a well-known image sensor. The image pickup unit180is provided on the front surface of the projector100, i.e., in a position where the image pickup unit180can pick up, with the CCD camera181, an image in a direction in which the projection optical system150projects an image to the screen SC. In the image pickup unit180, a camera direction and an angle of view of the CCD camera181are set such that an entire projected image projected on the screen SC at a recommended projection distance lies within at least an image pickup range. The CCD camera181may include, besides a CCD, a single focus lens that forms an image on the CCD, a mechanism such as an auto iris that adjusts an amount of light made incident on the CCD and a control circuit that reads out an image signal from the CCD. Data of a photographed image photographed by the CCD camera181is output from the image pickup unit180to the photographed image memory182and repeatedly written in a predetermined region of the photographed image memory182. When writing of image data for one screen is completed, the photographed image memory182sequentially reverses a flag of a predetermined region. Therefore, by referring to the flag, the CPU120can learn whether image pickup performed using the image pickup unit180is completed. The CPU120accesses the photographed image memory182and acquires necessary photographed image data while referring to the flag.

The motion detecting unit185includes a gyro sensor and an acceleration sensor. The motion detecting unit185detects a motion of a main body of the projector100and outputs a detection value to the CPU120. A threshold is set for the detection value of the motion detecting unit185in advance. When a motion exceeding the threshold is detected by the motion detecting unit185, the CPU120determines that the projector100has moved. When a motion detected by the motion detecting unit185is equal to or smaller than the threshold and this state continues exceeding a standby time set in advance, the CPU120determines that the projector100has stood still. The motion detecting unit185may be configured to output a detection signal to the CPU120when the threshold is set in the motion detecting unit185and the detection value of the motion detecting unit185exceeds the threshold and when the detection value of the motion detecting unit185is equal to or smaller than the threshold and the standby time elapses. In this case, it is possible to reduce a load on the CPU120.

The remote-controller control unit190receives a radio signal transmitted from the remote controller191on the outside of the projector100. The remote controller191includes operators (not shown in the figure) operated by a user. The remote controller191transmits an operation signal corresponding to operation of the operators as an infrared signal or a radio signal that is transmitted using a radio wave having a predetermined frequency. The remote-controller control unit190includes a light receiving unit (not shown in the figure) that receives the infrared signal and a receiving circuit (not shown in the figure) that receives the radio signal. The remote-controller control unit190receives a signal transmitted from the remote controller191, analyzes the signal, generates a signal indicating content of the operation by the user, and outputs the signal to the CPU120.

The operation unit195includes, for example, operators (not shown in the figure) of an operation panel arranged in a main body of the projector100. Upon detecting operation of the operators, the operation unit195outputs an operation signal corresponding to the operators to the CPU120. As the operators, there are a switch for instructing power on/power off, a switch for instructing a distortion correction processing start, and the like.

Functions of the CPU120and the processor for images131are explained.

The projection control unit121controls, on the basis of image data output by the A/D conversion unit110, an action of projection of an image by the projecting unit101. Specifically, the projection control unit121performs control for causing the light-source driving unit141to light/extinguish the light source140according to power on/off of the projector100, control for causing the processor for images131to process image data output by the A/D conversion unit110, and the like.

The projection control unit121has a function of starting and ending distortion correction processing by the correction control unit122for controlling the trapezoidal-distortion correcting unit132and correcting trapezoidal distortion. The projection control unit121functions as a correction controlling means. The correction control unit122cooperates with the trapezoidal-distortion correcting unit132and functions as a correcting means.

As a start condition for starting the distortion correction processing, it is set in advance that, for example, a motion of the projector100is detected on the basis of a detection value of the motion detecting unit185or the distortion correction processing is instructed by operation of the operation unit195or the remote controller191. When any one of the set conditions is met, the projection control unit121determines that the start condition for the distortion correction processing holds. The projection control unit121controls the superimposition processing unit133of the processor for images131to superimpose a correction pattern (an image for adjustment) stored in the correction-pattern storing unit172on an image being projected and project the correction pattern. Consequently, the image that has been projected from before the start of the distortion correction processing and the correction pattern are displayed one on top of the other.

