JP2009288689A - Image projection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently cool signal processing parts for processing input image signals, without using a temperature sensor. <P>SOLUTION: An image projection apparatus includes: a plurality of signal processing parts 108, 109, and 111 for processing input image signals different by types respectively; a cooling mechanism for cooling the plurality of signal processing parts by air flowing due to rotation of fans; and a control means 101 for controlling the rotation of fans 120 and 121. The control means varies rotational frequencies of the fans in accordance with a signal processing part which processes an input image signal, out of the plurality of signal processing parts. Furthermore, a flow path control means 901 is provided which changes a flow path of air in accordance with a signal processing part which processes an input image signal, out of the plurality of signal processing parts. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image projection apparatus such as a liquid crystal projector, and more particularly to cooling of the image projection apparatus.

  A liquid crystal projector has a heating element such as a light source lamp or an electric element (signal processing unit) for signal processing such as an IC on a printed circuit board in a housing. In order to stabilize the lamp life and the operation of the signal processing unit, it is necessary to appropriately cool them.

  As a cooling method, there is a method of flowing air around a heating element by rotating a fan. The cooling effect can be increased by increasing the number of rotations of the fan. However, increasing the number of rotations of the fan increases power consumption and noise from the fan. For this reason, conventionally, a temperature sensor for detecting the temperature around the heating element is provided, and the rotational speed of the fan is controlled in accordance with the detected temperature. As a result, it is possible to suppress an increase in power consumption and noise by increasing the rotational speed of the fan only when the heating element becomes high temperature.

  Further, various types of image signals (video signals) such as video signals, component signals, analog RGB signals, digital RGB signals, TMDS (Transition Minimized Differential Signaling) digital signals can be input to the projector. A plurality of connectors and a plurality of signal processing ICs corresponding to these various types of image signals are provided on a substrate in the projector. Of the plurality of signal processing ICs, a signal processing IC to which an image signal is input serves as a heating element. In addition, a plurality of different image signals may be input to the same signal processing IC. In this case, the amount of heat generated by the signal processing IC varies depending on the type of the input image signal.

  In many cases, the plurality of signal processing ICs are disposed on the same surface of the substrate so as to be separated from each other to some extent or separately on both surfaces of the substrate. In this case, it is better to cool mainly the signal processing IC that generates heat than cooling all the signal processing ICs with a common cooling air, and the power consumption and noise of the fan can be suppressed. .

Patent Document 1 discloses a projector in which a temperature sensor and a fan are provided near a plurality of heating elements (lamp and liquid crystal panel) that are separated from each other. In the projector, the rotational speed of the fan near the heating element is changed according to the temperature detected by the temperature sensor near each heating element. This projector cooling method can also be applied to the case of mainly cooling a signal processing IC that generates heat among a plurality of signal processing ICs arranged apart or on both sides on a substrate.
JP 2001-235797 A

  However, when adding a temperature sensor for each signal processing IC, it is often difficult to mount them on a board in space. Further, the number of temperature sensors required for the entire projector increases, which is not preferable.

  The present invention provides an image projection apparatus that can efficiently cool a signal processing unit that processes an input image signal without using a temperature sensor.

  An image projection apparatus according to an aspect of the present invention includes a plurality of signal processing units that respectively process different types of input image signals, and a cooling structure that cools the plurality of signal processing units by air that flows by rotation of a fan, Control means for controlling the rotation of the fan. And a control means changes the rotation speed of a fan according to the signal processing part which processes an input image signal among several signal processing parts, It is characterized by the above-mentioned.

  An image projection apparatus according to another aspect of the present invention includes a signal processing unit that processes input image signals of different types, a cooling structure that cools the signal processing unit with air flowing by rotation of the fan, and rotation of the fan And control means for controlling. The control means is characterized in that the rotational speed of the fan is changed according to at least one of the type and format of the input image signal.

