JP2017146520A - Projector and image displacement compensation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector and an image displacement compensation method, for suppressing swing of a projected image on a projection screen regardless of the presence/absence of a mark on the projection screen even when the projection screen swings.SOLUTION: A projector 10 for projecting an image onto a projection screen SC includes: an irradiation part 14a for irradiating the projection screen SC with invisible light; a light-receiving part 14b for receiving the invisible light projected by the irradiation part 14a and reflected by the projection screen SC; a detection part 15a for detecting relative displacement of the projector 10 with respect to the projection screen SC based on the received results of the light-receiving part 14b; and a compensation part 17 for compensating the relative displacement of the image with respect to the projection screen SC based on the detection results of the detection part 15a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a projector and an image displacement compensation method.

When an installation base on which a projector for projecting an image is mounted or a ceiling suspension device that suspends the projector from the ceiling or wall vibrates, the vibration is transmitted to the projector, and the projected image from the projector may be shaken.
As a technique for suppressing such a shake of the projected image, a technique for suppressing the shake of the projected image due to the vibration of the projector based on the detection result of the vibration sensor mounted on the projector is known (Patent Document 1). reference). In this method, the projection image from the projector is projected in a state having vibrations in the opposite phase to the vibrations of the projector.
In addition, the camera mounted on the projector sequentially captures the marks provided in advance on the screen, and controls the projection direction of the projected image based on changes in the position of the mark on the captured image to suppress the shaking of the projected image. A technique for doing this is also known (see Patent Document 2).

Japanese Patent No. 5556193 JP 2005-292563 A

In the method described in Patent Document 1, since the vibration of the projection image is adjusted based only on the vibration of the projector, when the projection surface such as a screen vibrates, the projection surface is based on the vibration of the projection surface. It becomes difficult to suppress the shaking of the projected image. For example, when both the projector and the projection surface are shaken in the same manner, the position of the projection image on the projection surface does not change, so the projector does not need to shake the projection image. Even in this case, the projected image is shaken.
On the other hand, in the method described in Patent Document 2, a mark is always required on the projection surface. Therefore, when a projection surface without a mark is used, it is difficult to suppress the shaking of the projected image on the projection surface. .

  The present invention has been made in view of the above-described circumstances, and suppresses the shaking of the projected image on the projection plane regardless of the presence or absence of the mark on the projection plane even when the projection plane is shaking. Let it be a solution issue

One aspect of the projector according to the present invention is a projector that projects an image on a projection surface, the irradiation unit irradiating the projection surface with invisible light, and the invisible light irradiated from the irradiation unit and reflected by the projection surface. A light receiving unit that receives light; a detection unit that detects a relative displacement of the projector with respect to the projection surface based on a light reception result of the light receiving unit; and a detection unit that detects a relative displacement of the projection surface based on a detection result of the detection unit. And a compensator for compensating for the relative displacement of the image.
The result of receiving invisible light (reflected light) reflected by the projection surface reflects the uneven state of the irradiation region on the projection surface of invisible light. Therefore, when the relative positional relationship between the projection surface and the projector changes and the irradiation area is shifted, the uneven state reflected in the light reception result of the reflected light is also shifted. Therefore, the light reception result of the reflected light changes according to the relative positional relationship between the projection surface and the projector. For this reason, according to this aspect, the relative displacement of the projector with respect to the projection surface is detected based on the light reception result of the reflected light according to the relative positional relationship between the projection surface and the projector, and the projection surface is based on the displacement. The relative displacement of the image with respect to is compensated. Therefore, the displacement of the image relative to the projection surface can be compensated according to the change in the relative positional relationship between the projection surface and the projector, and even if the projection surface is shaken, the image shake on the projection surface can be suppressed. Become.
In addition, because the displacement of the image relative to the projection surface is compensated based on the result of receiving invisible light reflected from the projection surface, image fluctuations on the projection surface can be suppressed even when a projection surface without a mark is used. become. Here, “compensation” is only required to reduce the relative displacement, and does not need to be completely eliminated.
In addition, since the invisible light is irradiated, the influence of the irradiated light on the image visibility can be reduced as compared with the case where the visible light is irradiated instead of the invisible light.

In one aspect of the projector described above, the projector further includes a distance measurement unit that measures a distance between the projector and the projection plane, and the compensation unit adjusts the compensation based on a measurement result of the distance measurement unit. Is desirable.
The magnitude of the detected displacement changes according to the distance to the projection plane.
According to this aspect, since the compensation can be adjusted according to the change in the distance between the projector and the projection surface, the relative displacement can be effectively compensated.

In one aspect of the projector described above, the distance measurement unit receives the invisible light reflected by the projection surface after the irradiation unit irradiates the invisible light, and outputs the light reception result. It is desirable to measure the distance by measuring the time until.
According to this aspect, since the irradiation unit and the light receiving unit are used for distance measurement, the configuration can be simplified.

In one aspect of the projector described above, it is preferable that the detection unit detects a relative displacement of the projector with respect to the projection plane based on a change in a light reception result of the light receiving unit.
As described above, the light reception result of the light receiving unit changes according to the change in the relative positional relationship between the projection surface and the projector. For this reason, according to this aspect, the relative displacement of the projector with respect to the projection plane can be detected based on the change in the relative positional relationship between the projection plane and the projector.