The projection control unit121causes the correction control unit122to execute the distortion correction processing. The correction control unit122causes the image pickup unit180to pick up a projected image in a state in which the correction pattern stored in the image storing unit171is projected on the screen SC. The correction control unit122acquires photographed image data from the photographed image memory182and causes the processing units, i.e., the zoom-ratio calculating unit123, the three-dimensional measurement unit124, and the projection-angle calculating unit125explained later to calculate a projection angle and a projection distance on the basis of the photographed image data. The correction control unit122outputs control data corresponding to the projection angle to the processor for images131and causes the focus-adjustment-value calculating unit126(focus-adjustment-value calculating means) to calculate a focus setting value corresponding to the projection distance. The projection control unit121sets the calculated focus adjustment value in the lens driving unit154and drives the motor for focus adjustment153according to the focus adjustment value to perform focus adjustment. The projection control unit121functions as a focus controlling means.

The correction control unit122calculates parameters for performing the distortion correction processing on the basis of the projection angle and the projection distance calculated by the functions of the processing units, i.e., the zoom-ratio calculating unit123, the three-dimensional measurement unit124, and the projection-angle calculating unit125. The parameters are parameters for deforming an image rendered by the light modulation device130such that the image compensates for distortion of a projected image on the screen SC. The parameters are data for defining the direction of the deformation, a deformation amount, and the like. The correction control unit122outputs the calculated parameters to the trapezoidal-distortion correcting unit132and causes the trapezoidal-distortion correcting unit132to execute the distortion correction processing.

The processing units, i.e., the zoom-ratio calculating unit123, the three-dimensional measurement unit124, and the projection-angle calculating unit125perform, according to the control by the correction control unit122, processing necessary for calculating a projection angle, which is a tilt of an optical axis of projected light projected from the projector100with respect to the plane of the screen SC. Specifically, the zoom-ratio calculating unit123calculates a zoom ratio of the projection optical system150. The three-dimensional measurement unit124and the projection-angle calculating unit125detects a correction pattern from photographed image data and calculates, on the basis of the size and the position of the detected correction pattern, taking into account the zoom ratio calculated by the zoom-ratio calculating unit123, a relative three-dimensional arrangement relation between the projector100and the screen SC including the projection distance, which is the distance from the projector100to the screen SC, and the projection angle, which is the tilt of the optical axis of the projected light projected by the projector100with respect to the screen plane. The focus-adjustment-value calculating unit126calculates a focus adjustment value suitable for the calculated projection distance.

The processor for images131is a functional unit that processes image data input from the A/D conversion unit110. The processor for images131applies, to projection target image data, processing for adjusting a display state of an image such as luminance, contrast, the depth of a color, and a tint and outputs the image data after the processing to the light-modulation-device driving unit134.

The trapezoidal-distortion correcting unit132included in the processor for images131performs, according to the parameters input from the correction control unit122, processing for deforming the image of the image data output by the A/D conversion unit110.

The superimposition processing unit133has a function of superimposing the correction pattern stored in the correction-pattern storing unit172on a projected image. The superimposition processing unit133is connected to the post stage of the trapezoidal-distortion correcting unit132. The image data after the processing by the trapezoidal-distortion correcting unit132is input to the superimposition processing unit133. Therefore, when the trapezoidal-distortion correcting unit132performs the distortion correction processing and when the trapezoidal-distortion correcting unit132does not perform the distortion correction processing, the superimposition processing unit133superimposes the correction pattern on the image data processed by the trapezoidal-distortion correcting unit132. With this configuration, the distortion correction processing is not applied to the image on which the superimposition processing unit133superimposes the correction pattern. In other words, the correction pattern projected by the projector100is always in a state in which the distortion correction processing is not applied to the correction pattern.

Subsequently, the operation of the projector100is explained.FIGS. 2A to 2Care explanatory diagrams showing the operation of the projector100for projecting an image and a correction pattern.FIG. 2Ashows an example of the image.FIG. 2Bshows an example of the correction pattern.FIG. 2Cshows an example in which the light modulation device130renders the image and the correction pattern in an image formable region136.

In this embodiment, an example in which a rectangular image175is projected as shown inFIG. 2Ais explained. In this embodiment, as an example of the correction pattern, a correction pattern177shown inFIG. 2Bis explained. The correction pattern177has a rectangular shape as a whole in which cross-shaped markers177aare arranged in the vicinity of the four corners. A portion other than the markers177ais colorless (transparent).

