JP2011081188A - Projection type image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a degradation in image quality when a plurality images are simultaneously displayed, in a projection type image display device having a function for simultaneously displaying the plurality images on one and the same screen. <P>SOLUTION: A projector includes: an input part 9 to which a plurality of image signals supplied from a plurality of image signal supplying devices are input through a plurality of input ports, respectively ; a display part including a one-screen display mode for selecting one of the plurality of image signals and displaying an image based on the one image signal in one display region and a two-screen display mode for selecting two of the plurality of image signals and displaying images based on the two image signals in two display regions, respectively; and an updating part for, when the operation mode of the display part is switched, rewriting EDID information stored in each of a plurality of EDID memories 20D and 20A corresponding to the plurality of image signals to EDID information including the resolution information of the display part in an operation mode after being switched. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a projection display apparatus, and more particularly to a projection display apparatus that displays a plurality of images simultaneously on the same screen.

  As a display device having a function of simultaneously displaying a plurality of videos on the same screen (hereinafter also referred to as a “multi-screen display function”), for example, Japanese Patent Laying-Open No. 2007-292281 (Patent Document 1) discloses a vehicle interior of a vehicle. Installed on the display screen, and a resolution detecting means for detecting the resolution of the first and second image inputs, and based on the resolution information detected by the resolution detecting means, Two-screen composition processing by resolution conversion that converts the first and second resolutions so that the difference between the horizontal and vertical aspect ratios of one image and the horizontal and vertical aspect ratios of the second image is equal to or less than a predetermined value. The structure which performs is disclosed.

  In the display device disclosed in Patent Document 1, in a conventional in-vehicle display device, when the aspect ratios of the image 1 and the image 2 to be displayed on the two screens are different, the image 1 and the image 2 are simply displayed. When combining and displaying two screens, the aspect ratio collapses and the manner in which the images collapse is different for each image. By converting the resolution of each image so that the difference is less than or equal to a predetermined value, it is possible to display an image with no sense of incompatibility when displaying two screens.

JP 2007-29281 A

  The display device disclosed in Patent Document 1 performs two-screen composition by resolution conversion that matches the vertical resolution of the image 2 with the vertical resolution of the image 1 as the two-screen composition processing, and the image 1 and the image 2 after the resolution conversion are combined. Display two screens.

  However, in such processing, when the resolution of at least one of image 1 and image 2 is significantly higher than the resolution that can be displayed on the display, the reduction ratio of the image in the two-screen display increases. This causes a problem that the original resolution of the image cannot be fully utilized and the image quality deteriorates.

  In the two-screen display, resolution conversion is performed for each of the resolutions of the image 1 and the image 2 so as to conform to the display resolution per one screen. A memory for temporary storage is required. Since such a memory has a fixed amount of data (memory bandwidth) that can be read and written per fixed time, it cannot read or write accurately to the memory at a speed higher than the memory bandwidth, resulting in the resolution of the input video signal. Will be limited. As a result, when both images are signals having high resolution, there arises a problem that the video cannot be displayed due to such limitation.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to deteriorate image quality when a plurality of images are simultaneously displayed in a projection display device having a multiple screen display function. Is to prevent.

  A projection display apparatus according to an aspect of the present invention includes n (n is a natural number of 2 or more) input ports, and converts n video signals supplied from n video signal supply devices into n pieces. As an operation mode for displaying an image based on the input unit and the video signal input through each of the input ports, one video signal selected from the n video signals input by the input unit is selected, One screen display mode for displaying video based on one video signal in one display area, and m (m is a natural number between 2 and n) of n video signals input by the input unit A display unit that selects a video signal and displays an image based on the m video signals in each of the m display areas, and an operation mode of the display unit is a single screen display mode. Switching to switch between m screen display modes And a non-volatile memory in which n pieces of EDID information including resolution information of the display unit are written corresponding to n video signals, and a non-volatile memory when the operation mode of the display unit is switched by the switching unit And an updating unit for rewriting the n EDID information stored in the information into n EDID information including the resolution information of the display unit in the operation mode after switching.

  Preferably, in the projection display apparatus, when each of the n input ports is connected to n video signal supply apparatuses via n transmission paths, n is connected via n transmission paths. Each of the video signal supply devices further includes a communication unit for instructing reading of n pieces of EDID information from the nonvolatile memory. The communication unit instructs each of the n video signal supply devices to read out the n pieces of EDID information from the nonvolatile memory when the operation mode of the display unit is switched by the switching unit.