In one aspect of the projector described above, it is preferable that the irradiation unit irradiates the invisible light on the entire projection surface.
According to this aspect, it is possible to detect the state of unevenness on the entire projection surface, and for example, it is possible to suppress a characteristic unevenness detection error that can easily specify the position on the projection surface. For this reason, compared with the case where a part of the projection surface is irradiated with invisible light, this characteristic unevenness cannot be detected, and the relative positional relationship between the projection surface and the projector is changed from the light reception result of the light receiving unit. The possibility of becoming difficult to detect can be reduced.

In one aspect of the projector described above, it is preferable that the irradiation unit irradiates a part of the projection surface with the invisible light.
According to this aspect, the invisible light irradiation area can be reduced as compared with the case of irradiating the entire projection surface with invisible light, and, for example, power consumption required for invisible light irradiation can be reduced.

One aspect of the image displacement compensation method of the present invention is an image displacement compensation method performed by a projector that projects an image on a projection surface, wherein the projection surface is irradiated with invisible light, and among the irradiated invisible light, the Receiving invisible light reflected by the projection surface, detecting a relative displacement of the projector with respect to the projection surface based on the result of the light reception, and based on a relative displacement of the projector with respect to the projection surface, The relative displacement of the image with respect to the projection plane is compensated.
According to this aspect, even if the projection surface is shaken, it is possible to suppress the shake of the projected image on the projection surface. In addition, since the displacement of the image relative to the projection plane is compensated based on the result of receiving invisible light reflected from the projection plane, even if a projection plane without a mark is used, the fluctuation of the projection image on the projection plane is suppressed. It becomes possible.

1 is a block diagram illustrating a configuration of a projector according to a first embodiment. It is a figure for demonstrating the influence of the vibration of the projector 10 and the projection surface SC. It is the figure which showed an example of the light-receiving part 14b. It is a figure which shows the irradiation area | region a1 on the projection surface SC. It is a figure which shows the irradiation area | region a2 on the projection surface SC. It is a figure which shows the image i1 of the irradiation area | region a1. It is a figure which shows the image i2 of the irradiation area | region a2. It is a figure which shows the image i1 + i2 which superimposed the image i1 and the image i2. 2 is a diagram illustrating an example of a projection optical system 20. FIG. It is a flowchart for demonstrating a displacement compensation operation | movement. FIG. 6 is a diagram in which a motion vector Δp is divided into an x component Δx and a y component Δy. It is a figure for demonstrating the method of determining the shift amount X. FIG. It is another figure for demonstrating the method of determining the shift amount X. FIG. It is a block diagram which shows the structure of the projector 101 which concerns on 2nd Embodiment. It is a figure for demonstrating the method of determining the shift amount X. FIG. It is another figure for demonstrating the method of determining the shift amount X. FIG. It is a figure showing an example of a plurality of projection fields on projection screen SC. It is the figure which showed an example which scans on the projection surface SC with invisible light. It is the figure which showed the example of a recording of the output of a light receiving element.

[First Embodiment]
Hereinafter, a projector 10 and an image displacement compensation method according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the projector 10. The projector 10 projects an image (hereinafter also referred to as “projected image”) onto a projection surface SC such as a screen or a wall. The projector 10 includes an image signal input unit 11, an operation panel 12, a remote control light receiving unit 13, an irradiation unit 14a, a light receiving unit 14b, a distance measuring unit 14c, a control unit 15, a storage unit 16, a compensation unit 17, a bus line 18, and projection optics. A system 20 is provided.

  The image signal input unit 11 has a plurality of image input terminals for inputting various image signals from an external device 30 such as a personal computer or a video player. The operation panel 12 has a group of buttons for performing various operations. The remote control light receiving unit 13 receives an operation signal (infrared signal) from the remote control 19. The remote controller 19 is used for remotely operating the projector 10 main body. The remote controller 19 has various buttons like the operation panel 12.

  The irradiation unit 14a irradiates the projection surface SC with invisible light (for example, infrared light). The light receiving unit 14b receives invisible light reflected on the projection surface SC (hereinafter referred to as “reflected invisible light”) among the invisible light irradiated from the irradiation unit 14a. The invisible light is not limited to infrared light and can be changed as appropriate.

  The irradiation region of the invisible light on the projection surface SC is caused by a change in the relative positional relationship between the projector 10 and the projection surface SC (for example, a change in the positional relationship caused by the vibration of the projector 10 or the vibration of the projection surface SC). Be changed.

  FIG. 2 is a diagram for explaining the influence of vibration on the projector 10 and the projection surface SC.

  In FIG. 2, for example, when the projector 10a receives vibration from the mounting base T in a state where the projection surface SC is not vibrating, the relative positional relationship between the projector 10a and the projection surface SC changes. In this case, the irradiation area of the invisible light on the projection plane SC and the projection position of the projection image on the projection plane SC change.

  Further, when the projection surface SC receives vibration from a wall or the like in a situation where the projector 10a is not vibrating, the relative positional relationship between the projector 10a and the projection surface SC changes. Therefore, also in this case, the irradiation area of the invisible light on the projection plane SC and the projection position of the projection image on the projection plane SC change.

  Also, when the projector 10a and the projection surface SC are both asynchronously vibrating, the relative positional relationship between the projector 10a and the projection surface SC changes. Therefore, also in this case, the irradiation area of the invisible light on the projection plane SC and the projection position of the projection image on the projection plane SC change.