In a state in which the trapezoidal-distortion correcting unit132is not performing the distortion correction processing, when the superimposition processing unit133superimposes the correction pattern177on the image175, an image shown inFIG. 2Cis rendered in the image formable region136of the light modulation device130. As in the example shown inFIG. 2C, in the state in which the distortion correction processing is not performed, the image is rendered widely using the image formable region136of the light modulation device130. Therefore, an image forming region137is provided in the entire image formable region136. The image175is formed (rendered) in the image forming region137. In the image forming region137, the correction pattern177is rendered to be superimposed on the image175. Since the correction pattern177excluding the markers177ais transparent, the markers177aare rendered while overlapping the image175.

FIGS. 3A to 3Care explanatory diagrams showing an example of the operation of the projector100for correcting distortion of a projected image.FIG. 3Ashows a projection example on the screen SC before correction.FIG. 3Bshows an example of an image formed in the image formable region136.FIG. 3Cshows a projection example on the screen SC after the correction. In the image projected on the screen SC, trapezoidal distortion occurs as shown inFIG. 3Aaccording to a projection angle of the projector100with respect to the screen SC. InFIG. 3A, an example in which the image obtained by superimposing the correction pattern177on the image175as shown inFIG. 2Cis projected is shown. In this example, the image175is projected while being distorted. The positions of the markers177adeviate in the arrangement in the rectangle according to trapezoidal distortion.

The correction control unit122executes the distortion correction processing. The trapezoidal-distortion correcting unit132deforms the image175. Consequently, the deformed image175is included in an image output from the processor for images131to the light-modulation-device driving unit134. Therefore, the deformed image175is rendered in the image forming region137of the light modulation device130as shown inFIG. 3B. It is necessary to render the deformed image175on the inside of the rectangular image formable region136. Therefore, the image forming region137in which the image175is rendered is a part of the image formable region136.

As explained above, the correction pattern177is superimposed on the image after the distortion correction processing, which is output by the trapezoidal-distortion correcting unit132, by the superimposition processing unit133connected to the post stage of the trapezoidal-distortion correcting unit132. Therefore, the distortion correction processing is not applied to the correction pattern177. Therefore, as shown inFIG. 3B, the four markers177aarranged at the four corners of the rectangle are rendered on the image175in a state same as the state shown inFIG. 2Cbefore the distortion correction processing.

Consequently, as shown inFIG. 3C, the trapezoidal distortion of the image175is corrected and the image175is projected in a rectangular shape on the screen SC. However, the state of the trapezoidal distortion is left in the correction pattern177. In other words, the positions of the markers177adeviate from the positions where the markers177aare arranged when there is no trapezoidal distortion.

When the correction control unit122corrects the trapezoidal distortion, the correction control unit122causes the image pickup unit180to photograph the screen SC, detects the positions of the markers177afrom a photographed image, and performs calculation by the three-dimensional measurement unit124and the projection-angle calculating unit125on the basis of the positions. The correction control unit122calculates parameters for distortion correction on the basis of results of the calculation and sets the calculated parameters in the trapezoidal-distortion correcting unit132. In the series of processing, the correction control unit122compares the positions of the markers177adetected in the photographed image data of the image pickup unit180with the positions of the markers177ain the data of the correction patterns177stored in the correction-pattern storing unit172. Therefore, after the distortion correction processing is performed as shown inFIG. 3C, when the distortion correction processing is further performed, the correction control unit122causes the image pickup unit180to photograph the screen SC anew, detects the markers177afrom new photographed image data, and calculates parameters.

When the distortion correction processing is performed, if not only the image175but also the correction pattern177is deformed according to the parameters, the markers177aare moved by the distortion correction processing. Therefore, the positions of the markers177aon the screen SC are different positions according to the processing performed by the trapezoidal-distortion correcting unit132in addition to the projection angle and the projection distance between the screen SC and the projector100. Therefore, it is impossible to accurately calculate the projection angle and the projection distance between the screen SC and the projector100simply by photographing the markers177amoved by the trapezoidal-distortion correcting unit132and comparing the positions of the markers177ain photographed image data with the positions of the markers177ain the correction pattern177stored in the correction-pattern storing unit172. In order to accurately calculate the projection angle and the projection distance, it is necessary to perform processing for excluding the influence of the distortion correction processing performed earlier.

