JPH0548185Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a low-cost camera that prevents underexposed photography.

[Conventional technology]

Due to recent advances in technology, many cameras that are now in widespread use have built-in devices that automatically measure and control exposure, but low-cost, simple cameras are not equipped with such devices. do not have.

Therefore, with this camera, you can take pictures without making any particular adjustments to the exposure amount, or you can judge the weather conditions at the time of shooting and manually adjust the aperture to roughly adjust the exposure amount. I'm making adjustments.

[The problem that the idea attempts to solve]

However, if no exposure adjustment is made, the subject will be photographed even if the brightness is insufficient and the camera is out of the allowable latitude range of the built-in film, which is likely to cause so-called underexposure. There was a problem.

Furthermore, even when equipped with a simple manual exposure adjustment device, it is difficult to operate the device appropriately depending on the weather conditions, and it is also possible to forget to operate the device. It was very hot.

Various attempts have been made to make the user aware of poor conditions using simple methods without using the expensive exposure adjustment method used in conventional general cameras, but no good solution has yet been found. Not served.

[Purpose of invention]

The present invention has been devised in view of these points, and it is an object of the present invention to provide a low-cost camera that can issue a warning of inappropriate exposure easily and inexpensively.

[Means to solve the problem]

The present invention solves the above problems by disposing a fading photochromic material in the window opening, which becomes transparent when the subject is bright enough for exposure, and develops color when the subject becomes dark.

[Effect]

A fading photochromic material that becomes transparent when the subject is bright enough for exposure and changes color when the subject gets dark is placed in the window opening, so when the surroundings are bright and the subject's brightness is high, the subject seen through the window window becomes transparent. The image is bright and clear. On the other hand, if the surroundings are dark and the brightness of the subject is low, the image of the subject seen through the window will be even darker and harder to see than when observed without passing through the window, making it difficult for the photographer to take pictures. It becomes possible to know.

Furthermore, since the present invention is constructed by simply arranging the fading photochromic material in the viewfinder opening, the construction of the camera itself does not become complicated.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail by taking a lens-fitted film unit as an example and referring to the accompanying drawings.

First, the overall structure of the lens-fitted film unit will be explained with reference to FIG.
FIG. 1 shows the appearance of a lens-fitted film unit in this embodiment. In the figure, the unit main body 10 is made as a box-shaped plastic molded product, and a photographing lens 12 is mounted on the front.
A shutter button 16 and a counter window 18 for checking the remaining number of films are provided on the top surface, and a film winding knob 20 for winding the film is provided at the rear.

The viewfinder 14 is a frame type viewfinder that allows the subject to be viewed directly with the naked eye, and a film 21 made of a photochromic material with color fading properties is bonded to the unit main body 10 so as to cover the viewfinder window 14 on the front surface.

This fading photochromic material has the opposite properties to that of ordinary photochromic materials; when ordinary photochromic materials are exposed to light, they darken, and when the light is removed, they return to their original transparency within a few minutes. On the other hand, this fading photochromic material has the property of increasing its transparency when the surroundings are bright and the subject is high in brightness, and becomes darker when the surroundings are dark and the subject's brightness decreases.

Further, the characteristics of the photochromic film 21 according to the present invention are adjusted so that it becomes dark when the brightness of the subject falls below the permissible exposure value.

As such a color-fading photochromic material, for example, a compound having a spiropyran structure or a compound having a thiazine structure (methylene blue, thionino blue J, etc.) is used as a compound that causes reverse photochromism. This is used as a coloring dye by dissolving it in an organic solvent such as methylethylkene, methylformamide or ethyl acetate, dispersing it in polyvinyl alcohol, polyvinyl pyrrolidone or polymetal acrylate copolymer, and coating it on a substrate. The substrate is glass,
A transparent plastic film or the like is used, and the surface of the coating film having reverse photochromism is preferably protected with another polymer.

The fading photochromic film 21 was prepared by mixing 0.5 g of the following compound and 45 g of polyvinyl pyrrolidone (molecular weight approximately 20 g) in tetrahydrofuran.
This is done by dissolving 45 g of the solution, coating it on a polyester film (5 g/m ² ), and drying it.

By producing the photochromic film 21 in this way, the film is usually colored magenta, and when visible light is irradiated, the density decreases and it becomes almost colorless. In this case, the conditions are lens brightness f = 11, shutter speed 1/100,
In the case of a film unit with a lens loaded with film with a film sensitivity of ISO400, the EV
It is desirable that the color develops at a luminance value of approximately 11 or less.

