JP7341856B2 - Control device, display device control method, program, and storage medium - Google Patents

Description

The present invention relates to a control device for controlling a display device, a method for controlling a display device, a program, and a storage medium.

2. Description of the Related Art Devices that output video (such as personal computers) are required to reduce power consumption. As a related technique, a video signal processing device disclosed in Patent Document 1 has been proposed. The video signal processing device of Patent Document 1 executes power saving control to stop the video signal input operation and the write operation in the frame memory access unit when the operation mode signal instructs the power saving mode.

Furthermore, in recent years, techniques have been used to continue displaying images while reducing the power consumption of video output devices. In this technique, when the video output device completely stops outputting video, the display device freeze-displays the video signal before the video output from the video output device was stopped. Thereby, it is possible to continue displaying while reducing power consumption of the video output device.

JP2013-76855A

By the way, in the above-mentioned technique that allows the video output device to continue displaying while saving power, the video output device notifies the display device of signal information regarding the video using a predetermined packet (auxiliary information packet). Here, when the video output device stops outputting video for the purpose of power saving of the video output device, the auxiliary information packet is no longer notified to the video output device. Therefore, the video output device cannot correctly display signal information regarding the video even though the screen is displayed in a frozen state. Therefore, uncertain signal information is presented to the user.

An object of the present invention is to display correct signal information regarding video when continuing display while stopping video output.

In order to achieve the above object, a control device of the present invention includes a video input section that inputs video from a video output device, video signal information regarding the video acquired through the video input section, and the video output device. a storage unit that stores a video stop signal indicating that the video has stopped transmitting the video; and a storage unit that transmits the video from the storage unit in response to receiving the video stop signal from the video output device. acquires the video immediately before the transmission of the video is stopped, controls to continue displaying the acquired video, and acquires the video signal information from the storage unit immediately before the transmission of the video is stopped; The present invention is characterized by comprising a control means for controlling display of video signal information.

According to the present invention, correct signal information regarding the video can be displayed when the display is continued while the video output is stopped.

FIG. 1 is a configuration diagram of a system of this embodiment. FIG. 2 is a block diagram showing the configuration of a projector. FIG. 3 is a functional block diagram of an image processing section. FIG. 2 is a block diagram showing the configuration of a video output device. 3 is a flowchart showing the flow of normal operation processing. It is a flowchart which shows the flow of power saving mode transition processing. It is a state transition diagram of this embodiment. FIG. 3 is a diagram showing an example of OSD display of video signal information.

Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings. However, the configurations described in each embodiment below are merely examples, and the scope of the present invention is not limited by the configurations described in each embodiment.

This embodiment will be described below. FIG. 1 is a configuration diagram of the system of this embodiment. In FIG. 1, a projector 100 is connected to a video output device 200. Projector 100 corresponds to a display device. The display device may be applied to any display device other than the projector 100. Video output device 200 is, for example, a personal computer. Projector 100 has one video input section, and is connected to video output device 200 via a cable. Under the control of the video output device 200, the projector 100 projects the video 300 onto the projection screen 400 for display. Video signal information is displayed on the OSD display 500. The OSD display 500 is displayed, for example, when a menu button on the projector 100 is pressed. The video signal information is signal information regarding the video input from the video output device 200, and is signal information about the video being projected by the projector 100.

FIG. 2 is a block diagram showing the configuration of the projector 100. The projector 100 (projector main body) has a control section 101 for controlling each block. The control unit 101 is connected to each unit shown in FIG. 2 via a bus 133. The control unit 101 can access each unit via the bus 133 to send and receive control instructions and data.

The projector 100 includes an operation section 102, a power supply section 103, a liquid crystal section 104, a liquid crystal drive section 105, and a light source 106. The operation unit 102 accepts user operations. The power supply section 103 controls power supply to each section of the projector 100. The liquid crystal section 104 is composed of one liquid crystal panel or a plurality of (for example, three) liquid crystal panels. An image is formed on the liquid crystal panel of the liquid crystal section 104. The liquid crystal driving section 105 causes the liquid crystal panel of the liquid crystal section 104 to form an image based on the input image signal. A light source 106 supplies light to the liquid crystal section 104.

The projector 100 includes a projection optical system 107, a light source control section 108, an optical system control section 109, and an image input section 110. Projection optical system 107 projects an optical image obtained by supplying light emitted from light source 106 to liquid crystal section 104 onto screen 400 . The light source control unit 108 controls the amount of light of the light source 106, etc. The optical system control unit 109 controls the operations of the zoom lens, focus lens, etc. of the projection optical system 107, and performs zoom magnification, focus adjustment, etc.

