JPS644101Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an overhead projector capable of partially enlarged projection.

Overhead projector (hereinafter simply OHP)
When performing partial enlargement projection with There is a method of attaching a converter lens to enlarge and project the image.

The former method, which uses a relay lens system, has the disadvantage that the amount of light transmitted through the material is constant, so the enlarged image on the screen becomes dark.

The latter method, which uses a converter lens, can increase the amount of light transmitted through the material, so the screen does not become dark, but it does require the work of attaching and removing the converter lens, as well as selecting an appropriate stand and placing it on the stage. The disadvantage is that the operations are troublesome because they have to be performed separately.

Therefore, in order to prevent the enlarged and projected screen from becoming dark in another application and to enable easy-to-operate partially enlarged projection, the present applicant made the stage movable up and down, and set the projection position above the stage. A standard lens that is selectively installed and projects the entire image on the stage, and at least one partial enlargement lens that has a different focal length from the standard lens and that enlarges and projects a part of the image. The height of the stage is automatically set according to the focal length of the projection lens set at the projection position by providing a projection lens group and linking the switching of these projection lens groups with the elevation and descent of the stage. We have proposed an overhead projector that is capable of partially enlarged projection.

However, with this overhead projector, if you accidentally place your hand on the top surface of the main body when the stage is lowered from the raised position, your hand may get caught between the stage and the main body, causing unexpected injury. If you place a thick book on top of the stage, there is a risk that it will get caught and damage the stage.

Therefore, an object of the present invention is to provide an overhead projector that does not cause such accidents.

The overhead projector according to the present invention is
The stage is formed of a transparent plate-like member, and a vertically extending support member is attached to the main body, and an elevating means for moving the support member up and down is provided, and a part of the periphery of the stage is attached to the upper end of the support member. , when the stage is placed in the raised position,
The stage is characterized in that it is attached via an elastic member that biases the stage in a horizontal state and at least allows it to tilt upward.

As mentioned above, the stage is installed to allow at least an upward tilt, so even if your hand is placed on the top surface of the main body, the stage will tilt and escape, causing your hand to be strongly pinched. This also reduces the risk of damage to the stage itself.

Hereinafter, an overhead projector capable of partially enlarged projection according to a preferred embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing the external shape of an overhead projector (hereinafter abbreviated as OHP) of the present invention.

In Fig. 1, the OHP main body 1 has a light source inside, and the light emitted from this light source is transmitted to the Fresnel lens F.
The light is focused. Further, on the front side of the OHP main body 1, a power switch 2 and an adjustment knob 3 for adjusting the brightness of the light source are provided.

The stage 4 provided on the top surface of the main body 1 and on which materials are set is made of a transparent plate-like member such as tempered glass, and is arranged so that it can take a position above the above-mentioned Fresnel lens F and at least one raised position. It is installed so that it can be raised and lowered freely.

A support column 6 is fixed to one corner of the OHP main body 1. An arm 7 is attached above this column 6. This arm 7 has a prismatic portion 7
a fits into the support column 6, and the gear meshes with the rack gear 6a of the support column 6. This gear is linked to the adjustment knob 8, so when the knob 8 is turned, the arm 7 moves up and down along the column 6, thereby making it possible to adjust the focus.

A lens holder 9 is fixed to the tip of the arm 7, and a standard lens 10 is held by this lens holder 9. Further, a foldable mirror M is arranged above the standard lens 10.

A turret 11 is rotatably provided below the holder 9, and a plurality of (for example, three) lens mounting holes are formed in the turret 11. Two converter lenses 1 with different focal lengths (and angles of view) are installed in two of these lens mounting holes.
2a and 12b are attached. By combining the converter lenses 12a and 12b with the standard lens 10, a part of the document can be enlarged and projected to a desired size. Therefore, in the device of this embodiment, a partial magnification lens is configured by a combination of the standard lens 10 and any one of the two converter lenses 12a and 12b.

In FIG. 2, the stage 4 includes a column 13
is supported by the upper end of the A rack gear 13a is formed on this column 13, and a gear 14 meshes with this rack gear 13a.

A pinion 15 is fixed coaxially with this gear 14. The pinion 15 meshes with a worm gear 17 driven by a motor 16. This worm gear 17 is connected to the motor 1 via gears 18 and 19.
It is driven by 6. The means for lifting and lowering the column in this device includes the gear 14, pinion 15, and motor 1.
6, a worm gear 17, and gears 18 and 19.

The pillar 13 has a cam 2 having a protrusion 20a.
0 is attached, and when the stage 4 is raised and lowered by the motor 16, the micro switches 21 to 24 are opened and closed by the cam 20. The height of the stage 4 is detected by these microswitches 21-24.

