JP5345098B2 - Projector with increased resistance to electrostatic noise - Google Patents

Description

  The present invention relates to a projector, and more particularly to a technique for preventing malfunction due to electrostatic discharge from an input / output terminal mounting portion with an external device.

  Conventionally, projectors for enlarging and projecting images such as personal computers and document cameras have been used. For this reason, the projector body is provided with a connection terminal for inputting a video signal (including an audio signal) from these devices.

  An electronic device such as a projector is operated by an operator. If the operator is charged with static electricity, the electronic device is exposed to electrostatic discharge (hereinafter also referred to as electrostatic noise). There is a case where the transistor of the built-in integrated circuit device is electrostatically damaged. In order to prevent such electrostatic breakdown, a protection element (protective diode or the like) for preventing electrostatic breakdown is generally provided in an integrated circuit device.

  On the other hand, although electrostatic breakdown of the transistor does not occur due to electrostatic discharge from the operator, malfunctions such as an abnormal display state of the display panel of the electronic device may occur. When such a malfunction occurs, the reliability of the electronic device is impaired. Therefore, in recent years, resistance to malfunction due to electrostatic discharge (ESD) (Electro Static Discharge Immunity) has been emphasized. For this reason, conventionally, various measures have been taken in integrated circuit devices to ensure a predetermined ESD immunity.

  As a conventional circuit for preventing malfunction caused by an ESD pulse, there is one disclosed in Patent Document 1, for example. In the technique described in Patent Document 1, when an abnormal signal is output from an output pin due to an ESD pulse, an abnormality of the output pin is detected via a feedback path, and a reset signal is generated. Therefore, the electronic device is recovered from the abnormal state by resetting the next-stage electronic device or the like.

JP 2003-234647 A

However, the technique described in Patent Document 1 has a problem in that it may not be effective for an electronic device that originally uses a reset signal.
For example, an electronic device may be configured with a single circuit board, but may be configured with a plurality of circuit boards according to functions, etc., and the plurality of boards must be returned to the initial state at the same timing and restarted. This is the case.

  That is, the function of the reset signal is for restarting the electronic device, and the original reset signal may require a reset signal to return the function provided in the electronic device to the initial state at the same timing. is there. In this case, the reset signal is generated by a circuit element mounted on a circuit board that realizes the main control function, and is supplied to not only the same board but also other circuit boards. In addition, since many signals are usually exchanged between the circuit boards, the reset signal is also connected by a cable (in many cases, a flat cable) together with these signals.

  In such an electronic device, the reset signal line is affected by electrostatic noise, causing fluctuations in the voltage level. As a result, when the threshold value is exceeded, this electronic signal is not generated even though no reset signal is actually generated. The device operates as if a reset signal was generated, and once returned to the initial state and started to operate, or in the worst case, when the reset signal is continuously generated, the initial state continues. It will also stop the original operation.

  Since the technology described in Patent Document 1 provides an ex-post remedy by detecting an abnormal signal from the output pin and resetting the next-stage circuit erroneously reset, such a technique is provided. The situation cannot be prevented.

  The present invention has been made to solve such problems, and it is an object of the present invention to provide a projector capable of preventing malfunction due to the influence of static noise entering the apparatus from a signal input terminal or the like. .

  The inventor of the present application applies a conductive paint that can obtain an equivalent effect even when the outer frame of an electronic device, which is usually used as a countermeasure against electrostatic noise, is made of a conductor from the viewpoint of weight. Since the method cannot be adopted from the viewpoint of manufacturing cost, it was decided to search for a solution on the assumption that a certain amount of static noise enters the inside of the apparatus.

  Therefore, after confirming what kind of phenomenon is caused to the device by generating electrostatic noise, we noticed that the same phenomenon occurred when the device was reset and malfunctioned due to electrostatic noise in the reset signal connection method. I thought that there might be a cause. Next, when checking the wiring of the reset signal, it was discovered that the reset signal was routed with a single wiring pattern and connected between the boards inside the device with a cable. Are considered to have caused voltage level fluctuations sufficient to invert the logic level by influencing each other and influencing each other, leading to the present invention.