A digital video signal is input to the video input unit 110 from the video output device 200 . The video input unit 110 is capable of transmitting and receiving not only digital video signals but also DP signals. The DP signal is a video signal, audio signal, metadata, control signal, etc. based on a protocol defined by the DP standard (DisplayPort standard). In the DP standard, metadata and control signals are transmitted in auxiliary information packets called SDPs (Secondary Data Packets). The video input unit 110 acquires the SDP and extracts information regarding the input video (video signal information) included in the acquired SDP. The control unit 101 stores the extracted video signal information in the RAM 132.

The auxiliary information packet is a packet defined by the video standard. The auxiliary information packet may be an InfoFrame defined by HDMI (High-Dfinity Multimedia Interface). The auxiliary information packet is transmitted from the video output device 200 to the projector 100 during a video blanking period using the main link that transmits the video. Further, the video input unit 110 has a built-in function to store information based on a predetermined format, such as receivable video format information, signal transmission rate, and information on whether or not it is compatible with optional functions. Examples of the above information include EDID (Extended Display Identification Data) and DPCD (Display Port Configuration Data). The EDID can be read and written based on instructions from the control unit 101. Further, the DPCD can perform not only reading and writing based on instructions from the control unit 101 but also reading and writing based on a request from the video output device 200. When reading and writing from the video output device 200 to EDID and DPCD, access is made through an auxiliary communication channel called AUX-CH (Auxiliary-Channel). Further, the video input section 110 directly outputs the input video signal to the image processing section 116.

The projector 100 includes a USB I/F 112, a card I/F 113, and a communication section 114. The USB I/F 112 (USB interface) can receive various information data files such as video data, image data, and video files from the video output device 200 via a USB cable. Further, the USBI/F 112 can also write the above file to the video output device 200. A pointing device, a keyboard, a USB type flash memory, etc. can also be connected to the USB I/F 112. The card I/F 113 (card interface) is a card interface that reads and writes various information data files such as video data, image data, and video files to and from a card-type recording medium. An SD card, compact flash, etc. can be inserted into the card I/F 113. For example, the file reproduction unit 121 reproduces a document file input to the card I/F 113. The file reproduction section 121 generates an image signal to be presented to the user from the document file, and outputs it to the image processing section 116.

The communication unit 114 transmits and receives various information data files such as video data, image data, and video files, or command signals via an intranet, the Internet, or the like. The communication unit 114 is configured with, for example, a wired LAN or a wireless LAN. The internal memory 115 is an internal memory that stores files of various information data such as image data and user setting data. For example, the internal memory 115 is composed of a semiconductor memory, a hard disk, or the like.

Projector 100 includes an image processing section 116. The image processing section 116 acquires an image signal from the video input section 110 or the file reproduction section 121. The image processing unit 116 performs correction suitable for display by the liquid crystal unit 104 on the acquired image signal based on the control content from the control unit 101. The image processing unit 116 also performs superimposition of an OSD (On Screen Display) image on the input video.

For example, the image processing unit 116 converts the number of pixels of the image signal according to the number of pixels of the liquid crystal panel of the liquid crystal unit 104, doubles the frame rate of the input video signal for AC driving of the liquid crystal panel, Make corrections suitable for image formation on a liquid crystal panel. Here, AC driving of the liquid crystal panel is a method of displaying images by alternately changing the direction of the voltage applied to the liquid crystal of the liquid crystal panel. This takes advantage of the property that liquid crystal panels can generate images whether the voltage applied to the liquid crystal is in the forward or reverse direction. At this time, since it is necessary to send one image for the forward direction and one image for the reverse direction to the liquid crystal driving section 105, the image processing section 116 performs a process of doubling the frame rate of the video signal.

The liquid crystal driving section 105 forms an image on the liquid crystal panel of the liquid crystal section 104 based on the image signal processed by the image processing section 116. Although an example in which a liquid crystal panel driven by an analog signal is employed has been described here, a liquid crystal panel that can be driven by a digital signal may also be employed, for example. In this case, the liquid crystal drive unit 105 controls the liquid crystal panel by driving a predetermined pulse width modulation (PWM) based on the image signal output by the image processing unit 116. Further, even if a liquid crystal panel driven by a digital signal such as PWM is employed, the image processing unit 116 may perform processing to double the frame rate. This makes it possible to apply techniques for reducing image quality deterioration such as disclination caused by the drive method.