  An image projection apparatus according to another aspect of the present invention controls a signal processing unit that processes an input image signal, a cooling structure that cools the signal processing unit by air flowing through rotation of the fan, and rotation of the fan. Control means. And a control means changes the rotation speed of a fan according to at least one among the content and size of an input image signal, It is characterized by the above-mentioned.

  An image projection apparatus according to another aspect of the present invention cools a plurality of signal processing units that respectively process a plurality of types of input video signals, and air that flows by rotation of a fan. A cooling structure and a flow path control unit that changes a flow path of air in the cooling structure in accordance with a signal processing unit that processes an input image signal among a plurality of signal processing units.

  According to the present invention, it is possible to supply appropriate cooling air according to the position (heat generation position) and the heat generation amount to a signal processing unit that needs to be cooled on the printed circuit board without using a temperature sensor. In addition, it is possible to suppress an increase in power consumption and noise due to unnecessary driving of the fan.

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

  FIG. 1 shows a configuration of a part related to electrical processing of a liquid crystal projector (image projection apparatus).

  First, a configuration related to processing of a plurality of input image signals of different types will be described. The input image signal referred to here includes a moving image signal (that is, a video signal) and a still image signal, and those in which these image signals are in a file format. In the following description, the video signal and the still image signal are collectively referred to as an image signal.

  In the projector of this embodiment, TMDS digital signals and analog RGB signals can be input as video signals. However, these video signals are merely examples, and other types of video signals (for example, video signals, component signals, digital RGB signals) may be included.

  The projector of this embodiment is connected to an external memory (USB memory) via a USB connector, and can input a JPEG format still image file stored in the USB memory.

  A solid line arrow in FIG. 1 indicates a transmission path of an input image signal, and a broken line arrow indicates a transmission path of a control signal of each signal processing unit.

  The control unit (control unit) 101 controls a power supply circuit (not shown) and a DA converter 119 provided for controlling the fans 120 and 121. The control unit 101 also controls various operations set by the user, and initializes and sets the operation of each signal processing unit for processing an image signal.

  The ROM 102 stores a computer program that causes the control unit 101 to perform various operations. The nonvolatile RAM 103 stores various setting values by the user that are referred to by the control unit 101.

  The HDMI connector 104 and the DVI connector 105 are connectors to which TMDS digital signals are input. A video output device (not shown) such as a personal computer connected to the HDMI connector 104 and the DVI connector 105 via a cable is based on information unique to the projector stored in a memory (not shown) in the projector. Control the output of the signal.

  The HDMI / DVI receiver 108 as a signal processing unit (signal processing element) that processes the TMDS digital signal performs processing (signal processing) for converting the TMDS digital signal into a digital RGB signal, and converts the digital RGB signal into the main signal processing unit 113. Transmit to.

  The DVI connector 105 and the D-sub 15-pin connector 106 are connectors to which analog RGB signals are input. The analog RGB signal is input to the AD converter 110 and the synchronization signal processing unit 109. The synchronization signal processing unit 109 performs processing (signal processing) for separating the synchronization signal from the analog RGB signal, and outputs the synchronization signal to the AD converter 110.

  The AD converter 110 performs processing (signal processing) for converting the input analog RGB signal and the synchronization signal into digital RGB signals, and transmits the digital RGB signals to the main signal processing unit 113.

  The USB connector 107 is connected to an external memory such as a removable USB memory. A JPEG image file (image signal) from the external memory is transferred to the image file processing unit 111 and temporarily stored in the volatile RAM 112. The image file processing unit 111 performs processing (signal processing) for decoding the JPEG image file stored in the volatile RAM 112 and converting it into a digital RGB signal. This digital RGB signal is transmitted to the main signal processing unit 113. The image file processing unit 111 performs read / write processing (signal processing) with the volatile RAM (SDRAM) 112 functioning as a frame buffer for the decoded data.

