JP2019087940A - Video processing apparatus - Google Patents

Abstract

To reduce interference in wireless communication caused by a video signal without degrading image quality.SOLUTION: A video processing apparatus 1 includes: a video input unit 5 to which a video signal is input; a wireless communication unit 10 capable of communicating with an outside in a plurality of frequency bands; and a control unit 9 setting a use frequency band used for communication among the plurality of frequency bands. The control unit acquires a frequency of an interference wave generated due to the video signal and sets a frequency band not including the frequency of the interference wave among the plurality of frequency bands as a use frequency band.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a video processing apparatus that performs processing such as video display and video recording using an input video signal, and more particularly to a video processing apparatus having a wireless communication function.

  Some video processing apparatuses such as a projector and a recorder have a wireless communication function capable of receiving and transmitting control signals and video signals using a wireless LAN. Furthermore, by including an access point (base station) function in such a video processing apparatus, it becomes possible to use the so-called ad hoc mode (ad hoc mode), and it is possible to communicate directly with other wireless LAN equipped devices. Become.

  On the other hand, the frequency of the dot clock of the video signal (hereinafter referred to as dot clock frequency) is increasing with the increase in resolution of the video signal input to the video processing apparatus. As a result, an event occurs in which unwanted electromagnetic interference (Electro Magnetic Interference) that appears at a frequency that is an integral multiple of the dot clock frequency of the input video signal with respect to the communication frequency used in wireless LAN communication interferes with wireless LAN communication. . This phenomenon is called "self-poisoning phenomenon" in which the performance of its own function is impaired due to unwanted radiation generated inside the image processing apparatus.

  In order to reduce the influence on the wireless LAN communication of unwanted radiation that appears at a frequency that is an integral multiple of the dot clock frequency of the video signal, for example, Patent Document 1 describes that the video signal input in the device A video processing apparatus is disclosed which transmits at a clock frequency different from the dot clock frequency. Further, Patent Document 2 discloses a video processing device which shifts the dot clock frequency of a video signal generated inside the device to a dot clock with less influence.

JP, 2013-109272, A Japanese Patent Application Publication No. 2007-43246

  However, if the dot clock frequency of the video signal is changed with respect to the communication frequency used in the wireless LAN as in the video processing apparatus disclosed in Patent Documents 1 and 2, the size of the circuit for changing the dot clock frequency becomes large. . In addition, there is a possibility that the image quality of the display video may be degraded because the clock signal for determining the position (coordinates) of each pixel on the video displayed according to the video signal is changed.

  The present invention provides a video processing apparatus capable of reducing interference in wireless communication caused by a video signal without degrading the image quality.

  A video processing apparatus according to one aspect of the present invention includes a video input unit to which a video signal is input, a wireless communication unit capable of communicating with the outside in a plurality of frequency bands, and communication among a plurality of frequency bands. And a control unit for setting a use frequency band used for the The control unit is characterized in that the frequency of the interference wave generated due to the video signal is acquired, and a frequency band not including the frequency of the interference wave among the plurality of frequency bands is set as a use frequency band.

  The control method according to another aspect of the present invention is applied to a video processing apparatus capable of performing communication with the outside in a plurality of frequency bands while receiving a video signal. The control method includes a setting step of setting a use frequency band among a plurality of frequency bands and a step of performing communication in the use frequency band. In the setting step, the frequency of the interference wave generated due to the video signal is acquired, and a frequency band not including the frequency of the interference wave among a plurality of frequency bands is set as a use frequency band.

  A computer program that causes a video processing apparatus to execute processing according to the above control method also constitutes another aspect of the present invention.

  According to the present invention, it is possible to reduce interference in wireless communication caused by a video signal without degrading the image quality.

