Display device, display control method, and program

Abstract

To more appropriately set a search time for confirming the existence / nonexistence of a video signal in searching the video signal from a plurality of external input terminals.SOLUTION: A display device 100 includes: an input part 130 having a digital video signal terminal being a terminal for inputting at least a digital video signal; a display part 140 for displaying a video based on the digital video signal inputted from the input part 130; a connection determination part 111 for determining whether an external device is connected to the digital video signal terminal, and acquiring information relating to connection timing being timing when the external device is connected to the digital video signal terminal; and a search time setting part 112 for setting a search time being time for confirming the existence / nonexistence of a video signal in the signal inputted from the digital video signal terminal on the basis of the information on the connection timing acquired by the connection determination part 111.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a display device, a display control method, and a program. [Background technology]

[0002] Display devices such as projectors are usually provided with a number of different terminals as external input terminals, such as an RGB (Red Green Blue) terminal, an HDMI (High-Definition Multimedia Interface) (registered trademark) terminal, a composite video terminal, etc., so that a number of types of external devices can be connected as source devices that provide images to be displayed, such as a personal computer, a video device, a television tuner, etc. A user can manually switch the external input terminal to determine which external input terminal is connected to the external device to display the image from on the display device.

[0003] In addition, to save the user the trouble of manually switching the display device, the display device has an auto-search function that sequentially switches the external input terminals, searches which external device is inputting a video signal, and displays based on the input video signal. In this video signal search, the time required to determine whether or not a video signal is present (search time) varies depending on the standard of the external input terminal. Therefore, for example, Patent Document 1 discloses a display device that changes the time to determine whether or not a video signal is present depending on the type of terminal, thereby preventing the search time from becoming too long and increasing the reliability of the determination of whether or not a video signal is present. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-191945 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the display device disclosed in Patent Document 1, the search time for a video signal from an HDMI (registered trademark) terminal is set longer than for video signals from other terminals, thereby preventing failure to determine the presence or absence of a video signal from the HDMI terminal. However, if the search time is uniformly made longer for all video signals from HDMI terminals, there is a problem in that it takes more time than necessary to search for a video signal.

[0006] The present invention has been made in consideration of the above-mentioned situation, and aims to provide a display device, a display control method, and a program that can more appropriately set the search time for checking the presence or absence of a video signal when searching for video signals from multiple external input terminals. [Means for solving the problem]

[0007] In order to achieve the above object, one aspect of a display device according to the present invention is to an input section having at least a digital video signal terminal which is a terminal for inputting a digital video signal; a display unit that displays an image based on the digital image signal input from the input unit; a connection determination unit that determines whether or not an external device is connected to the digital video signal terminal and obtains information related to a connection timing that is a timing at which the external device is connected to the digital video signal terminal; Information related to the connection timing acquired by the connection determination unit a search start timing at which a search for the digital video signal is started and a video transmission preparation period a search time setting unit that sets a search time for checking whether or not a video signal is present in the signal input from the digital video signal terminal based on the search time setting unit; Equipped with. Effect of the Invention

[0008] According to the present invention, when searching for video signals from a plurality of external input terminals, the search time for checking the presence or absence of a video signal can be set more appropriately. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of a display system including a display device according to an embodiment. [Diagram 2] 1 is a block diagram showing an example of a configuration of a display device according to an embodiment; [Diagram 3] 11A and 11B are diagrams illustrating an auto search function provided in the display device according to the embodiment. [Figure 4] FIG. 11 is a diagram illustrating an example of an HDMI connection sequence. [Diagram 5] 11A and 11B are diagrams illustrating the relationship between the timing at which an external device is connected and a search time in the display device according to the embodiment. [Figure 6] 4 is a flowchart of a signal search process according to the embodiment. [Figure 7] 11 is a flowchart of an HDMI signal confirmation process according to the embodiment. [Figure 8] 11 is a flowchart of a connection determination process according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An input device according to an embodiment and a display device including the input device will be described with reference to the drawings, in which the same or corresponding parts are denoted by the same reference numerals.

[0011] (Embodiment) For ease of understanding, the following description will be given taking as an example a case where a display device 100 according to an embodiment is applied to a display system 1000 shown in Fig. 1. In this example, the display system 1000 includes the display device 100, and a PC (Personal Computer) 201, a BD (Blu-ray (registered trademark) Disc) recorder 202, and a DVD (Digital Versatile Disc) recorder 203, all of which are connected to the display device 100.

