JPH03214144A - Head for overhead projector - Google Patents

Abstract

PURPOSE:To make foreign matters hardly enter a case and to efficiently cool the inside of the case with the aid of cooling air by adopting the case provided with a cooling air discharging port on the lower surface side thereof. CONSTITUTION:The cooling air is blown against a lamp 14 by a ventilation device 11 and heat on the surface of the lamp is taken by the cooling air when it is passed through the surface of the lamp. Then, the warmed cooling air is blown out downward from the discharging port 43 provided on the lower surface side of the case 10. In such a case, the cooling air which becomes light caused by the rise of a temperature is not easily blown out to the outside. Thus, the case 10 can be efficiently cooled by the cooling air extending over the wide range thereof. Besides, the foreign matters hardly enter the case 10 even when an overhead projector is not used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to heads, and in particular to heads for overhead projectors.

[Conventional technology]

Generally, an overhead projector has a base on which a translucent original is placed, and a head disposed above the base. The head includes a light emitting section, a projection section, a fan for blowing cooling air onto the light emitting section, and a case for housing them. A conventional case has a slit-shaped outlet at its upper end, and the cooling air generated by the fan is discharged upward from the outlet through the lamp portion.

[Problem to be solved by the invention]

In the conventional configuration, a discharge port is provided at the upper end of the case. Therefore, when the cooling air generated by the fan is warmed in the lamp portion, it becomes lighter and easily escapes from the upper discharge port. Therefore, in a traditional configuration,
It is not easy to spread cooling air sufficiently throughout the case.

On the other hand, while using an overhead projector, the air that cools the lamp blows out from its outlet.
Foreign matter entering from above is not a problem. However, while the overhead projector is not in use, there is no cooling air blown out, so foreign matter such as dust can easily enter the head from above through the discharge port.

SUMMARY OF THE INVENTION An object of the present invention is to provide a head for an over-the-air projector that prevents foreign matter from entering the case and can be efficiently cooled by cooling air.

[Means to solve the problem]

The head of the Overherad projector according to the present invention includes:
The device includes a lamp, a blower for blowing cooling air onto the lamp, and a case that houses the lamp and the blower and has a discharge port on the lower surface side.

(Function) In the over-rad projector according to the present invention, the blower blows cooling air onto the lamp.The cooling air removes heat as it passes over the lamp surface.The heated cooling air It blows downward from the outlet provided on the bottom side of the case.In this case, the cooling air, which has become lighter due to the rise in temperature, does not easily blow out to the outside, allowing efficient cooling over a wide area inside the case. Cooling can be performed by wind. Also, in this case, since the discharge port is arranged on the lower surface side of the case, foreign objects are less likely to enter the case even when the overhead projector is not in use.

〔Example〕

FIG. 1 is a schematic perspective view of an over-the-radar projector employing an embodiment of the present invention. In the figure, the overhead projector includes a base 1 on which a document is placed, a head 2 placed above the base l, and a stay 3 that stands up from the base 1 so as to support the head 2 from below. .

The base 1 is a molded product made of resin, and has a space 4 therein for housing the head 2 and the stay 3, as shown in FIG. A flat lid 5 is placed on the L end of the base 1. A Fresnel lens 6 is attached to the - side of the lid 5.
is fixed. A notch 7 is provided in the stake side portion of the lid 5, and the stay 3 is fitted into the notch 7.

The head 2 has a case IO mainly made of resin. Inside the case 10, there is a base side (stay 3 side)
A light emitting device 12 having an air blower 11 is housed in the space, and a projection device 13 placed ahead of the light emitting device 12 is housed. Further, the blower device 11 includes a fan (not shown) and a motor that rotates the fan. Furthermore, the light emitting device 12
is a lamp 14 arranged in the center, and a lamp 14
The condenser lens 15 and the lamp 1 arranged below the
4, and a reflecting plate 16 disposed above the reflector 4. The projection device 13 includes a projection lens 17 that receives reflected light from the base l, and a projection mirror 18 disposed above the projection lens 17.

The projection lens 17 has a focus adjustment function.