Further, when the image 300 is projected onto the screen 400 from an oblique direction, the image 300 may be displayed distorted into, for example, a trapezoid shape. For this reason, the image processing unit 116 may perform keystone correction to transform the shape of the image so as to cancel out the distortion occurring in the image 300 projected on the screen 400. By performing the keystone correction, the image 300 projected on the screen 400 can be approximated to a rectangular shape with a normal aspect ratio. Projector 100 has a tilt sensor 117. The keystone correction may be performed automatically based on the tilt angle obtained from the tilt sensor 117, or may be performed by the user operating the operating unit 102 or the like.

The image processing unit 116 acquires the video signal input to the video input unit 110, performs image processing and OSD synthesis processing, and outputs the processed video. Next, the image processing section 116 will be explained. FIG. 3 is a functional block diagram of the image processing unit 116. The input signal processing section 171 outputs a vertical synchronization signal from the acquired video signal to the output timing generation section 176. The control unit 101 reads video format information stored in the RAM 132 and notifies the scaling unit 172 of the video format information. The scaling unit 172 acquires the video signal from the input signal processing unit 171, and in order to convert the input video format information to the projection resolution of the projector 100, the scaling unit 172 enlarges or reduces the input video and outputs it to the color conversion unit 173. At this time, a frame buffer for performing enlargement processing or reduction processing may be used.

The control unit 101 reads the color/range information of the input video stored in the RAM 132 and notifies the color conversion unit 173 of the color/range information. The color conversion unit 173 performs color conversion processing to convert the color/range of the input video to the panel specifications of the projector 100. The write control unit 174 performs address control for writing the video frame (input video) output from the color conversion unit 173 into the frame buffer 175. Further, the write control unit 174 stops writing when the power save mode is ON based on an instruction from the power save mode control unit 181. The frame buffer 175 temporarily buffers the video frame output from the color conversion section 173 in order to match the timing generated by the output timing generation section 176.

The output timing generation section 176 acquires the vertical synchronization signal output from the input signal processing section 171. The output timing generation unit 176 outputs a signal (hereinafter referred to as a timing signal) indicating the timing to read the video frame to the readout control unit 177. The readout control unit 177 reads video frames from the frame buffer 175 based on the timing signal generated by the output timing generation unit 176. Further, when the power saving mode is ON, address control is performed to continue reading the same frame. Thereby, the projector 100 can continue to project the frozen image even when no image is input to the projector 100 from the image output device 200.

The OSD generation unit 178 generates an OSD image for OSD display. For example, in response to a user operation received by the operation unit 102, the control unit 101 issues an OSD display instruction. The OSD generation unit 178 receives an OSD display instruction. When the OSD display instruction indicates display of video signal information, OSD generation section 178 generates an image for OSD display of the video signal information received from power saving control section 181. The video signal information includes video format information, color/range information, power saving mode ON/OFF information, and the like. The video format information includes, for example, resolution and frequency. Further, the color/range information includes color space, chroma subsampling, color range, bit depth, and the like. The video signal information may also include other information. The OSD superimposing section 179 superimposes the OSD image generated by the OSD generating section 178 on the video frame read out from the readout control section 177 . The OSD superimposing unit 179 passes the video frame on which the OSD image is superimposed to the power saving mode control unit 181.

The power saving control unit 181 controls the power saving mode. The power saving mode of this embodiment is a mode in which the video output device 200 stops outputting video to save power, and the projector 100 continues to display video. The control unit 101 reads power saving mode information (information indicating whether the power saving mode is ON or OFF) stored in the RAM 132 and notifies the power saving control unit 181 of the power saving mode information. The power saving control unit 181 manages the state of the power saving mode based on the power saving mode information. State management of the power saving mode will be described later. Furthermore, the power saving control unit 181 notifies the write control unit 174 and the read control unit 177 of power saving mode information. Furthermore, the power saving control unit 181 receives video format information and color/range information from the control unit 101, and stores the received information for each state of whether the power saving mode is ON or OFF. Then, power saving control section 181 determines video format information and color/range information to be output to OSD generation section 178, depending on whether the power saving mode is ON or OFF. The signal output unit 180 processes the video frame received from the OSD superimposition unit 179 into a video signal that can be received by the liquid crystal drive unit 105 and outputs the video signal.

As shown in FIG. 2, the projector 100 includes a tilt sensor 117, a timer 118, a thermometer 119, and a cooling unit 120. Tilt sensor 117 detects the tilt of projector 100. The timer 118 detects the operating time of the projector 100, the operating time of each block, and the like. The thermometer 119 measures the temperature of the light source 106, the temperature of the liquid crystal section 104, the outside air temperature, and the like. The cooling unit 120 cools the projector 100 by discharging the heat inside the projector 100 to the outside. The cooling unit 120 includes, for example, a heat sink and a fan.