  On the other hand, when the projector 10a vibrates in the same manner as the projection plane SC (for example, when the entire room where the projector 10a and the projection plane SC are arranged is shaken), the relative position between the projector 10a and the projection plane SC. The relationship does not change. For this reason, the irradiation area of the invisible light on the projection plane SC and the projection position of the projection image on the projection plane SC do not change.

From the above description, when the relative positional relationship between the projector 10a and the projection surface SC changes, that is, when the irradiation area on the projection surface SC of invisible light changes, the projection image SC on the projection surface SC. It is understood that it is necessary to compensate for the displacement of the projection position.
Note that the above-described relationship between the projector 10a and the projection surface SC includes the positional relationship between the projector 10b suspended from the ceiling by the ceiling suspension device S and the projection surface SC, the irradiation area on the projection surface SC of invisible light, and the projection. This also applies to the relationship with the projection position of the image on the projection plane SC.

FIG. 3 is a diagram illustrating an example of the light receiving unit 14b.
In FIG. 3, the light receiving unit 14b includes a light receiving lens 14b1 and an image sensor 14b2. The light receiving lens 14b1 forms an image represented by the reflected invisible light (an image representing the irradiation area of the projection surface SC irradiated with the invisible light) on the image sensor 14b2.
The image sensor 14b2 is, for example, a two-dimensional sensor (for example, a CCD sensor or a CMOS sensor) that is sensitive to invisible light. The image sensor 14b2 outputs image data corresponding to the image represented by the reflected invisible light. The image data output by the image sensor 14b2 is an example of a light reception result of the light receiving unit 14b.

  Here, an image represented by reflected invisible light, that is, an image formed on the image sensor 14b2, that is, an image represented by image data output from the image sensor 14b2 will be described.

  In general, the projection surface SC is not strictly flat but has at least a concave portion and a convex portion. The unevenness of the projection surface SC becomes prominent when, for example, a room wall is used as the projection surface SC. The unevenness of the projection surface SC may be recognized as a pattern of the projection surface SC. This is due to the fact that the light reflection direction at the uneven portion of the projection surface SC is different from the light reflection direction at the flat portion of the projection surface SC.

  4 to 8 show an uneven state on the projection surface SC, irradiation regions a1 and a2 of invisible light on the projection surface SC, an image i1 represented by reflected invisible light reflected by the irradiation region a1, and an irradiation region a2. It is the figure which showed an example of the image i2 which the reflected invisible light reflected.

  Specifically, FIG. 4 is a diagram showing an irradiation area a1 on the projection surface SC. FIG. 5 is a diagram showing an irradiation area a2 on the projection surface SC. The irradiation region a2 is an irradiation region where invisible light is irradiated after the irradiation region a1 is irradiated with invisible light. The displacement Δn (see FIG. 5) from the irradiation region a1 to the irradiation region a2 on the projection surface SC is caused by a change in the relative position between the projector 10 and the projection surface SC.

FIG. 6 is an image i1 (an image represented by reflected invisible light reflected by the irradiation area a1, and is represented by image data output when the image sensor 14b2 receives the reflected invisible light reflected by the irradiation area a1. FIG. FIG. 7 is an image i2 (an image represented by reflected invisible light reflected by the irradiation area a2, and is represented by image data output when the image sensor 14b2 receives the reflected invisible light reflected by the irradiation area a2. FIG.
FIG. 8 is a diagram showing a superimposed image i1 + i2 obtained by superimposing the image i1 and the image i2.

  4 and 5, the irradiation areas a1 and a2 are part of the projection plane SC. 4 to 8 show only three convex portions b1 to b3 among the concaves and convexes on the projection surface SC, and the convex portions b1 to b3 are exaggerated for easy explanation.

  As shown in FIG. 6, the image i1 represented by the reflected invisible light reflected by the irradiation area a1 is an image showing the uneven state of the irradiation area a1. Further, as shown in FIG. 7, the image i2 represented by the reflected invisible light reflected by the irradiation region a2 is an image showing the uneven state of the irradiation region a2.

  As shown in FIGS. 4 to 8, when the relative positional relationship between the projection surface SC and the projector 10 changes and the irradiation area shifts, the unevenness state (convex part b <b> 1) indicated by the image corresponding to the irradiation area is changed. ˜b3) will be shifted in the image (see the superimposed image i1 + i2 in FIG. 8).

  Next, the shift of the convex portions b1 to b3 in the image will be described with reference to a superimposed image i1 + i2 shown in FIG.

In the superimposed image i1 + i2, there is a “deviation” Δr from the position of the protrusions b1, b2, and b3 in the image i1 to the position of the protrusions b1, b2, and b3 in the image i2.
The direction of the shift Δr is opposite to the direction of the displacement Δn (shift of the irradiation area with respect to the projection plane SC) shown in FIG. 5, that is, the direction of the relative displacement of the projector 10 with respect to the projection plane SC. The magnitude of the deviation Δr corresponds to the magnitude of the relative displacement of the projector 10 with respect to the projection plane SC.
For this reason, when the relative displacement of the projector 10 with respect to the projection surface SC (hereinafter referred to as “first displacement”) is Δp, the first displacement Δp has a direction opposite to the displacement Δr, and the displacement It can be expressed as a “motion vector” having the same magnitude as Δr. Therefore, hereinafter, Δp that is the first displacement is also referred to as “motion vector Δp”.

