CN112782917A

CN112782917A - Image projection apparatus

Info

Publication number: CN112782917A
Application number: CN202011179983.1A
Authority: CN
Inventors: 藤沼繁; 根本贵章
Original assignee: Ricoh Industrial Solutions Inc
Current assignee: Ricoh Co Ltd
Priority date: 2019-11-01
Filing date: 2020-10-29
Publication date: 2021-05-11
Anticipated expiration: 2040-10-29
Also published as: JP7394586B2; CN112782917B; JP2021071690A

Abstract

The invention provides an image projection apparatus which can prevent the temperature rise of the image projection apparatus and the invasion of dust, the image projection apparatus (1) comprises: an illumination optical system (4) for generating illumination light; an image display element (51) for modulating the illumination light to produce projection light; a projection optical system (6) for amplifying the projection light; a case (2) for hermetically accommodating the illumination optical system (4), the image display element (51), and the projection optical system (6) therein; a heat conduction unit (3A) for conducting heat from a heat source inside the case (2); and a heat dissipation part (3) provided outside the housing (2).

Description

Image projection apparatus

Technical Field

The present invention relates to an image projection apparatus such as a projector for projecting an image onto a screen or the like.

Background

The image projection apparatus includes a control unit for controlling the image display element in addition to the light source and the image display element. These light source, image display element, and control unit generate heat, and the image projection apparatus may be damaged if the inside of the image projection apparatus becomes high in temperature.

Therefore, in the image projection apparatus, the intake fan and the exhaust fan are disposed inside the casing, and the casing is provided with a plurality of holes for taking in air from the outside and for letting out air to the outside.

When the hole is provided in the housing in this manner, dust floating outside the image projection apparatus enters through the hole. When dust enters and adheres to a substrate of the control unit, the part may be damaged due to high temperature. Further, the transmittance of the optical member is lowered, and thus deterioration of image quality may occur.

Therefore, conventionally, there is an image projection apparatus which implements the following measures (see patent document 1): a dust-proof filter is attached to the air inlet, or the interior of the housing is partitioned into a region where the optical component is disposed and a region where the control unit is disposed, and the dust-proof property of the region where the optical component is disposed is improved.

< Prior Art document >

< patent document >

Patent document 1: japanese unexamined patent publication No. 2016-080957

Disclosure of Invention

< problems to be solved by the present invention >

However, the above-mentioned conventional techniques cannot completely prevent the intrusion of dust into the housing, and when the image projection apparatus is used outdoors, particularly in a space where a large amount of dust is present, the temperature abnormality of the image projection apparatus is detected, and the operation is stopped, thereby causing the performance of the image projection apparatus to deteriorate.

An object of the present invention is to provide an image projection apparatus capable of preventing dust from entering while preventing a temperature rise of the image projection apparatus.

< means for solving the problems >

The present invention provides an image projection apparatus, including: an illumination optical system for generating illumination light; an image display element for modulating the illumination light to produce projection light; a projection optical system for amplifying the projection light; a housing for hermetically accommodating the illumination optical system, the image display element, and the projection optical system therein; a heat conduction portion for conducting heat from a heat generation source inside the case; and a heat dissipation portion provided outside the housing.

The heat radiating unit may include an intake fan, an exhaust fan, and a heat sink.

Preferably, the intake fan and the exhaust fan are not disposed in the casing, and the intake port and the exhaust port are not provided in a wall portion of the casing.

Preferably, a control board for controlling the image projection apparatus is disposed inside the housing.

Preferably, the heat conduction unit conducts heat from the heat source to a rear surface of the housing opposite to a front surface on which the projection light is irradiated.

A recess may be provided in a rear surface of the housing, and the heat dissipation portion may be disposed in the recess.

The heat source may include a light source of the illumination optical system and the image display element, and the light source and the image display element may be disposed on an inner surface of a portion of the housing where the recess is provided.