FIG. 1 is a block diagram showing the configuration of a projector that is Embodiment 1 of the present invention. The figure which shows the channel and interference wave in IEEE801.11n of wireless LAN specification. 6 is a flowchart showing the operation of the projector of the first embodiment. FIG. 2 is a block diagram showing the configuration of a projector that is Embodiment 2 of the present invention. 6 is a flowchart showing the operation of the projector of the second embodiment. FIG. 7 is a block diagram showing the configuration of a projector that is Embodiment 3 of the present invention. 10 is a flowchart showing the operation of the projector of the third embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows the configuration of a projector (image projection apparatus) 1 as a video processing apparatus according to a first embodiment of the present invention. The projector 1 according to the present embodiment incorporates a wireless communication unit that performs wireless communication with an external device using a wireless LAN (for example, communication standard IEEE 801.11 n).

  A video output device 2 such as a personal computer is equipped with a video output IC 3 for outputting various video signals (video data). The video output IC 3 can transmit a video signal including a dot clock signal to the projector 1 through the DVI cable 4. There are various video signals transmitted (input) to the projector 1 such as digital signal DVI and HDMI (registered trademark), and analog signal NTSC.

  An input control (I / F) IC 5 as a video input unit sends a video signal input from the video output device 2 through the input connector 6 to the image processing IC 7. Reference numeral 8 denotes a recording unit (ROM), in which data of a dot clock signal frequency (hereinafter referred to as dot clock frequency) corresponding to various video signal characteristics is recorded. Here, the characteristics of the video signal include resolution, horizontal synchronization signal frequency, vertical synchronization signal frequency and bit depth (eg, 8 bits / 10 bits). The recording unit 8 is connected to the CPU 9 as a control unit.

  The CPU 9 detects the characteristics of the video signal input to the input control IC 5. Then, the data of the dot clock frequency corresponding to the detected characteristic among the dot clock frequencies corresponding to the characteristics of various video signals recorded in the recording unit 8 is read out. The CPU 9 uses this dot clock frequency for the ch setting process described later.

  10 is a wireless LAN unit as a wireless communication unit. The wireless LAN unit 10 can operate in an infrastructure mode, and can communicate with an external PC or the like through an external access point that controls the network. The wireless LAN unit 10 can also operate in an access point mode having an access point function. When operating in the access point mode, the CPU 9 can set (select) the frequency band used by the wireless LAN unit 10 in the wireless LAN (hereinafter referred to as the used frequency band) by the channel setting process.

  A control PC 11 controls the projector 1 from the outside, and is connected to the external wireless LAN unit 12. The external wireless LAN unit 12 can communicate in the infrastructure mode via an external access point, and can transmit a control signal from the control PC 11 to the projector 1 by a wireless LAN (for example, communication standard IEEE 801.11 n). it can.

  Reference numeral 13 denotes a light source such as a high pressure mercury lamp, and the ballast unit 19 receives a power supply from the external power supply 20 to generate a voltage for lighting the light source 13. White light emitted from the light source 13 enters the prism unit 14. The prism unit 14 separates the white light from the light source 13 into red light, blue light and green light, and guides them to the red image panel 15, the blue image panel 16 and the green image panel 17. Each video panel is constituted by a light modulation element such as a liquid crystal display element.

  The image processing IC 7 converts the video signal input from the input signal control IC into a video signal having an appropriate resolution and format for the red, blue and green video panels 15 to 17 and sends the video signal to the panel driver 21. The panel driver 21 drives the red, blue and green image panels 15 to 17 in accordance with the converted video signal. Thereby, the red light, blue light and green light incident on the red image panel 15, the blue image panel 16 and the green image panel 17 are modulated to form an image of each color.

  The red light, blue light and green light as modulated light emitted (reflected) from the red image panel 15, the blue image panel 16 and the green image panel 17 are synthesized by the prism unit 14 and guided to the projection lens 18. The projection lens 18 projects the combined red light, blue light and green light (that is, a full color image) onto a projection surface such as a screen (not shown).

  Next, an outline of the ch setting process performed by the CPU 9 in the present embodiment will be described. A video signal including a high-speed dot clock signal is transmitted from the video output device 2 to the projector 1 through the DVI cable 4. If this video signal has a resolution of 1920 × 1080 pixels, for example, the basic dot clock frequency is 74.25 MHz. As shown in FIG. 2, the wireless LAN unit 10 uses from 2401 MHz (2.401 GHz) to 2495 MHz (2.495 GHz) as the entire communicable band (predetermined frequency band) of the wireless LAN (IEEE 801. 11 n). Then, 1ch to 14ch, which are a plurality of channels each having a 22 MHz band, are provided in the entire band.