  The motion vector Δp can be obtained by using image data output when the image sensor 14b2 receives the image i1 and image data output when the image sensor 14b2 receives the image i2. In the present embodiment, the detection unit 15a described later detects the motion vector Δp using the image i1 and the image i2.

In the example shown in FIGS. 4 to 8, since the irradiation area is a part of the projection plane SC, compared with the case where the irradiation area is the entire projection plane SC, the burden required for irradiation with invisible light (for example, consumption) (Electric power) can be reduced.
The irradiation area may be the entire projection surface SC.
For example, when the irradiation area is a part of the projection surface SC, the irradiation area includes characteristic concave portions and convex portions (for example, convex portions b1, b2, and b3 as shown in FIGS. 4 to 8). May occur. In this case, a characteristic concave portion or convex portion is not shown in the image representing the irradiation region, and it may be difficult to specify which portion of the projection plane SC the irradiation region represented by the image is.
On the other hand, when the irradiation area is the entire surface of the projection surface SC, the irradiation area includes a characteristic concave portion or convex portion, and the irradiation region is a part of the projection surface SC. Compared to the above, it becomes easier to specify which part of the projection plane SC the irradiation area represented by the image is.

Returning to FIG. The distance measuring unit 14c measures the distance L between the projector 10 and the projection surface SC. In the present embodiment, the distance measuring unit 14c measures the time from when the irradiation unit 14a irradiates invisible light to when the light receiving unit 14b receives the reflected invisible light reflected by the projection surface SC and outputs image data. Then, a value obtained by multiplying the measured value by a constant or the measured value is used as the distance L (information indicating the distance L). In the present embodiment, the measurement value of the distance measurement unit 14c is used as the distance L.
In the present embodiment, since the irradiation unit 14a and the light receiving unit 14b are also used for distance measurement, the configuration can be simplified.

  In the case where the projector 10 is provided with an irradiation unit and a light receiving unit dedicated to distance measurement, the distance measuring unit 14c is configured such that after the irradiation unit dedicated to distance measurement emits light, the light receiving unit dedicated to distance measurement is the projection plane SC. Alternatively, the distance L may be measured by measuring the time from receiving the light reflected in step S4 and outputting the light reception result. Further, when the projector 10 is provided with a transmission unit that transmits ultrasonic waves and a reception unit that receives ultrasonic waves, the distance measurement unit 14c is configured such that the transmission unit transmits ultrasonic waves and the reception unit is the projection plane SC. The distance L may be measured by measuring the time taken to receive the reflected ultrasonic wave and output the reception result.

The control unit 15 is configured by a CPU (Central Processing Unit) or the like. The control unit 15 performs overall control of the entire projector 10 by inputting / outputting signals to / from each unit via the bus line 18.
The control unit 15 has a detection unit 15a.
The detector 15a detects the motion vector Δp based on the light reception result (image data) of the light receiver 14b. Based on the image data output from the image sensor 14b2, the detection unit 15a detects the projections b1, b2, and b3 on the image i1 from the positions of the projections b1, b2, and b3 on the image i2, as shown in FIG. A motion vector Δp representing the magnitude and direction of the deviation up to the position is detected. In this case, the detection unit 15a detects the motion vector Δp based on the change in the light reception result of the light reception unit 14b. The motion vector Δp is used in the compensation unit 17 described later.

  The storage unit 16 includes a ROM (Read Only Memory) that stores a control program and control data used for control performed by the control unit 15, a RAM (Random Access Memory) that is used as a work area, and the like (both illustrated). (Omitted).

The compensation unit 17 performs predetermined image processing on the image signal input to the image signal input unit 11.
The predetermined image processing includes image correction processing (hereinafter referred to as “image displacement compensation processing”) for compensating for the relative displacement (hereinafter referred to as “second displacement”) of the projection image with respect to the projection surface SC. . The predetermined image processing may further include at least one of known image processing such as image inversion processing, keystone distortion correction processing, image quality adjustment processing, image size adjustment processing, and gamma correction processing.
The compensation unit 17 outputs an image signal subjected to predetermined image processing to the light valve driving unit 21.

  The compensation unit 17 performs processing for compensating for the second displacement (relative displacement of the projection image with respect to the projection surface SC) based on the detection result (motion vector Δp) of the detection unit 15a as image displacement compensation processing. Here, “compensating for the second displacement” includes, for example, correcting the image signal so that the second displacement is reduced.

As an example, the compensation unit 17 first cuts out a frame from an image (original image) corresponding to an image signal that has not been subjected to image displacement compensation processing. Subsequently, the compensation unit 17 corrects the original image by performing shift correction on the cut frame in the direction opposite to the direction of the motion vector Δp in the original image by an amount corresponding to the magnitude of the motion vector Δp. To do. Here, the original image has a spare image area around the frame to be cut out. The compensation unit 17 performs correction for shifting the frame in the original image based on the motion vector Δp so that the cut-out frame enters the spare image region. The compensation unit 17 outputs an image signal representing the image after the shift correction (an image signal subjected to the image displacement compensation process) to the light valve driving unit 21.
In the present embodiment, the compensation unit 17 compensates the second displacement based on the detection result (motion vector Δp) of the detection unit 15a and the measurement result of the distance measurement unit 14c.

  The projection optical system 20 employs a liquid crystal system. The projection optical system 20 includes a light valve driving unit 21, a lamp driving unit 22, a light source lamp 23, a liquid crystal light valve 24, and a projection lens 25.

  The light valve driving unit 21 is a driver for driving the liquid crystal light valve 24. The light valve drive unit 21 sets the light transmittance of each pixel by applying a drive voltage corresponding to the image signal received from the compensation unit 17 to each pixel of the liquid crystal light valve 24.

  The lamp driving unit 22 is a driver for lighting a light source lamp 23 which is a discharge light emitting type lamp. The lamp driving unit 22 includes an igniter unit that generates a high voltage to form a discharge circuit, and a ballast circuit for maintaining a stable lighting state after lighting (all not shown).

  The light source lamp 23 emits light. As the light source lamp 23, for example, an ultra-high pressure mercury lamp, a metal halide lamp, or a xenon lamp is used. The light source lamp 23 is not limited to these discharge light emitting lamps, and various self-light emitting elements such as a light emitting diode, an organic EL element, a silicon light emitting element, and a laser diode may be used.

  The liquid crystal light valve 24 modulates the light emitted from the light source lamp 23 in accordance with the image signal processed by the compensation unit 17 (specifically, the drive voltage output from the light valve drive unit 21), thereby generating an image (image). Light).

  The projection lens 25 projects the image generated by the liquid crystal light valve 24 onto the projection plane SC. As the projection lens 25, a combined lens in which a plurality of lenses are combined is used.

FIG. 9 shows an example of the projection optical system 20 when the liquid crystal light valve 24 has three color-specific liquid crystal light valves 24R, 24G, and 24B corresponding to the three primary colors (R, G, and B) (the light valve drive unit 21 and It is the figure which showed (except the lamp drive part 22).
In FIG. 9, the projection optical system 20 has a light separation optical system 40 and a synthesis optical system 43 in addition to the light source lamp 23, the liquid crystal light valve 24, and the projection lens 25 shown in FIG.

The light separation optical system 40 separates the light emitted from the light source lamp 23 into R, G, and B color lights.
The light separation optical system 40 includes dichroic mirrors 41a and 41b and mirrors 42a to 42c. Of the light emitted from the light source lamp 23, the dichroic mirror 41a reflects red light and transmits light having a color different from that of the red light. The dichroic mirror 41b reflects green light out of the light transmitted through the dichroic mirror 41a and transmits light of a color different from the green light (in this case, blue light). This green light is incident on the liquid crystal light valve 24G. The mirror 42a reflects the red light reflected by the dichroic mirror 41a toward the liquid crystal light valve 24R. The mirror 42b reflects the blue light transmitted by the dichroic mirror 41b. The mirror 42c reflects the blue light reflected by the mirror 42b toward the liquid crystal light valve 24B.

Each color liquid crystal light valve 24R, 24G, 24B has a liquid crystal panel and polarizing plates provided on the incident side and the emission side (all not shown). As the liquid crystal panel, for example, a liquid crystal panel using a polysilicon TFT (Thin Film Transistor) as a switching element is used.
Each color liquid crystal light valve 24R, 24G, 24B modulates incident light according to an image signal.

  The synthesizing optical system 43 is an optical element that forms a color image by synthesizing each color light modulated by each color liquid crystal light valve 24R, 24G, 24B. The combining optical system 43 is, for example, a dichroic prism. The projection lens 25 projects the color image formed by the combining optical system 43 onto the projection surface SC.

<Explanation of operation outline>
Next, an outline of a displacement compensation operation for a projected image using invisible light will be described.

  The irradiation unit 14a intermittently irradiates the projection surface SC with invisible light. The light receiving unit 14b intermittently receives reflected invisible light reflected by the projection surface SC among the invisible light irradiated by the irradiation unit 14a. Each time the image sensor 14b2 of the light receiving unit 14b receives reflected invisible light, the image sensor 14b2 outputs image data representing an image corresponding to the reflected invisible light.

  Each time the irradiating unit 14a irradiates invisible light, the distance measuring unit 14c receives reflected invisible light reflected by the projection surface SC after the irradiating unit 14a irradiates invisible light, and receives image data. Measure the time to output.

  Each time the image sensor 14b2 outputs image data, the detection unit 15a determines whether or not the relative position of the projector 10 with respect to the projection plane SC has changed based on the image data. For example, the detection unit 15a determines that there is no change when the latest image data from the image sensor 14b2 matches the image data output immediately before, and determines that there is change when the image data does not match. .

  When the relative position of the projector 10 with respect to the projection surface SC changes, the detection unit 15a detects the motion vector Δp using the two image data used for determining the presence or absence of the change (see FIG. 8). .

  Subsequently, the compensation unit 17 performs the above-described image displacement compensation process on the image signal based on the motion vector Δp so as to cancel the variation of the projection image with respect to the projection plane SC. At this time, the compensation unit 17 performs the above-described image displacement compensation process using the measurement value of the distance measurement unit 14c together with the motion vector Δp. The image displacement compensation process using the measurement value of the distance measurement unit 14c will be described later.

Subsequently, the compensation unit 17 outputs the image signal subjected to the image displacement compensation process to the light valve drive unit 21.
The light valve drive unit 21 controls each pixel of the liquid crystal light valve 24 according to the image signal subjected to the image displacement compensation process. For this reason, the projection optical system 20 projects an image corresponding to the image signal subjected to the image displacement compensation process onto the projection surface SC. The image corresponding to the image signal subjected to the image displacement compensation processing is an image in which the relative displacement (second displacement) of the projection image with respect to the projection surface SC is compensated, that is, an image in which the second displacement is reduced. .