[0012] The display device 100 is a DLP (Digital Light Processing) (registered trademark) type projector device that displays a projection screen 145 on a screen. The display device 100 includes an RGB terminal 131, an HDMI (registered trademark) terminal 132, and a composite video terminal 133 as external input terminals for inputting a video signal from an external device. The PC 201, the BD recorder 202, and the DVD recorder 203 are respectively connected to the external input terminals. Note that this is just an example, and for example, the display device 100 may include a plurality of HDMI (registered trademark) terminals as external input terminals, and the PC 201, the BD recorder 202, and the DVD recorder 203 may be connected to the display device 100 via an HDMI (registered trademark) cable. Also, the display device 100 and the PC 201 may each include a DisplayPort (registered trademark) terminal, and both devices may be connected via a DisplayPort (registered trademark) cable.

[0013] Since the display device 100 can output only one projection screen 145, the display device 100 selects and outputs one of the images input from the multiple external input terminals. This selection can be performed manually by the user, but the display device 100 has a function for automatically searching for a video signal (auto search function). This function is a function in which the display device 100 automatically searches which of the multiple external input terminals is inputting a video signal, and outputs a video based on the input video signal. When the auto search function is executed, a process is required to check whether or not a video signal is input to each external input terminal, and the time required to check whether or not a video signal is present for each external input terminal is called a search time.

[0014] As shown in FIG. 2, the display device 100 includes a control unit 110, a storage unit 120, an input unit 130, a display unit 140, and an operation unit 150.

[0015] The control unit 110 is composed of a processor such as a CPU (Central Processing Unit). The control unit 110 executes a program stored in the storage unit 120 to perform a signal search process, a connection determination process, and the like, which will be described later, and realizes the functions of each unit (a connection determination unit 111, a search time setting unit 112) described later and the functions of the display device 100 (such as a video projection function for projecting a video based on a video signal input to the input unit 130 on the display unit 140). The control unit 110 supports a multi-thread function for executing multiple processes in parallel, and also has a function for counting time using a system counter and an RTC (Real Time Clock).

[0016] The storage unit 120 stores programs executed by the control unit 110 and necessary data. The storage unit 120 may include, but is not limited to, a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, etc. Note that the storage unit 120 may be provided inside the control unit 110.

[0017] The input unit 130 includes an external input terminal for inputting a signal including a video signal from an external device, and a signal processing unit for processing the input signal and outputting it to the control unit 110. In this embodiment, the input unit 130 includes, as external input terminals, an RGB terminal 131 for inputting an analog RGB signal, an HDMI terminal 132 for inputting a signal of HDMI (registered trademark) which is an interface for a digital video signal, and a composite video terminal 133 for inputting a composite video signal. The input unit 130 also includes, as signal processing units, an A / D (Analog / Digital) conversion unit 134 for digitizing the analog RGB signal inputted to the RGB terminal 131 and outputting it to the control unit 110, an HDMI receiver 135 for decoding the HDMI signal inputted to the HDMI terminal 132 and outputting it to the control unit 110, and a video decoder 136 for decoding the composite video signal inputted to the composite video terminal 133 and outputting it to the control unit 110.

[0018] The display unit 140 includes a light source, a lens, a DMD (Digital Mirror Device), a color wheel, a motor, and the like, and projects an image provided by the control unit 110 onto a screen. This image is based on an image signal (digital image signal or analog image signal) input from the input unit 130.

[0019] The operation unit 150 includes a push button switch, a touch panel, a remote control light receiving unit, etc., and receives operations from the user.

[0020] Next, a description will be given of the functional configuration of the control unit 110. As described above, the control unit 110 functions as a connection determination unit 111 and a search time setting unit 112.

[0021] The connection determination unit 111 determines whether or not an external device is connected to the HDMI terminal 132, which is a digital video signal terminal, and obtains information related to the connection timing, such as the timing when the external device was connected to the HDMI terminal 132 (connection timing).

[0022] Based on information relating to the connection timing acquired by the connection determination section 111, the search time setting section 112 sets a search time which is a time for checking whether or not a video signal is included in the signal input from the HDMI terminal 132.

[0023] Next, the auto search function of the display device 100 will be described with reference to Fig. 3. In the display device 100, the auto search function is performed by starting a signal search process, which will be described later, automatically when the power is turned on or by a user operation. Fig. 3 shows an example in which only the DVD recorder 203 connected to the composite video terminal 133 is playing back video, and no video signal is input to the RGB terminal 131 or the HDMI terminal 132.

[0024] In this case, when the signal search process is started, first, the control unit 110 checks for a specified search time (Ta: for example, 3 seconds) whether or not a video signal is input to the RGB terminal 131. If no video signal is confirmed, it determines that no video signal is input to the RGB terminal 131 (no signal). Next, the control unit 110 checks for a specified search time (Tb: for example, 6 seconds) whether or not a video signal is input to the HDMI terminal 132. If no video signal is confirmed, it determines that no video signal is input to the HDMI terminal 132 (no signal).