Further, the base of the projection mirror 1B is rotatably supported by the case 10, so that the projection mirror 1B can rotate around a support shaft 19.

The lower part of the case 1O is a sheet metal mold, and the head 2 from which the resin part of the case 1O is removed is as shown in FIG. 3. As shown in FIG. 3, a pair of lamps 14 are provided including a spare lamp. The base of the lamp 14 is fixed to the slide member 21. The slide member 21 is a rod 2 extending in the left-right direction of the head 2 (vertical direction in FIG. 3).
It is slidably supported by 2. The rod 22 has both ends fixed to the case 10. The slide member 21
Inside the rod 22, a torsion spring 23 is fitted, as shown in FIG. One end of the torsion spring 23 is
It is fixed to the slide member 21 using screws 24.

The other end of the torsion spring 23 is connected to the vertical wall 10 of the case 10, which is located further forward than the slide member 21 (to the right in FIG. 4).
It is elastically pressed against a. As a result, the torsion spring 23
The lamp 14 is urged downward by this force. At the center of the upper end of the slide member 21, there is a slider.
A pair of knobs 25 are provided that stand upward from the base side of the guide member 21. The knobs 25 protrude upward from the projection device 13 side extension 16a of the reflection plate 16.The slide member 21, case 10
A switch 26 is arranged inside. This switch 2
6 is switched so that only the lamp 14 of the pair of lamps 14 disposed on the condenser lens 15 can be energized based on the change in the position of the slide member 21. Furthermore, a convex portion 27 that protrudes downward is provided at the lower end of the end portion of the slide member 21 on the lamp 14 side. This convex portion 27 is for positioning the slide member 21 in the extending direction of the rod 22, as will be described later.

A condenser lens 15 placed below the lamp 14 is fixed to a holding plate 20 provided at the bottom of the case 10. A pair of positioning holes 28 (concave portions) are formed in the holding plate 20 at the rear (periphery) of the condenser lens 15. A pair of 71, 28 are provided with an interval in the left-right direction (up-down direction in the figure) of the head 2.

The convex portion 27 (the fourth
If the two lamps shown in the figure are fitted, the center of one of the lamps 14 and the optical axis of the condenser lens 15 will coincide.

As shown in FIG. 4, the reflecting plate 16 has a spherical portion, portions extending downward on both sides of the spherical portion, and the extension portion 16a described in 1- above. This reflective plate 16 is connected to the support member 3
0 to the lower surface of the lid 31. The lid 31 is
The part is made of resin and has a protrusion 32 provided on the base side of the head 20 and a spring member 33 provided on the tip side. Therefore, the protrusion 32 is locked to the case lO side,
By press-fitting the spring member 33 into the hole 34 of the vertical wall 10a, the lid 31 can be fixed to the corner of the nose 10.

When the MB2 is fixed to the top of the case 10, the knob 2 of the slide member 21 is lower than the extension 16a of the reflector 16.
5 protrudes upward. On the other hand, at a position corresponding to the knob 25, the extension portion 16a is provided with a notch 35 as shown in FIG. A pair of notches 35 are provided at intervals in the left-right direction of the head 2 (vertical direction in FIG. 7). That is, both notches 35 are provided corresponding to the position where the knob 25 is arranged at the fixed position of the slide member 21 shown in FIGS. 5 and 6.

Below the condenser lens 15, a large diameter hole 1 is formed in the case 10 at a portion corresponding to the condenser lens 15.
0b is formed. Further, as shown in FIG. 8, on the base side of the head 2, an air intake port 40 is provided in the side wall of the case IO facing the blowing bag ff1ll. Further, a large number of ventilation holes 41 are formed in the partition wall between the ventilation device &11 and the chamber housing the lamp 14 and the like. Furthermore, discharge ports 42 and 43 are provided in the lower part of the holding plate 20 and the lower part of the partition wall between the light emitting device 12 and the projection device 13, respectively.

