JPS59192236A - Projecting device - Google Patents

Abstract

PURPOSE:Not to hinder the visual field of an audience by forming a projecting device so that the optical axial line of projection from an original to a screen is not orthogonal to the surface of the original, which is arranged in the projection face side of a condenser lens, and the surface of the screen for projection. CONSTITUTION:Centers of projection lens 4 and a screen 6 are not arranged on the center normal of an original 3, but an optical axis 8 connecting centers of the screen 6 and the original 3 is inclined at an angle to the normal. The optical axis can be bent in the direction of the screen, which is hung approximately vertically, by a reflective mirror 5. Though a light source 1 is arranged at a point on the extension of the line of the projection optical axis connecting centers of the screen 6 and the original 3, the light source can be arranged in another position by another reflection system or an eccentric condenser lens or the like. Thus, an OHP body 7 is placed aside from the axis vertical to the center of the screen 6 not to hinder the visual field of an audience.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a projection device such as an overhead projector or slide used in conference halls, projection halls, etc.

Conventionally, all document projection devices such as an overhead projector (hereinafter referred to as OHP) or a slide projector (hereinafter referred to as SP) are designed so that the original axis and the projection screen surface are perpendicular to each other.

Regarding OHP, in most cases, a reflective surface such as a mirror is provided after the condenser lens surface or projection lens to refract the original axis, but in this case as well, the relationship between the projection screen and the optical axis is orthogonal. is designed to.

FIG. 1 is an optical path diagram of a conventional overhead glow projector.

A light beam emitted from a light source using a halogen bulb or the like is focused by a condenser lens 2 onto an aperture of a projection lens 4. At this time, the light beam passes through the original 3 placed on the screen side of the condenser lens 2, and the projection lens 4 forms an enlarged projected image of the original 3 on the entire screen 6. In an actual OHP, the original axis 8 is refracted by 70° to 90° by a reflecting mirror 5 placed between the projection lens 4 and the screen 6, and is projected onto a substantially upright screen.

FIG. 2 is a front view of a conventional Overherad projector and screen.

The overhead glow projector main body 7 has a built-in condenser lens. The optical axis 8 is a 3° projection lens for the original;
It is perpendicular to the plane on which the screen 6 is arranged.

In a projection device designed in this way, in order to provide the best possible image to the viewer, the screen is placed so that the surface of the screen is perpendicular to the line connecting the center of the viewer group and the center of the screen surface. However, in order to project the original onto the screen surface arranged in this way without distortion, in conventionally designed OHPs and SPs, the projection device must be placed on the normal line from the center of the screen surface. With the exception of slide projectors with special ultra-long focus projection lenses, which must be placed in front, the projection device is placed in front of the viewer on the screen side or in the viewer group.

This has the drawback that a portion of the view of the screen surface of some or many viewers is obstructed by the projection device. In addition, particularly in the case of OHP, it is customary to place the entire person near the OHP device in order to replace the original and explain the contents, so there is a drawback that this person further obstructs the viewer's view.

The present invention eliminates the above-mentioned drawbacks, sets the optical axis without being orthogonal to the screen surface, projects the original onto the screen surface without distortion, and allows projection that can be arranged so as not to block the viewer's view. It provides equipment.

The present invention provides a projection device that includes an illumination light source, a co/dimple lens that condenses the light beam, and a projection lens.
One feature is that the projection source axis from the original to the screen is not perpendicular to the original surface and the projection screen surface arranged on the projection surface side of the condenser lens.

Next, embodiments of the present invention will be described using the drawings.

FIG. 3 is a front view of an embodiment of the present invention, and FIG. 4 is a 5'eM diagram of the embodiment shown in FIG.

In the OHP of this embodiment, the OHP main body 7 is placed horizontally offset from the axis perpendicular to the center of the screen 6, so that the viewer's field of view cannot be blocked.

FIG. 4 is an optical path diagram when viewed from directly above an axis perpendicular to the center of the screen, and the optical path diagram when viewed from directly across from the vertical axis is the same as FIG. 1. Fourth
As shown in the figure, a projection lens 4.
The center of screen 6 is not placed and screen 6
The original axis 8 connecting the center of the original a3 and the center of the original a3 has a certain angle with respect to the normal line.

This structure is similar to tilt shooting in photography,
If a large tilt angle (angle between the normal line and the projection source axis) is used, problems such as peripheral light amount and distortion of the projection lens 4 will arise. But OH
In the P, the optical system from the single source to the projection lens can be freely designed, and the optical elements such as the angle of view of the projection lens have a greater degree of freedom in design than in a camera, so the structure shown in Figure 4 is sufficient. A sufficient amount of light can be obtained for practical use. It is similar to the conventional OHP in that the original axis can be refracted by the reflecting mirror 5 in the direction of the screen hanging in a nearly vertical direction.

In this practical example, one light source l is also placed at an extension point on the line of the projection optical axis connecting the centers of the screen 6 and the document 3, but the light source is moved to another position using another refraction system or an eccentric condenser lens. The arrangement can be freely performed as in the prior art. Furthermore, the arrangement structure of the present invention can be similarly applied to other optical devices that produce images by projecting them onto a screen in front of the viewer, such as a slide projector.

As explained above, 1. With OHP and other projection devices according to the present invention, there is no need to place the projection device on the normal line to the center of the screen, and the device can be placed laterally to the viewer's seat, and there is no distortion on the screen in front of the viewer. Since the image can be projected, the viewer's view on the screen is not obstructed by the projection device, and there are also minimal restrictions on the posture and position of the person explaining the manuscript or handling the OHP. This has the effect of keeping it within limits.

[Brief explanation of the drawing]

Figure 1 is an optical path diagram of a conventional overhead glow projector.
FIG. 2 is a front view of a conventional overhead glow projector and screen, FIG. 3 is a front view of an embodiment of the present invention, and FIG.
The figure is an optical path diagram of one example of winding shown in FIG. 3. l...51, 2... Condenser lens, 3... Original, 4... Projection lens, 5
...Reflector, 6...Screen, 7.
... OHP body, 8... Optical axis. 1 time 2 times 3 times + solid

Claims (1)

[Claims] In a projection device consisting of an illumination light source, a condenser lens that condenses the light beam, and a projection lens, projection from the document to the screen is performed on the document surface and the projection screen surface placed on the projection surface side of the condenser lens. A projection device characterized in that the original axes are configured so that they are not perpendicular to each other.