The projector having improved electrostatic noise resistance according to the first aspect of the present invention is an image from a first circuit board that is connected to a first circuit board having an imaging means in a box that is not electromagnetically shielded by a cable. a projector comprising a second circuit board which receives the information processed into video for enlarging and projecting by adding a predetermined processing, generates a reset signal that triggers a restart circuit element of the second circuit board The reset signal generator that performs the output outputs the signal divided into at least two systems, supplies the reset signal of the first system to a predetermined circuit element of the second circuit board, and connects the reset signal of the second system to the cable. It connects to the said 1st circuit board via this.

  According to a second aspect of the present invention, there is provided a projector with increased resistance to electrostatic noise, wherein the processing generation unit for the video to be enlarged and projected by adding a predetermined process to the video information mounted on the second circuit board and the reset signal generation Is provided in the same FPGA, and the reset signal required during this period is connected only in this FPGA.

  According to the first and second aspects of the present invention, the necessary number of reset signals are generated, and the reset signals are connected to the necessary locations in different systems. Even if electrostatic noise is superimposed on the cable connecting the second circuit board, it is less likely to be linked to the electrostatic noise superimposed on the reset signal wiring pattern formed on the second circuit board. Therefore, it does not fall into the reset state. Therefore, it is possible to provide a projector with increased resistance to electrostatic noise.

  In particular, according to the second aspect of the present invention, the reset signal generation unit and the enlarged projection video processing generation unit formed on the second circuit board are formed by the same FPGA. Since the wiring pattern of the reset signal routed upward is reduced, it is less susceptible to the influence of electrostatic noise, so that a projector with improved resistance to electrostatic noise can be provided.

It is a schematic block diagram of the projector which becomes this invention. It is a figure which shows the connection of the reset signal between the schematic block of the projector which becomes this invention, and a block.

Next, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a projector according to the present invention, and FIG. 2 is a diagram showing a schematic block of the projector according to the present invention and a reset signal connection between the blocks.
The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not always.

  1 and 2, a projector 100 mainly includes a main substrate 1 having a function of controlling the whole, a CMOS substrate 2 having a function of imaging a document or the like placed on a placement table (not shown), and a main substrate 1. And a power supply board 3 having a function of supplying power to the CMOS substrate, a power supply board 31 having a function of supplying power for a lamp, an optical engine 32 having a function of optically enlarging and projecting an image, and a lens 33. .

  The main board 1 is provided with an RGB signal input terminal 23 for inputting video output from a personal computer, a DVD recorder or the like, and a video / audio input terminal (not shown). One video or audio is selected from the video and audio input from these terminals and the video input from the CMOS substrate 2 by the operator's selection.

  The main board 1 mainly includes a control unit 11, a first video input unit 12, a second video input unit 13, a frame memory 14, a DMD control unit 15, a fan control unit 16, a motor drive unit 17, and a lamp drive unit 18. . The CMOS substrate 2 mainly includes a CMOS sensor module 2a that generates an image based on charges obtained by a CMOS sensor that is a photoelectric conversion element, and is initialized by a reset signal from the main substrate 1 as necessary. . Further, the power supply board 3 receives commercial power and generates power used by the main board 1 and the CMOS board 2.

  The first video input unit 12 receives a video obtained by the CMOS sensor module 2a input via the cable 21 connecting the CMOS substrate 2 and the main substrate, and performs predetermined processing such as amplification and shading correction. This is sent to the control unit 11. The first video input unit 12 is initialized by a reset signal from the control unit 11. On the other hand, the second video input unit 13 receives an analog RGB video signal input from the personal computer 101 via the RGB signal input terminal 23, A / D converts it to digital video data, and sends the digital video data to the control unit 11. .

  The control unit 11 stores video data input using the memory control unit 11a in the frame memory 14 or stored in the frame memory 14 based on a program stored in the EEPROM by a CPU, EEPROM, RAM, or the like (not shown). The video data for each frame is read out and subjected to video processing such as resolution conversion to prepare video data to be enlarged and projected.

  In addition, video data to be enlarged and projected is sent to a DMD (digital micromirror device) control unit 15 to control a DMD (not shown) which is a light modulation element. In addition, power is supplied to a portion of the projector 100 that is at a high temperature (for example, a lamp serving as a light source and each part of the projector (constituting components such as the control unit 11, the frame memory 14, and the DMD control unit 15). The fan drive unit 16 that drives a fan (not shown) that generates cold air for cooling the power supply unit 3 to be supplied is controlled.

