WO2015145599A1

WO2015145599A1 - Video projection device

Info

Publication number: WO2015145599A1
Application number: PCT/JP2014/058453
Authority: WO
Inventors: 益岡　信夫; 将史山本; 崎田　康一; 鈴木　基之
Original assignee: 日立マクセル株式会社
Priority date: 2014-03-26
Filing date: 2014-03-26
Publication date: 2015-10-01

Abstract

This video projection device (1) is provided with a laser light source (21) that emits laser light modulated by an inputted video signal, a variable-reflection-angle mirror (22) that projects video onto a projection target (3) by scanning said projection target with the laser light, a light-receiving unit (23) that detects laser light reflected off of the projection target (3), a distance computation unit (11) that computes the distance to the projection target on the basis of a light signal received from the light-receiving unit (23), and an image processing unit (13) that determines the position and shape of the projection target (3) from the computed distance and performs a mapping process to map the projected video to a region of the determined projection target. This results in a video projection device (1) that produces nice-looking video with minimal projection-position misalignment with respect to the projection target (3) even if said projection target moves.

Description

Video projection device

The present invention relates to an image projection apparatus that projects an image on the surface of an object such as an object or a building.

A technique for projecting an image created by a personal computer or the like onto the surface of an object to be projected such as an object or a building using an image projection apparatus such as a projector, so-called projector mapping (hereinafter referred to as mapping) is known. When mapping, it is necessary to set the image to be projected according to the shape of the projection object.If the position or shape of the projection object changes, the projection direction and projection image will be adjusted accordingly. It is necessary to set the size.

Patent Document 1 discloses an imaging unit and a projection imaged by the imaging unit so that an object such as a pattern or a color can be mapped on the surface of the projection object even if the shape of the projection object changes or moves. Image acquisition means for acquiring an image including an object, area extraction means for extracting the projection area of the projection object from the image acquired from the image acquisition means, and mapping means for mapping an object corresponding to the projection area to the projection area A configuration comprising is disclosed.

JP 2013-192189 A

According to Patent Document 1, in order to extract a projection area of a projection object, an image including an image of the projection object is acquired by an imaging unit (camera), and an object corresponding to the extracted projection area is used as the projection area. The mapping is configured.

According to Patent Document 1, the size of the projection screen changes according to the distance between the screen and the projection apparatus main body. The size also varies depending on the zoom position of the projection lens. Furthermore, the projection screen is distorted into a trapezoid depending on the perpendicularity between the screen and the projector main body. Therefore, the size and shape of the projection screen (such as trapezoidal distortion) vary greatly depending on the positional relationship between the screen and the projection apparatus main body. Also, the imaging range changes depending on the zoom position of the camera.

As described above, since the size and shape of the projection screen and the imaging range vary depending on the installation state, the projection apparatus body, and the zoom position of the camera, the coordinate system of the image displayed on the projection apparatus body before the projection mapping display is performed. The calibration process for matching the coordinate system of the image acquired by the camera is necessary, which is inconvenient.

Also, since the object to be projected is detected by photographing with a camera, it is necessary to stop the object drawing process during photographing. For this reason, when the projection object moves, a time during which the object is not displayed intermittently occurs. That is, it is difficult to project an object in real time while extracting a projection area.

An object of the present invention is to provide a video projection apparatus capable of mapping in almost real time without reducing a gap between extraction of a projection area and timing of projecting an object, and the projected video is not interrupted.

The present invention relates to a laser light source that emits laser light modulated by an input video signal, and a reflection angle that scans the laser light and projects the image onto the projection object in a video projection apparatus that projects an image onto the projection object. Based on the calculated distance, a variable mirror, a light receiving unit that detects laser light reflected by the projection, a distance calculation unit that calculates a distance to the projection based on a light reception signal from the light receiving unit, An image processing unit that performs a mapping process on an image projected on the projection object.

According to the present invention, it is possible to realize a video projection apparatus with a good appearance with little deviation of the projection position with respect to the projection object even when the projection object moves.