  The main signal processing unit 113 performs signal processing such as digital zoom processing, trapezoidal correction processing, and resolution conversion processing on the input digital RGB signal. The digital RGB signal subjected to these processes is transmitted to the color correction processing unit 115. The main signal processing unit 113 performs data read / write processing with a volatile RAM (SDRAM) 114 existing as a frame buffer before each of the above-described processing.

  The projector of this embodiment includes a liquid crystal panel (which may be a reflection type or a transmission type) 130 as a liquid crystal display element.

  The color correction processing unit 115 corrects the color processing corresponding to each pixel of the liquid crystal panel 130 in the input digital RGB signal and the color unevenness unique to the liquid crystal panel 130 according to the γ value. For the purpose. At this time, the color correction processing unit 115 uses γ conversion data and color unevenness correction data stored in the nonvolatile RAM 114. The processed digital RGB signal is transmitted to the panel processing unit 117. The panel processing unit 117 converts the input digital RGB signal into an analog signal, and applies a voltage corresponding to the analog signal to the liquid crystal panel 130. Thereby, an image corresponding to the input image signal is displayed.

  The optical processing unit 118 controls zoom and focus of a projection lens (not shown). The optical processing unit 118 also controls a light source lamp that emits illumination light that illuminates the liquid crystal panel 130. Furthermore, the optical processing unit 118 also controls a filter for adjusting the color space.

  FIG. 2 shows an example of a printed circuit board that realizes the function of the portion surrounded by a dotted line in FIG. The upper diagram in FIG. 2 shows one mounting surface (hereinafter referred to as A surface) of the printed circuit board, and the lower diagram illustrates the other mounting surface (hereinafter referred to as B surface) of the printer substrate. In FIG. 2, the constituent elements having the same reference numerals as those in FIG. 1 realize the function shown in FIG. 1 with one IC.

  An LSI 201 has functions of the control unit 101 and the main signal processing unit 113. 202 is for connecting the printed circuit board to another printed circuit board (a circuit board on which an IC or LSI having the functions of the color correction processing unit 115, the panel processing unit 117, and the optical processing unit 118 shown in FIG. 1 is mounted). This is the connector used. Note that wiring on the printed circuit board and chip elements and other electrical components not shown in FIG. 1 are omitted in FIG.

  As shown in FIGS. 1 and 2, the path for processing the image signal and the IC as the signal processing unit for processing the image signal differ depending on the connector 104 to 106, 107 that receives the input image signal. In other words, the HDMI / DVI receiver IC 108, the AD converter IC 110, and the image file processing IC 111 process these when an image signal is input, and do not perform these processes unless an image signal is input.

  Accordingly, the position of heat generation on a printed circuit board (hereinafter simply referred to as a substrate) differs depending on the IC that processes the input image signal. For example, when the TMDS digital signal from the HDMI connector 104 is processed by the HDMI / DVI receiver IC 108 and when the analog RGB signal from the D-sub 15-pin connector 106 is processed by the AD converter IC 110, the heat generation position on the substrate A surface Is different. Also, when the TMDS digital signal input from the HDMI connector 104 is processed by the HDMI / DVI receiver IC 108 and when the image data input from the USB connector 107 is processed by the image file processing IC 111, the heat generation position is opposite to the substrate. Become side.

  Although not shown in FIG. 2, if a regulator that supplies power to each IC is mounted on the substrate, the mounting position of the power supply regulator is also a heat generation position.

  Further, even if the connector that receives the input image signal is the same, the type of the image signal is different, so that the IC that processes it is also different, and as a result, the heat generation position is different. For example, the DVI connector 105 is a connector that supports both TMDS digital signals and analog RGB signals. However, ICs that process TMDS digital signals and analog RGB signals are processed differently (HDMI / DVI receiver IC 108 and AD converter IC 110).