On the other hand, although not shown, a cam having one protrusion on the outer circumferential surface is provided on the rotating shaft of the turret 11, and near the outer circumference of the cam, the turret 11 is rotated by hand to attach the lens. Micro-switches 25a, 25b, and 25c (FIG. 3) are provided which engage the protrusions of the cam to turn the cam from an OFF state to an ON state when the hole is placed in a predetermined position. One of these microswitches is ON
When the state is reached, the motor 16 is rotated.

A positioning device may be provided on the turret for setting the lens mounting hole in a predetermined position and holding the turret 11 in that position.

FIG. 3 is a circuit diagram showing a motor control circuit. When the above-mentioned turret 11 is rotated by hand and one of the converter lens mounting holes is positioned at a predetermined position (a position matching this below the standard lens 10), the micro switches 25a, 25b, 2
5c is turned on by a protrusion of a cam disposed on the rotating shaft of the turret.

The motor 16 is supplied with power from a power source 26 or 27 and rotates forward or backward, thereby moving the stage 4 up and down.

The micro switch 21 is for detecting that the stage 4 has moved to the uppermost position, and is turned off at the upper edge of the cam 20 at this time.

The micro switch 22 has a movable contact piece 22a.
selectively contacts the fixed contact pieces 22b and 22c.
This micro switch 22 is for determining the rotation direction of the motor 16 to raise or lower the stage 4. The cam 20 descends and the protrusion 2
When micro switch 23 is turned off at 0a,
The movable contact piece 22a is switched to the fixed contact piece 22b.

The micro switch 24 is for detecting that the stage 4 has descended, and is turned off at the lower end of the cam 20.

These micro switches 21, 22, 23
are arranged at equal intervals keeping a distance equal to the entire length of the cam 20, thereby detecting that the stage 4 has been displaced to three levels of height.

Next, the operation of the control circuit for the motor will be explained.

In the standard position where stage 4 is lowered, stage 4 is
The material above is illuminated, and the light transmitted through the material enters the standard lens 10. The light emitted from this standard lens 10 is reflected forward by a mirror M and is enlarged and projected onto a screen.

When increasing this magnification and projecting part of the material onto the screen, the magnification can be changed to two levels by rotating the turret 11 by hand.

When the converter lens 12a is set at a predetermined position and the micro switch 25b is closed, the movable contact piece 22a of the micro switch 22 is in contact with the fixed contact piece 22b, so that the motor 16 is powered from the power source 26. .

Therefore, the motor 16 rotates in the forward direction and moves to the stage 4.
to rise. When the stage 4 rises by one stage (total length of the cam 20), the micro switch 23 is activated.
OFF, and at the same time, the movable contact piece 22a of the micro switch 22 switches to the fixed contact piece 22c, so the motor 16 stops.

Since the converter lens 12a is set and the material is projected with the stage 4 raised by one step, a part of the material can be enlarged and projected without darkening the screen.

Further, when the converter lens 12b is set at a predetermined position and the microswitch 25a is closed, power is supplied from the power supply 26 as before, so that the motor 16 rotates in the forward direction.

As a result, as shown in Figure 1, stage 4
rises to the top. Then, when the micro switch 21 is turned off, the rising stops.

When the turret 11 is rotated and both converter lenses 12a and 12b are removed from the optical axis of the standard lens 10, the micro switch 25
c is closed and the motor 16 is supplied with power from the power source 27 to start reverse rotation, so that the stage 4 is lowered to above the upper surface of the main body 1. When the lower end of the cam 23 turns off the micro switch 24, the motor 1
6 stops.

In this way, when the stage 4 descends onto the top surface of the main body 1, if a person's hand or the like is placed on this top surface, the hand will be caught between the descending stage 4 and the main body 1, causing an unexpected You may get injured.

Therefore, in the overhead projector of the present invention, a part of the periphery of the stage 4 is connected to a support post 13 so as to keep the stage in a horizontal state and at least allow it to tilt upward when the stage is placed in the raised position. It is attached to the upper end of the

Specifically, the pillar 13 is made hollow as shown in FIGS. A plug-like member 31 is provided on the lower surface of the reinforcing member 30 so as to fit into the hole of the pillar 13, and the stage 4 is placed on the upper surface of the pillar 13 with the plug-like member 31 fitted into the pillar 13. do. A spring 33 is disposed between the plug-like member 31 and a stop member 32 disposed at a predetermined distance from the lower surface of the column 13, and this spring causes the stage 4 to move to the position shown in FIG. As shown, while the stage is biased to remain horizontal, when it is in the lowered position, i.e., above the main body 1, this spring stretches and the stage tilts to prevent injury to people's hands, etc. ing. It is desirable that the spring 33 be attached to the plug-like member as far back as possible so that the stage can be held in a horizontal state with a small spring force.