  According to the present invention, in a projection display apparatus having a multi-screen display function, it is possible to prevent deterioration in image quality when a plurality of images are displayed simultaneously.

1 is a schematic configuration diagram of a projection display apparatus according to an embodiment of the present invention. It is a figure which shows the structure of the projector in FIG. It is a figure which shows an example of the display image by the projector which concerns on this Embodiment. It is a figure which shows a part of FIG. 2 in detail. . It is a figure which shows a part of FIG. 4 in detail. It is a figure which shows the control sequence between the digital video signal supply circuit using the digital transmission line of FIG. 5, and a projector.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a diagram for explaining the configuration of a peripheral device when an image is projected by a projection display apparatus according to an embodiment of the present invention.

  Referring to FIG. 1, a projection display apparatus (hereinafter also referred to as “projector”) 1 according to the present embodiment is a liquid crystal projector that projects an image using a liquid crystal device. The image is projected (displayed) by projecting light of the image displayed by the liquid crystal device. The projection surface is not limited to the screen 6 and may be a wall surface.

  The projector 1 includes a remote control receiving unit 20 that receives an infrared-modulated remote control signal transmitted from a remote control (abbreviated as a remote controller) 4 operated by a user, and an input unit 9. The remote control signal includes a command signal for remotely controlling the projector 1. The input unit 9 includes a plurality of input ports, and different types of video signals can be input from each port. In the present embodiment, for simplicity, two external video signal supply devices are provided, and the input unit 9 includes two input ports corresponding to these video signal supply devices 2D and 2A. Assume that

  A digital transmission path 3 and an analog transmission path 7 are connected to the input unit 9. The digital transmission path 3 includes an HDMI (High Definition Multimedia Interface) cable. The HDMI cable transmits a signal conforming to HDMI between the external digital signal supply device 2 </ b> D and the projector 1. The communication cable is connected to the input port of the input unit 9. Here, the digital transmission path is a path for transmitting data / signals according to HDMI, but may be a transmission path according to DVI (Digital Visual Interface).

  The analog transmission path 7 includes a wired or wireless transmission path. The transmission path transmits a signal between the analog signal supply device 2 </ b> A and the projector 1. The analog transmission line 7 is connected to the input port of the input unit 9.

  Here, the digital signal supply device 2D is assumed to be a digital signal supply device that outputs a digital signal such as a DVD (Digital Versatile Disc) reproduction device or a Blue-Ray disc reproduction device, and the analog signal supply device 2A is a computer or the like. Assume a device that outputs an analog signal.

  For simplicity of explanation, it is assumed that the analog signal transmitted from the analog signal supply device 2A is a video signal, and the digital signal supplied from the digital signal supply device 2D is a video signal. Although an audio signal is transmitted together with the video signal, the description of the transmission of the audio signal and the audio signal processing in the projector 1 is omitted for the sake of simplicity.

FIG. 2 is a diagram showing the configuration of the projector 1 in FIG.
Referring to FIG. 2, projector 1 includes video signal processing circuit 10, OSD (On Screen Display) circuit 50, DAC (Digital Analog Converter) 12, microcomputer (microcomputer) 13, and liquid crystal display drive unit 14. An optical system 15, a power supply unit 17, a connector 19, and a lamp 16.

  The microcomputer 13 generates a control command based on a command signal input from the remote control 4 (FIG. 1) via the remote control receiving unit 20 and outputs the control command to each unit of the projector 1.

  The video signal processing circuit 10 processes the video signal input from the input unit 9 into a signal for display and outputs it. Specifically, the video signal processing circuit 10 writes the video signal from the input unit 9 to a frame memory (not shown) for each frame (one screen) and reads the video stored in the frame memory. In the process of writing and reading, various video processes are performed to convert the input video signal and generate video data that is a video signal for a projected video.

  The OSD circuit 50 superimposes the image data signal based on the information given from the microcomputer 13 on the video signal output from the video signal processing circuit 10, and outputs the video signal after being superimposed.

  The DAC 12 receives the video signal output from the OSD circuit 50, converts it into an analog signal, and outputs the analog signal to the liquid crystal display driving unit 14.

