JP2021039200A - Projection type video display device and video display method - Google Patents

Abstract

To provide a projection type video display device which displays a visible light communication video capable of rightly detecting a visible light communication signal regardless of a display size.SOLUTION: A projection type video display device comprises: a light source unit in which an illumination light is generated by a light source current; a display unit in which a frame interval of a video signal is divided into a plurality of sub frame intervals including at least one video projection interval and at least one visible light communication interval, the illumination light is converted into a video light and projected based on the video signal during the video projection internal, thereby projecting a video of a video signal, and the illumination light is projected as it is during the visible light communication internal, thereby projecting a visible light communication video of the visible light communication signal; and a light source control unit which controls the light source current based on the inputted visible light communication signal. In the projection type video display device, the light source control unit controls the light source current during the visible light communication interval so as to be enlarged as the display size is enlarged based on the display size of the display video on a projection screen.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a projection type image display device and an image display method.

Various methods for visible light communication have been proposed. For example, Patent Document 1 discloses a video display method capable of appropriately transmitting a visible light communication signal. The video display method according to Patent Document 1 comprises a step of generating a striped image as a visible light communication image, a step of calculating the average brightness of the visible light communication image, and an image of a video signal displayed in a frame. Of at least one subframe in which each divided image is displayed, the visible light communication image is superimposed only on the divided image displayed in a specific subframe which is a subframe for expressing the calculated average brightness. This includes a step of generating a visible light superimposed image and a step of displaying the visible light superimposed image in a specific subframe.

International Publication No. 2014/103158

However, in the image display method disclosed in Patent Document 1, the brightness of the visible light communication image decreases as the display size of the visible light communication image increases. The receiving device has a predetermined receiving sensitivity, and the visible light communication image whose brightness is lowered to a level lower than the receiving sensitivity may not be correctly detected by the receiving device.

The present disclosure provides a projection type image display device and an image display method capable of displaying a visible light communication image capable of correctly detecting a visible light communication signal regardless of the display size of the visible light communication image.

The projection type image display device according to the present disclosure includes a light source unit that generates illumination light by a light source current, and a plurality of subframe periods including at least one image projection period and at least one visible light communication period for the frame period of the image signal. In the video projection period, the illumination light is converted into video light and projected to project the image of the video signal, and in the visible light communication period, the illumination light is projected as it is. In a projection type image display device including a display unit that projects a visible light communication image of a visible light communication signal and a light source control unit that controls a light source current based on an input visible light communication signal during the visible light communication period. Based on the display size of the display image on the projection surface, the light source control unit controls so that the larger the display size, the larger the light source current during the visible light communication period, and the smaller the display size, the smaller the light source current.

According to the projection type image display device or the like according to the present disclosure, it is possible to display a visible light communication image capable of correctly detecting a visible light communication signal regardless of the display size of the visible light communication image.

Perspective view showing an external example of the projection type image display device 100 according to the first embodiment. Front view showing an external example of the projection type image display device 100 of FIG. A block diagram showing a detailed configuration example of the projection type image display device 100 of FIG. Timing chart showing the display brightness of the image 210 in the projection type image display device 100 of FIG. The figure which shows the table of the time ratio of a pause signal period and a signal period in a visible light communication period. FIG. 4B is a diagram showing a table of the relationship between the value of the pause signal period and the time ratio of the signal period and the composite signal. The figure which shows the graph of the relationship between the luminance value of the input video signal and the display luminance of the displayed video 210 in the projection type video display device 100 of FIG. The figure which shows the graph of the relationship between the display size of the image 210 and the display brightness of the image 210 in the projection type image display device according to the prior art. In the projection type image display device 100 of FIG. 1, a timing chart showing the light source current of the light source unit 190 when the display size of the image 210 is small. FIG. 5 is a diagram showing a graph of the relationship between the brightness value of the video signal and the display brightness of the video 210 when the display size of the video 210 is small in the projection type video display device 100 of FIG. In the projection type image display device 100 of FIG. 1, a timing chart showing the light source current of the light source unit 190 when the display size of the image 210 is large. FIG. 5 is a diagram showing a graph of the relationship between the brightness value of the video signal and the display brightness of the video 210 when the display size of the video 210 is large in the projection type video display device 100 of FIG. A timing chart showing the display brightness of the image 210 in the projection type image display device 100A according to the second embodiment. In the projection type image display device 100A of FIG. 12, a timing chart showing the light source current of the light source unit 190 when the display size is small. In the projection type image display device 100A of FIG. 12, a timing chart showing the light source current of the light source unit 190 when the display size is small. A block diagram showing a detailed configuration example of the projection type image display device 100B according to a modified example.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed explanations of already well-known matters and duplicate explanations for substantially the same configuration may be omitted. This is to avoid unnecessary redundancy of the following description and to facilitate the understanding of those skilled in the art.

It should be noted that the inventor intends to limit the subject matter described in the claims by those skilled in the art by providing the accompanying drawings and the following description in order to fully understand the present disclosure. Absent.

It should also be noted that the drawings are schematic and the ratio of each dimension is different from the actual one. Therefore, the specific dimensions should be determined in consideration of the following explanation. In addition, it goes without saying that the drawings include parts having different dimensional relationships and ratios from each other.

(Embodiment 1)
Hereinafter, the first embodiment will be described with reference to FIGS. 1 to 11.

FIG. 1 is a perspective view showing an external example of the video display system 1 according to the first embodiment. In FIG. 1, the image display system 1 includes a projection type image display device 100, a screen 200, and a receiving device 300. The projection type image display device 100 superimposes the input visible light communication signal on the content image indicated by the input image signal, and projects and displays the image 210 on the screen 200. For example, a projection type image display device such as a projector. Is. The receiving device 300 is a terminal device such as a smartphone having an imaging unit that captures the screen 200, images the image 210, and detects the superimposed visible light communication signal.

FIG. 2 is a front view showing an external example of the projection type image display device 100 of FIG. In FIG. 2, the projection type image display device 100 includes a projection lens 145 and a camera 155. These details will be described later.

FIG. 3 is a block diagram showing a detailed configuration example of the projection type image display device 100 of FIG. In FIG. 3, the projection type video display device 100 includes a video signal input unit 110, a video signal processing unit 120, a display control unit 130, a projection display unit 140, a projection size detection unit 150, and a visible light communication signal input. A unit 160, a visible light communication signal processing unit 170, a light source control unit 180, and a light source unit 190 are provided. The video signal input unit 110, the video signal processing unit 120, the display control unit 130, and the projection display unit 140 are collectively referred to as a display unit 400.

In FIG. 3, the video signal processing unit 120 divides the frame period Tfr of each frame of the video signal into a plurality of periods including at least one video projection period Tbp and at least one visible light communication period Tlc. The video signal processing unit 120 outputs a timing signal indicating the timing of the plurality of periods to the display control unit 130 and the visible light communication signal processing unit 170. Further, the video signal input unit 120 inputs a video signal from an external device such as a personal computer and outputs the video signal to the video signal processing unit 120. Here, the input video signal is generally composed of a plurality of frames, and each frame is composed of a plurality of subframes. The video signal processing unit 120 performs general processing such as decoding or resolution conversion on the input video signal, and outputs the input video signal to the display control unit 130 corresponding to each subframe.

The visible light communication signal input unit 160 inputs, for example, a visible light communication signal from the above-mentioned external device and outputs it to the visible light communication signal processing unit 170. The visible light communication signal processing unit 170 generates a PWM modulation signal according to the visible light communication signal input from the visible light communication signal input unit 160 (details will be described later), and outputs the PWM modulation signal to the light source control unit 180. The light source control unit 180 controls the light source current Ils flowing through the light source unit 190 so that the illumination light output from the light source unit 190 follows the PWM modulation signal. The light source unit 190 is on / off controlled by the light source control unit 180, and outputs PWM-modulated white illumination light to the projection display unit 140. However, during the video projection period, the light source unit 190 is always controlled to be ON.

The projection size detection unit 150 includes a camera 155 that captures an image 210 on the screen 200 in front of the projection type image display device 100. The projection size detection unit 150 detects the display size of the image 210 (for example, the width in centimeters or the diagonal length in inches) based on the image captured by the camera 155, and displays the display size signal in the display control unit. Output to 130 and the light source control unit 180.