1 is a configuration diagram (Example 1) showing an embodiment of a video projection apparatus according to the present invention. FIG. The figure which shows an example of the image | video projection by a mapping process. The figure which shows an example of a structure of the laser light source. The figure which shows an example of the distance data table memorize | stored in the memory. The figure which shows the flowchart of an image | video projection and a mapping process. FIG. 6 is a diagram showing a configuration of a laser light source 21 ′ in Embodiment 2.

An image projection apparatus according to the present invention is configured to project an image on a projection object using a laser light source, and measures the position and shape of the projection object using the projected laser beam, and the measured projection object The image to be projected is mapped according to the position and shape of the object.

FIG. 1 is a block diagram showing an embodiment of a video projection apparatus according to the present invention. The image projection apparatus 1 includes a laser module 2 that emits laser light, and a drive circuit for the laser module 4, a laser light source drive unit 5, a light amount light receiving unit 6, an amplification factor control unit 7, a control signal generation unit 9, The generator 10, the distance calculator 11, the memory 12, and the image processor 13 are included. The laser module 2 includes a laser light source 21, a reflection angle variable mirror 22, and a light receiving unit 23. The light receiving unit 23 is arranged outside the housing of the laser module 2 or inside the housing via a lens, a mirror, or the like. For the light receiving unit 23, for example, a highly sensitive photodiode called APD (Avalanche Photo Diode) is used.

The image processing unit 13 processes the input video signal, the laser light source driving unit 5 drives the laser module 2, and emits laser light modulated by the video signal toward the projection object 3. The laser light emitted from the laser module 2 is irradiated onto the projection object 3 to display an image, and the reflected light is detected by the light receiving unit 23. The detection signal from the light receiving unit 23 is processed by the light quantity light receiving unit 6 and the pulse generating unit 10, and the distance calculating unit 11 calculates the distance to the projection object 3. The calculated distance data is stored in the memory 12. The image processing unit 13 determines the position and shape of the projection object 3 from the distance data to the projection object 3 stored in the memory 12, and determines a projection area on which a video object such as a pattern or a color is to be projected. . Then, a mapping process of a video to be projected is performed in accordance with the determined projection area. In this way, an image is projected onto the surface of the projection object 3 with the laser light emitted from the laser module 2, and the position and shape of the projection object 3 are determined based on the reflected light of the laser light, thereby mapping the projected image. It is set as the structure which processes.

First, the operation of the drive circuit will be described. The control signal generation unit 9 generates a mirror drive unit control signal 100, a laser light source drive unit control signal 101, a bias voltage control signal 102, and a synchronization signal 200 based on the input video signal. The laser light source drive unit control signal 101 and the synchronization signal 200 are input to the laser light source drive unit 5. The laser light source driving unit 5 generates a laser driving signal 203 in accordance with the laser light source driving unit control signal 101 and the synchronization signal 200, and adjusts the light amount of the laser light source 21 according to the signal level of the laser driving signal 203 and its application time. Further, the mirror drive unit control signal 100 and the synchronization signal 200 are input to the mirror drive unit 4. The mirror driving unit 4 generates a horizontal driving signal 201 and a vertical driving signal 202 in accordance with the mirror driving unit control signal 100 and the synchronization signal 200. The horizontal direction drive signal 201 and the vertical direction drive signal 202 control the angle of the reflection angle variable mirror 22 in the horizontal direction and the vertical direction, respectively. The bias voltage control signal 102 and the synchronization signal 200 are input to the amplification factor control unit 7. The amplification factor control unit 7 applies a bias voltage to the light receiving unit 23 according to the bias voltage control signal 102 and the synchronization signal 200.

By the operation of the drive circuit described above, the laser module 2 adjusts the light amount of the laser light source 21 and the angle of the reflection angle variable mirror 22 and scans the projection object 3 with the laser light to project an image. Although only one laser light source 21 is shown in FIG. 1, a color image or the like can be projected using a plurality of laser light sources as will be described later.

