JP2007304145A - Projector and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inexpensively and efficiently cool a heat generation part by controlling the flow of cooling air generated by a cooling fan without adding a member such as a heat insulating member and an air flow control plate or the like in an electronic apparatus such as a projector. <P>SOLUTION: A part or all of a light source driving circuit 23 and a power supply circuit 24 are provided at a position where cooling air generated by the cooling fan 3 does not directly blow off or hardly blows off, and a circuit board 26 on which a part or all of a DMD driving circuit 21 and a whole control circuit 22 are mounted is provided to form a predetermined angle θ to the rotary shaft 31 of the cooling fan 3 on the downstream side of the cooling air. The circuit board 26 is used as the air flow control plate, so that the cooling air is guided to the light source driving circuit 23 and the power supply circuit 24. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cooling structure for an electronic apparatus having a heat generating part such as a projector.

  Conventionally, various devices have been made to efficiently cool the heat generating portion of the electronic device. For example, in Patent Document 1, a closed space is formed by enclosing a space between an intake port and an exhaust port with a heat insulating member, and a substrate on which a heating element such as a switching element is mounted is generated and generated by a cooling fan. The cooling air is configured to directly hit the circuit board.

  In Patent Document 2, in an electronic device having a plurality of cooling fans, an air flow control plate is continuously connected to a plurality of cooling fans, and even if one cooling fan stops, another cooling fan is used. The heat generating part is cooled with the cooling air generated by the air and the electronic device can be used continuously.

  In Patent Document 3, the circuit board is divided into a high heat generation board portion with a large heat generation amount and a low heat generation substrate portion with a small heat generation amount, and a flow of cooling air flows between the high heat generation substrate portion and the low heat generation substrate portion through a heat insulating member. They are arranged side by side in a direction orthogonal to the direction.

  However, in the conventional electronic devices described in each patent document, a dedicated member is required to regulate the flow of cooling air, such as a heat insulating member and an air flow control plate, and this increases the cost of the electronic device. It was.

JP 2002-353676 A JP 2002-208791 A JP-A-6-61674

  The present invention has been made to solve the above-described problems of the conventional example, and controls the flow of cooling air generated by a cooling fan without adding a member such as a heat insulating member or an air flow control plate. An object of the present invention is to provide an electronic device such as a projector that is inexpensive and can efficiently cool a heat generating portion.

In order to achieve the above object, the invention of claim 1 is a color which is provided on the optical path of the light source and the light emitted from the light source, and color filters corresponding to the three primary colors are formed at a predetermined angular pitch and rotated at a constant speed. A light collecting member having at least a reflecting plate for condensing light emitted from the light source onto a part of the color wheel, and an optical path of a light beam transmitted through the color wheel; An assembly of two-dimensionally arranged micromirrors that changes the angle of the micromirrors according to a video signal input from the outside, and transmits the light beam transmitted through the color wheel in a predetermined direction and a direction other than the predetermined direction DMD (digital micromirror device) that reflects in the direction of the light beam, and a light beam that is disposed in the predetermined direction with respect to the DMD and reflected by the DMD on the screen A projection lens for shadowing, a DMD driving circuit for driving the DMD using the video signal, an overall control circuit for controlling the entire projector, a light source driving circuit for driving the light source, the DMD driving circuit, and the overall control A power supply circuit for supplying power to each part of the projector including a circuit and the light source driving circuit, a cooling fan for generating cooling air for cooling at least the light source and the power supply circuit, and a housing for housing the members. In the provided projector,
At least a part or all of the light source drive circuit and the power supply circuit are mounted on a first circuit board provided at a position where the cooling air generated by the cooling fan does not directly hit or is hard to hit,
At least part or all of the DMD drive circuit and the overall control circuit are mounted on a second circuit board different from the first circuit board on which the light source drive circuit and the power supply circuit are mounted,
The second circuit board is configured such that, on the downstream side of the cooling air, the soldered surface faces the cooling fan side, and the cooling air is supplied to the light source driving circuit and the power supply circuit on the first circuit board. It is provided so as to make a predetermined angle with respect to the rotation axis of the cooling fan so as to lead to a part or all of the cooling fan,
By using the second circuit board as an air flow control plate, it is possible to control the flow of cooling air generated by the cooling fan without adding a member such as a heat insulating member or an air flow control plate. In addition, the heat generating portion can be efficiently cooled.