When it is determined by the control by the projection control unit121that a start condition for the distortion correction processing holds, the projector100executes the distortion correction processing before the projector100stands still and, thereafter, repeatedly executes the distortion correction processing at a period set in advance until a condition for completing the distortion correction processing is met. Consequently, the distortion correction processing is periodically performed and an image after correction is projected on the screen SC. Therefore, a user who uses the projector100can see a state of the correction even before the projector100stands still or the operation for completing the distortion correction processing is performed. Before the standby time elapses after the movement of the projector100stops, the distortion correction processing is executed in a state in which the projector100stands still. Therefore, the corrected image is projected on the screen SC according to a position where the projector100stands still. Consequently, substantially, it is possible to project the corrected image before the standby time elapses and promptly project an image without distortion. In this case, it is desirable that the period of the repeated execution of the distortion correction processing by the projector100is time shorter than the standby time.

When the distortion correction is continuously executed a plurality of times in this way, if the distortion correction processing is applied to the correction pattern177as well, it is necessary to perform, concerning the positions of the markers177a, calculation for excluding the influence of the distortion correction performed the plurality of times. A load of the processing for calculating the parameters increases. Therefore, as in this embodiment, if the distortion correction processing is not performed concerning the correction pattern177, the positions of the markers177aare always positions shifted by reflecting the projection angle and the distance between the screen SC and the projector100. Therefore, even if the distortion correction processing is repeatedly performed, it is possible to promptly calculate the projection angle and the distance between the screen SC and the projector100accurately and calculate accurate parameters on the basis of the positions of the markers177a. A load of the processing for calculating the parameters does not increase even if the distortion correction processing is repeatedly performed.

Furthermore, in this embodiment, the superimposition processing unit133that performs processing for superimposing the correction pattern177on the image projected by the projecting unit101is connected to the post stage of the trapezoidal-distortion correcting unit132that performs the distortion correction processing. An image subjected to the superimposition processing by the superimposition processing unit133is output to the light-modulation-device driving unit134and rendered on the light modulation device130. Therefore, since a procedure of the processing in the projector100is a procedure in which the correction pattern177is not affected by the distortion correction processing, it is possible to prevent, without performing special processing, the correction pattern177from being deformed in the distortion correction processing.

When the projection control unit121causes the correction control unit122to execute the distortion correction processing, the projection control unit121causes the lens driving unit154to execute focus adjustment. The focus adjustment is executed before the correction control unit122calculates parameters for distortion correction after the start condition for the distortion correction processing holds. The correction pattern177and the image175are clearly projected according to the processing. Therefore, it is possible to surely detect the correction pattern177from photographed image data in the distortion correction processing performed thereafter. Further, when the correction pattern177in the photographed image data is unclear, processing for detecting an image of the correction pattern177often takes time. Therefore, by executing the focus adjusting first, it is possible to promptly execute the processing for detecting the correction pattern177.

Further, after once executing the focus adjustment, the projection control unit121restricts the execution of the focus adjustment until the completion condition for the distortion correction processing holds. In other words, until the completion condition for the distortion correction processing holds, the projector100repeatedly executes, a plurality of times, the operation for calculating parameters for the distortion correction and correcting distortion of the projected image175. However, the projector100does not perform the focus adjustment. In the focus adjustment, since the zoom lens151is moved by the motor for focus adjustment153, the focus adjustment takes time compared with the distortion correction processing including the calculation processing and the image processing. Therefore, it is possible to execute the distortion correction processing in a short time and promptly correct distortion of a projected image on the screen SC by restricting the focus adjustment. Therefore, it is possible to repeatedly execute the distortion correction processing in a shorter time.

FIG. 4is a flowchart for explaining the operation of the projector100.

When a power supply for the projector100is switched to ON, the CPU120of the projector100controls the light-source driving unit141to light the light source140(step S11). Further, the CPU120controls the lens driving unit154to execute optical adjustment in the projection optical system150and causes the processor images131to execute, for example, adjustment adapted to the brightness of an image and a designated color mode (step S12). Thereafter, the projection control unit121included in the CPU120projects an image output from the A/D conversion unit110(step S13).

After starting the projection, the projection control unit121determines whether the start condition for the distortion correction processing holds (step S14). As explained above, the start condition is that start instruction operation by the remote controller191or the operation unit195is performed or a detection value of the motion detecting unit185exceeds the threshold. When the start condition for the distortion correction processing holds (Yes in step S14), the projection control unit121reads out the correction pattern stored in the correction-pattern storing unit172, causes the superimposition processing unit133to superimpose the correction pattern on the image, and causes the projecting unit101to project the correction pattern on the screen SC (step S15).