The display control unit 130 controls the projection display unit 140 based on an input signal including a video signal divided into a plurality of subframes and a display size signal (details will be described later). The projection display unit 140 includes a dichroic mirror, three digital mirror devices (DMDs), and a projection lens 145. The dichroic mirror decomposes the light from the light source 190 into three colors of red (R) light, green (G) light, and blue (B) light, and outputs the light to one of the three DMDs corresponding to each color light. .. Each DMD inputs a video signal corresponding to the input colored light, and controls the input colored light on and off for each pixel. That is, each pixel is output to the projection lens 145 or reflected in a direction other than the projection lens 145 to be excluded. The projection lens 145 superimposes the input three color lights to form an image light, and projects the light on the screen 200 to display the image 210. However, during the visible light communication period in which no video signal is input, each color light is controlled to be turned on in all pixels, and all the light from the light source unit 190 is output to the projection lens 145.

The image display operation of the projection type image display device 100 configured as described above will be described below with reference to FIGS. 4A to 11.

FIG. 4A is a timing chart showing the display brightness of the image 210 in the projection type image display device 100 of FIG. In FIG. 4A, each frame period Tfr is divided into a video projection period Tbp and a visible light communication period Tlc. Further, the R component of the display brightness of the image 210 refers to the brightness of the R light of the image 210 (the same applies to the G component and the B component. Hereinafter, in the present embodiment, the R component will be described unless otherwise specified). During the image projection period Tbp, illumination light is always output from the light source unit 190, and by turning it on and off for each pixel by the DMD, the image 210 that follows the image signal is displayed. Originally, the display brightness of the image 210 during the image projection period Tbp differs for each frame, but for the sake of simplicity in FIG. 4A, the brightness of the R light of the image 210 during the image projection period Tbp is indicated by the display brightness Rvp.

In FIG. 4A, in the visible light communication period Tlc, since the DMD of the projection display unit 140 is turned on in all the pixels, the illumination light from the light source unit 190 is output as it is as the brightness of the image 210. Therefore, the light source control unit 180 controls the light source unit 190 on and off according to the visible light communication signal to repeatedly and alternately display the all-white and all-black images, and the image 210 is used as the visible light communication image. Visible light communication is achieved by the receiving device 300 capturing the visible light communication image and decoding it (details will be described later).

The visible light communication period Tlc is further divided into a preamble period Tpa and a data period Tdt. The preamble period Tpa includes pause signal periods S1 to S4 in which an all-black image is displayed, and preamble signal periods P1 to P3 in which an all-white image is displayed. Further, the data period Tdt includes pause signal periods S5 to S8 in which an all-black image is displayed, and data signal periods D1 to D4 in which an all-white image is displayed. Hereinafter, the pause signal periods S1 to S8, the preamble signal periods P1 to P3, and the data signal periods D1 to D4 are collectively referred to as a "signal period". The visible light communication image of the preamble period Tpa indicates the start of the visible light communication image. Further, the visible light communication image of the data period Tdt shows the data to be communicated by the visible light communication.

FIG. 4B is a diagram showing a table of time ratios of pause signal periods S1 to S8 and signal periods P1 to P3 and D1 to D4 in the visible light communication period Tlc of the example of FIG. 4A. In FIG. 4B, the length of the preamble signal period P1 which is the shortest signal period in the signal period is set to 1.0, and the value of the length of each signal period with respect to the length is shown.

FIG. 5 is a diagram showing a table of the relationship between the value of the time ratio of the signal period of FIG. 4B and the decoded signal. As shown in FIG. 5, there is a one-to-one correspondence between the value of the time ratio of each signal period in the visible light communication video and the decoded signal represented by a 4-bit binary number. Therefore, the receiving device 300 can capture and decode the visible light communication image. For example, when the visible light communication image having a time ratio as shown in the examples of FIGS. 4A and 4B is imaged, the time ratio of the signal period of the visible light communication image in the preamble period Tpa is {1.5, 1.0, It can be expressed as 1.1, 1.3, 1.0, 1.2, 1.4}. Replacing these time ratios with the corresponding decoding signals gives {0101, million 1,1011,0000, 1010, 0100}. Since the visible light communication image of the preamble period Tpa indicates the start of the visible light communication image, the receiving device 300 can recognize that when the 28-bit signal is detected, the data period Tdt continues thereafter.

