JPH036907Y2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) This invention is an overhead projector (hereinafter referred to as
(referred to as OHP), particularly regarding the Fresnel plate removal mechanism of transmission type OHP.

(Prior Art) In a conventional transmission type OHP, a stage is arranged on the upper surface of the projector body, and a Fresnel plate is arranged below the stage to condense the light beam from the light source at the bottom of the projector body. A projection unit consisting of a projection lens and a projection mirror is installed on this projector body via a support. Transparent type like this
The projection operation of an OHP is to first place a subject sheet on the stage and turn on the light source.The light flux from the light source is focused by a Fresnel plate, passes through the stage and subject sheet, and passes through the projection lens and projection mirror onto the screen. projected on.

The image of the object sheet is focused on the screen by adjusting the projection lens.
During this focusing, if the stage on which the subject sheet is placed and the Fresnel plate are placed close to each other, when the subject sheet is focused, the concentric pattern of the Fresnel plate will appear on the screen together with the image of the subject sheet. As a countermeasure for this, in order to prevent the pattern of the Fresnel board from appearing on the screen, the stage should be set to such an extent that the pattern of the Fresnel board will be completely blurred when the subject sheet is in focus, taking into account the depth of focus of the projection lens, etc. A technique is known in which the Fresnel plates are separated from each other.

In a transmission type OHP where the stage and Fresnel plate are installed inside the projector body, if a predetermined distance is provided between the stage and the Fresnel plate as described above,
When dirt or dust adheres to the stage or the inner surface of the Fresnel board, cleaning this surface is very time consuming.

On the other hand, Japanese Utility Model Application Publication No. 49-110639 discloses an OHP in which the position of the Fresnel plate can be adjusted and taken out. However, such OHP
In this case, since the Fresnel board is simply stored in a guide groove etc. so that it can slide freely, there are problems such as the Fresnel board rattling internally, and if the Fresnel board is not installed accurately, problems such as the projected image may be distorted. do. Also, the OHP of Utility Model Publication No. 52-105427
Now, hold the Fresnel plate with the stopper member,
It is possible to fix and remove the Fresnel board. However, in this case, since the stopper member is fixed with screws, there is a problem in that it takes time and effort to remove the Fresnel plate.

(Purpose of the invention) This invention is intended to solve the above-mentioned problems, and it is possible to easily remove the Fresnel plate and maintain it, and also to fix the Fresnel plate with precision. Transparent type
The goal is to provide OHP.

(Structure of the invention) The above purpose is to provide a stage for placing an object on the top surface of a rectangular projector body, a Fresnel plate provided inside the projector body at a predetermined distance from the stage, and a Fresnel plate inside the projector body. In an overhead projector consisting of a light source provided below the projector, a support provided on the projector body, and a projection unit held by the support that includes a projection mirror and a projection lens, one wall of the projector body can be opened and closed. A door in which the Fresnel plate can be freely removed; and a wedge-shaped edge portion formed by obliquely cutting out the upper corner of the door-side end and the opposite end of the Fresnel plate to form a slope portion. , a Fresnel plate holding groove having a wedge-shaped cross section, formed horizontally on the inner wall surface facing the door, into which the wedge-shaped edge fits, and the upper surface of the holding groove being located at the same level as the lower groove surface of the holding groove; , a beam provided between the wall surfaces on both sides of the door in close proximity to the door in the closed state, and a wedge-shaped edge of the Fresnel plate that fits into the retaining groove, and a wedge-shaped edge of the Fresnel plate adjacent to the door on the beam; The upper corner of the beam where the tip of the wedge-shaped edge of the door side is located when the part is placed is diagonally cut out, and the slope is made to have the same slope as the slope of the wedge-shaped edge of the Fresnel board. and a guide hole on the sloped part and a guide pin inserted into the guide hole to allow the Fresnel plate to be slid diagonally up and down.When displaced upward, the Fresnel plate is biased and held, and when it is displaced downward, the Fresnel plate is released from being biased. This is achieved by a transmission-type overhead projector characterized in that it is equipped with a locking member.

(Example) FIG. 1 is a front view of a transmission type OHP according to the present invention. Figure 2 shows the first transmission type OHP according to the present invention.
It is a - sectional view in the figure. FIG. 3 is an explanation of the Fresnel plate mounting structure of the transmission type OHP according to the present invention.

In FIGS. 1 and 2, a projector main body 1 is provided with legs 2 at the lower end, and a light source 3 is provided at the lower part of the interior. A stage 4 is held on the upper surface of the projector body 1 by a mechanism described later, and a Fresnel plate 5 is held below the stage 4 by the same mechanism as the stage 4. A door 6 is provided on the front surface of the projector body 1 via a shaft 7 so as to be openable and closable. This door 6 can be locked in the closed state by engagement between a stopper arm 13 rotatable via a pin 11 on the left side wall 10 of the projector main body 1 and a stopper pin 15 provided on the door 6. There is. Supports 17 and 18 are provided at the rear of the projector main body 1, and a projection lens 20 and a projection mirror 2 are mounted on the supports 17 and 18.
A projection unit 23 consisting of 1 is held.

In the OHP with the above-mentioned configuration, during projection, when the subject sheet is placed on the stage 4 and the light source 3 is turned on, the light beam from the light source 3 is focused by the Fresnel plate 5 and passes through the stage 4 and the subject sheet. , are projected onto a screen (not shown) via the projection lens 20 and the projection mirror 21.