Next, the internal structure of the lens-fitted film unit according to this embodiment will be briefly explained. FIG. 2 shows a horizontal section of the unit main body 10, and the unit main body 10 includes a film supply chamber 26 which accommodates film rolls with an exposure window 22 in between.
and a cartridge accommodating chamber 30 that accommodates a cartridge 28 for winding the film. A cartridge shaft 28a that rotates in conjunction with the winding knob 20 described above is inserted into the cartridge 28, and the film 36 is actually wound around this cartridge shaft 28a.

Film support surface 3 on which the exposure window 22 is formed
2 is raised at the rear of the unit body 10 as shown, and correspondingly, a curved film regulating surface 34 is formed on the inside of the back surface of the unit body 10. Since the film support surface 32 and the film regulation surface 34 press down the film 36 around the exposure window 22, the film 36 can be brought into pressure contact with the film support surface 32 by utilizing the curl of the film 36. . This results in
The film 36 located behind the exposure window 22 is accurately positioned at a predetermined exposure position without floating or undulating.

Further, the photographing lens 12 is connected to the unit main body 1.
The shutter 40 is attached to the back of a lens window 38 formed at 0, and a shutter 40 is further arranged behind it.

Next, the operation and effect of the above embodiment will be explained.

In the lens-fitted film unit of the present invention, a roll of film is loaded in advance into a film supply chamber 26, and the leader portion of the film 36 pulled out from the film supply chamber 26 is wound around a cartridge shaft 28a. In addition, the unit body 10 is sold in a paper box (not shown).

When using this lens-equipped film unit, first the film winding knob 20 is turned to wind the film. In this film winding operation, the cartridge shaft 28a rotates in conjunction with the film winding knob 20, so that the unexposed film 36 is pulled out by one frame by the sprocket 43 and positioned behind the exposure window 22.

Then, the unit main body 10 is directed toward the subject and the subject is viewed through the viewfinder window 14. At this time, if the subject is bright, the photochromic film 21 becomes transparent and the subject can be clearly seen. On the other hand, if the object is dark below the exposure tolerance, the photochromic film 21 will rapidly become dark, and the object seen through the viewfinder 14 will be even darker and harder to see than when viewed directly.

Therefore, when the subject viewed through the viewfinder 14 is dark and has low brightness, photography is stopped; on the other hand, when the subject is bright and bright, the shutter 40 is activated by pointing the unit body 10 toward the subject and pressing the shutter button 16. The film 36 is exposed to a sufficient amount of light passing through the photographing lens 12.

Thereafter, by operating the film winding knob 20 and the shutter button 16, a predetermined number of frames can be sequentially photographed. After shooting the last frame, press the film winding knob 20.
Even if the shutter is operated, the shutter charge is not performed and only the film is rolled into the cartridge 28. After that, leave the unit in the paper box and submit it to a processing shop.

As described above, in this embodiment, since the fading photochromic film 21 is adhered to the front surface of the unit main body 10 so as to cover the viewfinder 14, the photographer can easily detect insufficient exposure due to the simple structure. This has the effect of being able to notify the user in advance, preventing inappropriate exposure from being taken, and ensuring that good exposure is always achieved.

Furthermore, if the present invention is applied to a lens-fitted film unit equipped with a strobe, it is possible to clearly notify when the strobe is being used.

Note that the present invention is not limited to the lens-equipped film unit shown in the above embodiment;
Needless to say, the present invention can be applied to any low-cost camera that does not have a device that automatically adjusts the exposure amount.

Further, instead of using the film 21, a thin glass material may be used as the fading photochromic material, and various other design changes are possible.

[Effect of idea]

In this invention, a fading photochromic material that becomes transparent when the subject is bright enough for exposure and becomes colored when the subject becomes dark is placed in the window opening, so the simple structure prevents inappropriate exposure. This has the effect that a warning can be issued easily and inexpensively.

Furthermore, this effect ultimately leads to prevention of waste of film, which is also advantageous from an economic point of view.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a horizontal sectional view of FIG. 1. 10...Unit body, 12...Photographing lens,
14...Finder, 21...Fadeable photochromic film, 36...Film.

Claims (1)

[Scope of Claim for Utility Model Registration] In a low-cost camera that does not have an exposure measurement means, a fading photochromic material that becomes transparent when the subject is bright enough for exposure and becomes colored when the subject becomes dark is used in the window opening of the camera. A low-cost camera characterized by the fact that