JPH06317815A - Stop plate and film unit with lens using the same - Google Patents

Abstract

PURPOSE:To obtain a distinct image not only in the case of photographing under high illuminance but also in the case of photographing under low illuminance by arranging a stop plate which has photochromic property and where a minimum stop aperture is formed coaxially with the stop aperture. CONSTITUTION:The stop aperture 24 is formed at a position corresponding to an exposure aperture 22 on a lens holder 20, and a photographing lens 4 is put thereon. The aperture 24 is formed to be largish so that object light under the low illuminance can be fully taken in. The stop plate 25 is installed on the back surface side of the aperture 211. On the plate 25, a photochromic layer 27 is formed by applying photochromics on a transparent supporting body 26, and the minimum stop aperture 28 is formed in the center part of the layer 27. The plate 25 is formed in a disk state having a size large enough to fully cover the aperture 24, and the aperture 24 is installed so that the center of the aperture 28 may be positioned on an optical axis 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm plate that widens the range of illuminance that can be photographed, and a lens using this diaphragm plate that enables photographing under low illuminance without deteriorating image quality under high illuminance. It relates to the film unit.

[0002]

2. Description of the Related Art Currently, a large number of types of cameras are manufactured and used according to their applications and functions. A diaphragm aperture for restricting the luminous flux of the subject light that has passed through the photographing lens and is uniformly provided in the photographing optical path of these cameras. Generally, the aperture of the diaphragm is continuously changed in accordance with the illuminance of the subject light so that the amount of light reaching the image plane can be adjusted appropriately.

On the other hand, a lens-fitted film unit that does not require a troublesome film loading operation, for example, "Sharan-run Hi (brand name)" is manufactured and sold, and is generally widely used so that a photograph can be taken immediately after purchase. It's being used. This lens-fitted film unit is an unexposed photo film built into the unit body that incorporates a simple shooting mechanism, and the shutter button is pressed after film winding operation, similar to general camera operation. Then, the shutter blades are opened and closed to expose the subject image on the photographic film set in the aperture.

[0004]

The lens-fitted film unit as described above has an advantage that it can be provided at a low price, and has a very simple structure because it needs to be manufactured at the lowest possible cost. Therefore, the aperture opening used in the lens-fitted photo film unit is formed only by forming the opening in the lens holder for holding the taking lens, and its aperture cannot be changed. Further, the aperture diameter of this aperture opening is set to be small so that the image becomes sharp, and thus it is not suitable for photographing under low illuminance.

The present invention has been made in view of the above circumstances, and uses an aperture plate that widens the range of illuminance that can be photographed, and uses this aperture plate in low illuminance without deteriorating the image quality in high illuminance. An object is to provide a film unit with a lens that enables photographing.

[0006]

In order to achieve the above object, the present invention provides a first diaphragm opening formed in a lens holder, wherein a first diaphragm opening is formed in a photochromic material whose light transmittance decreases as the light illuminance increases. A diaphragm plate having a second diaphragm opening with a smaller diameter than that of the diaphragm plate is covered. Further, it is preferable that the light transmittance of the photochromic material becomes smaller as the distance from the second diaphragm aperture increases. Further, it is preferable to fill the second aperture with a transparent material having the same refractive index as the photochromic material.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows an example of a film unit with a lens using the diaphragm plate of the present invention. The unit body 2 is mainly made of plastic and is entirely covered with the outer case 3. The outer case 3 is for making the appearance of the lens-fitted film unit clean, and a paper box or the like having a printed outer surface is used. The outer case 3 is provided with holes for exposing the taking lens 4, the viewfinder 5, the winding knob 6, the display window 7 for confirming the number of remaining films, and the shutter button 8. The photo is taken up to.

FIG. 4 is an exploded view of a unit main body of a lens-fitted film unit using the diaphragm plate of the present invention. The unit main body 2 includes a main body 10 and a front cover 11 that covers the main body 10 from the upper surface to the front surface.
And a rear cover 12 that covers the back surface of the main body 10. In the main body portion 10, a cartridge chamber 15 for accommodating the cartridge body 14 of the photographic film cartridge 13 and a film roll chamber 17 for accommodating the unexposed photograph film 16 pulled out from the cartridge body 14 in a roll form are formed. There is. A light-shielding tube 18 is provided between the cartridge chamber 15 and the film roll chamber 17, and a lens holder 20 on which the taking lens 4 is mounted is attached to the front surface of the light-shielding tube 18. Then, by attaching the front cover 11 to the main body 10, the photographing lens 4
Is fixed.