The projector 100 includes a file playback section 121, an infrared receiving section 122, a focus detection section 123, an imaging section 124, a photometry section 125, a display section 128, a display control section 129, a battery 130, a power input section 131, and a RAM 132. The file playback unit 121 decodes encoded file data and the like based on instructions from the control unit 101, and plays back the file. The infrared receiving unit 122 receives infrared rays from a remote control attached to the projector 100 or other equipment, and sends a signal to the control unit 101. The infrared receiving sections 122 are installed at a plurality of locations, for example, in the front and rear directions of the projector 100. The focus detection unit 123 detects the distance between the projector 100 and the screen 400, and detects the focal length. The imaging unit 124 captures an image in the direction of the screen 400. The photometry unit 125 is a screen photometry unit that measures the amount and brightness of light reflected by the screen 400.

The display unit 128 is arranged on the main body of the projector 100 and displays the status of the projector 100, warnings, etc. Display control section 129 controls display section 128. The battery 130 is used to supply power when the main body of the projector 100 is carried around and used. The power input unit 131 receives AC power from the outside, rectifies it to a predetermined voltage, and supplies the rectified voltage to the power supply unit 103 . The RAM 132 is an area that temporarily stores information used for program expansion and control processing stored in the internal memory 115. For example, when the control unit 101 is configured by a CPU, the processing of this embodiment may be realized by executing a program expanded to the RAM 132. Further, the control unit 101 may be realized by a predetermined programming circuit. The various parts shown in FIG. 2 are connected to the bus 133. Among the units in FIG. 2, the control unit 101, video input unit 110, image processing unit 116, and RAM 132 correspond to the control device. The controller may include other blocks in FIG. 2.

Next, the video output device 200 will be explained. As described above, the video output device 200 is, for example, a personal computer. FIG. 4 is a block diagram showing the configuration of the video output device 200. The video output device 200 includes a control section 201, an optical drive 202, an operation section 203, a power supply section 204, and a power input section 205. Control section 201 controls each section of video output device 200. The optical drive 202 reads and writes data from optical media. The operation unit 203 includes buttons and the like for performing operations such as power control and reset of the video output device 200. The power supply section 204 supplies power to each section based on instructions from the control section 201. The power input unit 205 receives AC power from the outside, rectifies it to a predetermined voltage, and supplies the rectified voltage to the power supply unit 204 .

The video output device 200 includes a USB I/F 206, a communication section 207, a video output section 208, a RAM 209, an HDD 210, and an image processing section 211. The USB I/F 206 is a USB interface to which input devices such as a mouse and a keyboard can be connected. The communication unit 207 transmits and receives various information data files such as video data, image data, and video files, command signals, and the like via an intranet or the Internet. The communication unit 207 is configured with, for example, a wired LAN or a wireless LAN. Video output unit 208 transmits a video signal generated based on an instruction from control unit 201 and information regarding the video signal to projector 100 in a predetermined format. In this embodiment, it is assumed that the video output unit 208 is capable of transmitting a DP video signal compliant with the DP standard.

The RAM 209 is used for developing programs and various data stored in the HDD 210, storing a frame buffer for image processing performed by the image processing unit 211, and the like. The HDD 210 is a storage device for storing various information such as programs such as an OS (Operating System), documents, videos, and image contents. The image processing unit 211 performs various image processing based on information stored in the HDD 210 using the RAM 209 as a frame memory, and outputs a video signal to the video output unit 208.

Next, the flow of normal operation processing in this embodiment will be explained. The normal operation is an operation in which the projector 100 receives an image from the image output device 200 and projects the received image without transitioning to the power saving mode. FIG. 5 is a flowchart showing the flow of normal operation processing. FIG. 5A is a flowchart showing the process flow of normal operation of the projector 100. FIG. 5(b) is a flowchart showing the flow of normal operation processing of the video output device 200. Hereinafter, it is assumed that the projector 100 and the video output device 200 are connected by a DP cable. Further, it is assumed that the video 300 is displayed on the screen 400 through control specified by the DP standard.

First, the projector 100 and the video output device 200 are connected with a DP cable. In this case, the control unit 101 detects the connection by the DP cable by polling or interrupting (S101). After the process in S101, the control unit 101 asserts an HPD (Hot Plug Detect) signal defined by the DP standard via one line in the DP cable (S102). As a result, information indicating that the connection has been established is notified to the video output device 200. The video output device 200 that has received the HPD signal notification issues an EDID read request to the projector 100 via the auxiliary communication channel (AUX-CH) within the DP cable. When the video input unit 110 receives the EDID read request from the video output device 200, it reads the stored EDID and notifies the read result via the AUX-CH (S103).

After reading the EDID from the projector 100, the video output device 200 issues a DPCD read request via the AUX-CH. The DPCD includes information necessary for determining transmission parameters such as the transmission rate of signals that the projector 100 can receive and the number of transmission lanes. The DPCD is stored in the video input section 110. When the video input unit 110 receives a DPCD read request from the video output device 200, the video input unit 110 reads the stored DPCD and notifies the read result via the AUX-CH (S104). Here, information such as the transmission data rate that the projector 100 can support and the number of lines used is notified as a read result.

Video output device 200 determines the number of lanes and transmission rate based on the EDID and DPCD read from projector 100 and according to video format information to be transmitted (resolution, frame rate, bit depth, etc.). Then, the video output device 200 transmits the video signal to the projector 100. When the video output device 200 reads the DPCD from the projector 100, it notifies the projector 100 of a link training start request based on the read DPCD. Link training is a so-called handshake process for establishing a communication channel, such as determining communication parameters. The control unit 101 performs link training based on a request from the video output device 200 (S105). Here, link training is performed based on information on the DPCD transmission data rate and the number of lines in use, which have been exchanged in advance. In link training, various checks are sequentially confirmed based on a test pattern using symbol data encoded using the 8B10B method. Here, it is assumed that success or failure of clock data recovery check, channel equalization check, 8B10B symbol data alignment check, etc. are sequentially confirmed.

The control unit 101 writes the success/failure results of checking each item to the DPCD stored in the video input unit 110. The control unit 101 reads the results of the link training from the DPCD stored in the video input unit 110, and determines whether the link training was successful or not (S106). If the control unit 101 determines that link training has failed (No in S106), the process moves to S105. Then, the control unit 101 changes the transmission conditions according to the procedure defined by the DP standard (S107). After the transmission conditions are changed, link training is performed again in S105.

If the control unit 101 determines that the link training was successful, the video output device 200 transmits a predetermined number of 8B10B symbol data as an idle pattern based on the transmission rate and the number of lanes when the link training was performed. The video input unit 110 receives the idle pattern (S108). After completing the transmission of the idle pattern for a certain period, the video output device 200 transmits the video signal using the video format information determined based on the read EDID. The video input unit 110 receives the video signal (S109).

The control unit 101 detects that a video signal has been received by polling or by an interrupt notification to the control unit 101 from the video input unit 110. Then, the control unit 101 acquires video signal information from the video input unit 110 (S110). The control unit 101 stores the acquired video signal information in the RAM 132 as a storage unit.

The control unit 101 sets the video signal format of the video signal information to the scaling unit 172 of the image processing unit 116 (S111). The control unit 101 sets color/range information in the color conversion unit 173. Image processing is thereby performed. By performing the above processing, a video signal in a predetermined format received by the video input section 110 is formed into an image on the liquid crystal section 104 through the image processing section 116 and the liquid crystal driving section 105. The projection optical system 107 uses the light source 106 to project the image formed on the liquid crystal section 104 onto the screen 400 (S112).

Next, the flow of processing of the video output device 200 will be described with reference to the flowchart in FIG. 5(b). As described above, once the connection is established, the video output unit 208 of the video output device 200 receives the HPD signal notification. Thereby, the video output unit 208 detects that the HPD signal is asserted (S201). Then, the control unit 201 transmits an EDID read request via the AUX-CH to read the EDID from the projector 100 (S202). Further, under the control of the control unit 201, the video output unit 208 transmits a DPCD read request via the AUX-CH, and reads the DPCD from the projector 100 (S203). After reading the DPCD, the control unit 201 performs link training based on the read DPCD (S204).

The control unit 201 transmits a read request for information related to the success or failure of link training to the projector 100 via the AUX-CH. The control unit 201 determines the success or failure of link training based on the read information (S205). If the control unit 201 determines that link training has failed (No in S205), the control unit 201 changes the transmission conditions (S207). The process then moves to S204, and link training is performed again under the changed transmission conditions. If the control unit 201 determines that the link training was successful (Yes in S205), the video output unit 208 transmits a predetermined number of 8B10B symbol data as an idle pattern based on the transmission conditions when the link training was successful. (S207). After transmitting the idle pattern for a certain period of time, the video output unit 208 determines the format of the video signal based on the read EDID. Then, the video output unit 208 transmits the video signal in the determined format (S208).