  According to a second aspect of the present invention, in the electronic device having a cooling fan for generating cooling air, a circuit board on which electronic components are mounted, and a heat generating part, part or all of the heat generating part is generated by the cooling fan. The circuit board is provided at a position where the cooling air does not directly hit or is hard to hit, and the circuit board is arranged at a predetermined position with respect to the rotation axis of the cooling fan so as to guide the cooling air to the heat generating portion on the downstream side of the cooling air. It is provided to form an angle.

  According to a third aspect of the present invention, in the electronic device according to the second aspect, the circuit board is provided such that a soldered surface faces the cooling fan side.

  According to a fourth aspect of the present invention, in the electronic device according to the second or third aspect, the heat generating portion is a power supply circuit.

  According to the first aspect of the invention, in the projector, the second circuit board on which a part or all of the DMD driving circuit and the overall control circuit with a relatively small amount of heat generation are mounted is used as the air flow control board, and the cooling air is supplied. Since the light source driving circuit and the power supply circuit having a large amount of heat generated on the first circuit board are guided to a part or all of them, the cooling fan can be used without adding a member such as a heat insulating member or an air flow control plate. By controlling the flow of the cooling air generated by the above, it is possible to cool the heat generating portion efficiently at low cost. In addition, since the second circuit board is disposed so that the soldered surface faces the cooling fan side, the electronic components mounted on the second circuit board can also be efficiently cooled. Furthermore, since part or all of the light source drive circuit and the power supply circuit can be provided at a position where the cooling air generated by the cooling fan does not directly hit, the degree of freedom of component placement in the projector is increased, and the projector is reduced in size and weight. It is also possible to plan.

  According to the invention of claim 2, in general electronic equipment, a circuit board on which electronic components are mounted is used as an air flow control board, and the cooling air is guided to a heat generating part such as a power source or a light source. Without adding a member such as a heat insulating member or an air flow control plate, the flow of the cooling air generated by the cooling fan can be controlled, and the heat generating portion can be efficiently cooled at a low cost. In addition, the electronic components mounted on the circuit board are also cooled at the same time. Further, since the heat generating portion can be provided at a position where the cooling air generated by the cooling fan does not directly hit, the degree of freedom in designing the electronic device can be increased, and the size and weight can be reduced.

  According to the invention of claim 3, since the soldered surface of the circuit board is provided so as to face the cooling fan side, the electronic components mounted on the circuit board can also be efficiently cooled.

  Generally, in an electronic device equipped with a cooling fan, the cooling fan is provided close to the power supply unit. According to the invention of claim 4, the power supply circuit is provided at a position away from the cooling fan. Therefore, the degree of freedom in designing electronic devices can be increased.

  A projector and an electronic apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional plan view showing a configuration of a projector 1 which is an example of an electronic apparatus according to the invention. FIG. 2 is a cross-sectional view of the projector 1 as seen from the back side. Further, FIG. 3 is a block diagram showing a circuit configuration of the projector 1. The projector 1 is an apparatus that forms an image using a video signal (image data) input from a personal computer, a video camera, or the like, and magnifies and projects it on a screen provided in front.

  As shown in FIG. 1, the projector 1 is roughly disposed on the front side of the housing 2, forms an image using a video signal input from the outside, and enlarges and projects the image on a front screen; The control unit 20 is disposed on the rear side of the housing 2 and processes an image signal input from the outside to control the optical engine 10.