[0025] Next, the control unit 110 checks for a specified search time (Tc: for example, 3 seconds) whether or not a video signal is being input to the composite video terminal 133. Then, when a composite video signal, which is a video signal, is detected, the control unit 110 displays a video obtained by decoding the composite video signal input to the composite video terminal 133 on the display unit 140. In this way, the display device 100 uses the auto search function to automatically select and display a video from an external device that is outputting a video signal.

[0026] 3, the video signals input to the RGB terminal 131 and the composite video terminal 133 are analog video signals, and no complicated communication occurs between the external device and the display device 100. For this reason, if the search time Ta of the RGB terminal 131 and the search time Tc of the composite video terminal 133 are normally set to 2 to 3 seconds, no problem such as erroneous determination of the presence or absence of a video signal will occur.

[0027] However, the HDMI terminal 132 is a terminal for digital video signals, and various information is exchanged between an external device (a source device that supplies video) and a display device (a sink device that plays and outputs video) through this terminal. This exchange (HDMI connection sequence) begins when an external device is connected to the HDMI terminal 132 via an HDMI cable, but as described below, it takes several seconds or more from when the external device is connected until the transmission of a video signal begins. Therefore, even if an external device connected to the HDMI terminal 132 is playing video, no video signal is being transmitted in the middle of the HDMI connection sequence, and therefore unless the search time Tb is set appropriately, there is a possibility that it will be erroneously determined that there is no signal.

[0028] This HDMI connection sequence will be described with reference to Fig. 4. First, when a source device (external device) and a sink device (display device) are connected with an HDMI cable, a voltage of +5V is applied from the source device to the sink device via the power line of the HDMI cable. When the sink device detects this applied voltage, it sets the Hot Plug Detect (HPD) line to the source device to the "H" level, thereby establishing a link.

[0029] Once the link is established, the source device reads the EDID (Extended Display Identification Data) from the sink device for device-to-device authentication. The sink device holds data such as the display resolution and refresh rate it can support as EDID. The source device can obtain the EDID from the sink device via a digital video signal interface such as HDMI, DVI (Digital Visual Interface), or DisplayPort. By obtaining the EDID, the source device can transmit a video signal to the sink device that corresponds to the playback capabilities of the sink device.

[0030] Next, the source device starts initial authentication with the sink device using HDCP (High-bandwidth Digital Content Protection), and data is exchanged between the two devices for the initial authentication. This HDCP authentication is necessary when the content being played is encrypted for copy protection. Once the HDCP initial authentication is obtained, the source device performs encryption in accordance with HDCP.

[0031] Then, transmission begins using TMDS (Transition Minimized Differential Signaling), a transmission method used to transmit digital video signals. In this TMDS transmission, after detecting TMDS access in the sink device, processes such as frequency detection, HDCP on / off determination, HDMI and DVI signal distinction determination, InfoFrame detection, sync signal detection, video format determination, audio format determination, and encryption decryption are executed as needed, and then transmission of the video signal begins.

[0032] In other words, even if an HDMI cable is connected, no video signal is transmitted from the source device for several seconds (which for convenience will be referred to as the "video transmission preparation period" here), and unless the search time Tb in the above-mentioned auto search function is set to a time longer than the video transmission preparation period (for example, 6 seconds), there is a possibility that the sink device will erroneously determine that there is no video signal by the time the video signal is output.

[0033] However, since the above HDMI connection sequence is started when the source device and sink device are connected via an HDMI cable, if the two devices are connected a sufficiently long time before the auto search function is started (for example, 6 seconds or more), a video signal is already being output when the auto search function is started, and the sink device can detect the video signal even if the search time Tb is short. However, even in this case, it takes about 2 to 3 seconds from when the sink device starts receiving a signal until it determines that the signal contains video, similar to the search time Ta and search time Tc. For convenience, this time is referred to as the minimum search time.

[0034] Therefore, if the search time Tb in the display device 100 is not set appropriately according to the time difference between the timing when an external device is connected via an HDMI cable and the timing when the auto search function starts to determine whether or not a video signal is present, erroneous determination may occur or unnecessary time may be wasted. Therefore, with reference to Fig. 5, how to determine the search time Tb according to the timing when an external device is connected will be described.

[0035] Note that the display device (projector device) 100 is not ready to output (display) an image immediately after the power is turned on, but rather, as shown on the left side of Fig. 5, first it becomes possible to detect +5V on the power line of the HDMI terminal 132 (this makes it possible to start the HDMI connection sequence), and then the light source of the display unit 140 starts to light up (projection onto the screen begins). After that, an auto search function is started, and it is determined in turn for each of the external input terminals whether or not a video signal has been input, and if a video signal has been input, an image based on that video signal is projected onto the screen.