Next, a process flow when the video output device 200 transitions to the power saving mode while the projector 100 is projecting an image will be described. The DP standard defines a function for the sink device (projector 100) to continue displaying buffered video frames when the source device (video output device 200) transitions to power saving mode. This function is called PRM (Panel Replay Mode). This allows the video output device 200 to save power and to continue displaying. When the PRM function is operating, the video output device 200 is in a power saving mode. When transitioning to the power saving mode, the projector 100 does not receive video signal information from the video output device 200. Therefore, undefined video signal information is displayed on the OSD display 500 of the video 300 projected on the screen 400. Therefore, in this embodiment, when the video output device 200 transitions to the power saving mode according to the DP standard, the projector 100 and the video output device 200 execute the following power saving mode transition process.

FIG. 6 is a flowchart showing the flow of power saving mode transition processing. When the video output device 200 satisfies a predetermined condition, it transitions to the power saving mode. For example, if projector 100 or video output device 200 has not received a user operation for a predetermined period of time, video output device 200 may transition to power saving mode. Alternatively, if there is no change in the video being output for a predetermined period of time, the video output device 200 may transition to the power saving mode. The predetermined conditions are not limited to these examples.

FIG. 6A is a flowchart showing the flow of power saving mode transition processing performed by the video output device 200. The control unit 201 instructs the video output unit 208 to transmit a request to the projector 100 for response capability information for the power saving mode. The video output unit 208 transmits the instruction to the projector 100 and acquires the compatibility information of the projector 100. The control unit 201 reads the acquired capability information from the video output unit 208 (S301). Then, the control unit 201 determines whether the projector 100 has the ability to handle power saving mode transition (S302). If the projector 100 can stop writing the received video signal to the frame buffer 175, that is, can freeze display, it has the ability to support a power saving mode. If the control unit 201 determines that the projector 100 does not have the corresponding capability (No in S302), the process of this embodiment is not performed. In this case, the process ends.

If the control unit 201 determines that the projector 100 has the capability to cope with the problem (Yes in S302), the video output device 200 collaborates with the projector 100 to perform pre-settings and configurations for power-saving mode transition ( S303). As a preliminary setting, for example, in order to save internal state information of the video output device 200, the control unit 201 writes the state information to the RAM 209. Further, the control unit 201 performs processing such as instructing the projector 100, via the video output unit 208, to set a communication method when an error occurs during the power saving mode. Further, as part of the configuration, for example, the video output unit 208 re-establishes a communication path with the projector 100 through handshake processing before transitioning to the power saving mode, based on instructions from the control unit 201. The control unit 201 may perform processing such as instructing the power supply unit 204 to stop supplying power to parts of the video output device 200 that do not require operation.

After completing the process in S303, the video output unit 208 transmits an instruction to enable the power saving mode to the projector 100 (S304). When the control unit 201 receives a reply from the projector 100 indicating that support for power saving mode transition has been enabled, it recognizes that preparations for power saving mode transition are ready. The video output unit 208 transmits a signal (power consumption ON signal) instructing to turn on the power saving mode to the projector 100 (S305). The power consumption ON signal is a signal that prompts the projector 100 to stop writing video frames to the frame buffer 175, that is, to perform freeze display. When the video output unit 208 transmits the power consumption ON signal, the output of video from the video output unit 208 is stopped. The power consumption ON signal corresponds to the video stop signal. In this embodiment, the video output device 200 notifies the projector 100 of a power consumption ON signal using SDP. However, the power consumption ON signal may be notified to the projector 100 by a method other than SDP. Furthermore, SDP may also be used for notification to turn off the power saving mode.

While the video output device 200 is operating in the power saving mode, the video output device 200 periodically transmits a power consumption ON signal and continuously transmits a dummy signal (S306). The dummy signal is a valid SYNC signal (synchronization signal) that indicates video synchronization timing, but video pixel data is invalid data, and the video format information and color/range information regarding SDP, which is an auxiliary information packet. This is a signal indicating that the is invalid. Note that in the dummy signal, the SYNC signal indicating the video timing may also be invalid data.

Next, a power saving mode transition process of the projector 100 that is linked to the operation of the video output device 200 will be described. FIG. 6B is a flowchart showing the flow of the power saving mode transition process of the projector 100. When the video input unit 110 receives a request for capability information corresponding to the power saving mode transition from the video output device 200, it notifies the video output device 200 of the stored capability information (S401). The projector 100 performs processing (presetting and configuration) necessary for interlocking the video output device 200 and the projector 100 in response to the presetting and configuration in S303 described above (S402). The video input unit 110 changes settings based on an instruction sent from the video output device 200 to the video input unit 110 (instruction for settings regarding a communication method when an error occurs during power saving mode). Further, as a configuration, the video input unit 110 performs handshake processing with the video output unit 208 of the video output device 200.