After projecting the image and the correction pattern on the screen SC, the projection control unit121executes the focus adjustment (step S16).

FIG. 5is a flowchart for explaining the operation of the projector100. The focus adjustment in step S16is shown in detail.

The projection control unit121causes the image pickup unit180to photograph the screen SC and acquires photographed image data from the photographed image memory182(step S31). The projection control unit121detects markers of a correction pattern in the photographed image data, performs calculation by the three-dimensional measurement unit124, and calculates a projection distance (step S32). The projection control unit121causes the focus-adjustment-value calculating unit126to calculate a focus adjustment value on the basis of the calculated projection distance (step S33).

The projection control unit121compares a focus adjustment value currently set in the lens driving unit154and the focus adjustment value calculated by the focus-adjustment-value calculating unit126in step S33(step S34). The projection control unit121discriminates whether the focus adjustment value calculated in step S33is a value outside a range set in advance centering on the set focus adjustment value (step S35). For example, when the motion detecting unit185detects the movement of the projector100and the start condition holds, it is likely that a projection distance changes from a projection distance before the start condition holds. In such a case, since the focus adjustment value set in the lens driving unit154is a value set before the start condition holds, the focus adjustment value does not match the projection distance after the start condition holds. It is desirable to perform the focus adjustment in order to accurately and promptly perform the distortion correction. Therefore, in step S33, the projection control unit121discriminates, with reference to the range set in advance concerning the set focus adjustment value, whether a change in the projection distance that makes it necessary to perform the focus adjustment occurs.

When the focus adjustment value calculated in step S33is outside the range set in advance centering on the set focus adjustment value (Yes in step S35), the projection control unit121sets the new focus adjustment value calculated by the focus-adjustment-value calculating unit126in step S33in the lens driving unit154(step S36). The lens driving unit154drives the motor for focus adjustment153according to the control by the projection control unit121and executes the focus adjustment by the zoom lens151(step S37). Consequently, the focus adjustment is performed according to the projection distance. The screen SC is made clear. The projection control unit121ends the processing and shifts to step S17inFIG. 4.

When the focus adjustment value calculated in step S33is within the range of the focus adjustment value set in the lens driving unit154(No in step S35), the projection control unit121ends the processing without executing the focus adjustment and shifts to step S17.

As explained above, in the operation shown inFIG. 5, the CPU120discriminates presence or absence of necessity of the focus adjustment and, only when the focus adjustment is necessary, performs the focus adjustment. Therefore, after the execution of the operation shown inFIG. 5, irrespective of whether the focus adjustment by the lens driving unit154is performed, a projected image on the screen SC is clear.

In step S17inFIG. 4, the projection control unit121causes the image pickup unit180to photograph the screen SC and acquires photographed image data from the photographed image memory182. The projection control unit121detects markers in a correction pattern in the photographed image data, performs calculation by the three-dimensional measurement unit124and the projection-angle calculating unit125, and calculates a projection distance and a projection angle (step S18). When the focus adjustment in step S37inFIG. 5is not executed, the projection control unit121may use the photographed image data photographed in step S31without executing the photographing in step S17or may use the projection distance and the like calculated in step S32without performing the calculation in step S18.

Thereafter, the correction control unit122calculates, on the basis of the projection distance and the projection angle calculated by the three-dimensional measurement unit124and the projection-angle calculating unit125, parameters for the distortion correction for correcting trapezoidal distortion and updates the parameters set in the trapezoidal-distortion correcting unit132with new parameters (step S19). Consequently, the distortion correction processing based on the new parameters is applied by the trapezoidal-distortion correcting unit132. An image obtained by the superimposition processing unit133superimposing the correction pattern on an image after the processing is projected on the screen SC (step S20).

The projection control unit121determines whether the condition for completing the distortion correction processing holds (step S21). As explained above, the condition for completing the distortion correction processing is that instruction operation for completing the distortion correction processing is performed by the remote controller191or the operation unit195or the detection value of the motion detecting unit185is equal to or smaller than the threshold and a standby time elapses. When both the conditions do not hold (No in step S21), the projection control unit121returns to step S17. In other words, the projection control unit121repeats the processing for calculating and update parameters for distortion correction without executing the focus adjustment.