The heat generating source may include a main substrate, and the main substrate may be disposed on an inner surface of a portion of the case where the recess is not provided.

< effects of the invention >

According to the present invention, there is provided an image projection apparatus capable of preventing dust from entering while preventing a temperature rise of the image projection apparatus.

Drawings

Fig. 1 is a perspective view of an image projection apparatus 1 according to an embodiment.

Fig. 2 is a block diagram of the image projection apparatus 1.

Fig. 3 is a front view of the image projection apparatus 1 in a state where the front case 2F is removed.

Fig. 4 is an exploded perspective view of the image projection apparatus 1.

Fig. 5 is a diagram illustrating a heat dissipation structure of the image projection apparatus 1.

Detailed Description

The image projection apparatus 1 according to the embodiment of the present invention will be described below.

Fig. 1 is a perspective view of an image projection apparatus 1 according to an embodiment. The image projection apparatus 1 is a substantially rectangular parallelepiped, and includes a casing 2 and a heat dissipation portion 3 disposed outside the casing 2. The case 2 has a front case 2F and a rear case 2B, which are made of metal respectively, and have high thermal conductivity. Fig. 2 is a block diagram of an image projection apparatus. Fig. 3 is a front view of the image projection apparatus 1 in a state where the front case 2F is removed. Fig. 4 is an exploded perspective view of the image projection apparatus 1.

The image projection apparatus 1 includes a housing 2 and a heat dissipation portion 3 disposed outside the housing 2. The image projection apparatus 1 further includes, inside the casing 2, an illumination optical system 4, an image display unit 5, a projection optical system 6, a concave mirror 7, an interface unit 9, and a control unit 8 for controlling these components.

(front case 2F)

The front case 2F on the front surface side of the case 2 is provided with: an opening 25 for irradiating projection light; and an adjustment hole 21 for operating a focus adjustment unit 61, which will be described later, provided in the projection optical system 6 from the outside.

Hereinafter, as shown in the drawing, the side of the housing 2 where the opening 25 is provided is set to the front side, and the opposite side thereof is set to the rear side, the traveling direction of the projection light in the optical axis OA of the projection optical system 6 is set to the upper side (enlargement side), and the opposite side thereof is set to the lower side (reduction side), and the description will be given by setting the image projection apparatus 1 to the upper and lower sides and the left and right sides when viewed from the front side as the left and right sides.

As shown in fig. 1, a transparent member 27 such as a glass plate is attached to the opening 25 of the front case 2F, and a lid 26 is attached to the adjustment hole 21. The lid 26 allows the adjustment hole 21 to be opened and closed.

(rear case 2B)

As shown in fig. 3 and 4, a groove portion 22 is provided at the outer peripheral edge of the rear case 2B on the rear surface side of the case 2, and an elongated sealing member 23 having elasticity is disposed in the groove portion 22. An internal space 2Ba having a predetermined depth and in which the projection optical system 6 and the concave mirror 7 are disposed is provided in an upper portion of the rear case 2B. A substantially plate-shaped mounting base 2Bb on which the illumination optical system 4 and the image display unit 5 are disposed is provided at a lower portion of the rear case 2B.

In a state where the sealing member 23 is disposed in the groove portion 22 of the rear case 2B, the front case 2F is disposed in front of the rear case 2B, and is fixed by screws 24 around the front case 2F and the rear case 2B so as to be closely joined to each other, thereby achieving a state of fig. 1 where the front case 2F and the rear case 2B are fixed to each other. At this time, the opening 25 of the front case 2F is sealed by the transparent member 27, and the interface 9 is also attached to the case 2 in a dust-proof manner. Thus, when the adjustment hole 21 is closed by the lid 26, no other hole is present in the front case 2F or the rear case 2B, and the inside of the case 2 is in a sealed state in which dust does not enter from the outside.