  The frequency of the 33rd harmonic which is one of the multiple waves of the dot clock frequency 74.25 MHz is 2450 MHz (2.45 GHz), and this frequency overlaps near the center of 9 ch (2441-2463 MHz). Further, the bands of the chs partially overlap each other, for example, 2410 to 2423 MHz for 1 ch and 2046 to 2428 MHz for 2 ch. Therefore, in addition to 9 ch, there are 8 ch (2436 to 2458 MHz), 7 ch (2431 to 2453 MHz), 10 ch (2446 to 2473 MHz) and 11 ch (2451 to 2473 MHz) in addition to 9 ch. These 7 to 11 ch are affected by the interference wave (unwanted radiation) which is the 33rd harmonic.

  Therefore, in the present embodiment, the CPU 9 acquires the frequency of the multiplied wave of the dot clock signal of the input video signal. Then, as a channel used by the access point function of the wireless LAN unit 10 (usable frequency band: hereinafter referred to as a used channel), a channel not affected by the multiple wave which is an interference wave is set (selected). Specifically, when the resolution of the input video signal is 1920 × 1080 and the dot clock frequency is 74.25 MHz, the CPU 9 selects 1 to 6 channels and 12 to 14 channels that do not include the interference wave frequency as use channels. Set one ch. Then, communication is performed in the access point mode by the access point function through the set use channel.

  Next, the specific flow of the ch setting process by the CPU 9 will be described with reference to the flowchart of FIG. The CPU 9 executes this ch setting process in accordance with a control program as a computer program. In the figures and the following description, "S" denotes a step.

  In S301, when an instruction to use the access point function of the wireless LAN is input from the outside or the resolution of the video signal input from the video output device 2 changes in S301, the CPU 9 proceeds to S302. The following steps S302 to S306 correspond to setting steps.

  At S302, the CPU 9 detects the above characteristics of the video signal input to the input control IC 5. Then, the dot clock frequency corresponding to the detected characteristic among the dot clock frequencies corresponding to the characteristics of the plurality of video signals recorded in the recording unit 8 is acquired from the recording unit 8. The CPU 9 may obtain the dot clock frequency directly from the input control IC 5. Also, the dot clock frequency may be obtained from resolution, horizontal synchronization signal frequency, vertical synchronization signal frequency, bit depth, and the like.

  Next, in step S303, the CPU 9 calculates a multiplication frequency of the acquired dot clock frequency (hereinafter referred to as an interference frequency), and determines whether the interference frequency is included in any of the 1 to 14 ch. In other words, a ch whose interference wave according to the dot clock frequency (resolution) of the input video signal interferes with the communication by the wireless LAN (hereinafter referred to as a disturbed ch) is specified. When there is no disturbed ch, the CPU 9 proceeds to S304, and when there is a disturbed ch, it proceeds to S305.

  In S304, the CPU 9 sets an arbitrary free channel in the wireless LAN unit 10 as a use channel. Then, the process proceeds to step S306.

  On the other hand, in S305, the CPU 9 selects a free channel different from the disturbed channel among 1 to 14 channels, that is, a free channel in which the wireless LAN is not affected by the interference wave. As a result, 7 to 10 chs are not selected even if they are empty chs. Then, the CPU 9 causes the wireless LAN unit 10 to set the selected free channel as the use channel, and the process proceeds to step S306.

  In S306, the CPU 9 causes the wireless LAN unit 10 to start communication with the external wireless LAN unit 12 in the access point mode by the access point function.

  In the present embodiment, the CPU 9 dynamically sets a ch in which an interference wave generated due to an input video signal does not interfere with wireless LAN communication as a used channel. Thus, the wireless LAN unit 10 incorporated in the projector 1 can perform good communication with the external wireless LAN unit 12.