  In addition, a motor drive unit 17 that drives a motor (not shown) that rotates a color wheel (not shown) that rotates at a constant speed, with color filters corresponding to the three primary colors formed at a predetermined angular pitch. And a lamp driver 18 that drives a lamp (not shown) serving as a light source for modulating the video data together with the DMD controller 14.

  Further, the control unit 11 is provided with a reset signal generation unit 11b, which outputs reset 1 as a reset signal to the CMOS sensor substrate 2 and reset 2 to the first video input unit 12, and initializes them. As described above, the reset signal is common, but is a signal of a different system according to the CMOS sensor substrate 2, the first video input unit 12, and the like connected thereto. The control unit 11 is incorporated into an application-specific integrated circuit such as an FPGA (Programmable Logic Gate Array) that allows a user to freely set functions.

Next, the operation of the projector having such a configuration and the influence of electrostatic noise will be described.
When the projector 100 is turned on by operating a power switch (not shown), a reset signal is generated by the reset signal generation unit 11b, and the program operates to initialize the control unit 11 in response to the reset signal. Also, the generated reset signal is output to the CMOS substrate 2 and the first video input unit 12 in a separate system from the reset 1 and reset 2, respectively, and the CMOS sensor module 2a and the first video input unit 12 of the CMOS substrate 2 are initialized. Initialization is performed for each.

  In this way, when each is initialized, the lamp is turned on by the lamp driving unit 18 after a certain period of time, and the projector 100 becomes operable. Here, for example, when a personal computer is selected as video input, the video of the personal computer is input to the control unit 11, and under the control of the control unit 11, the memory control unit 11 a, the frame memory 14, the DMD control unit 15, and the motor drive unit. This image is enlarged and projected by 17 and the like operating as described above.

  In this way, it is assumed that when the projector 100 enlarges and projects the selected image, static noise is generated for some reason and enters the projector 100 through the RGB signal input terminal, for example. As described in the background art, this electrostatic noise affects the circuit elements mounted on the first and second circuit boards and the formed circuit pattern, and particularly in a cable or circuit pattern that is not shielded. Jump in and change the voltage of the signal flowing through it.

  Certainly, although this voltage variation occurs, it does not cause the logic level to be reversed, so that malfunction due to electrostatic noise is not caused. This is because, as described above, the reset signal having the greatest influence is divided into a separate system between the CMOS substrate 2 to be connected and the first video input unit 12, so that each reset signal line (wiring pattern or cable) is statically charged. This is because even if the noise jumps in, since it is a separate system, it does not affect each other, so synergistic effects can be reduced.

  In addition, since the circuit requiring the reset signal is formed in the same FPGA, it is not necessary to form the reset signal as a wiring pattern on the second circuit board, and it is difficult to be affected by electrostatic noise. It is.

By doing so, it is possible to provide a projector with high electrostatic noise resistance without forming the outer frame with a conductor or without applying a conductive paint even if it is not formed with a conductor.
It goes without saying that this method is suitable not only for projectors that are required to be compact, lightweight, and low cost, but also applicable to a wide range of general electronic devices.

1 main board, 2 CMOS board, 3 power supply board, 11 control unit,
11a memory control unit, 11b reset signal generation unit, 12 first video input unit,
13 Second video input unit, 14 frame memory, 15 DMD control unit,
16 fan drive unit, 17 motor drive unit, 18 lamp drive unit,
21 cable, 23 RGB signal input terminal, 31 power supply board for lamp,
32 optical engine, 33 lens, 100 projector

Claims (2)

Receiving video information from a first circuit board that is connected to a first circuit board that is provided with imaging means in a box that is not shielded by electromagnetic waves, a predetermined process is performed to process the image to be enlarged and projected. a projector comprising a second circuit board, the reset signal generator for generating a reset signal that triggers a restart circuit element of the second circuit board, and outputs divided into at least two systems The reset signal of the first system is supplied to a predetermined circuit element of the second circuit board, and the reset signal of the second system is connected to the first circuit board via a cable. A projector with increased resistance to electrostatic noise. The processing generation unit for video to be enlarged and projected by applying predetermined processing to video information mounted on the second circuit board and the reset signal generation unit are provided in the same FPGA, and the necessary reset signal is 2. The projector with improved resistance to electrostatic noise according to claim 1, wherein the projector is connected only within the FPGA.

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