As shown in FIG. 1, an aperture 21 for defining the photographing screen of the photographic film 16 is formed at the rear portion of the light-shielding cylinder 18, and an exposure opening 22 having a shape similar to that of the aperture 21 is formed at the front portion. Has been done. Exposure opening 22
A shutter blade 23 for opening and closing the exposure opening 22 is rotatably provided on the front surface of the lens holder 20, and the lens holder 20 is mounted in front of the shutter blade 23. A diaphragm opening 24 is formed in the lens holder 20 at a position corresponding to the exposure opening 22, and the taking lens 4 is placed so as to cover the diaphragm opening 24. Aperture opening 2
Reference numeral 4 is formed to be large so that the subject light under low illuminance can be sufficiently taken in. A diaphragm plate 25 is attached to the back side of the diaphragm opening 24.

The diaphragm plate 25, as shown in FIG.
A photochromic layer 27 is formed by coating photochromic mix on a transparent support 26, and a minimum aperture opening 28 is formed at the center of the photochromic layer 27. The diaphragm plate 25 is formed in a disk shape having a size sufficient to cover the diaphragm opening 24, and is attached to the diaphragm opening 24 so that the center of the smallest diaphragm opening 28 is located on the optical axis 29. Photochromic is a substance whose light transmittance changes over almost the entire wavelength range of visible light, and it is difficult for high illuminance light to pass through and low illuminance light for easy passage. The support 26 may be made of any material having optical characteristics such that the imaging performance and brightness of the taking lens 4 do not pose any practical problems. For example, synthetic resin such as acrylic resin or glass may be used. Good.

Next, the operation of the present invention will be described. When a photographer purchases a lens-fitted film unit and takes a picture, the photographer first rotates the winding knob 6 until the rotation is locked, and confirms that the preparation for photographing is completed and the shutter is charged. To do. Next, when the framing is determined so that the main subject is contained within the field of view of the finder 5 and the shutter button 8 is operated, the shutter blade 23 opens and closes the exposure opening 22 to expose the photographic screen on the photographic film 16. It

At this time, the subject light entering from the taking lens 4 first reaches the diaphragm plate 25 after its luminous flux is limited by the diaphragm aperture 24. When the illuminance of the subject light is low, the transmittance of the photochromic layer 27 formed on the diaphragm plate 25 is high, so that the subject light whose luminous flux is limited by the diaphragm opening 24 has the same diameter as the diaphragm opening 24.
9 and passes through the exposure opening 22. Further, when the illuminance of the subject light is high, the transmittance of the photochromic layer 27 becomes low to make it difficult to transmit the subject light. Therefore, the luminous flux of the subject light passes through the exposure aperture 22 with the same diameter as the minimum aperture opening 28. To do. Therefore, a clear image is formed on the photographic film 16 set on the aperture 21.

When one photographing is completed, the winding knob 6
Is operated to wind the exposed photographic film 16 into the cartridge main body 14. When the sprocket that rotates following the feeding of the photographic film 16 detects one frame fixed length feeding,
The winding knob 6 is locked to notify that the next shooting preparation is completed. When the exposure is repeated as described above and "0" appears in the display window 7 for displaying the number of remaining films, it means that the whole frame photographing is completed.

After shooting all frames, take the lens-equipped film unit to a photofinishing shop and request a DPE. Film development and print processing will be performed in the same way as in the past, and clear negatives and print photographs will be obtained. Passed to the photographer.