After completing the execution of the process in S402, the video input unit 110 receives an instruction to enable support for the power saving mode from the video output device 200 (S403). In response to receiving the above instruction, the video input unit 110 transmits information indicating that the instruction has been successfully received to the video output device 200 (S404). Then, the video input unit 110 receives the power saving ON signal transmitted from the video output device 200 (S405). The video input unit 110 notifies the control unit 101 that the power saving mode ON signal has been received. Upon receiving the notification, the control unit 101 notifies the power saving control unit 181 inside the image processing unit 116 to turn on the power saving mode. The power saving control unit 181 notifies the write control unit 174 and the read control unit 177 of an instruction to stop updating, thereby stopping updating of the frame buffer (S406). As a result, the projector 100 enters a state in which it continues to project the image immediately before the update was stopped onto the screen 400. Further, the video input unit 110 receives a dummy signal from the video output device 200 (S407). Therefore, by operating the projector 100 in conjunction with the video output device 200, the projector 100 can continue projecting video while the video output device 200 transitions to the power saving mode.

Next, the operation of displaying video signal information of the projector 100 on the OSD display 500 when the video output device 200 transitions to the power saving mode will be described. FIG. 7 is a state transition diagram of this embodiment. In FIG. 7, state A is a state before the video output device 200 transitions to the power saving mode, that is, a state in which it is transmitting normal video. In state A, the projector 100 is in a state where the power saving mode is OFF and is projecting the video input from the video output device 200. State A is the normal operation described above. In state A, the projector 100 receives the SDP periodically transmitted from the video output device 200, acquires video signal information from the received SDP, and stores it in the RAM 132. Assume that in state A, the user uses the operation unit 102 to perform an operation to display video signal information in OSD. In this case, the control unit 101 transfers the latest video signal information stored in the RAM 132 to the image processing unit 116 based on the received operation. As described above, the image processing section 116 transmits the video signal information determined by the power saving control section 181 to the OSD generation section 178 and performs OSD display. In this case, the latest normal input information is displayed on the OSD.

When the projector 100 receives the power saving ON signal transmitted by the video output device 200, the state changes from state A to state B. In state B, the power saving mode is ON, so one frame of the input video received from the video output device 200 is captured in the frame buffer 175. Here, when the video input unit 110 receives a signal for turning off the power saving mode (power saving OFF signal), the state changes from state B to state A. In state B, the video input section 110 of the projector 100 has not received the SDP from the video output device 200, so the video signal information is undefined. Further, the video input unit 110 does not receive a video signal from the video output device 200. In state B, if projector 100 does not receive the power saving OFF signal, control unit 101 determines that the power saving mode continues. In this case, the state transitions from state B to state C.

In state C, the power saving mode of the projector 100 is ON, and the control unit 101 continues reading out the video frames captured in the frame buffer 175 in state B, and performs freeze display. State C continues until the video input unit 110 receives the power saving OFF signal from the video output device 200. Also in state C, as in state B, the video input section 110 does not receive the SDP from the video output device 200. Therefore, the video signal information is undefined. In state B and state C, the video signal and SDP transmitted by the video output unit 208 of the video output device 200 are dummy signals, which are not correct signals but unstable signals. Therefore, in this embodiment, when in state B and state C, projector 100 does not use the video signal information transmitted by video output device 200. That is, the projector 100 performs OSD display using the video signal information acquired last in state A where the power saving mode is OFF. The last acquired video signal information is the video signal information immediately before receiving the video stop signal. Since the projector 100 projects the last video frame buffered in the frame buffer 175 onto the screen 400, the OSD display 500 displays video signal information corresponding to the video 300 being projected onto the screen 400. Ru. Thereby, the video signal information being displayed on the screen 400 can be correctly notified to the user. Note that in state B and state C, if the DP cable is disconnected, the state transitions to state A.

FIG. 8 is a diagram showing an example of OSD display of video signal information. FIG. 8A shows an example of an OSD display on the screen 400 when a user operation is performed on the operation unit 102 while the power saving mode is ON. The OSD display 500 displays signal format information 601 and color/range information 602. Signal format information 601 and color/range information 602 displayed on OSD display 500 are information before the power saving mode is turned ON. In addition to FIG. 8(a), FIG. 8(b) shows an example in which a power saving display 603 is displayed on an OSD to clearly indicate that the power saving mode is ON. As described above, when the power saving mode is ON, the video input section 110 of the projector 100 receives the dummy signal. Therefore, there is a discrepancy between the video signal information of the video projected on the screen 400 and the dummy signal (video signal information) input in real time.

