JPS6257978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an information mark display device, in particular, a relief type diffraction grating (also referred to as a relief type diffraction grating structure) arranged in the viewfinder light beam of a cine camera, etc. The present invention relates to an information mark display device in which reproduction marks from a diffraction grating can be observed.

The present applicant has already filed an application for an information mark display device using a relief type hologram (Japanese Patent Laid-Open No. 18664/1983). However, the hologram in the above application is a normal relief type hologram, and the first-order diffracted light is used as the information mark reproduction light to prevent harmful diffracted light from being mixed into the eyepiece, and the noise light of the finder light beam generated by being diffracted by the hologram is Avoid being observed. For these reasons, it was necessary to increase the spatial frequency of the hologram, that is, to use a relief structure with a fine period. For this reason, there was a drawback in that it was technically difficult to produce the original hologram.

The present invention uses a relief hologram or a diffraction grating in a special form to use high-order diffracted light for information mark reproduction light, and provides a novel information mark display device that does not have much of an adverse effect on the finder luminous flux.

The present invention will be explained below using the drawings. FIG. 1 shows a first embodiment in which the information mark display device of the present invention is applied to an 8 mm cine camera. In Figure 1, 1 is a point on the object, 2 is the front group of the photographic lens, 3 is a half mirror, 4 is the rear group of the photographic lens, 5 is the film surface, 6 is the imaging lens, 7 is the mirror, and 8 is the display Focus plate with a special relief-type focused image hologram on which a pattern is recorded, 9
is a white light source for hologram illumination, 10 and 11 are finder relay lenses, 12 is a secondary focusing surface, 1
3 is an eyepiece. Now, the light beam from the point 1 on the object passes through the photographing lens front group 2, the half mirror 3, and the imaging lens 6, and forms an object image on the focusing plate 8. In addition, a special relief-type focused image hologram on the focusing plate illuminated by the white light source 9 also reproduces an information mark near the focusing plate, and these object images and information marks overlap,
It is observed at approximately the same diopter through the finder relay lens and eyepiece.

The special relief-type focused image hologram used in this example has a cross-sectional structure as shown in FIG. The structure is the same as that of the light splitter shown in No. 10190.
That is, a dielectric reflective film 17 having a designed reflectance is deposited on a relief diffraction grating formed on a focusing plate 15, which is a first optically transparent medium having a split distance measuring section 16, and the focusing plate member is This relief diffraction grating structure is embedded with a transparent adhesive 18, which is a second optically transparent medium having substantially the same refractive index as that of the second optically transparent medium. 19 is a transparent member for a cover.

Furthermore, the recording of the information pattern in this embodiment is performed by using the relief diffraction grating 20 as shown in FIG.
This is realized by the presence of a reflective film 17 in the area corresponding to the pattern "OK" on the top. This can be done by providing a mask having an opening corresponding to "OK" on the relief diffraction grating when depositing the reflective film, and depositing the reflective film through this opening.

By adopting the structure shown in FIG. 2, as detailed in the specification of the above-mentioned Japanese Patent Application No. 10190/1980, the adverse effect of the relief diffraction grating on the finder beam can be almost completely eliminated. Can be done. In other words, out of the finder light flux, the light that passes through the relief diffraction grating section without a reflective film will not be affected by the relief structure at all if the mutual refractive index matching of the focusing plate 15 and the transparent adhesive 18 is good, and therefore the finder image will not be affected by the relief structure. is clear. On the other hand, in pattern areas with a reflective film, the amount of light that passes through the hologram and reaches the eye is reduced by an amount corresponding to the reflectance of the reflective film, so the pattern area appears dark and the visibility of the viewfinder image deteriorates. , this is not a problem if the reflectance of the reflective film is kept at a low value, for example, about 4%.

On the other hand, as shown in FIG. 4, the illumination light 21 from the reproduction light source is reflected and diffracted by the pattern section provided with the reflective film section 22 to generate diffracted light 23 to reproduce the information mark. 24 is O-order diffracted light. At this time, if the relief diffraction grating is designed so that the N-time diffracted light (N2) mainly goes to the finder optical system, the diffraction grating will have a period N times coarser than when the first-order diffracted light is used as the reproduction light. Since a grid can be used, it is advantageous in manufacturing. In particular, an N-order blazed diffraction grating is desirable from the viewpoint of light utilization efficiency. The conditions for this are β=Nπ...(1) where, β=2π・n・△ /λ...(2).