[0036] In Fig. 5, timing T1 indicates the timing when +5V detection becomes possible, timing T3 indicates the timing when the light source starts to turn on, and timing T5 indicates the timing when the auto search function starts searching for a video signal from HDMI terminal 132 (checking the presence or absence of a video signal). In this example, the time difference between timing T1 and timing T5 is equal to or longer than the video transmission preparation period. The arrows (1) to (5) on the right side of Fig. 5 indicate the time before the HDMI connection sequence is executed using dashed line arrows, the video transmission preparation period using dotted line arrows, and the time after the start of video signal transmission using solid line arrows.

[0037] First, the case where a user connects an external device via an HDMI cable before turning on the power of the display device (projector) 100 is shown by the arrow (1) in Fig. 5. In this case, initially (dash-dotted arrow), the display device 100 cannot detect that an external device has been connected, but at timing T1 when it becomes possible to detect +5V on the power line of the HDMI cable, the connection of the external device is confirmed and the HDMI connection sequence is started (dotted arrow). If the transmission of the video signal is started at the portion indicated by the solid arrow, the display device 100 has already received the video signal at timing T5 when it starts searching for the video signal from the HDMI terminal 132, so the search time ST1 is sufficient for the minimum search time (2 to 3 seconds) for determining the video signal.

[0038] Next, the arrow in Fig. 5(2) shows a case where an external device is connected at timing T2 after timing T1 when display device 100 becomes able to detect +5V on the power line and which is at least a video transmission preparation period before timing T5 when a search for a video signal from HDMI terminal 132 starts. In this case, when an external device is connected, an HDMI connection sequence starts immediately (dotted arrow), and display device 100 is already able to receive the video signal at timing T5. Therefore, like search time ST1, the minimum search time (2 to 3 seconds) for determining a video signal is sufficient for search time ST2.

[0039] Next, the arrow in FIG. 5 (3) shows a case where an external device is connected at timing T4, which is less than the video transmission preparation period before timing T5, when the search for a video signal from HDMI terminal 132 starts. In this case, when an external device is connected, the HDMI connection sequence starts immediately (dotted arrow), but display device 100 has not yet received a video signal at timing T5. Then, display device 100 starts receiving a video signal at timing T6, when the video transmission preparation period ends. Therefore, search time ST3 is the time obtained by subtracting the time difference between timing T5 and timing T4 from the video transmission preparation period, plus the minimum search time (2 to 3 seconds) for determining a video signal.

[0040] Next, the case where an external device is connected at timing T7 after timing T5 when the search for a video signal from HDMI terminal 132 starts is shown by the arrow in (4) of FIG. 5. In this case, when the external device is connected, the HDMI connection sequence starts immediately (dotted arrow), but the display device 100 can receive a video signal only after the video transmission preparation period. Therefore, the search time ST4 is the video transmission preparation period plus the minimum search time (2 to 3 seconds) for determining the video signal. For convenience, the time obtained by adding the minimum search time to the video transmission preparation period will be referred to as the maximum search time.

[0041] Furthermore, if a search for a video signal from HDMI terminal 132 is performed when no external device is connected to HDMI terminal 132, it is determined that there is no HDMI signal, but the case in which an external device is then connected to HDMI terminal 132 is shown by the arrow (5) in FIG. 5. In this case, when an external device is connected, the HDMI connection sequence starts immediately (dotted arrow), but display device 100 can only receive a video signal after the video transmission preparation period. Therefore, like search time ST4, search time ST5 is the video transmission preparation period plus the minimum search time (2 to 3 seconds) for determining a video signal (=maximum search time).

[0042] As described above, an appropriate search time is determined mainly based on the time difference between the timing (connection timing) when an external device is connected to the HDMI terminal 132 and the timing (search start timing) when a search for a video signal from the HDMI terminal 132 is started. Here, if the time difference between the timing (CT) when an external device is connected and the timing (DT) when a search for a video signal from the HDMI terminal 132 is started is represented as TDIF (=DT-CT), the video transmission preparation period is represented as PT, and the minimum search time for determining a video signal is represented as TMIN, then the search time ST can be expressed as follows: (1) If TDIF is equal to or greater than PT: ST = TMIN (= minimum search time) (2) If TDIF is 0 or greater but less than PT: ST = PT - TDIF + TMIN (3) If TDIF is less than 0: ST = PT + TMIN (= maximum search time)

[0043] More specifically, if PT is 3 seconds and TMIN is also 3 seconds, then the following will occur: (1) If TDIF is 3 seconds or more: ST = 3 seconds (2) If TDIF is between 0 and 3 seconds: ST = 6 seconds - TDIF (3) If TDIF is less than 0 seconds: ST = 6 seconds

[0044] Next, the signal search process by which the display device 100 realizes the auto search function will be described with reference to Fig. 6. This process is started automatically when the display device 100 is powered on, or by a user operation. In the signal search process, a "no signal flag" is referenced as a variable indicating that there is no HDMI video signal. In the HDMI signal confirmation process described later, this variable is set to 1 if there is no HDMI signal, and to 0 if a video signal is being received.