  Further, when ICs are arranged at positions close to each other, the heat generation position on the substrate can be regarded as the same regardless of which IC generates heat. Of course, when processing with the same IC, heat generation on the substrate is possible. The position does not change. However, even in these cases, the amount of heat generated varies depending on the type of the input image signal. Furthermore, VGA and WUXGA have different IC loads for processing image signals. This is because the resolution differs between VGA and WUXGA, and the amount of image data to be processed differs for each frame time, so the amount of heat generated varies depending on the difference in the amount of image data.

  In an IC to which a memory such as an SDRAM is connected, power consumption occurs due to the switching operation of the memory connection IO port. In particular, when the image data is read / written to the memory, the power consumption increases when the data bus is always switched to perform the Hi / Lo transition. For example, when 1-dot image data is represented by RGB data 0 to 255, when processing image data such as black and white vertical stripes, all data of RGB data is always accessed when memory is accessed. Since the bus switches, the power consumption increases. On the other hand, when processing black image data, the data bus always has the IO port Lo, reducing the power consumption. That is, the amount of heat generation varies depending on the contents of the image data to be processed (that is, the contents of the input image signal).

  As described above, the position and amount of heat generation on the printed circuit board vary depending on the connector that receives the input image signal, the IC that processes the connector, the type, format (resolution, etc.) and content of the input video signal. Therefore, in order to efficiently cool each IC without adding a temperature sensor, it is appropriate to employ the control of the fans 120 and 121 as described below.

  FIG. 3 shows the cooling structure in this embodiment, that is, the arrangement of a plurality of fans (the first fan 120 and the second fan 121) with respect to the substrate. FIG. 3 is a view of the substrate as viewed from a direction parallel to the A surface (lower surface) and the B surface (upper surface). The first fan 120 is arranged on the downstream side of the air (wind or airflow) flowing along the A-side and B-side with respect to the substrate, and sucks the air after cooling each IC to remove it from the projector casing. To discharge. The second fan 121 is disposed on the upstream side of the air flowing along the board with respect to the board, sucks air inside or outside the housing of the projector, and blows air toward the B surface of the board. Blow out.

  As shown in FIG. 2, an image file processing IC 111 for processing an image file from the USB memory is arranged on the opposite side of the board with respect to the HDMI / DVI receiver IC 108 and the AD converter IC 110. Therefore, when the image file processing IC 111 is cooled, it is necessary to use a cooling method different from that for cooling the HDMI / DVI receiver IC 108 and the AD converter IC 110.

  The fan control when the image file processing IC 111 mounted on the B surface of the board is cooled will be described with reference to the flowchart of FIG. Here, it is assumed that the fans 120 and 121 shown in FIG. 3 are rotating at a predetermined rotational speed.

  The control unit 101 performs the following control according to the computer program. This is the same in other embodiments described later.

  In step S <b> 601, the control unit 101 detects whether a USB memory is connected to the USB connector 107. If the USB memory is not connected, the rotation speed of the second fan 121 is not changed. If the USB memory is connected, the process proceeds to step S602.

  In step S602, the control unit 101 checks whether there is an image file that can be displayed in the external memory through the image file processing unit 111. Specifically, the control unit 101 causes the image file processing unit 111 to access an external memory and search for a file in the unit memory. Thus, the presence or absence of an image file that can be displayed in the external memory is checked. If there is no image file that can be displayed, the rotational speed of the second fan 121 is not changed. Further, the rotational speed of the first fan 120 is not changed. If there is a displayable image file, the process proceeds to step S603.

  In step S603, if there is an image file that can be displayed, the control unit 101 generates heat when the image file processing unit 111 loads, decodes, and transmits data, and thus increases the rotation speed of the second fan 121. (Change). In this case, the rotation speed of the first fan 120 is not changed. Then, the process proceeds to next Step S604.

  In step S604, the control unit 101 causes the image file processing unit 111 to load the image file into the volatile RAM 112. Then, the process proceeds to the next step 605.