  Next, a projector 1 'according to a second embodiment of the present invention will be described with reference to FIG. The configuration of the projector 1 'of the present embodiment is basically the same as the configuration of the projector 1 of the first embodiment, for example, the wireless LAN unit 10 is built-in. The same reference numerals as in 1 are attached. However, in the present embodiment, the image output IC 3 'of the video output device 2' simultaneously transmits a plurality of video signals having the same or different resolutions to the projector via the plurality of DVI cables 4a, 4b, 4c, 4d. It is possible. The input control IC 5 'of the projector can receive simultaneous input of the plurality of video signals through the plurality of input connectors 6a, 6b, 6c, 6d to which the DVI cables 4a, 4b, 4c, 4d are connected. A video signal can be sent to the image processing IC 7.

  Further, as in the first embodiment, the data of the dot clock frequency corresponding to various resolutions of the video signal is recorded in the recording unit 8, and the number of input video signals and the intensity of the radio wave emitted Data indicating the relationship is recorded.

  The CPU 9 can detect the characteristics (resolution, horizontal sync signal frequency, vertical sync signal frequency and bit depth) of the video signal input to the input control IC 5 and the number of inputs of the video signal. Further, the CPU 9 reads data of the dot clock frequency corresponding to the characteristics of the video signal from the data recorded in the recording unit 8, and the radio wave intensity (accumulation in the video processing apparatus) emitted in the projector 1 ' Read out the data of value).

  Next, an outline of the ch setting process performed by the CPU 9 in the present embodiment will be described. A plurality of video signals including high-speed dot clock signals are transmitted from the video output device 2 'to the projector 1' through the DVI cables 4a to 4d. If these video signals have a resolution of 1920 × 1080 pixels, for example, as described in the first embodiment, the basic dot clock frequency is 74.25 MHz. As in the first embodiment (FIG. 2), the wireless LAN unit 10 uses 2401 MHz (2.401 GHz) to 2495 MHz (2.495 GHz) as the entire communicable band of the wireless LAN. Then, 1ch to 14ch, which are a plurality of channels each having a 22 MHz band, are provided in the entire band.

  Furthermore, as described in the first embodiment, the frequency of the 33rd harmonic, which is one of the multiple waves of the dot clock frequency 74.25 MHz, is 2450 MHz (2.45 GHz), and this frequency is the center of 9 ch (2441-2463 MHz). Overlap. Further, the bands of the chs partially overlap each other, for example, 2410 to 2423 MHz for 1 ch and 2046 to 2428 MHz for 2 ch. Therefore, there are 8ch (2436 to 2458MHz), 7ch (2431 to 2453MHz), 10ch (2446 to 2473MHz) and 11ch (2451 to 2473MHz) in addition to 9ch as ch overlapping 2450MHz of 33rd harmonic. These 7 to 11 ch are affected by the disturbance wave which is the 33rd harmonic.

  In addition, when a plurality of video signals are input, the strength of interference waves increases as the number of input video signals having the same characteristics (that is, the same dot clock frequency) increases. Furthermore, in the case where a plurality of video signals having different characteristics (that is, different dot clock frequencies) are input, the multiple wave of each dot clock signal may interfere with communication with more channels.

  Therefore, in the present embodiment, the CPU 9 acquires information on the frequency of the multiplied wave of the dot clock signal of the input video signal as in the first embodiment, and is not affected by the multiplied wave (disturbance wave) as a use channel. Set ch. At this time, the CPU 9 obtains the number of input video signals, that is, the number of interference waves. Then, if the strength of the disturbance wave corresponding to the number of disturbance waves is equal to or more than a predetermined number, a ch not affected by the disturbance wave is set (selected) as a use channel. Specifically, when the resolution of the input video signal is 1920 × 1080, the dot clock frequency is 74.25 MHz, and the number of inputs is 2 or more, the CPU 9 selects 1 to 6 channels and 12 to 14 channels as use channels. Set one ch.