[0045] First, the control unit 110 sets a variable "no signal flag" to 1 as an initialization process (step S101). Then, the control unit 110 checks the signal input to the RGB terminal 131 via the A / D conversion unit 134 for a first search time (e.g., 3 seconds) (step S102) and determines whether or not there is a video signal (step S103). If there is a video signal (step S103; Yes), the control unit 110 sets the video to be projected by the display unit 140 to a video based on the RGB signal input from the RGB terminal 131 (step S104) and ends the signal search process. In this case, from this point on, the display device 100 projects a video based on the video signal input to the RGB terminal 131 on the display unit 140 until the signal search process is executed again or the user manually switches the external input.

[0046] If there is no video signal input to the RGB terminal 131 (step S103; No), an HDMI signal confirmation process is executed (step S105). The details of the HDMI signal confirmation process will be described later, but as a result of this process, if a video signal is input from the HDMI terminal 132, the no-signal flag is cleared to 0, and if there is no video signal, the no-signal flag is set to 1.

[0047] Then, the control unit 110 judges whether the no-signal flag is 0 or not (step S106). If the no-signal flag is 0 (step S106; Yes), the control unit 110 sets the image to be projected by the display unit 140 to an image based on the HDMI signal input from the HDMI terminal 132 (step S107). Step S107 is also called a display setting step. In this case, from this point on, the display device 100 projects an image based on the image signal input to the HDMI terminal 132 on the display unit 140 until the signal search process is executed again or the user manually switches the external input. Then, the control unit 110 ends the signal search process.

[0048] If the no-signal flag is not 0 (step S106; No), the control unit 110 checks the signal input to the composite video terminal 133 via the video decoder 136 for a third search time (e.g., 3 seconds) (step S108) and determines whether or not there is a video signal (step S109). If there is a video signal (step S109; Yes), the control unit 110 sets the image to be projected on the display unit 140 to an image based on the composite video signal input from the composite video terminal 133 (step S110) and ends the signal search process. In this case, from this point on, the display device 100 projects an image based on the video signal input to the composite video terminal 133 on the display unit 140 until the signal search process is executed again or the user manually switches the external input.

[0049] If there is no video signal input to composite video terminal 133 (step S109; No), control unit 110 terminates the signal search process, assuming that no video signal is input to any of the external input terminals of input unit 130. Note that if the determination in step S109 is No, control unit 110 may return to step S102 without terminating the signal search process, and repeatedly execute the signal search process until a video signal is input to any of the external input terminals.

[0050] The signal search process has been described above. With this process, the control unit 110 skips external input terminals that are not receiving a signal, automatically selects an external input terminal to which an external device that is transmitting a video signal is connected, and projects the video output by the external device on the display unit 140. As described above, this signal search process is started automatically when the power is turned on or by a user operation, but when a signal is no longer input to the selected external input terminal (this is assumed to be the case when the power of the external device is turned off or the connection cable is removed), the control unit 110 may execute the signal search process again.

[0051] Next, the HDMI signal confirmation process executed in step S105 of the signal search process will be described with reference to Fig. 7. In the HDMI signal confirmation process, in addition to the "no signal flag", the following variables are used: "start timing", "5V detection flag", and "5V detection timing". Values ​​of the variables "5V detection flag" and "5V detection timing" are set in the connection determination process described below.

[0052] First, the control unit 110 sets the current timing (current time=timing when the HDMI signal confirmation process starts=search start timing) to a variable "start timing" and stores it in the storage unit 120 (step S201). Then, the control unit 110 determines whether or not it has been detected by the HDMI receiver 135 that a video signal has already been input to the HDMI terminal 132 (step S202). If it has been detected that a video signal has already been input to the HDMI terminal 132 (step S202; Yes), the process proceeds to step S207.

[0053] If it is not detected that a video signal is being input to the HDMI terminal 132 (step S202; No), the control unit 110 determines whether or not the 5V detection flag is set to 1 in a connection determination process described later (step S203). The details of the connection determination process will be described later, but in this process, it continues to check whether or not 5V is being applied to the power line of the HDMI terminal 132, and when it is applied, it sets the 5V detection flag to 1 and sets the timing (time) of this application to a variable "5V detection timing" and stores it in the storage unit 120.

[0054] If the 5V detection flag is not set to 1 (step S203; No), this means that an external device is not connected to the HDMI terminal 132, so the control unit 110 determines that there is no video signal (no signal) and sets the no-signal flag to 1 (step S204). Then, the control unit 110 ends the HDMI signal confirmation process and proceeds to step S106 of the signal search process.

[0055] If the 5V detection flag is set to 1 (step S203; Yes), the search time setting unit 112 sets a second search time ST, which is a search time for checking the presence or absence of an HDMI video signal, based on the variables "start timing", "5V detection timing" and "no signal flag" (step S205). Step S205 is also called a search time setting step.

[0056] Setting of the second search time ST will be described in more detail. When the value of the no-signal flag is 0, the search time setting unit 112 sets TDIF as TDIF = "start timing" - "5V detection timing" and sets the second search time ST as follows: Note that the minimum search time and maximum search time can be adjusted depending on the performance of the display device 100 and the type, performance, etc. of the external device connected to the HDMI terminal 132 (which can be obtained from EDID, for example), but here the minimum search time is set to 3 seconds and the maximum search time is set to 6 seconds. (1) If TDIF is equal to or greater than (maximum search time - minimum search time): ST = minimum search time (2) If TDIF is 0 seconds or more and less than (maximum search time - minimum search time): ST = maximum search time - TDIF (3) If TDIF is negative: ST = maximum search time

[0057] In addition, in consideration of the accuracy of the RTC used by the control unit 110 and the calculation accuracy of the above-mentioned "maximum search time - TDIF", the search time setting unit 112 may set the second search time ST from among a plurality of candidate values. For example, when the minimum search time is 3 seconds, the maximum search time is 6 seconds, and the search time setting unit 112 sets the candidate values ​​of the second search time ST in 1-second increments, it is as follows. (1) If TDIF is 3 seconds or more, ST = 3 seconds (2) If TDIF is between 2 and 3 seconds, ST = 4 seconds. (3) If TDIF is 1 second or more but less than 2 seconds, ST = 5 seconds. (4) If TDIF is less than 1 second (including negative numbers), ST = 6 seconds.

[0058] On the other hand, if the value of the no-signal flag is 1, it means that there was no HDMI signal the last time it was checked. In this case, the search time setting unit 112 sets the maximum search time (for example, 6 seconds) as the second search time ST.

[0059] 7, the control unit 110 checks the signal input to the HDMI terminal 132 via the HDMI receiver 135, and determines whether or not a video signal can be detected within the second search time set in step S205 (step S206). If a video signal cannot be detected (step S206; No), the control unit 110 proceeds to step S204.

[0060] If a video signal is detected (step S206; Yes), the control unit 110 determines that a video signal is present, performs settings necessary for projection processing, such as resolution setting, and clears the no-signal flag to 0 (step S207). Then, the control unit 110 ends the HDMI signal confirmation processing, and proceeds to step S106 of the signal search processing.

[0061] Next, the connection determination process will be described with reference to Fig. 8. This process is automatically started when the display device 100 is powered on, in parallel with other processes performed by the display device 100, such as a signal search process.

[0062] First, the connection determination unit 111 clears the variables "5V detection flag" and "5V timing" to 0, and stores them in the storage unit 120 (step S301). Next, the connection determination unit 111 determines whether or not 5V is detected on the power line of the HDMI terminal 132 (step S302). Step S302 is also called a connection determination step. If 5V is not detected on the power line of the HDMI terminal 132 (step S302; No), the connection determination unit 111 returns to step S302.

[0063] If 5V is detected on the power line of the HDMI terminal 132 (step S302; Yes), the connection determination unit 111 sets the 5V detection flag to 1, sets the current timing (current time=timing when 5V is detected=connection timing) to the variable "5V detection timing" and stores it in the storage unit 120 (step S303). Step S303 is also called a connection timing acquisition step.

[0064] Then, the connection determination unit 111 determines whether or not 5V is detected on the power line of the HDMI terminal 132 (step S304). This is a determination as to whether or not an external device continues to be connected to the HDMI terminal 132. If 5V is detected on the power line of the HDMI terminal 132 (step S304; Yes), the connection determination unit 111 returns to step S304. Then, if 5V is no longer detected on the power line of the HDMI terminal 132 (step S304; No), the connection determination unit 111 returns to step S301.

[0065] Since the above-mentioned connection determination process operates in parallel with the signal search process of Figure 6 (and the HDMI signal confirmation process of Figure 7), the control unit 110 can refer to information on whether or not an external device is connected to the HDMI terminal 132 and the timing of the connection in the above-mentioned HDMI signal confirmation process using the variables "5V detection flag" and "5V detection timing".