In the above embodiment, the thickness of the photochromic layer is constant and the light transmittance is constant over the entire surface. However, as shown in FIG. 5, the thickness of the photochromic layer 32 is from the central portion to the outer periphery. The thickness may be increased stepwise toward the side, and the light transmittance may be reduced as the distance from the central portion increases. Further, as shown in FIG. 6, the thickness of the photochromic layer 37 may be changed by the inclination. Further, as shown in FIG. 7, the photochromic layers 42 to 44 having different light transmission characteristics may be arranged concentrically. In this case, the photochromic layers 42-44
As shown in FIG. 8, a material whose light transmittance is likely to be reduced may be arranged on the outer peripheral side so that the light transmittance decreases from the outer peripheral side as the light illuminance increases. According to this embodiment, the aperture of the diaphragm can be changed according to the illuminance, and the luminous flux can be adjusted more finely.

In the above embodiment, the minimum aperture opening formed in the photochromic layer is used as it is. However, as shown in FIG. 9, the minimum aperture opening 53 is formed in the photochromic layer 52. A transparent material 54 having the same refractive index as the photochromic layer 52 may be filled so that the thickness becomes uniform. According to this embodiment, it is possible to eliminate the disturbance of the image formation on the film surface due to the difference in the thickness of the photochromic layer, and it is possible to obtain a clearer image.

Further, in the above-mentioned embodiment, the photochromic is applied so as to form the minimum aperture on the support, but as shown in FIG. 10, the photochromic is applied to the entire surface of at least one surface of the support 61. May be applied to form the photochromic layer 62, and thereafter, the minimum aperture opening 63 may be punched out in the central portion.

Further, in the above-mentioned embodiment, the photochromic layer is formed on the support so as to have the photochromic property, but the glass plate or the resin plate itself may be mixed with the crystal or compound having the photochromic property.

[0019]

As described above, according to the present invention, the diaphragm plate having the photochromic property and having the minimum diaphragm aperture is arranged coaxially with the diaphragm aperture, and when the illuminance of the subject light is low, the diaphragm aperture is opened. When the illuminance of the subject light is high, the light flux is limited until it has the same diameter as the minimum aperture opening, so the aperture opening can be made larger. As a result, a clear image can be obtained not only when shooting under high illuminance but also when shooting under low illuminance.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a lens-fitted film unit using an aperture plate of the present invention.

FIG. 2 is a sectional view of a diaphragm plate of the present invention.

FIG. 3 is an external view showing an example of a film unit with a lens using the diaphragm plate of the present invention.

4 is an exploded perspective view showing a unit main body of the lens-fitted film unit shown in FIG.

FIG. 5 is a sectional view showing a second embodiment of the diaphragm plate.

FIG. 6 is a sectional view showing a third embodiment of the diaphragm plate.

FIG. 7 is a sectional view showing a fourth embodiment of the diaphragm plate.

8 is a graph showing the light transmission characteristics of the photochromic layer of the aperture plate shown in FIG.

FIG. 9 is a sectional view showing a fifth embodiment of the diaphragm plate.

FIG. 10 is a sectional view showing a sixth embodiment of the diaphragm plate.

[Explanation of symbols]

4 Photographic lens 16 Photo film 18 Light-shielding cylinder 20 Lens holder 24 Aperture aperture 25, 30, 35, 40, 50, 60 Aperture plate 26, 31, 36, 41, 51, 61 Support 27, 32, 37, 42, 43 , 44, 52, 62 Photochromic layer 29 Optical axis 54 Transparent material 28, 33, 38, 45, 53, 63 Minimum aperture aperture

Claims (4)

[Claims] 1. A diaphragm plate characterized in that a diaphragm opening is formed in a photochromic material whose light transmittance decreases as the light illuminance increases. 2. The diaphragm plate according to claim 1, wherein the photochromic material has a light transmittance that decreases as the distance from the diaphragm opening increases. 3. The diaphragm plate according to claim 1, wherein the diaphragm aperture is filled with a transparent material having the same refractive index as the photochromic material. 4. A photographic lens, and a lens holder having a first diaphragm opening for positioning and supporting the photographic lens and limiting a light flux transmitted through the photographic lens and incident thereon.
A lens-fitted film unit in which an unexposed photographic film is housed in advance in a unit body incorporating a shutter mechanism, wherein the first diaphragm is provided in the first aperture opening and the photochromic material whose light transmittance decreases as the light illuminance increases. A film unit with a lens, which is covered with a diaphragm plate having a second diaphragm opening having a diameter smaller than that of the opening.