  The liquid crystal display drive unit 14, the optical system 15, and the lamp 16 correspond to a display unit for displaying an image on the screen 6 under the control of the microcomputer 13 in accordance with the video signal output from the DAC 12.

  The operation of the display unit will be described. The lamp 16 that is an illuminating device is composed of, for example, an ultrahigh pressure mercury lamp, a metal halide lamp, a xenon lamp, or the like. The lamp 16 is detachably attached to the projector 1 via the connector 19. From the lamp 16, the light becomes substantially parallel light and is emitted to the liquid crystal display driving unit 14.

  The liquid crystal display driving unit 14 includes an optical system including a lens and a prism (not shown), and R, G, and B liquid crystal panels. In the liquid crystal display driving unit 14, the light from the lamp 16 that has passed through an internal lens system (not shown) enters the R, G, and B liquid crystal panels so that the light quantity distribution is uniform. Of the light incident through the lens system, light in the blue wavelength band (hereinafter referred to as “B light”), light in the red wavelength band (hereinafter referred to as “R light”), and light in the green wavelength band (hereinafter referred to as “R light”). "G light") is substantially parallel light and enters each of the R, G, and B liquid crystal panels. Each liquid crystal panel is driven in accordance with video signals corresponding to R, G, and B supplied from the DAC 12, and modulates light in accordance with the driving state. The R light, G light, and B light modulated by the liquid crystal panel are color-combined by the dichroic prism and then enlarged and projected on the screen 6 by the projection lens. The projection lens includes a lens group for forming an image of projection light on the screen 6 and an actuator for adjusting a zoom state and a focus state of the projected image by changing a part of the lens group in the optical axis direction. Yes.

  The power supply unit 17 is supplied with power via a plug 18 that is plugged into an AC (Alternating Current) power supply (not shown), and supplies the supplied power to each part in the projector 1.

  The user can make various inputs using the remote controller 4. The remote control signal transmitted from the remote control 4 is input to the microcomputer 13 via the remote control receiving unit 20 and corresponding processes are executed.

  As one of the processes, the projector 1 according to the present embodiment has an analog signal and a digital signal respectively input from the two input ports of the input unit 9 as an operation mode for displaying an image based on the image signal. Select one video signal, select one screen display mode for displaying video based on the one video signal in one display area, select an analog signal and a digital signal, Each of the two display areas has a “two-screen display mode” for displaying an image based on an analog signal and an image based on a digital signal. Switching between the single-screen display mode and the dual-screen display mode is performed by the microcomputer 13 in accordance with a video signal processing based on an operation mode switching request input from the remote controller 4 via the remote control receiver 20 by a method described later. This is performed by controlling the circuit 10.

FIG. 3 is a diagram showing an example of a display image by the projector 1 according to the present embodiment.
Referring to FIG. 3A, when the one-screen display mode is executed, one of video Gi_A based on the analog signal and video Gi_D based on the digital signal is displayed in the display area 100 of the display unit (liquid crystal panel). Projected (displayed) on the entire screen.

  On the other hand, when the two-screen display mode is executed, the video Gi_A based on the analog signal and the video Gi_D based on the digital signal are simultaneously displayed in the display area 100 as shown in FIG. In the figure, the display area (window W1 in the figure) for displaying the video Gi_A and the display area (window W2 in the figure) for displaying the video Gi_B are the same size and in the single screen display mode. It is assumed that it corresponds to approximately 1/4 of the size of the display area 100.

  Therefore, in the example of FIG. 2, when the operation mode of the projector 1 is switched from the one-screen display mode to the two-screen display mode, the display size per screen is reduced to approximately ¼. For example, if the resolution of the display unit in the one-screen display mode is 1024 × 768 pixels (XGA), the resolution per screen in the two-screen display mode is 512 × 384 pixels. Therefore, when the video signal has a high resolution such as 1600 × 1200 pixels (UXGA), the reduction rate of the video signal in the two-screen display mode becomes large, and the image quality cannot be fully utilized. The problem of deterioration occurs.