  The optical engine 10 includes, for example, a light source 11 such as a discharge lamp, and a reflecting plate (condensing member) 12 that reflects light emitted backward from the light emitted from the light source and condenses it in a predetermined region. A color wheel 13 provided on an optical path of light emitted from the light source 11 and having color filters corresponding to the three primary colors formed at a predetermined angular pitch and rotating at a constant speed; and a motor for rotating the color wheel 13 at a constant speed. 14, an optical tunnel 15 provided to face the light source with the color wheel 13 interposed therebetween, a mirror 16 that reflects a light beam that has passed through the optical tunnel in a predetermined direction, and the optical tunnel 15 and the mirror 16. Is a set of two-dimensionally arranged micromirrors that are provided on the optical path of the light beam that has passed through the color wheel 13 and enters from the outside. DMD (digital micromirror device) that changes the angle of the micromirror according to the received video signal and reflects the light beam transmitted through the color wheel 13 in a predetermined direction (first direction) and a second direction other than the predetermined direction 17 and a projection lens 18 that is arranged in the first direction with respect to the DMD 17 and projects the light beam reflected by the DMD 17 onto the screen.

  The reflecting plate 12 is formed in, for example, a spheroid shape, the light source 11 is disposed in the vicinity of one focal point of the spheroid surface, and a part of the color wheel 13 is positioned in the vicinity of the other focal point of the spheroid surface. Is arranged. In the drawing, the right side of the color wheel 13 is configured as an independent unit as a light source unit, and the inner surface of the light source unit is mirror-finished, for example, in order to collect more light on the color wheel 13. On the other hand, the left side of the light tunnel 15 is formed as a dark box unit for reducing the influence of stray light, and the inner surface of the dark box unit is coated with an antireflection coating so as to absorb the reflected light. 1 and 2, the partition plate 4 drawn so as to partition the inside of the housing 2 into the optical engine 10 side and the control unit side 20 does not actually have such a partition plate 4. The walls of the light source unit and the housing of the dark box unit are schematically drawn.

  On the other hand, the control unit 20 uses a video signal to drive the DMD 17, a DMD drive circuit 21 that controls the entire projector 1, a light source drive circuit 23 that drives the light source 11, and a DMD drive circuit 21. A power supply circuit 24 for supplying power to each part of the projector 1 including the overall control circuit 22 and the light source drive circuit 23, and a cooling fan 3 for generating cooling air for cooling at least the light source 11 and the power supply circuit 24. is doing. The DMD drive circuit 21 and the overall control circuit 22 are constituted by, for example, a CPU, a ROM, a RAM, and the like. Further, a noise removal filter or the like is provided as necessary. The light source driving circuit 23 is an inverter circuit for controlling the light source 11 such as a discharge lamp so that electric power is constant, and is configured by a coil, a diode, an FET, and the like. Since the discharge lamp has a low temperature and a low voltage immediately after the start of lighting, there is a problem that if the electric power is controlled to be constant, a large current flows through the lamp and the lamp life is shortened. For this reason, the light source driving circuit 23 performs a warm-up operation for limiting the current flowing through the lamp for a certain time from the start of lamp lighting. The power supply circuit 24 is a circuit that generates a DC voltage power source such as 12 V or 24 V, for example, using an AC commercial power source such as 100 V or 200 V as an input, and is configured by a coil, a diode, an FET, or the like.

  In general, components constituting the light source driving circuit 23 and the power supply circuit 24 are larger and heavier than a CPU, ROM, RAM, or the like. Therefore, as shown in FIG. 2, the components of the light source drive circuit 23 and the power supply circuit 24 are mounted on a first circuit board 25 provided near the bottom of the housing 2. On the first circuit board 25, components constituting the circuit 27 other than the light source driving circuit 23 and the power supply circuit 24 are also mounted. On the other hand, the components constituting the DMD drive circuit 21 and the overall control circuit 22 are smaller and lighter than the components constituting the light source drive circuit 23 and the power supply circuit 24. Therefore, the components of the DMD driving circuit 21 and the overall control circuit 22 are mounted on a second circuit board 26 different from the first circuit board 25 on which the light source driving circuit 23 and the power supply circuit 24 are mounted.