In the case 2 in the assembled state, the upper portion of the internal space 2Ba is thick (the front-rear width is large) and the lower portion is thin (the front-rear width is small), and the lower portion thereof is provided with a recess P which is a space where the heat dissipation portion 3 can be disposed by recessing the rear side of the mounting table 2 Bb. When the heat dissipation portion 3 is disposed in the recess P, the entire case 2 and the heat dissipation portion 3 are substantially rectangular. Therefore, the heat dissipation portion 3 does not protrude from the housing 2, and does not become an obstacle when the image projection apparatus 1 is installed.

(illumination optical System 4)

The illumination optical system 4 is a light source, for example, an LED having three colors of RGB. However, the light source is not limited to this, and for example, an ultra-high pressure mercury lamp or a laser may be used. In the illumination optical system 4, light including R light, G light, and B light generated by the light source is incident on the image display unit 5.

(image display section 5)

The image display unit 5 includes an image display element (light modulation element) 51 and a prism 52 (only a reflection surface is displayed).

(image display element 51)

The image display element 51 is, for example, a DMD (digital micromirror device). The DMD has a substantially rectangular mirror surface constituted by a plurality of micromirrors, and generates predetermined projection light by time-division driving each micromirror based on data received from the control section 8 and modulating the illumination light generated by reflection in the illumination optical system 4, and causes the projection light to enter the projection optical system 6.

In the embodiment, the image display element 51 is formed using a DMD, but the DMD is not limited to this, and a liquid crystal panel, a light emitting element array in which minute light emitting elements are two-dimensionally arrayed, or the like can be suitably used.

(prism 52)

The prism 52 is a cross dichroic prism that directs the illumination light generated by the illumination optical system 4 toward the image display element 51 and reflects the projection light made by the image display element 51 to the projection optical system.

(projection optical System 6)

The projection optical system 6 is omitted in fig. 5, but the projection optical system 6 has a plurality of lens groups. The projection optical system 6 will be described in detail later. The lens groups are arranged along the optical axis OA centered on the optical axis OA, and are used to enlarge an image generated by the image display element 51.

(concave reflecting mirror 7)

The concave mirror 7 reflects the projection light amplified by the projection optical system 6 to change its optical path, and guides the transmitted light to the projection surface through the light transmitting member 27. Thereby, an image or video can be projected at a very wide angle.

(Heat radiating section 3)

As shown in fig. 4, the heat dissipation unit 3 includes one intake fan 31, two exhaust fans 32, and a heat sink 33, and is disposed in a recess P outside the casing 2. However, the number of the suction fan 31 and the exhaust fan 32 is not limited thereto. In the embodiment, the intake fan 31 is installed on the left side and the exhaust fan is installed on the right side, but the present invention is not limited thereto, and the reverse may be applied.

The heat sink 33 includes a plurality of plate-shaped fins arranged in parallel with each other. In the radiator 33, the fins 33a are arranged in a direction (extending left and right) from the intake fan 31 toward the exhaust fan 32, so that air flows between the plurality of fins 33 between the intake fan 31 and the exhaust fan 32.

The flow of air discharged from the heat dissipation portion 3 is shown by arrows in fig. 1 and 4. The arrow shown in the transparent member 27 of fig. 4 indicates the traveling direction of the projection light. The air in the heat dissipation portion 3 flows in a direction different from the direction in which the projection light is irradiated and in a different plane relationship, and does not intersect the projection light. Therefore, the projection light is not disturbed by the high-temperature air flowing by the heat dissipation portion 3.

(interface 9)

The interface 9 is provided with a connection terminal 91 for connection to the outside. The interface substrate 92 extends from the interface terminal portion 91 into the housing 2, and power and input signals are transmitted to the control portion 8 through the interface substrate 92 and the flexible substrate 94 or another interface substrate 95 extending from the interface substrate 92, and power and control signals are further transmitted from the control portion 8 to the illumination optical system 4, the image display portion 5, and the heat dissipation portion 3.