In the present embodiment, the motion vector Δp is detected based on the image data output from the image sensor 14b2, and the relative displacement of the projected image with respect to the projection plane SC is compensated based on the motion vector Δp. That is, the relative displacement of the projection image with respect to the projection surface SC is compensated according to the image data output from the image sensor 14b2.
Here, the image data output from the image sensor 14b2 changes in accordance with a change in the relative positional relationship between the projection surface SC and the projector 10. For this reason, in this embodiment, the relative displacement of the projection image with respect to the projection plane SC is compensated based on the relative positional relationship between the projection plane SC and the projector 10.

  The shaking of the projection screen SC, the shaking of both the projection screen SC and the projector 10, and the shaking of the projector 10 are reflected in the change in the relative positional relationship between the projection screen SC and the projector 10. For this reason, even if the projection surface SC is shaken, both the projection surface SC and the projector 10 are shaken, and even if the projector 10 is shaken, it is possible to suppress the shake of the projected image on the projection surface SC. In addition, since the displacement of the projected image with respect to the projection surface SC is compensated using the light reception result of the invisible light reflected by the projection surface SC, the image on the projection surface SC is used even when the projection surface SC without a mark is used. Can be suppressed. In addition, since invisible light is irradiated to detect the change in relative positional relationship, compared to the case of irradiating visible light instead of invisible light, the influence of the irradiated light on the visibility of the projected image is affected. Can be small.

<Detailed description of operation>
Next, the displacement compensation operation of the projected image using invisible light will be described in detail.
FIG. 10 is a flowchart for explaining a displacement compensation operation for a projected image using invisible light. Note that the processing shown in FIG. 10 is repeatedly executed while the projector 10 projects an image.

  When the projection optical system 20 starts projecting a projection image onto the projection surface SC, the control unit 15 outputs a pulsed irradiation signal to the irradiation unit 14a. The irradiation unit 14a irradiates the projection surface SC with invisible light for a predetermined time in accordance with the pulsed irradiation signal (step S101). At this time, the irradiation unit 14a may irradiate the entire projection surface SC with invisible light, or may irradiate a part of the projection surface SC with invisible light.

The image sensor 14b2 receives the reflected invisible light according to the irradiation of the invisible light from the irradiation unit 14a (Step S102).
When the image sensor 14b2 receives the reflected invisible light, the image sensor 14b2 outputs image data indicating an image represented by the reflected invisible light (for example, the image i1 shown in FIG. 6 or the image i2 shown in FIG. 7). The storage unit 16 sequentially stores the image data output from the image sensor 14b2.

  The distance measuring unit 14c is the time from when the irradiating unit 14a irradiates invisible light at step S101 to when the light receiving unit 14b receives the reflected invisible light reflected by the projection surface SC and outputs image data at step S102. Is measured (step S103). This measurement time corresponds to the distance from the projector 10 to the projection surface SC.

  The detection unit 15a includes, from the storage unit 16, image data output by the image sensor 14b2 this time (hereinafter referred to as “current image data”) and image data output previously by the image sensor 14b2 (hereinafter referred to as “previous image data”). Is read. Subsequently, the detection unit 15a determines whether or not there is a change between the current image data and the previous image data (step S104).

  In step S104, the detection unit 15a uses the images (for example, the image i1 and the image i2) indicated by the two image data, as illustrated in FIG. 8, and uses the motion vector Δp (the size of the shift and the direction of the shift). ) Is calculated.

For example, as illustrated in FIG. 11, the detection unit 15a calculates the motion vector Δp by dividing it into an x component Δx and a y component Δy.
Here, the x component Δx is a component of the motion vector Δp in the horizontal direction (x-axis direction shown in FIG. 11) of the image data output from the image sensor 14b2, and the y component Δy is the vertical direction of the image data. This is a component of the motion vector Δp in the y-axis direction shown in FIG.
The x component Δx indicates a magnitude by a numerical value, and indicates a direction by positive / negative of the numerical value (when positive, indicates a positive direction of the x-axis, and when negative, indicates a negative direction of the x-axis) . Similarly, the y component Δy indicates the magnitude by a numerical value, and indicates the direction by positive / negative of the numerical value (in the case of positive, it indicates the positive direction of the y axis, and in the negative case, the negative direction of the y axis) Showing).

For example, when the image indicated by the current image data is the image i2 shown in FIG. 7 and the image indicated by the previous image data is the image i1 shown in FIG. 6, the detection unit 15a performs the x component as follows. Δx and y component Δy are detected.
The detection unit 15a detects a value obtained by subtracting the uppermost x coordinate of the convex portion b1 of the image i2 from the uppermost x coordinate of the convex portion b1 in the image i1 as an x component Δx. Further, the detection unit 15a detects a value obtained by subtracting the uppermost y coordinate of the convex portion b1 of the image i2 from the uppermost y coordinate of the convex portion b1 in the image i1 as the y component Δy.

  When the magnitude of the motion vector Δp is zero (both the numerical value of the x component Δx and the numerical value of the y component Δy are both zero), the detection unit 15a determines that there is no change (NO in step S104), and indicates information indicating no change. Is output to the compensation unit 17, and the process illustrated in FIG. Thereafter, the process shown in FIG. 10 is repeated again.