  In the two-screen display mode, resolution conversion is performed for each of the resolutions of the two video signals respectively input from the two input ports to match the resolution of the display area per screen. This resolution conversion process requires a memory for temporarily storing video data. Since such a memory has a fixed amount of data (memory bandwidth) that can be read and written per fixed time, it cannot read or write accurately to the memory at a speed higher than the memory bandwidth, resulting in the resolution of the input video signal. Will be limited. As a result, when both of the two video signals are signals having high resolution, there arises a problem that the video cannot be displayed due to the limitation.

  In order to avoid such problems and ensure that stable video display is stably performed regardless of the operation mode, the projector 1 according to the present embodiment uses EDID indicating the display capability and specifications of the projector 1. The resolution information that can be displayed by the projector 1 included in the (Extended Display Identification Data) information is updated to the resolution information that can be displayed by the projector 1 in the operation mode after switching according to the switching of the operation mode of the projector 1. Hereinafter, the operation of the projector 1 according to the present embodiment will be described with reference to FIGS. 4 to 6.

(Projector operation)
FIG. 4 is a diagram showing in detail a part of FIG. 2 (input unit 9, video signal processing circuit 10).

  Referring to FIG. 4, input unit 9 includes input ports 9D and 9A. A digital signal supply device 2D is connected to the input port 9D by a transmission line (wired or wireless) of the digital transmission line 3. The analog signal supply device 2 </ b> A is connected to the input port 9 </ b> A through a communication cable of the analog transmission path 7. Each input port is supplied with an analog or digital video signal from the connected analog or digital signal supply device 2A or 2D, and inputs the supplied video signal.

  The video signal processing circuit 10 includes EDID memories 20D and 20A, a digital signal processing unit 22, scaling units 26 and 28, an A / D converter 24, and a two-screen synthesis unit 30.

  The EDID memory 20D is a non-volatile memory in which EDID information corresponding to a digital video signal is written. The EDID memory 20D is connected to the input port 9D. When the input port 9D is connected to the digital signal supply device 2D via the digital transmission path 3, the EDID information corresponding to the digital video signal is transmitted to the digital signal supply device. Can be sent to 2D.

  The EDID memory 20A is a nonvolatile memory in which EDID information corresponding to an analog video signal is written. The EDID memory 20A is connected to the input port 9A. When the input port 9D is connected to the digital signal supply device 2D via the digital transmission path 3, the EDID information corresponding to the analog video signal is sent to the analog signal supply device. 2A can be transmitted.

  The EDID information indicates the display capability and specifications of the projector 1 and is unique to the device such as the resolution (video information) that can be displayed by the projector 1, audio stream information (audio information such as audio format), and the manufacturing number. Contains information. When the operation mode of the projector 1 is switched between the one-screen display mode and the two-screen display mode, the microcomputer 13 updates the EDID information written in the EDID memories 20D and 20A by a method described later. To do.

  The digital signal processing unit 22 processes the digital video signal input from the input port 9D into a signal for display and outputs the signal. Specifically, the digital signal processing unit 22 writes the digital video signal into a frame memory (not shown) for each frame (one screen) and reads out the video stored in the frame memory. In the process of writing and reading, various video processes are performed to convert the input digital video signal to generate video data that is a video signal for display.

  The scaling unit 26 uses the resolution of the display unit in the one-screen display mode (in this embodiment, “1024 × 768 pixels (XGA)”) as a reference (hereinafter also referred to as “reference display size”). The conversion processing of the resolution of the video represented by the digital video signal is executed in accordance with a desired display size set in advance that is equal to or smaller than the reference display size. By this resolution conversion process, the scaling unit 26 generates video data representing a video for display having a resolution equal to or lower than the resolution of the display unit.

  When the operation mode of the projector 1 is switched from the one-screen display mode to the two-screen display mode, the scaling unit 26 displays the display size per screen (in the present embodiment, “512 × 384 pixels ”)), the conversion processing of the resolution of the video represented by the digital video signal is executed.

  The A / D converter 24 converts the analog video signal input from the input port 9 </ b> A into a digital signal, and outputs the converted signal to the scaling unit 28.

  The scaling unit 28 performs conversion processing of the resolution of the video represented by the analog video signal according to a desired display size set in advance that is equal to or smaller than the reference display size. By this resolution conversion process, the scaling unit 28 generates video data representing a video for display having a resolution equal to or lower than the resolution of the display unit.

  When the operation mode of the projector 1 is switched from the one-screen display mode to the two-screen display mode, the scaling unit 28 displays the display size per screen (in this embodiment, “512 × 384 pixels ”)), the conversion processing of the resolution of the video represented by the analog video signal is executed.