[0066] As described above, in the HDMI signal confirmation process executed in the signal search process, the display device 100 sets the second search time, which is the time for confirming the presence or absence of a video signal input to the HDMI terminal 132, to a shorter value (e.g., 3 seconds) if the timing at which an external device is connected to the HDMI terminal 132 is early, and sets it to a longer value (e.g., 6 seconds) if the timing at which an external device is connected to the HDMI terminal 132 is late. Thus, the display device 100 can prevent erroneous determination of the presence or absence of an HDMI video signal while preventing the search time from being unnecessarily long when the HDMI connection sequence has progressed halfway, and can more appropriately set the search time for confirming the presence or absence of a video signal when searching for video signals from a plurality of external input terminals.

[0067] Furthermore, in the HDMI signal confirmation process, if the 5V detection flag is not set to 1, the control unit 110 can determine that no external device is connected to the HDMI terminal 132, and therefore can immediately determine that there is no signal without needing to spend the second search time, thereby preventing unnecessary search time.

[0068] Furthermore, in the HDMI signal confirmation process, if a video signal has already been detected by the HDMI receiver 135, it is possible to immediately determine that a video signal is present without needing to spend the second search time, thereby preventing unnecessary search time from being wasted.

[0069] (Modification) In the above embodiment, the display device 100 is a projector device. However, the display device is not limited to a projector device. The display device may be any display device, such as a television, a monitor, or the like, as long as the display device has a plurality of external input terminals including a digital video signal terminal.

[0070] In the above embodiment, the input unit 130 has one each of the RGB terminal 131, the HDMI terminal 132, and the composite video terminal 133 as external input terminals, but this is merely an example. The input unit 130 only needs to have at least a digital video signal terminal, such as the HDMI terminal 132, which is a terminal for inputting a digital video signal, and may have terminals of other standards (for example, a D terminal, an S (Separate) terminal, etc.), or may have multiple terminals of the same standard. Even when multiple terminals are provided, the search time for the analog video signal terminal may be set to 2 to 3 seconds, similar to the RGB terminal 131 and the composite video terminal 133, and the above-mentioned second search time may be set for the digital video signal terminal, similar to the HDMI terminal 132, to sequentially search.

[0071] In the above embodiment, the HDMI signal is described as an example of the digital video signal, but the digital video signal is not limited to the HDMI signal. As the digital video signal, for example, a signal transmitted according to any standard such as DisplayPort, MHL (Mobile High-definition Link), HDBaseT, WirelessHD, etc. can be used. In this case, the HDMI signal confirmation process and the connection determination process need to be modified according to the standard, but the basic concept is the same, so they can be easily modified. Also, the video transmission preparation period may differ depending on the standard, but in that case, it can be handled by modifying the setting method of the second search time according to the standard.

[0072] Each function of the display device 100 can be implemented by a computer such as a normal PC. Specifically, in the above embodiment, the program for the signal search process and the like executed by the display device 100 has been described as being stored in advance in the ROM of the storage unit 120. However, the program may be stored in a computer-readable recording medium such as a flexible disk, a CD-ROM (Compact Disc Read Only Memory), a DVD, an MO (Magneto-Optical disc), a memory card, a USB (Universal Serial Bus) memory, or the like and distributed, and the program may be read and installed in a computer to configure a computer capable of implementing each of the above-mentioned functions.

[0073] Furthermore, the program may be superimposed on a carrier wave and applied via a communication medium such as the Internet. For example, the program may be distributed by posting it on a bulletin board system (BBS) on a communication network. The program may then be started and executed under the control of an operating system (OS) in the same manner as other application programs, thereby enabling the above-mentioned processing to be performed.

[0074] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and the present invention includes the inventions described in the claims and their equivalents. The inventions described in the original claims of this application are listed below.

[0075] (Appendix 1) an input section having at least a digital video signal terminal which is a terminal for inputting a digital video signal; a display unit that displays an image based on the digital image signal input from the input unit; a connection determination unit that determines whether or not an external device is connected to the digital video signal terminal and obtains information related to a connection timing that is a timing at which the external device is connected to the digital video signal terminal; a search time setting unit that sets a search time for checking whether or not a video signal is present in the signal input from the digital video signal terminal, based on information related to the connection timing acquired by the connection determination unit; A display device comprising:

[0076] (Appendix 2) the search time setting unit sets the search time based on the connection timing and a search start timing which is a timing at which a search for the digital video signal is started. 2. A display device according to claim 1.

[0077] (Appendix 3) the search time setting unit sets the search time based on whether the connection timing occurs after or before the search start timing. 3. A display device according to claim 2.

[0078] (Appendix 4) The search time setting unit sets the search time from among a plurality of candidate values. 4. A display device according to any one of claims 1 to 3.

[0079] (Appendix 5) the search time setting unit sets the search time by subtracting a time from the connection timing to the search start timing from a maximum search time. 4. The display device according to claim 2 or 3.

[0080] (Appendix 6) the connection determination unit determines whether the external device is connected to the digital video signal terminal based on whether application of 5V is detected. 6. A display device according to any one of claims 1 to 5.