  It is not necessary that all the components of the light source drive circuit 23 and the power supply circuit 24 are mounted on the first circuit board 25, and only one or both of the light source drive circuit 23 and the power supply circuit 24 are the first. It may be mounted on the circuit board 25 and the rest may be mounted on another circuit board (not shown). Similarly, it is not necessary that all of the components of the DMD drive circuit 21 and the overall control circuit 22 are mounted on the second circuit board 26, and only a part of one or both of the DMD drive circuit 21 and the overall control circuit 22 is not required. May be mounted on the second circuit board 26, and the rest may be mounted on another circuit board (not shown).

  As shown in FIGS. 1 and 2, the cooling fan 3 takes in air from the outside of the housing 2 into the inside of the housing 2, and generates heat generated from a heat source such as the light source 11, the light source driving circuit 23, and the power supply circuit 24. The hot air that has been absorbed and whose temperature has risen is exhausted to the outside of the housing 2. In the configuration shown in FIG. 1, a part of the cooling air generated by the cooling fan 3 is introduced to the optical engine 10 side, and the rest is introduced to the control unit 20 side. As described above, part or all of the light source driving circuit 23 and the power supply circuit 24 are mounted on the first circuit board 25 provided near the bottom of the housing 2, and the first circuit board 25 has a light source driving function. Since components constituting the circuit 27 other than the circuit 23 and the power supply circuit 24 are also mounted, they are provided at positions where the cooling air generated by the cooling fan 3 is not directly hit or hit.

  In the present embodiment, the second circuit board 26 is provided on the downstream side of the cooling air so as to form a predetermined angle θ (for example, about 15 to 45 degrees) with respect to the rotating shaft 31 of the cooling fan 3, thereby The cooling air is configured to be guided to part or all of the light source driving circuit 23 and the power supply circuit 24 on the first circuit board 25. That is, by using the second circuit board 26 as an air flow control plate, the flow of the cooling air generated by the cooling fan 3 without adding a member such as a heat insulating member or an air flow control plate as in the conventional example. And the light source driving circuit 23 and the power supply circuit 24, which are heat generating parts, are efficiently cooled.

  The second circuit board 26 is mounted with the CPU, ROM, RAM, noise removal filter, and the like that constitute the DMD driving circuit 21 and the overall control circuit 22 as described above. Generally, when a small semiconductor component such as a CPU, ROM, or RAM is mounted on a circuit board, a solder chip is sandwiched between the electronic component and the circuit board, and the solder is reflowed by heating in that state. . In this case, since the mounting surface of the electronic component coincides with the soldering surface, the electronic component mounted on the second circuit board 26 is directed by directing the soldered surface of the second circuit board 26 toward the cooling fan 3 side. Also, it can be cooled by the cooling air generated by the cooling fan 3. If the temperature of the semiconductor component becomes too high, the performance may be degraded, and further, the semiconductor component may become inoperable. Therefore, a certain performance can be maintained by cooling.

  On the other hand, when relatively large components such as noise filters, connectors, and switches are mounted on the circuit board, the components are mounted by penetrating the terminals of these components from the component mounting surface side to the soldering surface side. In this state, the soldering side of the circuit board is immersed in a molten solder bath for soldering. In this case, when the mounting surface of these electronic components is directed toward the cooling fan 3, the electronic components are directly cooled by the cooling air, but the flow of the cooling air is disturbed by these electronic components. Therefore, there is a possibility that the second circuit board 26 cannot sufficiently exhibit the function as an air flow control plate, and the light source driving circuit 23 and the power supply circuit 24 that are heat generating portions cannot be efficiently cooled. Therefore, in any case, the second circuit board 26 is preferably fixed so that the soldered surface faces the cooling fan 3 side.

  Note that the present invention is not limited to the projector described in the above embodiment, and can be applied to general electronic devices including a heat generating unit and a cooling fan. That is, in an electronic device having a cooling fan that generates cooling air, a circuit board on which electronic components are mounted, and a heat generating part, a part or all of the heat generating part is not directly exposed to the cooling air generated by the cooling fan. The circuit board may be provided at a position so as to form a predetermined angle with respect to the rotation axis of the cooling fan so as to guide the cooling air to the heat generating portion on the downstream side of the cooling air.