In FIG. 5, the same decoding can be performed during the data period Tdt. The time ratio of the signal period of the visible light communication video in the data period Tdt is {1.7, 1.2, 1.0, 1.1, 1.3, 1.5, 1.1, 1.6}. expressed. When this is decoded in the same manner, eight decoding signals of {1111,0010,1000001,1011,0101,1001,0110} are obtained. By doing so, the receiving device 300 can obtain a 32-bit signal by visible light communication. After that, the receiving device 300 provides the user with information corresponding to the decoded data. In other words, the visible light communication signal processing unit can convert the input visible light communication signal into visible light communication video by performing replacement based on the correspondence between the above time ratio and the decoded signal.

Here, as described above, in the visible light communication period Tlc, a visible light communication image including all white and all black images is displayed. Since the visible light communication image is displayed in each image projection period Tvp which is a part of each frame period Tfr, it affects the brightness value of the image 210. The correction for this effect will be described below.

FIG. 6 is a diagram showing a graph of the relationship between the brightness value of the input video signal and the display brightness of the displayed video 210 in the projection type video display device 100 of FIG. In FIG. 6, ideally, as shown in the relationship 610, it is desirable that the brightness value of the input video signal and the display brightness of the video 210 match. However, as described above, since the all-white image is projected during the visible light communication period Tlc, the actually displayed image becomes brighter by the brightness of the brightness value d as shown in the relationship 620. Here, the luminance value d is a luminance value corresponding to the luminance of the visible light communication image.

In FIG. 6, in order to correct this difference in brightness, the image 210 is displayed so as to satisfy the relationship 630. Specifically, the video 210 is projected using the video signal obtained by subtracting the brightness value d from the brightness value of the input video signal. However, in a frame in which the brightness value of the input video signal is smaller than the brightness value d, the brightness of the projected image cannot be less than 0, so that the brightness value of the input video signal is not performed without visible light communication. Is used as it is (so as to satisfy the relationship 610), and the image 210 may be displayed.

FIG. 7 is a diagram showing a graph of the relationship between the display size of the image 210 and the display brightness of the image 210 in the projection type image display device of FIG. As shown in FIG. 7, as the display size of the image 210 increases due to the screen 200 moving away from the projection type image display device 100 or the like, the display brightness of the image 210 decreases and the brightness of the visible light communication image also decreases. If the brightness of the visible light communication image is lower than the lower limit sensitivity of the receiving device 300, the receiving device 300 cannot receive the visible light communication signal. Such a problem is solved as follows. If the brightness of the visible light communication signal can be reduced, there is an advantage that an image of visible light communication can be inserted from a brightness lower than that of the prior art (details will be described later).

FIG. 8 is a timing chart showing the light source current Ils of the light source unit 190 when the display size of the image 210 is small in the projection type image display device 100 of FIG. In FIG. 8, the time change of the light source current Ils flowing through the light source of the light source unit 190 is shown in the frame period Tfr of one frame. The larger the light source current Ils, the stronger the illumination light from the light source unit 190, and conversely, the smaller the light source current Ils, the weaker the illumination light from the light source unit 190.

In FIG. 8, during the image projection period Tbp, a predetermined on-current Ion continues to flow through the light source of the light source unit 190, and illumination light having a predetermined brightness is output from the light source unit 190. Further, during the visible light communication period Tlc, as shown in FIG. 4A, the light source unit 190 is alternately and repeatedly turned on and off, so that the visible light communication image is projected on the screen 200. Here, when the display size of the image 210 is small, the values of the light source current Ils in the preamble signal periods P1 to P3 and the data signal periods D1 to D4 of the visible light communication period Tlc are set to a predetermined low current Il (<Ih). To reduce. The low current Il is a current having a value as small as possible under the condition that the receiving device 300 can receive the visible light communication image. As a result, the brightness of the visible light communication image is reduced from the brightness of the brightness value d to the brightness of the brightness value dl corresponding to the constant current Il.