Next, distance measurement to the projection object 3 will be described. The principle of distance measurement uses a TOF (Time of Flight) method in which the measurement is performed from the time difference between the light emission time from the laser light source 21 and the light reception time of the light reflected from the projection object 3 by the light receiving unit 23. The laser light applied to the projection object 3 is scattered, and a part of the reflected light is detected by the light receiving unit 23. The distance d is calculated by multiplying the time difference Δt by the speed of light c (round-trip distance 2d = c · Δt).

The signal detected by the light receiving unit 23 is input to the light quantity light receiving unit 6 and the gain control unit 7. The light quantity light receiving unit 6 amplifies the detected minute signal. The gain control unit 7 sets the light receiving sensitivity of the light receiving unit 23 according to the intensity of the laser light emitted from the laser light source 21, that is, according to the drive signal 203 from the laser light source driving unit 5. Alternatively, the amplification factor control unit 7 sets the light receiving sensitivity of the light receiving unit 23 according to the signal level of the reflected light detected by the light receiving unit 23. Thereby, even if the intensity | strength of the emitted laser beam from the laser light source 21 changes, or the reflectance of the to-be-projected object 3 changes, the received light signal of a fixed level can be obtained. A signal from the light receiving unit 6 is input to the pulse generation unit 10. The pulse generator 10 compares the input signal with a reference voltage and converts an analog signal into a pulse signal. The distance calculation unit 11 receives the pulse signal generated by the pulse generation unit 10 and calculates the distance d based on the time difference Δt from the laser pulse emission timing signal 103 of the laser light source driving unit 5.

The distance calculation unit 11 obtains the distance to the projection object 3 for each position scanned by the reflection angle variable mirror 22 of the laser module 2. That is, the scan range is divided into predetermined intervals, and the distances at the horizontal and vertical positions are obtained and stored in the memory 12. For example, assume that the projection object 3 in FIG. 1 is composed of a planar object 31 on the back surface and a box-shaped object 32 on the front side. The distance d2 to the object 32 is smaller than the distance d1 to the object 31.

The image processing unit 13 refers to the distance data, compares the distance d at each position using the threshold value dth (where d2 <dth <d1), and the region where d> dth is the region of the object 31 on the back surface. It is determined that the region where d <dth is the region of the object 32 in front. Then, the projection image is mapped in accordance with the position and shape of the projection object 3.

FIG. 2 is a diagram illustrating an example of image projection by mapping processing. Here, two

objects

31 and 32 exist as the projection object 3, and the

video object

41 a and 41 b are projected on the planar object 31 and the video object 42 is projected on the box-shaped object 32. The image processing unit 13

extracts projection areas

31 a and 32 a (indicated by broken lines) of the

objects

31 and 32 from the distance data stored in the memory 12. The image processing unit 13 performs a mapping process of the input video signal so that

predetermined objects

41a, 41b, and 42 are projected in accordance with the positions and shapes of the extracted

projection areas

31a and 32a. Thereby, even if a projection object (for example, the object 32) moves, the desired object 42 can be projected on the projection area 32a following this.

FIG. 3 is a diagram illustrating an example of the configuration of the laser light source 21. The laser light source 21 includes three light sources: a light source 21R that generates red (R light), a light source 21G that generates green (G light), and a light source 21B that generates blue (B light), and can display a color image. Yes. The R light beam generated from the light source 21R is reflected by the total reflection mirror 24R and travels toward the reflection angle variable mirror 22. The G light beam generated from the light source 21G is reflected by the wavelength selective mirror 24R (reflects G light and transmits R light) and travels toward the reflection angle variable mirror 22. The B light beam generated from the light source 21 </ b> B is reflected by the wavelength selective mirror 24 </ b> B (reflects B light and transmits R light and G light) and travels toward the reflection angle variable mirror 22. These reflected color beams are combined into one image light beam, scanned by the reflection angle variable mirror 22, and projected onto the projection object 3. The arrangement of the light sources of R light, G light, and B light shown here is an example, and the arrangement may be changed as appropriate in consideration of the transmission efficiency of the light beam. In addition, although three light sources of R, G, and B are used here, the number of light sources and the light emission color may be appropriately determined according to the projected image. Moreover, it is good also as monochromatic light by one light source.