  In general electronic equipment, if a circuit board on which electronic components are mounted is used as an air flow control plate and cooling air is guided to a heat generating part such as a power source or a light source, a member such as a heat insulating member or an air flow control plate Therefore, the flow of the cooling air generated by the cooling fan is controlled, and the heat generating portion can be efficiently cooled at a low cost. In addition, the electronic components mounted on the circuit board are also cooled at the same time. Further, since the heat generating portion can be provided at a position where the cooling air generated by the cooling fan does not directly hit, the degree of freedom in designing the electronic device can be increased, and the size and weight can be reduced.

1 is a plan sectional view showing a configuration of a projector according to an embodiment of the invention. Sectional drawing which looked at the said projector from the back side. The block diagram which shows the circuit structure of the said projector.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projector 2 Housing 3 Cooling fan 10 Optical engine 11 Light source 12 Reflector 13 Color wheel 14 Motor 15 Optical tunnel 16 Mirror 17 DMD (digital micromirror device)
18 Projection lens 20 Control unit 21 DMD drive circuit 22 Overall control circuit 23 Light source drive circuit 24 Power supply circuit 25 First circuit board 26 Second circuit board 31 Rotating axis θ (of cooling fan) θ Predetermined angle

Claims (4)

A light source;
A color wheel provided on the optical path of the light emitted from the light source, the color filters corresponding to the three primary colors are formed at a predetermined angular pitch, and rotated at a constant speed;
A condensing member including at least a reflector for condensing light emitted from the light source onto a part of the color wheel;
An assembly of two-dimensionally arranged micromirrors provided on an optical path of a light beam transmitted through the color wheel, and changing the angle of the micromirrors according to an image signal input from the outside, DMD (digital micromirror device) that reflects the light beam transmitted through the color wheel in a predetermined direction and a direction other than the predetermined direction;
A projection lens disposed in the predetermined direction with respect to the DMD and projecting a light beam reflected by the DMD onto a screen;
A DMD driving circuit for driving the DMD using the video signal;
An overall control circuit for controlling the entire projector;
A light source driving circuit for driving the light source;
A power supply circuit for supplying power to each part of the projector including the DMD drive circuit, the overall control circuit, and the light source drive circuit;
A cooling fan that generates cooling air for cooling at least the light source and the power supply circuit;
In a projector provided with a housing for storing each member,
At least a part or all of the light source drive circuit and the power supply circuit are mounted on a first circuit board provided at a position where the cooling air generated by the cooling fan does not directly hit or is hard to hit,
At least part or all of the DMD drive circuit and the overall control circuit are mounted on a second circuit board different from the first circuit board on which the light source drive circuit and the power supply circuit are mounted,
The second circuit board is configured such that, on the downstream side of the cooling air, the soldered surface faces the cooling fan side, and the cooling air is supplied to the light source driving circuit and the power supply circuit on the first circuit board. It is provided so as to make a predetermined angle with respect to the rotation axis of the cooling fan so as to lead to a part or all of the cooling fan,
By using the second circuit board as an air flow control plate, it is possible to control the flow of cooling air generated by the cooling fan without adding a member such as a heat insulating member or an air flow control plate. A projector characterized in that the heat generating part can be cooled efficiently. In an electronic device having a cooling fan that generates cooling air, a circuit board on which electronic components are mounted, and a heat generating part,
A part or all of the heat generating part is provided at a position where the cooling air generated by the cooling fan does not directly hit or is hard to hit,
The circuit board is provided on the downstream side of the cooling air so as to form a predetermined angle with respect to the rotation axis of the cooling fan so as to guide the cooling air to the heat generating portion. machine.   The electronic device according to claim 2, wherein the circuit board is provided such that a soldered surface faces the cooling fan side.   The electronic device according to claim 2, wherein the heat generating unit is a power circuit.

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