FIG. 9 is a diagram showing a graph of the relationship between the brightness value of the video signal and the display brightness of the video 210 when the display size of the video 210 is small in the projection type video display device 100 of FIG. In FIG. 9, as described above, the brightness of the visible light communication image is reduced from the brightness value d to the brightness value dl. As a result, even if the display brightness of the image 210 during the image projection period Tbp is less than the brightness of the brightness value d, visible light communication is possible if the brightness is equal to or more than the brightness of the brightness value dl.

FIG. 10 is a timing chart showing the light source current of the light source unit 190 when the display size of the image 210 is larger than a predetermined value in the projection type image display device 100 of FIG. In FIG. 10, similarly to FIG. 8, the light source current Ils in the image projection period Tbp is a predetermined on-current Ion. Further, the light source current Ils in the preamble signal periods P1 to P3 and the data signal periods D1 to D4 of the visible light communication period Tlc is increased to a predetermined high current Ih (> Il) (as opposed to FIG. 8). As a result, even when the display size of the image 210 is large, the brightness of the visible light communication image can be increased so that the receiving device 300 can receive the visible light communication image.

FIG. 11 is a diagram showing a graph of the relationship between the brightness value of the video signal and the display brightness of the video 210 when the display size of the video 210 is larger than a predetermined value in the projection type video display device 100 of FIG. The display brightness of the visible light communication image has increased from the brightness of the brightness value d to the brightness of the brightness value dh. Therefore, in order to obtain the ideal relationship 1110, the relationship 1120 that reduces the luminance value of the input video signal by the luminance value dh may be used. However, it should be noted that even if the luminance value of the video signal is equal to or greater than the luminance value d, visible light communication is not performed when the luminance value of the video signal is less than the luminance value dh.

As described above, the projection type video display device 100 according to the first embodiment inputs video signals of a plurality of frames, divides the frame period of each frame into a video projection period Tbp and a visible light communication period Tlc, and projects the video. In the period Tbp, the image of the input video signal is displayed, and in the visible light communication period Tlc, the visible light communication image is displayed. Further, by reducing the display brightness of the image 210 during the image projection period Tbp by the brightness value of the brightness value of the visible light communication image, the display brightness of the image 210 approaches (substantially matches) the brightness value of the image signal. Correct to. At this time, the larger the display size of the image 210, the larger the light source current Ilc of the light source unit 190 in the visible light communication period Tlc, and conversely, the smaller the display size of the image 210, the larger the light source current of the light source unit 190 in the visible light communication period Tlc. To make it smaller. As a result, the image of visible light communication can be inserted from a brightness lower than that of the prior art while ensuring the minimum display brightness that the receiving device 300 can receive the visible light communication signal.

(Embodiment 2)
FIG. 12 is a timing chart showing the display brightness of the image 210 in the projection type image display device 100A according to the second embodiment. In FIG. 12, the projection type image display device 100A differs from the projection type image display device 100 in the following points.
(1) The projection type image display device 100A includes a light source unit 190A that sequentially and selectively switches the color of the illumination light, and a single plate type projection display unit 140A.
(2) The projection display unit 140A includes only one DMD.

In FIG. 12, the projection type image display device 100A divides the frame period Tfr of one frame into a plurality of image projection periods Tbp, and red (R), green (G), and blue (B) are used for each image projection period Tvp. , Yellow (Y) is associated. The light source unit 190A of the projection type image display device 100A outputs colored light of the corresponding color as illumination light by using, for example, a combination of a rotating phosphor wheel and a color filter wheel in each image projection period Tbp. The projection display unit 140A controls the input color light on and off for each pixel with one DMD, and outputs an image of the corresponding color as an image 210. As in FIG. 4A, the display brightness of the image 210 during the image projection period Tbp differs for each frame. However, for the sake of simplicity in FIG. 12, the brightness of the image 210 during the image projection period Tbp is shown by the display luminances Rbp, Gbp, Bbp, and Yvp of the corresponding colors, respectively.

Here, one of the plurality of video projection periods Tbp corresponding to blue is used as the visible light communication period Tlc. In the visible light communication period Tlc, the DMD is turned on for all pixels and the light source unit 190A is turned on and off, so that the all-blue display image and the all-black display image are alternately displayed. Visible light communication is achieved by the receiving device 300 taking an image of this and decoding it in the same manner as in the first embodiment. In addition, the influence that the image of visible light communication had on the image 210 in the first embodiment occurs only in the blue (B) component in the present embodiment.