- When using the Overhead Rad projector described in L, a document made of transparent resin is placed on the Fresnel lens 61 of the base 1 shown in FIG. Then, when the - lamp 14 is turned on, the light from the lamp 14 is transferred to the 21-densifying lens 1.
5 and is reflected by Fresnel lens 6 , and the reflected light passes through the document and reaches projection lens 17 . Further, the reflected light is reflected by the projection mirror 18, and an image of the original is projected onto a screen (not shown).

When the lamp 14 is turned on, it generates heat, so the blower device 11 is driven. When the unillustrated fan of the blower 11 rotates out of rotation, outside air is guided into the case 10 from the air intake port 40 (FIG. 8). The cooling air from the blower 11 passes through the ventilation opening 41 and reaches the room where the lamp 14 and the like are housed. After the cooling air cools each part including the lamp 14, it is discharged downward from the discharge ports 42 and 43.The outline of the air flow in this case is shown by the arrows in Fig. 8. Here, an opening for cooling air is not provided at the upper end of the case 10 including the lid 31, and discharge ports 42 and 43 are provided at the bottom of the case 10. Since the structure is such that the air is discharged to the lower blade, even if the cooling air is warmed by the heat generated by the lamp 14 and becomes lighter, the cooling air is easily discharged to the outside before it has a sufficient cooling effect. Therefore, according to this configuration, the inside of the case 10 can be efficiently and widely cooled.

When the use of the Overherad projector is finished, the lamp 14 is turned off. Along with this, the supply of cooling air by the air blower 11 is also stopped. Even during the stop period of the Overhead Rad projector, since no opening for discharging cooling air is provided at the upper end of the case 1O including the lid 31, foreign matter will not enter the case from above through the opening. Therefore, even if the head 2 is left alone for a long time without being housed in the space 4 of the base 1, there is little dirt inside the case 10.

If one of the lamps 14 becomes defective during use of the OVERERAD projector, the OVERERADO projector is stopped and the lid 31 is lifted upward as shown by the solid line in FIG. 4 to open it. Pinch knob 25,
The slide member 21 is rotated against the torsion spring 23. As a result, the convex portion 27 is pulled out from the hole 28 of the holding plate 20.

Further, using the knob 25, slide the slide member 21 in the left-right direction of the radar 2 to place another lamp 14 at the optical axis position of the condenser lens 15. Then, when the user releases the knob 25, the slide member 21 is rotated by the torsion spring 23, and the convex portion 27 is fitted into another hole 28. The engagement of the protrusion 27 and the hole 28 ensures accurate positioning of the lamp 14. If this positioning is inaccurate, the lid 31 cannot be closed because the knob 25 does not match the notch 35 of the reflector 16.

This can prevent incorrect setting of the lamp 14. Also, since the position of the slide member 21 changes as the lamp 14 moves, the changeover switch 2
6 is switched. As a result, only the one located at the center of the condenser lens 15 among the pair of lamps 14 can be energized.

In use, the knob 25 is located above the extension 16a of the reflection plate 16 through the notch 35. Therefore, heating of the knob 25 by the lamp 14 is suppressed. Therefore, when a failure occurs in the lamp 14,
Even immediately after the lamp 14 is turned off, the knob 25 can be easily operated with a finger.

(Effects of the Invention) Since the head of the overhead projector according to the present invention employs a case having a cooling air outlet on the lower surface side, it is difficult for foreign matter to enter the horn. can be cooled efficiently.

[Brief explanation of drawings]

Fig. 1 is a perspective view of an oat head jetter in which an embodiment of the present invention is adopted, Fig. 2 is a schematic vertical cross-sectional view thereof, and Fig. 3 is a plan view with the case removed. , FIG. 4 is an enlarged partial view of FIG. 2, FIGS. 5 and 6 are views corresponding to enlarged partial views of FIG. 3 showing different operating states, and FIG. 7 is an enlarged partial view of FIG. 4. A partial VU cross-sectional view and FIG. 8 are vertical cross-sectional partial views showing the air blowing state. 2...Head, 10...Seat, 11...Blower, 14...Lamp, 42.43...Discharge port.

Claims (1)

[Claims] (1) A head for an overhead projector, comprising: a lamp; a blower for blowing cooling air onto the lamp; and a case that houses the lamp and the blower and has a discharge port on the lower surface side.