  The video data generated by the scaling unit 26 and the scaling unit 28 is given to the two-screen composition unit 30. During the execution of the two-screen display mode, the two-screen composition unit 30 synthesizes a digital video signal for one frame to be displayed on the screen 6 based on the two pieces of given video data. The video signal for one frame obtained by the synthesis is output to the DAC 12 via the OSD circuit 50.

  On the other hand, during the execution of the one-screen display mode, the two-screen composition unit 30 corresponds to one frame to be displayed on the screen 6 based on one video data given from either the scaling unit 26 or 28. A digital video signal is generated. The generated video signal for one frame is output to the DAC 12 via the OSD circuit 50.

  According to FIG. 4, the video signal applied to either of the input ports 9D and 9A can be displayed on the entire screen during the execution of the single screen display mode, and the input port 9D can be displayed during the execution of the dual screen display mode. The applied video signal and the video signal applied to the input port 9A can be displayed simultaneously.

(About updating EDID information)
The procedure for updating the EDID information stored in the EDID memories 20D and 20A shown in FIG. 4 will be described with reference to FIGS.

  FIG. 5 is a diagram showing in detail a part of FIG. 4 (digital transmission path 3, input port 9D, EDID memory 20D).

  Referring to FIG. 5, a digital transmission line (HDMI cable) 3 includes a TMDS line L1 for transmitting a video signal of digital signal supply device 2D to projector 1 by a TMDS (Transition Minimized Differential Signaling) method, and a digital signal supply. Control and status between the HPD (Hot Plug Detector) line L2 for detecting whether or not the apparatus 2D is connected to the projector 1 through the digital transmission path 3 (communication cable), and between the digital signal supply apparatus 2D and the projector 1 And a DDC (Display Data Channel) line L3 for performing two-way communication. The digital signal supply device 2 </ b> D can read EDID information from the projector 1 by the DDC line L <b> 3 of the HDMI cable 3.

  FIG. 6 is a diagram showing a control sequence between the digital video signal supply circuit 2D using the digital transmission path 3 of FIG.

  Referring to FIG. 6, when digital signal supply device 2D and projector 1 are connected by HDMI cable 3 and both devices are turned on, microcomputer 13 in projector 1 changes the hot plug detection signal from Low to High. .

  A control unit (not shown) inside the digital signal supply device 2D constantly monitors the hot plug detection signal on the HPD line L2, and detects that the hot plug detection signal has changed from Low to High. The supply device 2D and the projector 1 are physically connected, and it is determined that the EDID information can be read, and the EDID information is read from the EDID memory 20D. The microcomputer 13 changes the state of the hot plug detection signal. For example, when the video signal of the digital signal supply device 2D is selected as the video signal to be displayed, the state of the hot plug detection signal is set to High. On the other hand, when the video signal of the digital signal supply device 2D is in the non-selected state, the microcomputer 13 sets the state of the hot plug detection signal to Low. The digital signal supply device 2D is allowed to read EDID information from the EDID memory 20D only when the hot plug detection signal is in a high state, and is not allowed to read EDID information when the hot plug detection signal is in a low state. This is defined, for example, in [HDMI Ver1.3 Specification] that defines the HDMI standard.

  Next, when the control unit of the digital signal supply device 2D acquires the resolution information of the display unit of the projector 1 included in the EDID information read from the EDID memory 20D, the control unit outputs it so as to match the acquired resolution of the display unit. Select the resolution of the video signal. As a result, the video signal is processed to a desired resolution suitable for the resolution of the display unit by a video processing unit (not shown), and then input to the input port 9D of the projector 1 via the TMDS line L1.

  Here, in projector 1, it is assumed that microcomputer 13 receives a command signal for requesting switching of the operation mode via remote control receiver 20. Upon receiving the command signal, the microcomputer 13 updates the resolution information of the display unit included in the EDID information stored in the EDID memory 20D to the resolution information that can be displayed by the projector 1 in the operation mode after switching.

  Specifically, when the operation mode of the projector 1 is switched from the one-screen display mode to the two-screen display mode, the microcomputer 13 controls the EDID memory 20D to control the one-screen display mode included in the EDID information. The display resolution (1024 × 768 pixels (XGA)) is rewritten to the display resolution (512 × 384 pixels) in the two-screen display mode.