FIG. 13 is a timing chart showing the light source current of the light source unit 190 when the display size is small in the projection type image display device 100A of FIG. In FIG. 13, R, G, B, and Y indicate that the image projection period Tbp corresponds to red (R), green (G), blue (B), and yellow (Y), respectively. In the visible light communication period Tlc of FIG. 13, since the display size of the image 210 is small, the light source current Ils is reduced to the low current Il and the luminance value of the image signal is set to the visible light as in the case described above in FIG. The brightness value of the communication image is reduced by dl. As a result, the display brightness of the image 210 as a whole of the frame period Tfr is corrected to the brightness value indicated by the image signal.

FIG. 14 is a timing chart showing the light source current of the light source unit 190 when the display size is large in the projection type image display device 100A of FIG. However, the input video signal is the same as in FIG. In FIG. 14, R, G, B, and Y have image projection periods Tbp corresponding to red (R), green (G), blue (B), and yellow (Y), respectively, as in FIG. Show that. In the visible light communication period Tlc of FIG. 14, since the display size of the image 210 is large, the light source current Ils is increased to a high current Ih and the luminance value of the image signal is set to the visible light as in the case described above in FIG. The brightness value dh of the communication image is reduced. As a result, the display brightness of the image 210 as a whole of the frame period Tfr is corrected to the brightness value indicated by the image signal.

Comparing FIGS. 13 and 14, the visible light communication image in the visible light communication period Tlc is the image 210 containing only blue (B) light. Therefore, the light source current Ils of the light source unit 190A in the image projection period Tbp other than blue (R, G, Y in the figure) does not depend on the luminance value of the visible light communication image, the display size of the image 210, or the like. Here, since the input video signals are the same in FIGS. 13 and 14, the light source current Ils of the video projection period Tbp corresponding to red (R), green (G), and yellow (Y) changes. Not done. On the other hand, the light source current Ils of the image projection period Tbp corresponding to blue (B) is the display of the image 210 in FIG. 13 in order to correct the change in the brightness value of the visible light communication image due to the change in the display size of the image 210. When the size is small, the size is small, and when the display size of the image 210 in FIG. 14 is large, the size is large.

As described above, the projection type image display device 100A according to the second embodiment divides one frame of the image display into a plurality of image projection periods Tbp corresponding to any of red, green, blue, and yellow. Of the plurality of video projection periods Tbp, at least one video projection period Tbp corresponding to blue is defined as the visible light communication period Tlc. The projection type image display device 100A displays the image 210 of the corresponding color according to the image signal in the image projection period Tbp, and displays the blue visible light communication image in the visible light communication period Tlc. Further, in the video projection period Tbp, the blue display brightness of the video 210 in the video projection period Tbp is reduced by the value of the display brightness of the visible light communication video, so that the display brightness of the video 210 as a whole of the frame period Tfr is reduced. Is corrected to the brightness value indicated by the video signal. At this time, the larger the display size of the video 210, the larger the light source current Ilc of the light source unit 190A in the visible light communication period Tlc, and conversely, the smaller the display size of the video signal 210, the larger the light source of the light source unit 190A in the visible light communication period Tlc. Reduce the current. Thereby, the same effect as that of the first embodiment can be obtained. In the present embodiment, the image projection period Tbp corresponding to blue is set as the visible light communication period Tlc, but the image projection period Tbp corresponding to any of red, green, or yellow, or a plurality of images corresponding to different colors. The image projection period Tbp may be set as the visible light communication period Tlc.

(Embodiment 3)
FIG. 15 is a block diagram showing a detailed configuration example of the projection type image display device 100B according to the third embodiment. In FIG. 15, the projection type image display device 100B differs from the projection type image display device 100 of FIG. 3 in the following points.
(1) Instead of the projection size detection unit 150, a projection size setting unit 150B is provided.
(2) The projection size setting unit 150B includes a user interface 155B.

In FIG. 15, the projection size setting unit 150B causes the user to input a value of the display size of the image 210 via the user interface 155B, and outputs the input display size value to the display control unit 130 and the light source control unit 180. To do. As a result, the projection type image display device 100B is the same as that of the first embodiment based on the value of the display size set by the projection size setting unit 150B instead of the display size detected by the projection size detection unit 150. Since the operation is performed, the same effect as that of the first embodiment can be obtained. Instead of the display size of the image 210, the user may be allowed to input the distance from the projection type image display device 100B to the screen 200.