(control section 8)

The control unit 8 is provided on a main board 8a, and the main board 8a is disposed on an interface board 95 extending from the interface board 92. The main substrate 8a is disposed at the bottom of the internal space 2Ba of the rear case 2B.

The control unit 8 controls the illumination optical system 4, the image display element 51, and the heat dissipation unit 3 based on the signal received from the interface unit 9. The control unit 8 operates the illumination optical system 4 and drives the intake fan 31 and the exhaust fan 32 of the heat dissipation unit 3. Also, the control section 8 drives the image display element 51 based on a signal received through the interface section 9. The image display element 51 generates projection light based on the control of the control unit 8.

(sealing effect)

In the present embodiment, as described above, the case 2 is not provided with an opening for mounting a fan, such as an air inlet or an air outlet. The opening 25 as the other hole is sealed by a transparent member 27, and the focus adjustment hole 21 is covered with a lid 26. Thereby, the case 2 is in a sealed state in which dust does not enter from the outside.

Therefore, the possibility that the dust adheres to the main substrate 8a of the control unit 8 or the like and the portion becomes high temperature and is damaged is reduced, and the life of the image projection apparatus 1 is extended. Further, the possibility that the transmittance of the optical member is lowered by the dust, and the image quality is deteriorated is reduced. Meanwhile, the image projection apparatus 1 can be used without maintenance at 20000H or more.

(Heat radiation structure)

On the other hand, since the casing 2 is sealed, air cannot be sent to the inside of the casing 2 to cool the air.

Thus, in the embodiment, the following heat dissipation structure is provided: the case 2 is made of metal having high thermal conductivity, and heat of a heat source disposed in the case 2 is conducted to the case 2 and radiated from the rear surface of the case 2.

Fig. 5 is a diagram illustrating a heat dissipation structure of the image projection apparatus 1 according to the embodiment. The heat dissipation structure comprises: a heat conduction portion 3A provided inside the case 2 or a part of a side surface of the case 2; and a heat dissipation portion 3 provided outside the case 2.

(Heat source)

In the image projection apparatus 1, the heat sources which are particularly high in temperature during use are the image display element 51, the

light sources

41, 42, 43, 44 of the illumination optical system, and the main substrate 8 a.

(Heat conduction portion 3A of image display element 51)

A metal base member 10 is fixed to the mounting table 2Bb of the metal rear case 2B. The base member 10 is in thermal contact with the mounting table 2 Bb. In the specification, the thermal contact means a contact by heat conduction and a contact by which thermal energy can be conducted. Further, a thermal pad may be disposed between the base member 10 and the mounting table 2 Bb.

The image display element 51 is held by a metal holding plate 51a, and is disposed above the base member 10. One end side of the metal heat pipe 12 is in thermal contact with the holding plate 51a on the front surfaces of the image display element 51 and the holding plate 51 a. The heat pipe 12 is provided across an opening of the holding plate 51a for holding the image display element 51, is bent toward the rear side, and has the other end side in thermal contact with the upper surface of the base member 10. The heat conduction portion 3A extending from the image display element 51 to the heat dissipation portion 3 includes the heat pipe 12, the base member 10, and the mounting table 2 Bb.

The heat generated in the image display element 51 is conducted to the heat pipe 12, the base member 10, and the mounting table 2Bb as the heat conduction portion 3A through the holding plate 51a or by direct radiation.

(Heat conduction portion 3A of illumination optical System 4)

The

light sources

41, 42, 43, and 44 of the illumination optical system 4 are, for example, LEDs, which generate light and become high in temperature. In the embodiment, the illumination optical system 4 includes four

light sources

41, 42, 43, and 44.

A heat receiving unit 11a for absorbing heat generated by the

light sources

41 and 42 is provided on the mounting table 2Bb immediately outside the

light sources

41 and 42. A heat receiving unit 11b for absorbing heat generated by the light source 43 is provided on the mounting table 2Bb immediately outside the light source 43. A heat receiving unit 11c for absorbing heat generated by the light source 44 is provided on the mounting table top 2Bb immediately outside the light source 44.