  When the update of the EDID information is completed, the microcomputer 13 changes the hot plug detection signal from low to high. When the control unit inside the digital signal supply device 2D detects that the hot plug detection signal has changed from Low to High, it determines that the EDID information is in a readable state, and reads the EDID information from the EDID memory 20D.

  Thereby, in the digital signal supply device 2D, the updated EDID information is read, and the resolution information of the display unit in the operation mode after switching included in the updated EDID information is acquired. Therefore, the video signal is processed to a desired resolution that matches the resolution of the display unit in the operation mode after switching, and is input to the input port 9D of the projector 1 via the TMDS line L1.

  Thus, according to the projector 1 according to the present embodiment, when the operation mode is switched, the EDID information is updated to EDID information including the resolution information of the display unit in the operation mode after switching, The digital signal supply device 2D is instructed to reread the updated EDID information. With such a configuration, a video signal having a resolution suitable for the resolution of the display unit is received from the digital signal supply device 2D, although the displayable resolution changes by switching the operation mode of the projector 1. It will be supplied stably. As a result, it is possible to prevent the image quality from being deteriorated due to the switching of the operation mode, and it is possible to stably display a good image.

  In the present embodiment, projector 1 is remotely controlled by remote controller 4, but an operation panel may be provided on projector 1, and the user may input a command by operating the operation panel.

  In addition, the arrangement of the display areas for displaying different video signals is not limited to the aspect of being arranged in parallel as shown in FIG. 3, and may be an aspect of being arranged in parallel in the vertical direction. Further, the size of the display area may be the same size as shown in FIG. 3, or may be different sizes. The video displayed in each display area can be either a moving image or a still image.

  In this embodiment, the example in which the number of input ports is two and the two-screen display mode for displaying two different video signals on the screen 6 has been described. However, the present invention is not limited to this. The present embodiment is widely applied to a multi-screen display mode in which the number is n (n is a natural number of 2 or more) and m (m is a natural number of 2 to n) different video signals are simultaneously displayed. Is possible.

  In this embodiment, a liquid crystal projector is used as the projector, but the present invention is not limited to this. For example, the technology of the present invention may be applied to other projectors such as a DLP (Digital Light Processing) (registered trademark) projector.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  1 projector, 2A analog signal supply device, 2D digital signal supply device, 20A, 20D EDID memory, 3 digital transmission path, 4 remote control, 6 screen, 7 analog transmission path, 9A, 9D input port, 9 input section, 10 video signal Processing circuit, 13 microcomputer, 14 liquid crystal display drive unit, 15 optical system, 16 lamp, 17 power supply unit, 18 plug, 19 connector, 20 remote control receiving unit, 22 digital signal processing unit, 24 A / D converter, 26, 28 scaling Part, 302 screen composition part, 50 OSD circuit, W1, W2 window.

Claims (2)

an input unit that includes n (n is a natural number of 2 or more) input ports, and inputs n video signals supplied from n video signal supply devices via each of the n input ports; ,
As an operation mode for displaying a video based on a video signal, one video signal is selected from the n video signals input by the input unit, and the one video signal is displayed in one display area. Select one screen display mode for displaying video based on the video signal, and m (m is a natural number between 2 and n) of the n video signals input by the input unit, and select m A display unit having an m screen display mode for displaying video based on the m video signals in each of the display areas;
A switching unit for switching an operation mode of the display unit between the one-screen display mode and the m-screen display mode;
a non-volatile memory in which n pieces of EDID information including resolution information of the display unit are written corresponding to n pieces of video signals;
When the operation mode of the display unit is switched by the switching unit, the n pieces of EDID information stored in the nonvolatile memory include n pieces of resolution information of the display unit in the operation mode after switching. A projection display apparatus comprising: an update unit for rewriting each of the EDID information. When each of the n input ports is connected to the n video signal supply devices via n transmission paths, the n video signal supply devices are connected via the n transmission paths. Each further comprising a communication unit for instructing reading of the n pieces of EDID information from the nonvolatile memory,
The communication unit instructs each of the n video signal supply devices to read out the n pieces of EDID information from the nonvolatile memory when the operation mode of the display unit is switched by the switching unit. The projection display apparatus according to claim 1.

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