JP3240224B2 - Light source device for projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device for a projector of an overhead projector having a lamp replacing function.

[0002]

2. Description of the Related Art An overhead projector is used to project images such as characters and drawings recorded on a transparent original onto a screen. Overhead projectors are classified into a transmission type and a reflection type depending on the difference in illumination method.
In the transmission overhead projector, an illumination lamp is built in a stage for placing a document, and illumination is directly applied from the back side of the document. In a reflection type overhead projector, a lamp is built in a projection head provided with a projection lens and a mirror, and illumination light is transmitted through a document once and is reflected by a Fresnel mirror provided on the surface of the stage. The reflected light illuminates the document from the back side. Further, there is also known a headless type projector in which a lamp and a projection lens are incorporated in a main body portion provided with a stage for mounting a document, and an image is directly projected on a screen from the main body portion.

In any of the projectors described above, the image of the original is projected onto the screen by the illumination light of the lamp, so that if the lamp burns out during use, it cannot be used thereafter. In order to be able to cope with such situations promptly, see, for example,
In an overhead projector known from Japanese Patent No. 1448, a light source device is used in which a plurality of lamps including a spare lamp are built in a projection head and these can be appropriately switched and used.

[0004]

However, in the conventional light source devices for projectors including those disclosed in the above-mentioned publications, the cut lamp is moved to the non-use position and the lamp to be newly used is moved to the predetermined use position. However, since the lamp is reconnected to the power supply terminal by this movement, there is a drawback that a connection failure easily occurs when the lamp is replaced. In order to eliminate such a connection failure, it is necessary to devise a structure such as pressing the lamp socket against the power supply terminal by urging the lamp socket with a spring.

An object of the present invention is to provide a light source device for a projector in which the lamp can be easily replaced without moving the lamp itself. With the goal.

[0006]

According to the present invention, in order to achieve the above object, first and second lamps are fixed at predetermined positions, respectively, and light from the lamps is transferred to a stage for placing a document. By moving the mirror to be reflected and moving the mirror to a position corresponding to each lamp, light from any lamp can be guided to the stage. The switch means is switched in conjunction with the movement of the mirror to supply power only to a predetermined lamp, and the blowing direction of the cooling fan is also switched in conjunction with the movement of the mirror.

[0007]

When the lamp has run out of the first lamp,
The mirror is moved from the first set position to the second set position. When the mirror moves to the second set position, the switching means is switched, and power is supplied to the second lamp instead of the first lamp, and the second lamp is turned on.
Light from the second lamp is directed at the document by a mirror moving to a second set position. Also, in conjunction with the movement of the mirror to the second set position, the direction of air flow of the cooling fan is switched from the first lamp to the second lamp, and the second lamp to be newly used is sufficiently switched. A large heat radiation effect can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an embodiment of the present invention will be described below with reference to the drawings. FIG. 4 shows an external appearance of a reflective overhead projector according to the present invention in use. A stage 3 made of a reflective Fresnel plate is provided on the upper surface of the pedestal portion 2, and a document 4 having an image recorded on a transparent sheet is placed thereon. A support arm 7 is rotatably mounted on the rear end side of the pedestal 2. A projection head 8 is rotatably attached to the tip of the support arm 7.

The projection head 8 is provided with a projection lens 9 and a projection mirror 10 as well known, and also incorporates a lamp for illuminating a document, a condenser lens, a fan for heat radiation, and the like. When the main switch 11 is turned on, the lamp is turned on, and illumination light is emitted toward the stage 3 from an opening formed in the bottom surface of the projection head 8. The illuminating light once passes through the document 4 placed on the stage 3 and is reflected by the stage 3 to illuminate the document 4 from the back side. Then, the light transmitted through the document 4 is reflected by the projection lens 9 and the projection mirror 1.
0 projects onto the screen.

Referring to FIG. 3, which shows a cross section of a main part of the projection head 8, the housing of the projection head 8 comprises a main body case 8a and a cover case 8b, and a partition plate 8c is provided between them. A projection lens 9 is incorporated in the main body case 8a so that the focus can be adjusted, and as shown in FIG.
The first and second lamp units 12 and 13 are fixed while being turned at an angle of 90 ° to each other. These lamp units 12 and 13 are first and second lamps 12a and 13 respectively.
a, a concave mirror, a lamp holder and the like, and only one of the lamps 12a and 13a is turned on by switching the correspondingly provided microswitches 14a and 14b.

Openings 15 and 16 are formed in the main body case 8a. One opening 15 is used for passing illumination light of the document 4, and the other opening 16 is for allowing light from the document 4 to enter the projection lens 9. The light beam that has passed through the projection lens 9 is projected on a screen via a projection mirror 10.