The

heat receivers

11a, 11b, and 11c are in thermal contact with the mounting table 2 Bb. In addition, a heat conductive pad may be disposed between the

heat receiving devices

11a, 11b, 11c and the base member 10. The heat conduction portion 3A from the illumination optical system 4 to the heat dissipation portion 3 includes

heat receiving devices

11a, 11b, and 11c and a mounting table 2 Bb.

Heat generated in the

light sources

41, 42, 43, and 44 of the illumination optical system 4 is conducted to the

heat receivers

11a, 11b, and 11c and the mounting table 2Bb serving as the heat conduction unit 3A.

(Heat radiating section 3)

The mounting table 2Bb is heated by the heat conducted from the image display device 51 through the heat conduction portion 3A and the heat conducted from the illumination optical system 4 through the heat conduction portion 3A. Since the mounting table 2Bb is made of a metal having high thermal conductivity, heat is conducted to the rear surface of the mounting table 2 Bb.

The heat dissipation portion 3 is disposed in the space S on the rear surface of the mounting table 2 Bb. The heat sink 33 of the heat dissipation unit 3 thermally contacts the rear surface of the mounting table 2 Bb. Therefore, the heat of the rear surface of the mounting table 2Bb is conducted to the heat radiation fins 33a of the heat sink 33.

When the suction fan 31 and the exhaust fan 32 are operated, air flows through the gaps between the fins 33a of the heat sink 33. The heat of the fins 33a is deprived by the flow of the air, and is cooled. Further, since the heat sink 33A is cooled, the cooling of the image display element 51 and the

light sources

41, 42, 43, and 44 of the illumination optical system 4 is promoted via the mounting table 2Bb and the heat conduction portion 3A.

(Heat conduction portion 3A of the main substrate 8 a)

The main substrate 8a of the controller 8 is disposed in thermal contact with the bottom surface of the internal space 2Ba of the rear case 2B. A thermal pad may be disposed between the bottom surface of the internal space 2Ba and the primary substrate 8 a. The heat conduction portion 3A of the primary base plate 8a includes the bottom surface of the internal space 2 Ba.

The heat generated in the primary base plate 8a is conducted to the inner surface of the internal space 2Ba as the heat conduction portion 3A. The heat of the inner surface of the internal space 2Ba heated by the primary base plate 8a is conducted to the rear surface. And, the heat conducted to the rear surface is directly radiated to the outside.

The area of the bottom of the internal space 2Ba is sufficiently larger than the main substrate 8 a. Therefore, when the heat of the main substrate 8a is radiated through the bottom of the internal space 2Ba, the main substrate 8a is sufficiently cooled.

In this way, the heat radiation source of the image projection apparatus 1 includes the

light sources

41, 42, 43, and 44 of the illumination optical system 4 and the image display device 51, and the

light sources

41, 42, 43, and 44 and the image display device 51 are disposed on the inner surface of the mounting table 2Bb in the housing 2 having the recess P provided on the back side.

That is, the

light sources

41, 42, 43, and 44 and the image display device 51, which are part of the heat generation source, are concentrated on the table 2 Bb. The portion where the heat generation source is concentrated becomes higher in temperature than the other portions in the casing 2, and therefore, a large amount of heat dissipation is required.

In the embodiment, a heat dissipation portion 3 having an intake fan 31, an exhaust fan 32, and a heat sink 33 is disposed on the rear surface of the mounting table 2Bb on which the heat generating sources are concentrated.

Therefore, the heat of the mounting table 2Bb, which requires more heat dissipation and in which the heat generation sources are concentrated, can be dissipated satisfactorily.

The other part of the heat dissipation portion includes a main substrate 8a, and the main substrate 8a is disposed on an inner surface of a portion of the case 2 where the internal space 2Ba where the recess P is not provided is provided.