In the first and second embodiments, the camera 155 was used as a means for detecting the display size of the image 210 in the projection size detection unit 150. However, this may be anything as long as the display size can be detected. For example, a distance sensor that measures the distance between the projection type image display devices 100, 100A and the screen 200 may be used to estimate the display size of the image 210 based on the distance. Further, in the first to third embodiments, when the display brightness of the visible light communication video is larger than the brightness of the brightness value of the video signal, the brightness of the video 210 can be substantially matched with the brightness of the brightness value of the video signal. It was not possible, and it was decided that visible light communication would not be performed in that frame. However, by using error diffusion or the like in the visible light communication period Tlc, even when the display brightness of the visible light communication image is larger than the brightness value of the image signal, the brightness of the image 210 can be changed to the brightness value of the image signal. In some cases, it can be substantially matched with the brightness of.

The present disclosure is applicable to a projection type image display device such as a projector.

100 Projection type video display device 110 Video signal input unit 120 Video signal processing unit 130 Display control unit 140 Display unit 145 Projection lens 150 Projection size detection unit 150A Projection size setting unit 155 Camera 160 Visible light communication signal input unit 170 Visible light communication signal Processing unit 180 Light source control unit 190 Light source unit 200 Screen 210 Display image 300 Receiver

Claims (9)

A light source unit that generates illumination light by the input light source current,
A plurality of frames of video signals are input, and the frame period of each frame is divided into a plurality of subframe periods including at least one video projection period and at least one visible light communication period. Based on this, the illumination light is converted into image light and projected to project an image following the image signal on the projection surface, and the illumination light is projected as it is during the visible light communication period to obtain a visible light communication signal. A display unit that projects the visible light communication image of
In a projection type image display device including a light source control unit that controls the light source current based on an input visible light communication signal during the visible light communication period.
Based on the display size of the display image on the projection surface, the light source control unit increases the light source current during the visible light communication period as the display size increases, and decreases the light source current as the display size decreases. To control,
Projection type image display device. By subtracting the brightness value of the visible light communication signal from the brightness value of the video signal, the display unit corrects the brightness value of the video so as to substantially match the brightness value of the video signal.
The projection type image display device according to claim 1. When the luminance value of the visible light communication signal is larger than the luminance value of the video signal, the light source control unit displays the video of the video signal even during the visible light communication period.
The projection type image display device according to claim 2. The light source control unit further includes a distance sensor that measures the distance between the projection surface and the projection type image display device, and estimates the display size based on the measured distance.
The projection type image display device according to any one of claims 1 to 3. The light source control unit further includes an imaging device that images the projection surface, and estimates the display size based on an image captured by the imaging device.
The projection type image display device according to any one of claims 1 to 3. The light source control unit sets the display size according to the input of the user.
The projection type image display device according to any one of claims 1 to 3. The illumination light is white
The display unit divides the white illumination light into a plurality of colored lights, and converts the plurality of colored lights into the video light according to the video signal.
The projection type image display device according to any one of claims 1 to 6. The illumination light is a plurality of color lights output while sequentially and selectively switching a plurality of colors for each of the at least one image projection period.
The display unit converts the plurality of colored lights into the video light according to the video signal.
The projection type image display device according to any one of claims 1 to 6. The step in which the light source unit generates illumination light by the input light source current,
The display unit inputs a plurality of frames of video signals, divides the frame period of each frame into a plurality of subframe periods including at least one video projection period and at least one visible light communication period, and in the video projection period, the display unit divides the frame period into a plurality of subframe periods. Visible light communication by converting the illumination light into video light based on the video signal and projecting it to project an image following the video signal, and projecting the illumination light as it is during the visible light communication period. Steps to project the visible light communication image of the signal,
In a video display method including a step in which the light source control unit controls the light source current based on an input visible light communication signal during the visible light communication period.
In the control step, based on the display size of the display image on the projection surface, the larger the display size, the larger the light source current during the visible light communication period, and the smaller the display size, the smaller the light source current. Including steps to control,
Video display method.

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