The plug-like member 31 has the following shape in order to help maintain the horizontal state of the stage in the raised position and tilt upward in the lowered position as described above. That is, in order to maintain the horizontal state, the rear surface 31a is a vertical surface as shown in FIG. 5, and this rear surface 31a collides with the inner surface of the rear wall of the support column 13, so that the stage does not tilt forward and downward. That's what I do. In addition, since the plug-like member 31 is arranged at the center of the rear edge of the stage 4, it is balanced left and right, and therefore tilts downward to the left and right under normal conditions, that is, when no external force is applied. There's nothing to do. On the other hand, in order to assist the inclination in the lowered position, the front surface 31b and both side surfaces 31c and 31d of the plug-like member 31 are rounded as shown in FIGS. The stage can be tilted as shown in . That is, the front surface 31b and both side surfaces 31c and 31d abut against the inner surfaces of the front wall and both side walls of the support column 13, so that the stage 4 is not prevented from tilting upward.
The overall shape of the plug-like member 31 is shown in FIG.

In order to allow the stage to tilt upward in the lowered position, the structure shown in FIG. 9 or 10 may be used instead of using the above-mentioned plug-like member.

In the structure shown in FIG. 9, a plate-like member 40 is fixed to the upper surface of the support column 13, and a through-hole 41 is provided that passes through the reinforcing member 30, the stage 4, and this plate-like member 40. A long rod-like member 42 is fitted, and a spring 44 is provided between the plate-like member 40 and a stop member 43 provided at the lower end of the rod-like member 42. Of course, at the top of the rod-shaped member,
It is necessary to provide a stopper 45 to prevent this rod-shaped member from slipping out of the through hole.

Furthermore, the structure shown in FIG.
and a through hole 51 passing through the stage 4,
A rod-shaped member 52 whose one end is fixed to the upper surface of the plate-shaped member 40 and extends upwardly through the through-hole 51 is disposed, and between a stop member 53 provided at the upper end of this rod-shaped member 52 and the reinforcing member 30. A spring 54 is arranged on the top.

The springs 44 and 54 shown in FIGS. 9 and 10 both have the same function as the spring 33 described above, that is, they hold the stage horizontally when it is in the raised position, and they hold it upward when it is in the lowered position. It has the effect of allowing inclination.

A plurality of these springs 44, 54 may be used for one stage.

In the above embodiment, the turret and stage are linked, but it goes without saying that the present invention is also effective in cases where the turret and stage are not linked. Furthermore, in the above embodiment, the standard lens is always placed at the projection position, whether the entire image is projected or a part of the image is enlarged, and only the converter lens is moved in and out of the projection position. , a standard lens and a partial magnification lens may be provided separately, and these lenses may be fixed to a turret so that they can be selectively moved in and out of the projection position.

According to the overhead projector of the present invention as described above, even if a hand or the like is caught between the stage and the main body, there is no risk of injury because the stage is tilted. There is no risk that the stage will be damaged even if it is pinched.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the appearance of the overhead projector of the present invention, Fig. 2 is a perspective view showing the stage elevating mechanism, Fig. 3 is a circuit diagram showing the motor control circuit, and Fig. 4. is a cross-sectional view taken along line A-A in FIG. 1 showing the support structure of the stage, FIG. 5 is a cross-sectional view taken along line B-B in FIG. 1, and FIGS. A sectional view similar to FIGS. 4 and 5 showing an upwardly inclined state, FIG. 8 a perspective view showing the outer shape of the plug-like member 31, and FIG. 9 showing a modification of the stage support structure. cross section,
FIG. 10 is a sectional view showing another modification of the stage support structure. 1... Main body, 4... Stage, 13... Support,
31... Plug-like member, 33... Spring.

Claims (1)

[Claims for Utility Model Registration] A main body housing a light source, etc. therein, a stage which is usually disposed on the upper surface of this main body and can assume at least one raised position above the front upper surface, and above this stage. a standard lens for projecting the entire image on the stage, which is selectively installed at a projection position; and at least one partial enlargement having a focal length different from the standard lens and for enlarging and projecting a part of the image. In the overhead projector, the stage is formed of a transparent plate-like member, a vertically extending support member is attached to the main body, and a lifting means for moving the support member up and down is provided. a part of the periphery of the stage is provided at the upper end of the support member, and an elastic member that urges the stage to a horizontal state when the stage is placed in the raised position and at least allows the stage to tilt upward. An overhead projector capable of partially enlarged projection, characterized in that it is attached through.