(However, n is the refractive index of the relief diffraction grating member, △
is the height of the relief. ) Also, if the N-th order diffracted light is reflected and diffracted in the optical axis direction, the diffraction angle θ is as shown in Fig. 4 in a medium with a refractive index n as P・sinθ=Nλ/n...(3) (here and P is the period of the lattice).

Therefore, from (1), (2), and (3), △/P=Nλ/2n・nsinθ/Nλ=1/2sin
θ (θ is the incident angle of the illumination light within the relief member). Therefore, a relief diffraction grating having such an inclined surface is a desirable relief diffraction grating for the present invention.

Further, FIG. 5 shows a second embodiment. FIG. 5 is a diagram corresponding to FIG. 3. Here, the relief diffraction grating exists only in a portion 25 corresponding to the pattern information to be reproduced, and the entire surface of the grating in the focusing plate 26 is coated with a reflective film. Further, this sectional view has a similar configuration to that in FIG. 2.
In this embodiment as well, the information pattern is reproduced by the reproduction light source from the relief diffraction grating portion in the same manner as in FIG. 4. However, the influence on transmitted light is slightly different from that in the first embodiment. That is, since the reflective film coating is applied over the entire surface of the grating surface in the focusing plate 26, although the entire screen becomes dark, only the information pattern portion does not appear dark.

What has been described so far is an arrangement in which the reproduction light source is located closer to the eye than the relief type diffraction grating member, but the present invention is also effective in the case of the opposite arrangement. This is shown in FIG.

6 is the same as FIG. 1 except for the light source 27 and relief grating member 28. FIG.

As shown in FIG. 7, the structure of the relief diffraction grating here requires a relief shape with sharp peaks so that the N-th order diffracted light 30 of the illumination light 29 is almost in the optical axis direction.

Yet another embodiment is shown in FIG. In this embodiment, the light source 32 is provided on the end face of the relief diffraction grating member, and the light beam traveling through this member while being totally reflected is reflected and diffracted by the reflective film on the relief grating, thereby displaying an information pattern. 33 is a light shielding member for cutting out excess light.

Depending on the fineness of the grating pitch, the relief diffraction grating in the embodiments described above can be manufactured in the same manner as in ordinary Fresnel lens manufacturing or spectroscopic diffraction grating manufacturing.
It can be created by mechanically carving grooves on metal at a certain frequency using a diamond blade. Plastic copies can be mass-produced from the molds made in this way by compression, etc.

Furthermore, by recording interference fringes on a photoresist using a holographic technique, a relief diffraction structure or a blazed diffraction structure can be obtained after development. By depositing a thin gold film on this photoresist, a nickel mold can be made using electroforming, and plastic copies can be mass-produced from this.

In addition, although a relief diffraction grating with a coarse period can be used in the present invention, since the reproduced image is less colored due to dispersion with such a coarse period diffraction grating, it is necessary to use a color filter in the light source when reproducing warning marks, etc. In some cases, it may be preferable to use a light source such as an LED.

Although the present invention has been described in detail above as applied to an information pattern display device for an 8 mm cine camera, the present invention is not limited to this.

Furthermore, by using a relief hologram instead of a relief diffraction grating, coating this with a dielectric reflective film, and embedding this relief structure, it is possible to create an information mark reproducing device similar to the embodiments described so far. It is.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an information mark display device used in a cine camera, FIGS. 2 and 3 are diagrams showing an information mark display device of the first embodiment, and FIG. 4 is a diagram showing the information mark display device of the first embodiment. 5 is a diagram illustrating information mark reproduction; FIG. 5 is a diagram showing the second embodiment; FIGS. 6 and 7 are diagrams illustrating an example in which the information mark display/mark display device of the third embodiment is applied to a cine camera; FIG. The figure shows a fourth embodiment. In the figure, 8... Relief type focused image hologram, 9... White light source for hologram illumination, 15... Focusing plate, 16... Split side rim, 17... Reflective film, 18... Transparent adhesive, 19
...Transparent member.

Claims (1)

[Claims] 1. A relief diffraction grating comprising first and second optically transparent media having substantially the same refractive index and a reflective film having a predetermined reflectance provided at the boundary between the first and second optically transparent media. The light from a predetermined object is incident on the relief diffraction grating, the object is observed by the light transmitted through the relief diffraction grating, and the relief diffraction grating is illuminated with light, and the relief diffraction grating is illuminated with light. An information mark display device characterized in that the information mark is displayed using reflected diffraction light generated by the information mark and the information mark is observed.