The intensity of the laser beam emitted from the laser light source 21 varies depending on the video signal. Therefore, the intensity of the reflected light reflected from the projection object 3 also changes with the video signal, and the level of the light receiving signal in the light receiving unit 23 varies. In this regard, since the intensity of the laser light emitted from the laser light source 21 is known from the video signal, the amplification factor control unit 7 adjusts the light receiving sensitivity of the light receiving unit 23 based on the laser drive signal 203 to obtain the distance. The influence on the measurement can be eliminated.

FIG. 4 is a diagram illustrating an example of a distance data table stored in the memory 12. The scan range (rectangular region) of the laser light is divided into m × n meshes, and distance data d at each mesh position is stored. That is, the data amount is for one screen (one frame). The mesh division may be performed in units of pixels, but it is preferable to use a plurality of pixels in units in consideration of storage capacity, distance calculation load, and the like.

When the

objects

31 and 32 are arranged as the projection object 3 as shown in FIG. 2, the distance data d1 for the region 31a corresponding to the object 31 and the region 32a corresponding to the object 32 are used. The distance data d2 is stored. The data to be stored is not the distance value itself, but is binarized as a result of comparing the distance data d with the threshold value dth, that is, “1” (d> dth) and “0” (d <dth). Stored data may be stored. The image processing unit 13 can determine the position and shape of the projection object 3 with reference to this table. Each time new distance data is input to the memory 12, the corresponding mesh position data is overwritten and saved, whereby the latest position and shape of the projection object 3 can be known.

FIG. 5 is a diagram showing a flowchart of video projection and mapping processing. In the following flow, loop processing is performed for each frame.

In S301, the laser module 2 irradiates the projection object 3 with laser light modulated by the video signal.

In S302, it is determined whether the irradiation position (pixel) is coincident with the measurement position. The measurement position here refers to the approximate center of the pixel area divided into meshes. If they match, the process proceeds to S303, and if they do not match, the process proceeds to S306.

In S303, the light receiving unit 23 receives the reflected light from the projection object 3. In S304, the distance calculation unit 11 measures the distance from the light reception signal to the projection object 3. In step S305, the measured distance data is stored in the memory 12. As described above, distance measurement is performed when the mesh division of the distance measurement is in units of a plurality of pixels and the position where the laser beam is irradiated matches the mesh position.

In S306, it is determined whether or not irradiation of the entire screen has been completed. If not completed, the process proceeds to S307, moves to the next irradiation position, and returns to S301. When the laser beam irradiation position is the measurement position, the distance measurement is repeated. If irradiation of the entire screen has been completed in S306, the process proceeds to S308.

In the above flow, the case where the mesh division is in units of a plurality of pixels has been described. However, when the mesh division is all pixels, distance measurement is performed at all irradiation positions.

In S308, the distance data for one screen is read from the memory 12. In step S309, the image processing unit 13 determines the position and shape of the projection object 3 from the distance data. In S310, the image processing unit 13 corrects the video signal according to the position and shape of the projection object 3 (mapping process). In this embodiment, since the image is projected by laser light, it is not necessary to adjust the focus according to the distance to the projection object.

In S311, it is determined whether or not the video projection operation is finished. If not completed, the process moves to the first irradiation position in S312, returns to S301, and repeats image projection, distance measurement, and mapping processing.

According to the above flowchart, it is possible to perform mapping processing of a video signal to be projected at any time while projecting a video. The delay time until the distance measurement result to the projection object is reflected in the mapping process is the time required for projection of one screen until the determination in S306 is switched to Yes at the maximum. Since the time required for general projection for one screen is sufficiently small, such as 1/60 second, delay is not particularly problematic.

Also, when the movement of the projection object is fast, for example, the vertical resolution is lowered to reduce the time required for projection for one screen. As a result, the delay time can be further shortened, and a shift occurring at the projection position (mapping position) can be reduced even with a fast-moving projection object. In other words, the vertical resolution may be appropriately switched according to the movement speed of the projection object.