When the condition for completing the distortion correction processing holds (Yes in step S21), the projection control unit121causes the focus-adjustment-value calculating unit126to calculate a focus adjustment value on the basis of the latest projection distance calculated in the processing in step S18(step S22), sets the calculated focus adjustment value in the lens driving unit154, and causes the lens driving unit154to execute the focus adjustment (step S23).

Subsequently, the projection control unit121causes the superimposition processing unit133to ends the processing for superimposing the correction pattern (step S24). Thereafter, the projection control unit121determines whether the projector100ends the projection (step S25). When the projector100does not end the projection (No in step S25), the projection control unit121returns to step S14. When the projector100ends the projection according to the operation by the remote controller191or the operation unit195(Yes in step S25), the projection control unit121stops the operation related to the projection of the image by the projecting unit101and extinguishes the light source140(step S26).

When the start condition for the distortion correction processing does not hold (No in step S14), the projection control unit121shifts to step S25and determines whether the projection ends. When the projector100does not end the projection in step S25, the projection control unit121returns to step S14and repeatedly determines whether the start condition holds. A period of the determination in step S14is set in advance. In other words, the determination is repeatedly executed at the set period while the start condition does not hold and the projector does not end the projection.

As explained above, the projector100according to the embodiment to which the invention is applied includes the projection optical system150. The projector100includes the projecting unit101that projects an image on the projection surface, the lens driving unit154that performs the focus adjustment for the projection optical system150, the trapezoidal-distortion correcting unit132that performs the distortion correction processing for correcting distortion of the image projected by the projecting unit101, and the projection control unit121that causes the trapezoidal-distortion correcting unit132to execute the distortion correction processing until the completion condition for the distortion correction processing holds after the start condition for the distortion correction processing holds and restricts, while causing the trapezoidal-distortion correcting unit132to execute the distortion correction processing, the execution of the focus adjustment for the projection optical system150by the lens driving unit154. Consequently, while the trapezoidal distortion correction for the projected image is performed, since the execution of the focus adjustment that consumes time for, for example, the driving of the zoom lens151is restricted, it is possible to promptly complete the distortion correction.

When the start condition for the distortion correction processing holds and the projection control unit121causes the trapezoidal-distortion correcting unit132to start the distortion correction processing, the projection control unit121causes the lens driving unit154to execute the focus adjustment. Consequently, since the distortion correction is executed in a state in which a focus is adjusted, it is possible to surely and promptly perform the distortion correction.

The projector100includes the focus-adjustment-value calculating unit126that calculates a focus adjustment value for the projection optical system150. The lens driving unit154is configured to execute the focus adjustment according to the set focus adjustment value. When the focus adjustment value calculated by the focus-adjustment-value calculating unit126when the distortion correction processing is started by the trapezoidal-distortion correcting unit132and a focus adjustment value already set in the lens driving unit154have a difference equal to or larger than a predetermined difference, the projection control unit121sets, as a new focus adjustment value, the focus adjustment value calculated by the focus-adjustment-value calculating unit126in the lens driving unit154and executes the focus adjustment. Consequently, the distortion correction is performed after the focus adjustment is performed to make the projected image clear when necessary. Therefore, it is possible to surely and more promptly execute the distortion correction.

Since the projection control unit121causes the trapezoidal-distortion correcting unit132to execute the distortion correction processing a plurality of times until the completion condition for the distortion correction processing holds after the start condition for the distortion correction processing holds, the distortion correction following a change in the projection condition can be executed. Therefore, by restricting the focus adjustment in this period, it is possible to promptly execute the distortion correction every time. Therefore, it is possible to promptly follow a change in the projection conditions.

The projection control unit121causes the projecting unit101to project the correction pattern177until the completion condition for the distortion correction processing holds after the start condition for the distortion correction processing holds. The trapezoidal-distortion correcting unit132corrects distortion of the image projected by the projecting unit101on the basis of a projection state of the correction pattern177projected by the projecting unit101. Therefore, it is possible to promptly execute the distortion correction on the basis of the correction pattern clearly projected on the screen SC.

The projection control unit121determines, on the basis of the movement of the projector100, whether the start condition for the distortion correction processing holds and whether the completion condition for the distortion correction processing holds. Therefore, when the distortion correction is necessary, it is possible to promptly execute the correction according to the movement of the projector100.