Next, hold the Fresnel plate 5 of the OHP in this example.
This will be further explained using FIG. The door side end 38 of the Fresnel board 5 and the rear end 36 on the opposite side have sloped parts 36A and 38A formed by cutting out the upper corners thereof diagonally, thereby forming wedge-shaped edges. It is considered as a department. Further, on the inner wall surface of the projector main body 1 facing the door 6, a Fresnel plate holding groove 37 having a wedge-shaped cross section is formed horizontally, into which the wedge-shaped rear end 36 is fitted. There is. In addition, the left side wall 10 of the projector main body 1
A beam 26 is provided horizontally between the right side wall 25 and the right side wall 25. This beam 26 is connected to the Fresnel plate holding groove 3.
It is provided close to the door 6 in the closed state so that the upper surface is located at the same level as the lower groove surface of the door 7. The upper part of the beam 26 on the door side is obliquely cut out to form a sloped surface 26A having the same slope as the sloped surface of the wedge-shaped edge of the Fresnel plate 5. A locking member 31 is provided on the slope portion 26A and is slidable diagonally up and down by guide pins 28, 29 and guide holes 33, 34. The locking member 31 is composed of a leaf spring, and when it is displaced diagonally upward, it biases and holds the Fresnel plate 5, and when it is displaced diagonally downward, it releases the bias and retention of the Fresnel plate 5, and the Fresnel plate 5 is released. It is possible to take out the Note that the stage 4 is also configured in the same manner as the holding structure of the Fresnel plate, and holds the stage 4 in a detachable manner. Note that the stage 4 is also biased and held by a similar configuration.

When cleaning the OHP Fresnel plate 5 of this embodiment, first release the stopper arm 13 from the pin 15 provided on the door 6 to open the door 6, and then slide the locking member 31 to the lower left. to release the Fresnel plate 5. In this way, by removing the Fresnel plate 5 from the projector main body 1, the Fresnel plate 5 can be easily cleaned.

In this embodiment, stage 4, Fresnel plate 5
Although both of them are removable, the stage 4 may be fixed.

(Effect of the invention) According to the invention, the door-side end and the opposite end of the Fresnel board are formed into wedge-shaped edges in which the upper corner is cut diagonally to form a sloped part. In order to hold these ends by a Fresnel plate holding groove with a wedge-shaped cross section and a locking member slidably attached to the beam and its slope, the Fresnel plate is pressed against the lower groove surface of the wedge-shaped groove. The lower groove surface allows the Fresnel plate to be firmly positioned and fixed to the projector body. As a result, the Fresnel plate is always attached to the correct position, which eliminates problems such as the Fresnel plate being tilted and the projected image being distorted. Moreover, since the wedge-shaped end portion is firmly fixed by the wedge-shaped groove, the Fresnel plate will not rattle inside the projector body.

In addition, the locking member can be slid diagonally up and down by the guide hole and the guide pin, and since the locking member is composed of a spring plate, it is possible to simply form the guide hole in the vertical direction and move the locking member in the vertical direction. Unlike a locking member that is slidable, the force when the locking member falls downward is dispersed into a horizontal component and a vertical component, so that falling is prevented. Furthermore, since the locking member is not fixed using screws or the like, the Fresnel plate can be easily removed. Therefore,
Since the Fresnel board can be easily removed from the projector body, cleaning of the stage and Fresnel board becomes easy.

[Brief explanation of the drawing]

FIG. 1 is a front view of a transmission type OHP according to the present invention. Figure 2 shows the first transmission type OHP according to the present invention.
It is a - sectional view in the figure. FIG. 3 is an explanation of the Fresnel plate mounting structure of the transmission type OHP according to the present invention. 1...Projector main body, 3...Light source, 4...
...Stage, 5...Fresnel board, 6...Door, 26
... Beam, 28 ... Pin, 31 ... Locking member.

Claims (1)

[Scope of utility model registration request] A stage for placing an object on the top of the projector body, a Fresnel plate installed inside the projector body at a predetermined distance from the stage, a light source installed below inside the projector body, and a Fresnel plate installed inside the projector body at a predetermined distance from the stage. In an overhead projector comprising a projection unit having a supporting pillar, a projection mirror and a projection lens held by the supporting pillar, one wall of the projector main body can be opened and closed to allow the Fresnel plate to be taken out; , a wedge-shaped edge formed by diagonally cutting out the upper corner of the door-side end and the opposite end of the Fresnel board to form a slope, and a wedge-shaped edge formed horizontally on the inner wall surface facing the door; and a Fresnel plate retaining groove having a wedge-shaped cross section into which the wedge-shaped end fits, and the upper surface of the retaining groove are located at the same level as the lower groove surface, between the walls on both sides of the door in the closed state. When the beam provided close to the door and the wedge-shaped edge of the Fresnel plate are fitted into the holding groove and the wedge-shaped edge of the Fresnel plate next to the door is placed on the beam, the door will The upper corner of the beam where the tip of the wedge-shaped end edge of the Fresnel plate is located is cut out diagonally to form a sloped surface that has the same slope as the sloped surface of the wedge-shaped end edge of the Fresnel plate, and a guide hole and a guide hole are formed on this sloped surface. The locking member is attached so as to be able to slide diagonally up and down by a guide pin that is inserted into the locking member, and holds the Fresnel plate biased when displaced upward, and releases the biased retention of the Fresnel plate when displaced downward. Transparent overhead projector.