  In step S605, the control unit 101 causes the image file processing unit 111 to decode the image file captured in the previous step. In the decoding process, the JPEG image file is converted into YUV or RGB color data by either hardware or software. The decoded image file may be temporarily stored in the volatile RAM 112 as a buffer.

  Next, in step S606, the control unit 101 transfers the data decoded and processed in step S605 to the main signal processing unit 113 in the subsequent stage. Then, this process ends.

  As described above, when the displayable image file in the USB memory connected to the USB connector 107 is displayed, the rotation speed of the second fan 121 is increased. In other words, in accordance with the image file processing unit 111 to which an image signal is input among a plurality of signal processing ICs (signal processing units), the second one that is one of the first and second fans 120 and 121. Only the rotation speed of the fan 121 is increased. As a result, when the image file processing unit 111 does not process an image file, the rotation speed of the second fan 121 can be lowered to suppress power consumption and noise generation. Further, when the image file processing unit 111 processes an image file, the rotation speed of the second fan 121 can be increased to cool the image file processing unit 111 efficiently.

  In addition, when a video signal is input from the HDMI connector 104, the DVI connector 105, and the D-sub 15-pin connector 106, it is necessary to efficiently cool the HDMI / DVI receiver 108 and the AD converter 110 that process the video signals and generate heat. . For this reason, the rotation speed of the first fan 120 is increased. That is, the rotational speed of one of the first and second fans 120 and 121 (first fan 120) is increased according to the IC that processes the image signal among the plurality of signal processing ICs.

  In this way, by changing the rotation speed of the fans 120 and 121 according to the signal processing IC that processes the input image signal among the plurality of signal processing ICs, the signal can be generated while suppressing unnecessary power consumption and noise generation. The signal processing IC that generates heat due to the processing can be efficiently cooled.

  In order to detect (determine) an IC that processes an image signal among a plurality of signal processing ICs, it may be detected whether a cable or a USB memory is connected to the connector, or the image signal is actually connected to the IC. May be detected.

  A projector that is Embodiment 2 of the present invention will be described below. The configuration of the projector of the present embodiment is the same as the configuration shown in FIGS. 1 to 3 in the first embodiment. For this reason, in this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment.

  As shown in FIG. 2, the AD converter 110 and the HDMI / DVI receiver 108 are mounted at positions close to each other on the same surface (A surface) of the printed circuit board. For this reason, whether the TMDS digital signal input from the DVI connector 105 is processed by the HDMI / DVI receiver 108 or the analog RGB signal input from the connector is processed by the AD converter 110, the same single fan rotation is performed. What is necessary is just to increase a number. In the present embodiment, these are cooled by increasing the rotation speed of the first fan 120 close to the AD converter 110 and the HDMI / DVI receiver 108.

  However, the amount of heat generated by the AD converter 110 and the amount of heat generated by the HDMI / DVI receiver 108 are different because the types of video signals to be processed are different. Furthermore, the amount of heat generated by the HDMI / DVI receiver 108 also varies depending on the format such as the resolution of the input video signal.

  The flowchart of FIG. 5 shows the procedure of fan control performed by the control unit 101 in this embodiment.

  In step S701, the control unit 101 analyzes whether the video signal input from the DVI connector 105 is a digital signal or an analog signal, that is, the type of the video signal. Then, the process proceeds to step S702.

  In step S702, the control unit 101 analyzes the format of the input video signal such as resolution and frequency. Then, the process proceeds to step S703.

  In step S703, the control unit 101 controls (increases or decreases) the rotation speed of the first fan 120 in accordance with the results analyzed in steps S701 and S702. Specifically, the rotational speed of the first fan 120 is set with reference to the set value corresponding to the analysis result among the set values of the fan control DA converter 119 stored as LTU in the nonvolatile RAM 103.

  According to this embodiment, by controlling the number of rotations of the first fan 120 according to the type and format of the image signal input to the same signal processing IC, it is possible to suppress unnecessary power consumption and noise generation. The signal processing IC can be efficiently cooled.

  In the present embodiment, the case where the rotation speed of the first fan 120 is controlled according to the type and format of the input image signal has been described. However, the first frequency is determined according to at least one of the type and format of the input image signal. The rotational speed of the fan 120 may be controlled.

  A projector that is Embodiment 3 of the present invention will be described below. The configuration of the projector of the present embodiment is the same as the configuration shown in FIGS. 1 to 3 in the first embodiment. For this reason, in this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment.

  As shown in FIG. 1, the image file processing unit 111 exchanges data with the volatile RAM 112. For this reason, wiring such as an address bus, a data bus, a control signal bus, and a clock is provided between the image file processing unit 111 and the volatile RAM 112.

  As described above, in the image file processing unit 111, one dot at the IO port connected to the volatile RAM 112 is determined according to the content of the image indicated by the input image signal (image file) (that is, the content of the input image signal). The power consumption due to the Hi / Lo transition for each data varies. In the present embodiment, when the image file processing unit 111 decodes an image file into RGB data, the rotational speed of the second fan 121 is set in accordance with the increase or decrease in power consumption by accessing the volatile RAM 112 (memory access). change.

  As a specific method for determining increase / decrease in power consumption due to memory access, there is a method for determining the size of an image file (file size, vertical / horizontal size, etc.). However, the content of the image file may be analyzed using a histogram or the like, and the increase or decrease in power consumption may be determined from the analysis result.

  The flowchart of FIG. 6 shows a fan control procedure performed by the control unit 101 in this embodiment.

  In steps S801 to S803, S807, and S808, processing similar to that in steps S601, S602, S604, S605, and S606 described in the first embodiment (FIG. 4) is performed. For this reason, here, the processing in steps S804 to S806, which is a feature of the present embodiment, will be described.

  In step S804, the control unit 101 analyzes the file size of the image file loaded into the volatile RAM 112 by the image file processing unit 111 and the vertical and horizontal size of the image described in the JPEG header.

  In step S805, the control unit 101 determines whether the size of the image file is larger than a predetermined threshold according to the analyzed file size and vertical / horizontal size. If it is larger, it is determined that the image file processing unit 111 is likely to generate heat due to memory access. If it is smaller than the predetermined threshold, the image file processing unit 111 determines that heat generation due to memory access is unlikely to occur. Further, in this step, it is determined whether or not the rotational speed of the second fan 121 needs to be increased or decreased based on the determination result.

  When the size of the image file is larger than a predetermined threshold and the current rotation speed of the second fan 121 is low, it is necessary to increase the rotation speed of the second fan 121. Conversely, when the image file size is smaller than the predetermined threshold and the current rotation speed of the second fan 121 is high, it is necessary to reduce the rotation speed of the second fan 121.

  In this way, if it is determined that there is no need to increase or decrease the rotational speed of the second fan 121, the process proceeds to step S807, and if it is determined that it is necessary, the process proceeds to S806.

  In step S806, the control unit 101 increases or decreases the rotational speed of the second fan 121 based on the determination result.

  As described above, in this embodiment, the rotational speed of the second fan 121 is controlled according to the size and content of the input image signal. Thereby, the image file processing unit 111 can be appropriately cooled with respect to the heat generation amount according to the size and content of the image. Of course, unnecessary power consumption and generation of noise can be suppressed by not increasing the number of rotations unnecessarily.

  In the present embodiment, the case where the rotation speed of the first fan 120 is controlled according to one of the size and content of the input image signal has been described. However, the first fan 120 is controlled according to both the size and content. The rotational speed may be controlled.

A projector that is Embodiment 4 of the present invention will be described below. The basic configuration of the projector of this embodiment is the same as that shown in FIGS. 1 and 2 in the first embodiment. However, the cooling structure in the present embodiment is provided with a duct 901 for controlling the flow path of the cooling air on the B surface of the printed board as shown in FIG. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment.

  As described in the first embodiment, the image file processing unit 111 as a signal processing IC that performs decoding processing and the like to display an image file in the USB memory is mounted with another signal processing IC on the printed circuit board. It is mounted on a B surface different from the A surface.

  The duct 901 provided on the B surface is provided with a lid (not shown) that can be opened and closed. By controlling the opening and closing of the lid, the first fan 120 sucks (draws in) the B surface side. ) The air volume can be controlled. Specifically, when the image file processing unit 111 processes an image file, the duct 901 is opened to increase the amount of air drawn by the first fan 120 from the B side.

  On the other hand, when the image file processing unit 111 does not process an image file, the lid of the duct 901 is closed to reduce the amount of air drawn by the first fan 120 on the B side, and drawn by the first fan 120 on the A side. Increase the amount of airflow. Thereby, the air volume which cools signal processing IC which processes an input image signal by the A surface side can be increased.

  In the present embodiment, the duct 901 and the control unit 101 that performs opening / closing control of the lid correspond to the flow path control means.

  The flowchart of FIG. 8 shows a fan control procedure performed by the control unit 101 in this embodiment. In this flowchart, steps S1002 to S1004 perform the same processing as steps S601 to S603 shown in the first embodiment (FIG. 4). For this reason, here, the processes in steps S1001 and S1005 to S1008, which are features of the present embodiment, will be described.

  In step S1001, the control unit 101 determines whether the interface selected by the user is USB. If it is USB, the process proceeds to step S1002, and if it is not USB, the process proceeds to step S1006.

  In Step S1005 from Step S1002 through Step S1003 and Step S1004 (increasing the rotation speed of the second fan 121), the control unit 101 opens the duct 901. Thereby, the air volume drawn into the 1st fan 120 by the B surface side of a board | substrate can be increased, and the cooling efficiency of the image file process part 111 can be improved. Therefore, the image file processing unit 111 can be sufficiently cooled without increasing the rotational speed of the second fan 121 so much in step S1004. Then, the process proceeds to step S1008.

  On the other hand, in step S1006, the control unit 101 controls the rotation speed of the second fan 121 to the rotation speed when cooling on the B surface side is almost unnecessary. For example, when the input interface is switched from USB to HDMI, the rotational speed is decreased. Further, when the input interface is switched from HDMI to DVI, the rotation speed is not changed.

  In step S1007, the control unit 101 closes the lid of the duct 901. As a result, the amount of air drawn into the first fan 120 on the B surface side decreases, and the amount of air drawn into the first fan 120 on the A surface side increases accordingly. Thereby, even if the rotation speed of the second fan 121 is not changed (or decreased) in step S1006, the signal processing IC provided on the A surface side can be sufficiently cooled. Then, the process proceeds to step S1008.

  In step S1008, the control unit 101 causes the signal processing IC to process the image signal in accordance with the input image signal (video signal or image file).

  As described above, according to the present embodiment, by changing the air flow path to the printed circuit board by opening and closing the lid of the duct 901, the cooling air can be efficiently supplied to the signal processing IC that needs to be cooled on the printed circuit board. Can be supplied.

  According to each of the above embodiments, an appropriate cooling air according to the position (heat generation position) and the heat generation amount is supplied to the signal processing IC that needs to be cooled on the printed circuit board without using a temperature sensor. can do. For this reason, unnecessary power consumption and noise increase due to unnecessary driving of the fan can be suppressed.

  In each of the embodiments described above, the cooling of the signal processing IC that processes the input image signal has been described. However, when the IC that controls the power supply to the signal processing IC generates heat, the power supply IC is also cooled together. You may do it.

  In each of the above embodiments, the case where two fans are provided to cool a plurality of signal processing ICs on the printed circuit board has been described. However, only one fan may be used. Also in this case, the rotational speed of the fan can be controlled as in the first to third embodiments. Further, similarly to the fourth embodiment, the duct lid can be opened and closed. Furthermore, the flow path of the cooling air can be changed by changing the direction of the fan. Of course, three or more fans may be used.