  When the information indicating no change is received, the compensation unit 17 performs predetermined image processing excluding image displacement compensation processing on the image signal input via the image signal input unit 11. The compensation unit 17 outputs an image signal subjected to predetermined image processing excluding the image displacement compensation processing to the light valve driving unit 21. The projection optical system 20 projects a projection image corresponding to the image signal onto the projection surface SC.

  On the other hand, when the magnitude of the motion vector Δp is not zero in step S104, the detection unit 15a determines that there is a change (YES in step S104), and outputs the x component Δx and the y component Δy to the compensation unit 17.

  Upon receiving the x component Δx and the y component Δy, the compensation unit 17 compensates for the second displacement (relative displacement of the projected image with respect to the projection plane SC) based on the x component Δx and the y component Δy (step S105). .

  In step S105, the compensation unit 17 cuts out a frame from an image (original image) corresponding to an image signal that has not been subjected to image displacement compensation processing.

  Subsequently, the compensation unit 17 shifts the cut frame in the original image by an amount X corresponding to the magnitude represented by the x component Δx in the opposite direction to the direction represented by the x component Δx, and the direction represented by the y component Δy. Correction is performed so as to shift by an amount Y corresponding to the magnitude represented by the y component Δy in the opposite direction. Thereafter, the process shown in FIG. 10 is repeated.

Here, an example of the shift amount X and the shift amount Y will be described.
12 and 13 are diagrams for explaining a method in which the compensation unit 17 determines the shift amount X and the shift amount Y. FIG.

The magnitude Dx of the x component of the shift amount of the irradiation area on the projection screen SC shown in FIG. 12 can be expressed by the following equation (1).
Dx = (| Δx | · L) / fJ (1)
Here, fJ is the focal length of the light receiving lens 14b1. L is the distance measured in step S103.

The shift amount X shown in FIG. 13 can be expressed by the following equation (2).
X = (fT · Dx) / L (2)
Here, fT is the focal length of the projection lens 25.

Similarly, the magnitude Dy of the y component of the deviation amount of the irradiation area on the projection surface SC can be expressed by the following equation (3).
Dy = (| Δy | · L) / fJ (3)

The shift amount Y can be expressed by the following equation (4).
Y = (fT · Dy) / L (4)

  The compensator 17 determines the shift amount X using the equations (1) and (2), and determines the shift amount Y using the equations (3) and (4). When the storage unit 16 stores the focal length fJ of the light receiving lens 14b1 and the focal length fT of the projection lens 25, the compensation unit 17 stores the focal length fJ of the light receiving lens 14b1 and the focal length fT of the projection lens 25. Read from.

  Thereafter, the projection optical system 20 projects a projection image corresponding to the image signal on which the above-described shift correction (image displacement compensation processing) has been performed onto the projection surface SC, whereby the projection position of the projection image on the projection surface SC. Returns to its original position.

  Note that there may be a case where the distance L between the projector 10 and the projection surface SC varies after the current image data is output from the image sensor 14b2. When this variation occurs, the projected image on the projection surface SC is enlarged or reduced according to the change in the distance L.

  In order to suppress this enlargement or reduction, the distance L is measured again between the execution of step S104 and the execution of step S105 (hereinafter, this measurement result is referred to as “distance La”). It is desirable to use the distance La instead of the distance L in the expressions (2) and (4). At this time, the measurement of the distance La is preferably performed in the same manner as in step S103 by irradiating the irradiation unit 14a with invisible light again.

  When the distance La is used instead of the distance L in the equations (2) and (4), the compensation unit 17 adjusts the shift amount X and the shift amount Y according to the distance La.

  According to the present embodiment, the motion vector Δp (first displacement) is detected based on the change in the image data output from the image sensor 14b2. The image data output from the image sensor 14b2 changes according to a change in the relative positional relationship between the projection surface SC and the projector 10. For this reason, the motion vector Δp can be detected based on the change in the relative positional relationship between the projection surface SC and the projector 10.

  According to the present embodiment, for example, even when the user is moving the projector 10 that is projecting a projection image on the projection surface SC, it is possible to suppress the projection image from shaking on the projection surface SC. .

[Second Embodiment]
The second embodiment of the present invention is different from the first embodiment in the method of determining the shift amount X and the shift amount Y. Specifically, in the second embodiment, the shift amount X and the shift amount Y are determined without using information on the distance from the projector to the projection plane SC. Hereinafter, the second embodiment will be described focusing on differences from the first embodiment.

  FIG. 14 is a block diagram illustrating a configuration of the projector 101 according to the second embodiment. In FIG. 14, the same components as those described in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

The projector 101 according to the present embodiment is different from the first embodiment in that the distance measurement unit 14 c is omitted and a compensation unit 17 a is provided instead of the compensation unit 17.
The compensation unit 17a compensates for the second displacement based on the detection result (motion vector Δp) of the detection unit 15a. Compensation performed by the compensation unit 17a differs from the compensation performed by the compensation unit 17 in the first embodiment in a method for determining the shift amount X and the shift amount Y. Hereinafter, this point will be mainly described.