In the embodiment, as explained with reference toFIG. 5, the focus adjustment is executed before the parameters for distortion correction are calculated after the start condition for the distortion correction processing holds. In this configuration, a focus adjustment value is calculated and, when the focus adjustment value deviates from a predetermined range of a focus adjustment value already set in the lens driving unit154, i.e., when a difference between the focus adjustment values exceeds a set range, the focus adjustment is executed. However, the invention is not limited to this. Besides, there are examples of operations related to the focus adjustment.

After calculating the focus adjustment value in step S33, without performing the comparison with the focus adjustment value set in the lens driving unit154(steps S34and S35), the projection control unit121may always execute the focus adjustment (steps S36and S37) on the basis of the calculated latest focus adjustment value. In this case, the projection control unit121performs the focus adjustment without discriminating a state of the focus adjustment. In this example, since only one operation of the focus adjustment is added, time required for the distortion correction does not substantially increase. There is an advantage that processing is simplified and a load is reduced.

When the focus adjustment value set in the lens driving unit154is not a value within a range set in advance, the projection control unit121may execute the focus adjustment (steps S36and S37) on the basis of the latest focus adjustment value calculated in step S33. In other words, when a standard range of a focus adjustment value during the distortion correction is set in the projector100in advance and a focus adjustment value deviating from the standard range is set in the lens driving unit154, the projection control unit121executes the focus adjustment during the start of the distortion correction processing. In this example, there is an advantage that it is possible to promptly discriminate whether the focus adjustment is performed.

When the focus adjustment value set in the lens driving unit154is not within the range set in advance, the projection control unit121may execute the focus adjustment (steps S36and S37) on the basis of a focus adjustment value set in advance. In this example, it is possible to execute the focus adjustment without performing the processing for calculating a projection distance. Therefore, there is an advantage that it is possible to further increase the speed of the distortion correction processing. Further, there is an advantage that it is possible to promptly discriminate whether the focus adjustment is performed.

The projection control unit121may execute the focus adjustment (steps S36and S37) on the basis of the focus adjustment value set in advance irrespective of the focus adjustment value set in the lens driving unit154. In this example, it is possible to execute the focus adjustment without performing the processing for calculating a projection distance. Therefore, there is an advantage that it is possible to further increase the speed of the distortion correction processing. Further, since it is not discriminated whether the focus adjustment is performed, it is possible to more quickly perform the distortion correction processing.

The embodiment explained above is only an example of a specific mode to which the invention is applied. The embodiment does not limit the invention. The invention can also be applied as a mode different from the embodiment. For example, in the example explained in the embodiment, the image input to the A/D conversion unit110via the cable200is projected. However, the invention is not limited to this. It is also naturally possible to apply the invention when an image or a video stored in the image storing unit171is projected. Setting values concerning times, thresholds, and the like for defining the operations of the units of the projector100in the embodiment are stored in the ROM170in advance. However, the setting values may be stored in a storage medium or a device on the outside of the projector100and acquired by the projector100according to necessity. The setting values may be input every time the remote controller191or the operation unit195is operated.

In the embodiment, the processing for correcting trapezoidal distortion that occurs in an image on the screen SC is explained. However, the invention is not limited to this. For example, the invention can also be applied to, for example, processing for correcting distortion called barrel distortion or pin-cushion distortion.

In the explanation in the embodiment, the image pickup unit180includes the CCD camera181including a CCD image sensor. However, the invention is not limited to this. A CMOS sensor may be used as the image sensor of the image pickup unit180. In the embodiment, the configuration including the three transmissive or reflective liquid crystal panels corresponding to the respective colors of RGB is explained as the example of the light modulation device. However, the invention is not limited to this. For example, the light modulation device may be configured by a system in which one liquid crystal panel and a color wheel are combined, a system in which three digital mirror devices (DMDs) that modulate the color lights of the RGB colors are used, or a system in which one digital mirror device and a color wheel are combined. When only one liquid crystal panel or DMD is used as a display unit, a member equivalent to a combination optical system such as a cross-dichroic prism is unnecessary. Besides the liquid crystal panel or the DMD, a configuration capable of modulating light emitted by a light source can be adopted without problems. The functional units shown inFIG. 1indicate the functional configuration of the projector100. A specific embodiment of the functional units is not specifically limited. In other words, hardware individually corresponding to each of the functional units does not always necessary to be mounted. It is also naturally possible to adopt a configuration in which one processor executes a program to realize functions of a plurality of functional units. A part of the functions realized by software in the embodiment may be realized by hardware. Alternatively, apart of the functions realized by hardware may be realized by software.

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