  The specific flow of the ch setting process by the CPU 9 will be described with reference to the flowchart of FIG. The CPU 9 executes this channel setting process in accordance with a computer program.

  The CPU 9 proceeds to step S502 when an instruction to use the access point function of the wireless LAN is input from the outside in S501, or when the characteristics, the number, and the like of the video signal input from the video output device 2 change. The following steps S502 to S306 correspond to setting steps.

  At S502, the CPU 9 detects the characteristics and the number of inputs of all the video signals input to the input control IC 5 '. Then, among the dot clock frequencies corresponding to the characteristics of the plurality of video signals recorded in the recording unit 8, the dot clock frequency corresponding to the characteristics of all the detected video signals is acquired from the recording unit 8. As in the first embodiment, the CPU 9 may directly acquire the dot clock frequency from the input control IC 5. Also, the dot clock frequency may be obtained from the resolution, the horizontal synchronization signal frequency, the vertical synchronization signal frequency, and the bit depth.

  Next, in S503, the CPU 9 calculates an interference frequency from each of all the acquired dot clock frequencies, and determines whether these interference frequencies are included in any of the 1 to 14 ch. In other words, it identifies a disturbed channel candidate that may cause interference waves in accordance with the dot clock frequency of the input video signal to disturb communication by the wireless LAN. The CPU 9 proceeds to S504 if there is no disturbed ch candidate, and proceeds to S505 if there is a disturbed ch candidate.

  In S504, the CPU 9 sets an arbitrary free channel as a use channel to the wireless LAN unit 10. At this time, if 7 to 10 channels are also free channels, they can be set as use channels. Then, the process proceeds to step S507.

  In step S505, the CPU 9 determines whether the number of input video signals detected in step S502 is equal to or more than the number (threshold value) at which an interference wave with an intensity that interferes with communication is generated. For example, if two or more video signals with a resolution of 1920 × 1080 pixels are input, the communication is interrupted (the disturbed ch candidate becomes the disturbed ch), and the process proceeds to S506, and only one video signal is input. If it is, the process proceeds to S504.

  In S506, the CPU 9 selects a free channel different from the disturbed channel among the 1 to 14 channels, that is, a free channel in which the wireless LAN is not affected by the interference wave. As a result, 7 to 10 chs are not selected even if they are empty chs. The CPU 9 makes the same determination on all input video signals that generate a multiple of the dot clock signal in the entire wireless LAN band. The CPU 9 causes the wireless LAN unit 10 to perform setting to use the selected free channel, and the process proceeds to S507.

  In S507, the CPU 9 causes the wireless LAN unit 10 to start communication with the external wireless LAN unit 12 in the access point mode by the access point function.

  Also in the present embodiment, the CPU 9 dynamically sets a ch where an interference wave generated due to the input video signal does not disturb the wireless LAN communication as a used channel. As a result, the wireless LAN unit 10 built in the projector 1 ′ can perform good communication with the external wireless LAN unit 12.

  6 shows the configuration of a projector 1 ′ ′ as a video processing apparatus according to a third embodiment of the present invention. In FIG. 6, the same components as those in the first embodiment are given the same reference numerals as the first embodiment. In the projector 1 ′ ′ of this embodiment, the CPU 9 is connected to the radio wave detection unit 22 that can detect radio waves present in the space and analyze its frequency. By using the frequency from the radio wave detection unit 22, it is possible to identify whether the detected radio wave is a radio wave due to unnecessary radiation or a radio wave of wireless communication.

  The CPU 9 acquires from the radio wave detection unit 22 the frequency of the radio wave emitted by the dot clock signal of the input video signal. Then, as in the first embodiment, as a channel used by the access point function of the wireless LAN unit 10, a channel that is not affected by the multiple wave of the dot clock signal that is an interference wave is set (selected). Further, communication is performed in the access point mode by the access point function through the set use channel.

  The flowchart of FIG. 7 shows a ch setting process by the CPU 9 in the present embodiment.