  Further, when a plurality of fans are used, the rotation of any one of the fans may be stopped.

  In each of the above embodiments, the case where a plurality of signal processing ICs are mounted on one printed board has been described. However, a plurality of printed boards may be provided, and a plurality of signal processing ICs may be separately mounted on each printed board. In each of the above embodiments, the case where the signal processing unit is configured by an IC has been described. However, the signal processing unit may be configured by an element other than the IC, such as an LSI.

  Further, in order to increase the projection image switching speed of the projector, the signal processing IC receives the input image signal but does not transmit the image signal to the subsequent stage (Hi-Z state). You may consider that fever occurs. In this case, the rotation speed of the fan and the opening / closing control of the duct lid may be controlled.

  Each embodiment described above is only a representative example, and various modifications and changes can be made to each embodiment in carrying out the present invention.

1 is a block diagram showing an electrical configuration of a projector that is Embodiment 1 of the present invention. FIG. 3 is a diagram illustrating a printed board on which the signal processing IC according to the first embodiment is mounted. FIG. 3 is a diagram illustrating an arrangement relationship between a printed circuit board and two fans that cool the printed circuit board according to the first embodiment. 3 is a flowchart illustrating fan control in the first embodiment. 9 is a flowchart showing fan control in a projector that is Embodiment 2 of the present invention. 10 is a flowchart showing fan control in a projector that is Embodiment 3 of the present invention. The figure which shows the arrangement | positioning relationship between the printed circuit board in the projector which is Example 4 of this invention, two fans which cool this, and a duct. 10 is a flowchart illustrating fan control in the projector according to the fourth embodiment.

  flowchart

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Control part 104 HDMI connector 105 DVI connector 106 D-sub 15 pin connector 107 USB connector 108 HDMI / DVI receiver 109 Synchronous signal processing part 110 AD converter 111 Image file processing part 113 Main signal processing part 115 Color correction processing part 117 Panel processing part 118 Optical Processing Unit 119 Fan Control DA Converter 120 First Fan 121 Second Fan 901 Duct

Claims (5)

An image projection device that projects an image according to an input image signal,
A plurality of signal processing units that respectively process the input image signals of different types;
A cooling structure for cooling the plurality of signal processing units by air flowing by rotation of a fan;
Control means for controlling the rotation of the fan,
The image projector according to claim 1, wherein the control unit changes a rotation speed of the fan in accordance with a signal processing unit that processes the input image signal among the plurality of signal processing units. The cooling structure includes a first fan and a second fan,
The control means changes the rotational speed of one of the first and second fans in accordance with a signal processing unit that processes the input image signal among the plurality of signal processing units. The image projection apparatus according to claim 1. An image projection device that projects an image according to an input image signal,
A signal processing unit that processes the input image signals of different types;
A cooling structure for cooling the signal processing unit with air flowing by rotation of the fan;
Control means for controlling the rotation of the fan,
The image projection apparatus, wherein the control means changes the number of rotations of the fan according to at least one of a type and a format of the input image signal. An image projection device that projects an image according to an input image signal,
A signal processing unit for processing the input image signal;
A cooling structure for cooling the signal processing unit with air flowing by rotation of the fan;
Control means for controlling the rotation of the fan,
The image projection apparatus, wherein the control means changes the number of rotations of the fan according to at least one of the content and size of the input image signal. An image projection device that projects an image according to an input video signal,
A plurality of signal processing units respectively processing a plurality of types of the input video signals;
A cooling structure for cooling the plurality of signal processing units by air flowing by rotation of a fan;
An image projection apparatus comprising: a flow path control unit that changes a flow path of the air in the cooling structure in accordance with a signal processing section that processes the input image signal among the plurality of signal processing sections.