In the present embodiment, since the projection of the image and the shape measurement of the projection object are performed using the laser light (image light) from the same laser light source 21, the time delay of the mapping process is small, and the projection of the image is performed. Can be executed almost in real time without interruption. Therefore, even when the projection object moves, a video projection device with a good appearance can be realized with little deviation of the projection position with respect to the projection object. In addition, since the irradiation position of the laser and the measurement position are the same, the projection coordinate system and the measurement coordinate system coincide with each other, so that calibration is unnecessary and the usability is good.

In the second embodiment, infrared light (IR light) is added to the laser light source.
FIG. 6 is a diagram illustrating a configuration of a laser light source 21 ′ according to the second embodiment. The laser light source 21 ′ includes a light source 21IR that generates infrared light (IR light) in addition to a red (R light) light source 21R, a green (G light) light source 21G, and a blue (B light) light source 21B. Each color beam corresponding to the video signal is emitted from the

light sources

21R, 21G, and 21B, and the added light source 21IR emits an infrared light (IR light) beam having a constant intensity regardless of the video signal. The IR light beam generated from the light source 21IR is reflected by the total reflection mirror 24IR and travels toward the reflection angle variable mirror 22. The other

light sources

21R, 21G, and 21B are also reflected by the wavelength selective mirrors 24R ′, 24G ′, and 24B ′, respectively, and travel toward the reflection angle variable mirror 22, which are combined into one beam. However, the IR light beam emitted from the light source 21IR does not affect the displayed image even if it is irradiated onto the projection object.

In the present embodiment, the light receiving unit 23 and the distance calculating unit 11 measure the distance to the projection object using the IR laser light emitted from the light source 21IR. Although not shown, the light receiving unit 23 is provided with a filter that transmits infrared light and reflects visible light so as to receive only IR light. Since the IR light beam emitted from the light source 21IR has a constant intensity, the intensity of the IR laser light reflected from the projection object is also substantially constant. Therefore, when the intensity of visible light (R, G, B light) changes according to the video signal, the distance measurement accuracy does not decrease and the mapping is performed even when a dark video is projected with a low video signal level. It is possible to realize a video projection apparatus with little misalignment and good appearance.

1: Video projection device,
2: Laser module,
3, 31, 32: Projected object,
4: Mirror drive unit,
5: Laser light source driving unit,
6: Light quantity receiving part,
7: Amplification rate control unit,
9: control signal generator,
10: pulse generator,
11: Distance calculation unit,
12: Memory,
13: Image processing unit
21, 21 ′: Laser light source,
22: Reflective angle variable mirror,
23: light receiving part,
24: Mirror
41, 42: Object.

Claims

In a video projection device that projects an image on a projection object,
A laser light source that emits a laser beam modulated by the input video signal;
A reflection angle variable mirror that reflects the laser light and projects it onto the projection object;
A mirror driving section for driving the variable reflection angle mirror;
A light receiving unit for detecting a laser beam reflected by the projection object;
A distance calculation unit that calculates a distance to the projection object based on a light reception signal from the light reception unit;
Based on the calculated distance, an image processing unit that performs mapping processing on the image projected on the projection object;
A video projection apparatus comprising:
The video projection device according to claim 1,
An image projection apparatus comprising: an amplification factor control unit that sets a light receiving sensitivity of the light receiving unit according to the intensity of laser light emitted from the laser light source.
The video projection device according to claim 1,
The laser light source includes a light source that emits infrared laser light having a constant intensity,
The image projection device, wherein the light receiving unit and the distance calculating unit detect a reflected light of the infrared laser light and calculate a distance to the projection object.
The video projection device according to any one of claims 1 to 3,
An image projection apparatus comprising: a memory that divides a scan range of laser light by the reflection angle variable mirror into meshes, and stores distance data calculated by the distance calculation unit for each mesh.
The video projection device according to claim 4,
When the projection object is moving, the distance calculation unit switches the time for scanning the entire screen according to the movement speed of the projection object.