That is, the substrate 8a, which is another part of the heat dissipation portion, is a portion different from the placement table 2Bb on which the

light sources

41, 42, 43, and 44, which are a part of the heat generating portion, and the image display element 51 are collectively arranged, and dissipates heat from the bottom surface of the case 2 provided at the step.

In this way, the heat source having a relatively small amount of heat generation is disposed at a position away from the heat source concentration position, and the heat generated by the heat source is naturally dissipated from the rear surface of the housing 2. Since the area of the rear surface of the case 2 is much larger than that of the main substrate 8a, the heat of the main substrate 8a, which is a heat generation source generating relatively less heat, is sufficiently dissipated.

Further, since the heat sources are dispersed and different heat conduction portions 3A are provided, heat is not concentrated in one portion, and the entire back surface of the case 2 can be efficiently used for heat dissipation.

As described above, the heat generated in the image display element 51 is conducted to the heat pipe 12, which is the heat conduction portion 3A, the base member 10, and the mounting table 2Bb of the rear case 2B through the holding plate 51a or by direct radiation. The heat generated in the main substrate 8a is conducted to the inner surface of the internal space 2Ba as the heat conduction portion 3A. The heat of the inner surface of the internal space 2Ba heated by the primary base plate 8a is conducted to the rear case 2B.

That is, the heat generated inside the case 2 is conducted to the rear case 2B, not to the front case 2F, which is the light irradiation side.

Since the high-temperature rear case 2B is attached to a wall portion or the like at the time of installation, the possibility of human contact is low. Also, since heat is not conducted to the front case 2F, which a person may contact, safety is high, and since the temperature of the optical path of the projection light does not rise, adverse effects on the image are also small.

Description of the reference numerals

1 image projection apparatus

2 casing

2B rear shell

2Ba inner space

2Bb mounting table

2F front case

3 Heat dissipating part

3A heat conducting part

4 illumination optical system

5 image display unit

6 projection optical system

7 concave reflector

8 control part

8a main substrate

9 interface part

10 base member

11a, 11b, 11c heat receiving device

12 heat pipe

21 adjusting hole

22 groove part

23 sealing member

24 screw

25 opening part

26 cover part

27 light-transmitting member

31 suction fan

32 exhaust fan

33 radiator

33a heat sink

41. 42, 43, 44 light source

51 image display element

51a holding plate

52 prism

61 Focus adjusting part

91 connecting terminal part

92 interface substrate

Claims

1. An image projection apparatus comprising:

an illumination optical system for generating illumination light;

an image display element for modulating the illumination light to produce projection light;

a projection optical system for amplifying the projection light;

a housing for hermetically accommodating the illumination optical system, the image display element, and the projection optical system therein;

a heat conduction portion for conducting heat from a heat generation source inside the case; and

and a heat dissipation part provided outside the housing.

2. The image projection arrangement of claim 1,

the heat dissipation part arranged outside the casing is provided with an air suction fan, an exhaust fan and a heat radiator.

3. The image projection arrangement of claim 1 or 2,

the suction fan and the exhaust fan are not arranged in the casing, and the wall of the casing is not provided with an air inlet and an air outlet.

4. The image projection arrangement of any of claims 1 to 3,

a control board for controlling the image projection apparatus is disposed inside the housing.

5. The image projection arrangement of any of claims 1 to 4,

the heat conduction unit conducts heat from the heat source to a rear surface of the housing opposite to the front surface on which the projection light is irradiated.

6. The image projection arrangement of any of claims 1 to 5,

a recess is provided in a rear surface of the housing, and the heat dissipation portion is disposed in the recess.

7. The image projection arrangement of claim 6,

the heat generating source includes the light source of the illumination optical system and the image display element,

the light source and the image display element are disposed on an inner surface of a portion of the housing where the recess is provided.

8. The image projection arrangement of claim 6 or 7,

the above heat generating source includes a main substrate,

the main substrate is disposed on an inner surface of a portion of the case where the recess is not provided.