  The CPU 9 proceeds to step S702 when an instruction to use the access point function of the wireless LAN is input from the outside or the resolution of the video signal input from the video output device 2 changes in step S701. The following steps S702 to S706 correspond to setting steps.

  In S702, the CPU 9 acquires the frequency of the radio wave emitted in the projector 1 ′ ′ through the radio wave detection unit 22.

  Next, in step S703, the CPU 9 determines whether the frequency of the radio wave acquired through the radio wave detection unit 22 (hereinafter referred to as an interference frequency) is included in any of the 1 to 14 ch described in the first embodiment. In other words, the disturbed channel corresponding to the dot clock frequency of the video signal interferes with the communication by the wireless LAN. The CPU 9 proceeds to S704 if there is no disturbed ch, and proceeds to S705 if there is a disturbed ch.

  In S704, the CPU 9 sets an arbitrary free channel in the wireless LAN unit 10 as a use channel. Then, the process proceeds to step S706.

  On the other hand, in S705, the CPU 9 selects a free channel different from the disturbed channel among 1 to 14 channels, that is, a free channel in which the wireless LAN is not affected by the interference wave. Then, the CPU 9 causes the wireless LAN unit 10 to set the selected free channel as the use channel, and the process proceeds to S706.

  In S706, the CPU 9 causes the wireless LAN unit 10 to start communication with the external wireless LAN unit 12 in the access point mode by the access point function.

  In the present embodiment, the CPU 9 dynamically sets a ch in which an interference wave generated due to a video signal does not interfere with wireless LAN communication as a use channel. Thus, the wireless LAN unit 10 incorporated in the projector 1 can perform good communication with the external wireless LAN unit 12.

In each of the above embodiments, the case has been described in which the multiple wave of the dot clock signal of the video signal is the disturbance wave, but even when the multiple wave of the clock signal other than the dot clock signal or the synchronization signal becomes the disturbance wave, The ch setting process similar to the example can be performed.
(Other embodiments)
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. Can also be realized. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.

  The embodiments described above are only representative examples, and various modifications and changes can be made to the embodiments when the present invention is implemented.

1,1 ′, 1 ′ ′ Projector 5,5 ′ Input control IC
9 CPU
10 Wireless LAN unit

Claims (7)

A video input unit to which a video signal is input;
A wireless communication unit capable of communicating with the outside in a plurality of frequency bands;
A control unit configured to set a use frequency band used for the communication among the plurality of frequency bands;
The control unit
Acquiring a frequency of an interference wave generated due to the video signal,
A video processing apparatus characterized in that a frequency band not including the frequency of the interference wave among the plurality of frequency bands is set as the use frequency band.   The video processing apparatus according to claim 1, wherein the interference wave is a multiple wave of a clock signal of the video signal.   The video processing apparatus according to claim 1, wherein the control unit acquires a frequency of the interference wave based on a characteristic of the video signal.   The image processing apparatus according to claim 1, wherein the control unit acquires a frequency of the interference wave using a detection unit that detects the interference wave. The video input unit can simultaneously input a plurality of video signals,
The control unit sets a frequency band not including the frequency of the interference wave as the use frequency band when the number of inputs of the plurality of video signals is a predetermined number or more. An image processing apparatus according to any one of the preceding claims. A control method of a video processing apparatus capable of performing communication with the outside in a plurality of frequency bands while receiving a video signal.
A setting step of setting a use frequency band among the plurality of frequency bands;
Performing the communication in the use frequency band;
In the setting step,
Acquiring a frequency of an interference wave generated due to the video signal,
A control method of a video processing apparatus, wherein a frequency band not including the frequency of the interference wave among the plurality of frequency bands is set as the use frequency band. A computer program that causes a computer of a video processing apparatus capable of performing communication with the outside in a plurality of frequency bands as well as a video signal being input to execute processing.
The process is
A setting step of setting a use frequency band among the plurality of frequency bands;
Performing the communication in the use frequency band;
In the setting step,
Acquiring a frequency of an interference wave generated due to the video signal,
A control program characterized by setting a frequency band not including the frequency of the interference wave among the plurality of frequency bands as the use frequency band.