Therefore, when the power saving mode is ON, the control unit 101 may perform control to project a display clearly indicating that the power saving mode is in the power saving mode (power saving display) on the screen 400. In the example of FIG. 8(b), "power saving" is displayed in the star mark. This makes it possible to clearly indicate that the power saving mode is ON. That is, the control unit 101 performs control to display information clearly indicating that transmission of video from the video output device 200 has been stopped. The display mode of the power saving display is not limited to the example shown in FIG. 8(b). For example, the control unit 101 may perform control to display "PRM in progress".

FIG. 8C is a diagram showing an example of an OSD display that clearly indicates that the power saving mode is ON and that the video signal information is a dummy signal. On the OSD display 500, indeterminate information as shown in FIG. 8C is displayed in the signal format information 604 and color/range information 605, and a power saving display is also displayed. In this case, although it is not possible to confirm the signal information regarding the video displayed frozen on the screen 400, it is possible to recognize that the power saving mode is ON and that the input signal is undefined. This can prevent the user from misrecognizing the signal information of the input video.

FIG. 8D is a diagram showing an example in which an OSD display is displayed in the display field 505 to notify only that the power saving mode is ON. In this case, the control unit 101 performs control to display only information indicating that video transmission has been stopped (information clearly indicating that the power saving mode is ON) without displaying the video signal information. Even in this case, the user can understand that the power saving mode is ON and the video signal information is undefined. Furthermore, the display in FIG. 8(d) may be performed without any user operation.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made within the scope of the invention. The present invention provides a system or device with a program that implements one or more functions of each embodiment described above via a network or a storage medium, and one or more processors of a computer in the system or device executes the program. It can also be realized by reading and executing processing. The present invention can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.

100 Projector 101 Control section 110 Video input section 116 Image processing section 132 RAM
175 Frame buffer 178 OSD generation section 179 OSD superposition section 181 Power saving control section 200 Video output device 300 Video 400 Screen

Claims (16)

A control device,
a video input section that inputs video from a video output device;
a storage unit that stores video signal information regarding the video acquired via the video input unit and a video stop signal indicating that the video output device has transitioned to a state in which transmission of the video has been stopped;
In response to receiving the video stop signal from the video output device, acquiring the video from the storage unit immediately before transmission of the video is stopped, and performing control to continue displaying the acquired video; a control unit that performs control to acquire the video signal information immediately before the transmission of the video is stopped from the storage unit, and display the acquired video signal information;
A control device comprising: While the video output device stops transmitting the video, the video input unit receives a valid synchronization signal from the video output device and receives a signal in which the video and the video signal information are invalid. The control device according to claim 1, characterized in that: 2. The video input unit receives from the video output device a communication method to be used when an error occurs while receiving the video stop signal, and sets the received communication method. Or the control device according to 2. 4. The video signal information includes at least one of resolution, frequency, color space, chroma subsampling, color range, and bit depth regarding the video. The control device described in . 5. The control device according to claim 1, wherein the control means controls to display information indicating that transmission of the video has been stopped together with the video signal information. Any one of claims 1 to 4, wherein the control means performs control to display only information indicating that the transmission of the video has been stopped, without displaying the video signal information. The control device described in . 7. The control device according to claim 1, wherein the video stop signal is a signal defined by the DisplayPort standard. A video input unit that inputs video from a video output device, video signal information regarding the video obtained through the video input unit, and a state in which the video output device transitions to a state where transmission of the video is stopped. A method for controlling a display device, the method comprising: a storage unit storing a video stop signal;
In response to receiving the video stop signal from the video output device, the video immediately before transmission of the video is stopped is acquired from the storage unit, and control is performed to continue displaying the acquired video. , acquiring the video signal information immediately before the transmission of the video is stopped from the storage unit, and controlling to display the acquired video signal information;
A method for controlling a display device, comprising: While the video output device stops transmitting the video, the video input unit receives a valid synchronization signal from the video output device and receives a signal in which the video and the video signal information are invalid. 9. The method for controlling a display device according to claim 8. 9. The video input unit receives from the video output device a communication method to be used when an error occurs while receiving the video stop signal, and sets the received communication method. Or the method for controlling a display device according to 9. 11. The video signal information includes at least one of resolution, frequency, color space, chroma subsampling, color range, and bit depth regarding the video. A method for controlling a display device according to . 12. The method for controlling a display device according to claim 8, further comprising controlling to display information indicating that the video transmission has been stopped together with the video signal information. The display device according to any one of claims 8 to 11, wherein the display device performs control to display only information indicating that the video transmission has been stopped without displaying the video signal information. control method. 14. The method of controlling a display device according to claim 8, wherein the video stop signal is a signal defined by the DisplayPort standard. A program for causing a computer to execute the method for controlling a display device according to claim 8. A computer readable storage medium storing the program according to claim 15.

Images