15 and 16 are diagrams for explaining a method in which the compensation unit 17a determines the shift amount X and the shift amount Y.
When the angle change in the projection direction of the projection image with respect to the projection surface SC when the x component Δx occurs is expressed as θx, the following relationship (5) is established (see FIG. 15).
θx = arctan (| Δx | / fJ) (5)
And the shift amount X according to the magnitude | size of x component (DELTA) x can be represented by the following (6) Formula (refer FIG. 16).
X = fT · tan (θx) (6)

Similarly, when the change in the angle of the projection direction of the projected image with respect to the projection surface SC when the y component Δy occurs is expressed as θy, the following relationship (7) is established.
θy = arctan (| Δy | / fJ) (7)
And the shift amount Y according to the magnitude | size of y component (DELTA) y can be represented by the following (8) Formula.
Y = fT · tan (θy) (8)

The compensation unit 17a determines the shift amount X using the equations (5) and (6), and determines the shift amount Y using the equations (7) and (8).
Thereafter, the projection optical system 20 projects a projection image corresponding to the image signal subjected to the shift correction (image displacement compensation processing) by the compensation unit 17a onto the projection plane SC, so that the projection image SC is projected on the projection plane SC. The projection position of returns to the original position.

  According to the present embodiment, the compensation unit 17a compensates for the second displacement based on the detection result (motion vector Δp) of the detection unit 15a without using information on the distance between the projector 101 and the projection surface SC. . For this reason, the distance measurement part 14c can be made unnecessary and a structure can be simplified compared with 1st Embodiment.

<Modification>
Each of the above embodiments can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined as long as they do not contradict each other.

<Modification 1>
The irradiation area on the projection surface SC irradiated by the irradiation unit 14a may be configured by a plurality of areas (for example, areas a3 to a7 as shown in FIG. 17) on the projection plane SC. Note that the number of the plurality of regions is not limited to five and may be two or more.

<Modification 2>
Instead of the image sensor 14b2, a light receiving element having only a single light receiving region may be used. In this case, as shown in FIG. 18, for example, the irradiation unit 14a scans the projection surface SC with invisible light in a predetermined direction, and the storage unit 16 displays the output of the light receiving element during the scanning. As shown in FIG. 19, recording is performed in association with the scanning position. When the irradiation unit 14a scans the projection surface SC at a predetermined speed, the scanning position may be represented by an elapsed time from the start of scanning.
The output data of the light receiving element associated with the scanning position as shown in FIG. 19 represents the uneven state of the irradiation area. For this reason, for example, the detection unit 15a generates image data of the irradiation region from this data, and uses the image data instead of the image data of the image sensor 14b2.

<Modification 3>
In each of the above-described embodiments, the deviation of the projected image with respect to the projection surface SC is suppressed by correcting the image signal. However, the projection optical system 20 is provided with an optical axis correction lens that changes the projection direction of the projected image, and the compensation unit 17 mechanically moves the optical axis correction lens so that the motion vector Δp is canceled without correcting the image signal. It may be driven to compensate for the deviation of the projected image with respect to the projection surface SC. In this case, it is included in “compensating for the second displacement” that the compensation unit 17 mechanically drives the optical axis correction lens to compensate for the deviation of the projection image with respect to the projection surface SC.

<Modification 4>
In each of the above-described embodiments, the transmissive liquid crystal type projection optical system 20 has been exemplified. However, the display principle is not limited to the reflection type liquid crystal display method, CRT display method, micromirror device method (light switch display method), or the like. A display method may be adopted. Further, a combination of one liquid crystal panel and a color wheel may be used instead of the three liquid crystal panels of RGB.

DESCRIPTION OF SYMBOLS 10 ... Projector, 11 ... Image signal input part, 14a ... Irradiation part, 14b ... Light receiving part, 14c ... Distance measurement part, 15 ... Control part, 15a ... Detection part, 16 ... Memory | storage part, 17 ... Compensation part, 20 ... Projection An optical system, 21: a light valve driving unit, 22: a lamp driving unit, 23: a light source lamp, 24: a liquid crystal light valve, 25: a projection lens, SC: a projection surface.

Claims (7)

A projector that projects an image on a projection surface,
An irradiation unit for irradiating the projection surface with invisible light;
A light receiving unit that receives the invisible light that is irradiated from the irradiation unit and reflected by the projection surface;
A detection unit that detects a relative displacement of the projector with respect to the projection plane based on a light reception result of the light receiving unit;
A compensation unit that compensates for a relative displacement of the image with respect to the projection plane based on a detection result of the detection unit;
A projector comprising: A distance measuring unit for measuring a distance between the projector and the projection surface;
The compensation unit adjusts the compensation based on a measurement result of the distance measurement unit;
The projector according to claim 1. The distance measuring unit measures the time from when the irradiating unit irradiates the invisible light to when the light receiving unit receives the invisible light reflected by the projection plane and outputs the light receiving result. Measuring the distance,
The projector according to claim 2. The detection unit detects a relative displacement of the projector with respect to the projection plane based on a change in a light reception result of the light receiving unit;
The projector according to claim 1, wherein the projector is a projector. The irradiation unit irradiates the entire surface of the projection surface with the invisible light;
The projector according to claim 1, wherein the projector is a projector. The irradiation unit irradiates a part of the projection surface with the invisible light.
The projector according to claim 1, wherein the projector is a projector. An image displacement compensation method performed by a projector that projects an image on a projection surface,
Irradiate the projection surface with invisible light,
Receiving the invisible light reflected by the projection surface among the irradiated invisible light,
Based on the result of the light reception, the relative displacement of the projector with respect to the projection plane is detected,
Compensating for the relative displacement of the image relative to the projection surface based on the relative displacement of the projector relative to the projection surface;
An image displacement compensation method characterized by the above.

Images