[0081] (Appendix 7) A display control method for a display device having an input unit having a digital video signal terminal which is a terminal for inputting at least a digital video signal, comprising: a connection determination step of determining whether or not an external device is connected to the digital video signal terminal; a connection timing acquisition step of acquiring information related to a connection timing, which is a timing at which the external device is connected to the digital video signal terminal, when it is determined in the connection determination step that the external device is connected to the digital video signal terminal; a search time setting step of setting a search time for checking whether or not a video signal is present in the signal input from the digital video signal terminal, based on information related to the connection timing acquired in the connection timing acquisition step; a display setting step of setting so as to display an image based on the digital video signal input from the digital video signal terminal when it is determined that the video signal is present within the search time set in the search time setting step; A display control method comprising:

[0082] (Appendix 8) A computer of a display device having an input unit having a digital video signal terminal which is a terminal for inputting at least a digital video signal, a connection determination step of determining whether or not an external device is connected to the digital video signal terminal; a connection timing acquisition step of acquiring information related to a connection timing, which is a timing at which the external device is connected to the digital video signal terminal, when it is determined in the connection determination step that the external device is connected to the digital video signal terminal; and a search time setting step for setting a search time for checking whether or not a video signal is present in the signal input from the digital video signal terminal, based on information relating to the connection timing acquired in the connection timing acquisition step; A program that executes the following. [Explanation of symbols]

[0083] 100...display device, 110...control unit, 111...connection determination unit, 112...search time setting unit, 120...storage unit, 130...input unit, 131...RGB terminal, 132...HDMI terminal, 133...composite video terminal, 134...A / D conversion unit, 135...HDMI receiver, 136...video decoder, 140...display unit, 145...projection screen, 150...operation unit, 201...PC, 202...BD recorder, 203...DVD recorder, 1000...display system

Claims

1. an input section having at least a digital video signal terminal which is a terminal for inputting a digital video signal; a display unit that displays an image based on the digital image signal input from the input unit; a connection determination unit that determines whether or not an external device is connected to the digital video signal terminal and obtains information related to a connection timing that is a timing at which the external device is connected to the digital video signal terminal; a search time setting unit that sets a search time that is a time for checking whether or not a video signal is included in the signal input from the digital video signal terminal, based on information related to the connection timing acquired by the connection determination unit, a search start timing that is a timing at which a search for the digital video signal is started, and a video transmission preparation period; A display device comprising:

2. the search time setting unit sets the search time based on a timing error, which is a time difference between the connection timing and the search start timing, and the video transmission preparation period. The display device according to claim 1 .

3. the search time setting unit sets a preset minimum search time as the search time when the timing error is equal to or greater than the video transmission preparation period. The display device according to claim 2 .

4. when the connection timing occurs after the search start timing, the search time setting unit sets the search time to a value obtained by adding the minimum search time to the video transmission preparation period. The display device according to claim 3 .

5. The video transmission preparation period is a period of at least a part of a connection sequence, which is a process executed when a connection is made between the external device and the display device. The display device according to claim 1 .

6. the connection determination unit determines whether the external device is connected to the digital video signal terminal based on whether application of 5 V is detected. The display device according to claim 1 .

7. A display control method for a display device having an input unit having a digital video signal terminal which is a terminal for inputting at least a digital video signal, comprising: a connection determination step of determining whether or not an external device is connected to the digital video signal terminal; a connection timing acquisition step of acquiring information related to a connection timing, which is a timing at which the external device is connected to the digital video signal terminal, when it is determined in the connection determination step that the external device is connected to the digital video signal terminal; a search time setting step of setting a search time, which is a time for checking whether or not a video signal is present in the signal input from the digital video signal terminal, based on information related to the connection timing acquired in the connection timing acquisition step, a search start timing, which is a timing at which a search for the digital video signal is started, and a video transmission preparation period; a display setting step of setting so as to display an image based on the digital video signal input from the digital video signal terminal when it is determined that the video signal is present within the search time set in the search time setting step; A display control method comprising:

8. A computer of a display device having an input unit having a digital video signal terminal which is a terminal for inputting at least a digital video signal, a connection determination step of determining whether or not an external device is connected to the digital video signal terminal; a connection timing acquisition step of acquiring information related to a connection timing, which is a timing at which the external device is connected to the digital video signal terminal, when it is determined in the connection determination step that the external device is connected to the digital video signal terminal; and a search time setting step for setting a search time, which is a time for checking whether or not a video signal is present in the signal input from the digital video signal terminal, based on information related to the connection timing acquired in the connection timing acquisition step, a search start timing, which is a timing at which a search for the digital video signal is started, and a video transmission preparation period; A program that executes the following.

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