Circular openings 17 and 18 are formed in the partition plate 8c, and a mirror holding frame 20 and a fan holding frame 21 are rotatably fitted in each of the openings. A mirror 22 is fixed at an angle below the mirror holding frame 20, and an operation knob 23 is fixed above the mirror. The operation knob 23 is exposed to the outside through an opening 24 provided in the cover case 8b. By rotating the operation knob 23, the direction of the mirror 22 can be rotated by 90 ° with respect to a vertical rotation center axis.

A cooling fan 25 having a blade fixed to a motor shaft is attached to the fan holding frame 21. The cooling fan 25 takes in outside air from an intake slit 26 formed in the main body case 8a by rotation of the motor, and blows air to one of the first and second lamp units 12, 13 according to the set position.

As shown in FIG. 1, one end of a first lever 27 is fixed to the mirror holding frame 20, and the other end of the first lever 27 passes through a slot 28 provided in the partition plate 8c in an arc shape.
It comes out on the upper surface. When the operation knob 23 is turned, the first lever 27 turns integrally with the mirror holding frame 20. One end of a second lever 29 is fixed to the fan holding frame 21. First lever 27 and second lever 29
Is interlocked with the engagement of the pin 27a and the slot 29a. When the first lever 27 rotates counterclockwise, the second lever 29 rotates clockwise, and the fan holding frame 21 is moved. Rotate in the same direction.

The operation of the above configuration will be described. As shown in FIGS. 1 and 2, when the operation knob 23 is in the first set position, the mirror 22 is in the first lamp unit 1.
2 and the micro switch 14 a is turned on by the tip of the first lever 27. Therefore, when the main switch 11 is turned on, the first lamp 12a
Lights up, the illumination light from the first lamp unit 12 is reflected downward by the mirror 22, passes through the opening 15, and
To illuminate. The mirror 22 is the first lamp unit 1
2, the cooling fan 25 faces the first lamp unit 12, so that the main switch 11
When the cooling fan 25 is driven by the ON operation of, cooling air is blown to the first lamp unit 12.

When the first lamp 12a is turned off during use in the above set state, the main switch 11
Is turned off, the operation knob 23 is turned counterclockwise in FIG. 1 by 90 ° to switch to the second set position. As a result, the mirror holding frame 20 rotates counterclockwise, and the mirror 22 faces the second lamp unit 13.
In addition, the first lever 27 also rotates counterclockwise, so that the micro switch 14a is turned off and the micro switch 14b is turned on. Therefore, when the main switch 11 is turned on, the second lamp 13a is turned on, and the illumination light from the second lamp unit 13
The document 4 is illuminated through 5.

Further, when the first lever 27 rotates counterclockwise, the second lever 29 rotates 90 ° clockwise through the pin 27a and the slot 29a. As a result, the fan holding frame 21 rotates in the same direction, and the cooling fan 25
Since the lamp unit 13 faces the lamp unit 13, air is blown to the second lamp unit 13. In order to switch the air blowing direction of the cooling fan 25, in addition to changing the direction of the cooling fan 25 itself as in the above embodiment, as shown in FIG. May be changed.

Although the present invention has been described with reference to the illustrated embodiment, the present invention can be equally applied not only to a reflection type overhead projector but also to a headless type projector as well as a transmission type overhead projector. It is. Further, it is also possible to adopt a configuration in which the number of lamps is set to three or more, and an appropriate one is selected from the lamps and used.

[0019]

As described above, according to the light source device for a projector of the present invention, one of the lamps is selected by changing the direction of the mirror, and the switch means is linked to the operation of changing the direction of the mirror. To turn on only one of the lamps, and also to switch the air blowing direction of the cooling fan, so that there is no electrical connection failure when replacing the lamp, and the lamp can be switched easily and reliably. . Further, since the air blowing direction of the cooling fan is automatically switched in conjunction with the operation of changing the direction of the mirror, the overheating of the lamp can be reliably prevented even when any lamp is used.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a projection head of a reflection type overhead projector using the present invention.

FIG. 2 is a plan view of a main part of a projection head of a reflection type overhead projector using the present invention.

FIG. 3 is a sectional view of a main part of a projection head of a reflective overhead projector using the present invention.

FIG. 4 is an external perspective view of a reflective overhead projector using the present invention.

FIG. 5 is a perspective view of a main part showing another embodiment of the present invention.

[Explanation of symbols]

 12a first lamp 12b second lamp 22 mirror 23 operation knob 27 first lever 29 second lever

Claims (1)

(57) [Claims] A first set position for reflecting light from the first and second lamps toward a stage for placing an original; and light from the second lamp to the stage. A mirror movable between a second set position for reflecting light toward the mirror, and switch means for switching only one of the lamps corresponding to the set position of the mirror to be turned on;
In accordance with the movement of the mirror between the first set position and the second set position, there is provided a blower switching means for directing the blow direction of the cooling fan to one of the lamps selected by the switch means. A light source device for a projector, comprising: