JPH11265010A - Focal plane shutter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce exposure unevenness from the upper end of a shutter aperture to the lower end of it at the time of photographing through a photographing lens. SOLUTION: A focal plane shutter for exposure while it is moved from the lower end of a shutter aperture 1a to the upper end of it is constituted so that the thickness of a substrate 1 is set to be gradually larger from the upper part of a shutter to the lower part of it on the side of a receiving plate 7 so as to bias an opening shutter blade 3a at the time of starting the exposure in the direction of the receiving plate 7 as compared with that at the time of finishing the exposure, and the plate thickness of the receiving plate 7 is similarly set to be gradually smaller from the upper part of the shutter to the lower part of it on the side of the substrate 1 so as to bias a closing shutter blade 5a at the time of finishing the exposure in the direction of the substrate 1, so that a distance between the opening and closing shutter blades 3a and 5a forming a slit in the direction of an optical axis is made short.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focal plane shutter for correcting exposure time unevenness of a camera shutter.

[0002]

2. Description of the Related Art As is well known, a focal plane shutter for a camera has a pair of open blades and a closed blade. The open blade opens a shutter opening in response to a shutter release signal, and exposure is started by a slit forming blade at the rear end. You. On the other hand, the closing blade operates after the opening operation of the opening blade,
The exposure of the shutter opening is terminated by the slit forming blade at the tip.

As shown in FIG. 6, a focal plane shutter that travels from the bottom to the top through a shutter opening for exposure includes a substrate 11 having a shutter opening 11a formed thereon and a receiving plate 7 as shown in FIG.
And a closed blade unit 5 housed between the camera unit and the pair of units 3, 5, which are in front of the film 8 loaded in the camera, and which are in the initial state. 3 is unfolded and shutter opening 1
The light from 1 a is shielded from the film 8. At this time, the slit forming shutter blades 3a are moved closer to the substrate 11 by the spacing blades 6a. On the other hand, the closing blade unit 5 is folded and positioned below the shutter opening 11a in the drawing. When the shutter is activated, the opening blade unit 3 is moved upward by one opening spring in the figure and folded, and after a predetermined time elapses according to the exposure time, the closing blade unit 5 is moved upward by one closing spring. Deploy to close the shutter opening. At this time, the spacing blade 6b
Thereby, the slit forming blades 5a are moved toward the receiving plate 7 side.

The rear end P of the slit forming shutter blade 3a at the rear end of the opening blade unit 3 in the opening direction and the slit forming shutter blade 5a at the front end of the closing blade unit 5 in the closing direction.
The slit formed by the front end Q of the shutter opening 11a moves from the lower end to the upper end of the shutter opening 11a in FIG.

[0005]

However, as shown in FIG. 7, when the blade unit moves from the lower end to the upper end, it moves while accelerating.
The width of the slit is different between the lower end and the upper end, but when parallel rays are incident on the film, the exposure amount is constant. However, when the image is taken through the photographing lens 12, the shutter blades 3a and 5a forming the slits of the open blade unit 3 and the closed blade unit 5 are far apart from each other in the optical axis direction. A uniform exposure dose cannot be obtained throughout. That is, the ratio of the exposure range D1 to the film 8 with the parallel rays at the start of the exposure (lower part in the figure) and the exposure range L1 to the film 8 with the oblique rays is the exposure of the parallel rays at the end of the exposure (upper part in the figure). The ratio is larger than the ratio between the range D2 and the exposure range L2 of the oblique ray, and the exposure amount is small at the lower end of the shutter opening 11a and is larger at the upper end. As the film sensitivity is improved, the exposure time must be shortened. In the case of achieving high-speed exposure only by narrowing the interval between the slits, the unevenness of the exposure amount is more remarkable.

[0006]

According to the present invention, there is provided a focal plane shutter in which a blade unit opens and closes a shutter opening. In a focal plane shutter in which a shutter opening is closed, the blade traveling space of the blade unit is moved along an optical axis. Direction and the other blade unit side, shorten the distance between the open and closed blades forming the slit in the optical axis direction, reduce the difference between oblique light and parallel light, and reduce the exposure unevenness of each part of the shutter opening. To get rid of it.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An opening or closing blade includes a substrate having a shutter opening, opening and closing blade units for opening and closing the shutter opening, and a receiving plate that defines a travel space of each blade unit between the substrate and the substrate. At a position where the blade unit closes the shutter opening, the substrate or the receiving plate is configured such that the slit forming blade of one blade unit gradually becomes thicker so as to approach the other blade unit in the optical axis direction.

When the shutter blade travels from the lower end to the upper end of the shutter opening, the lower end of the shutter opening is gradually thickened in the optical axis direction and the receiving plate side, and the upper end of the shutter opening is moved in the optical axis direction. It is preferable that the substrate side is provided with one or both of the receiving plate and the thicker receiving plate.

When the shutter blade travels from the upper end to the lower end of the shutter opening, the upper end of the shutter opening is gradually thickened in the optical axis direction and the receiving plate side, and the lower end of the shutter opening is moved in the optical axis direction. It is preferable that the substrate side is provided with one or both of the thicker receiving plate and the receiving plate.

[0010]

An embodiment of the present invention will be described below with reference to the accompanying drawings. 1 and 2 are an exploded perspective view and a side view showing one embodiment of a focal plane shutter according to the present invention. In FIG. 2, a shutter opening 1a is formed in the substrate 1 disposed in front of the film 8 and on the side of the photographing lens 12 mounted on the camera, and the thickness of the substrate 1 is set from above the shutter opening. It is formed gradually thicker downward. In FIG. 1, a shutter opening 1 is provided on a substrate 1.
The opening blade unit 3 for opening the shutter blade 4a is placed on the opening blade unit 3. A partition plate 4 having a shutter opening 4a is placed on the opening blade unit 3, and the closing blade unit 5 is placed on the partition plate 4. Is placed. On the closing blade unit 5, a receiving plate 7 having a shutter opening 7a is placed. In this manner, the open blade unit 3 is provided on the substrate 1.
The receiving plate 7 is attached with the partition plate 4 and the closing blade unit 5 incorporated therein.

That is, as shown in FIG. 2, the substrate 1 located on the taking lens 12 side and the receiving plate 7 located on the film 8 side constitute a storage chamber for shutter blades. The open blade unit 3 is located on the photographing lens 12 side, and the partition plate 4 is interposed between the open blade unit 3 and the closed blade unit 5. Here, the open blade unit 3 and the closed blade unit 5 are a plurality of shutter blades 3a, 3b, 3c, 3d, 3e and 5a, 5b in the embodiment shown in FIG.
5c and 5d are superimposed. However, each of the open and closed blade units 3 and 5 may be a single large shutter blade.

As shown in FIG. 3, the open blade unit 3 closes the shutter opening 1a (in the initial state) when the shutter blades 3a, 3b, 3c, 3d, and 3e are closed.
Wing arms 9, 1 each forming a pair of parallel links
0, and the pair of blade arms 9, 1
Numeral 0 is rotatably attached to the substrate 1 via pins 1b and 1c. FIG. 4 shows an embodiment of the drive unit of the opening and closing blade units 3 and 5. As shown in FIG. 4, the driving unit mainly includes an opening lever 3 for rotating each blade arm of the opening and closing blade units 3 and 5.
0, a closing lever 50, a set lever 60 for setting the opening lever 30 and the closing lever 50 to a predetermined set position shown in the figure, and an opening lever 30 and a closing lever 5
It is composed of electromagnets 40 and 80 for controlling 0 respectively.

The opening lever 30 and the closing lever 50 are urged by drive springs 31 and 51 to rotate leftward about shafts 32 and 52, respectively.
The speed of the shutter blades can be adjusted by adjusting the spring forces of 1, 51. The set lever 60 is urged by a spring 61 to turn clockwise about a shaft 62. However, during the setting operation, the set lever 60 is driven by a charging member 90 of the camera to turn counterclockwise. Also, the electromagnets 40, 8
Reference numeral 0 controls the operation of the opening lever 30 and the closing lever 50 when the iron cores 41 and 81 are in the suction state or the non-suction state with the iron pieces 34 and 54 of the opening lever 30 and the closing lever 50, respectively.

In such a driving section, the set lever 60 is rotated leftward during the setting operation, and the rollers 3 of the opening lever 30 and the closing lever 50 are moved by the projections 60a and 60b.
3 and 53, the opening lever 30 and the closing lever 50 are pressed.
Turn clockwise. As a result, the iron pieces 34 and 54 fixed to the opening lever 30 and the closing lever 50 respectively
When the electromagnets 40 and 80 are excited by an electric circuit (not shown) on the camera cores 41 and 81, the iron pieces 34 and 5 of the closing lever 30 and the opening lever 50 are pressed.
4 is attracted to the iron cores 41, 81 of the electromagnets 40, 80, respectively.

At the lower end of the shutter opening 1a, the shutter blades 3a of the open blade unit 3 are pushed in the direction of the receiving plate 7 as compared with the conventional shutter, because the thickness of the substrate 1 is thicker on the receiving plate side. The distance of the unit 5 from the shutter blades 5a in the optical axis direction becomes shorter. At the upper end of the shutter opening 7a, since the thickness of the receiving plate 7 is larger on the substrate side, the shutter blades 5a of the closing unit 5
Direction.

The operation of the shutter having the above configuration will be described below. When the shutter release operation is performed in the state of FIG. 4, the electromagnets 40 and 80 are first excited, and the open / close levers 30 and 50 are moved through the iron pieces 34 and 54 to the electromagnets 4 and 54.
It is adsorbed at 0 and 80. When the charging member 90 of the camera is retracted, the set lever 60 is turned clockwise by the spring 61. Thereafter, the electromagnets 40 and 80 are demagnetized and the release lever 30 is released.
Makes a left turn, the shutter blades 3a, 3b, 3c, 3d, 3e of the opening blade unit 3 move to the upper end and start opening the shutter opening 1a.

After a lapse of a predetermined time, the electromagnet 80 is demagnetized and the closing lever 50 turns left, so that the shutter blades 5a, 5b, 5c and 5d of the closing blade unit 5 move to the upper end in FIG. Then, the thickness of the substrate 1 gradually decreases, and the open blade units 3 are stacked and folded, so that the shutter blade 3a moves toward the photographing lens 12.
As a result, the distance in the optical axis direction between the shutter blade 3a of the open blade unit 3 and the shutter blade 5a of the closed blade unit 5 gradually increases. At this time, the rear end P of the shutter blade 3a of the open blade unit 3 and the closed blade unit 5
A slit is formed with the front end Q of the shutter blade 5a. FIG. 5 illustrates this configuration.

As shown in FIG. 5, when the open and closed blade units 3 and 5 move from the lower end to the upper end, at the lower end, blades 3a and 5a forming slits of the open blade unit 3 and the closed blade unit 5 are formed. The interval in the optical axis direction is small, and the difference between the exposure range L3 for parallel rays and the exposure range D3 for oblique rays is small. On the other hand, also at the upper end, the interval between the blades forming the slits of the open blade unit 3 and the closed blade unit 5 in the optical axis direction is small, and the difference between the exposure range L4 for parallel rays and the exposure range D4 for oblique rays is also small. Few. Therefore, the difference between L3 / D3 and L4 / D4 is small, and the difference between the lower and upper exposure amounts to the shutter opening 1a is reduced.

A shutter which travels from the upper end to the lower end of the shutter opening, the open blade unit 3 is mounted on the substrate 1 side, and the closed blade unit 5 is mounted on the receiving plate 7 side, The thickness of the substrate 1 may be gradually reduced from the upper end to the lower end, and the thickness of the receiving plate 7 may be gradually increased from the upper end to the lower end. Further, the shutter travels from the upper end to the lower end of the shutter opening, the closing blade unit 3 is mounted on the substrate 1 side, and the open blade unit 5 is mounted on the receiving plate 7 side. The thickness may be gradually increased from the upper end to the lower end, and the thickness may be gradually decreased from the upper end to the lower end of the receiving plate 7. The unit 3 is placed and the receiving plate 7
As for the shutter of the type in which the open blade unit 5 is placed on the side, the plate thickness is gradually increased from the lower end to the upper end of the substrate 1 and the plate thickness is gradually increased from the lower end to the upper end of the receiving plate 7. I just need. Further, in each of the above embodiments, both the plate thickness of the substrate 1 and the plate thickness of the receiving plate 7 are changed, but it is needless to say that only one of them is required.

[0020]

According to the construction of the present invention, in a focal plane shutter in which the blade unit runs up and down the shutter opening, the blade running space of the open blade unit near the start of exposure is narrowed to the receiving plate side to open and close the blade. The difference between the oblique light and the parallel light is reduced by shortening the distance between the slits in the optical axis direction. Therefore, the exposure amount to the film through the photographing lens becomes substantially uniform, and a photograph with less exposure amount unevenness can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a focal plane shutter according to the present invention.

FIG. 2 is a side view showing one embodiment of a focal plane shutter according to the present invention.

FIG. 3 is a front view showing the shutter blade of FIG. 1;

FIG. 4 is a front view showing an embodiment of a shutter driving unit.

FIG. 5 is a diagram illustrating a configuration according to an embodiment of the present invention;

FIG. 6 is a side view showing a conventional shutter.

FIG. 7 is a diagram illustrating a configuration of a conventional shutter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 3 Open blade unit 3a, 3b, 3c, 3d, 3e Open shutter blade 5 Closed blade unit 5a, 5b, 5c, 5d Closed shutter blade 7 Receiving plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kuni Takahashi, inventor 934-13 Shiwatari, Yokkaido, Chiba Pref.

Claims (3)

[Claims] An opening and closing blade unit for opening and closing the shutter opening; and a receiving plate for defining a travel space of each blade unit between the substrate and the substrate. Alternatively, at the position where the closing blade unit closes the shutter opening, the substrate or the receiving plate is gradually thickened so that the slit forming blade of the one blade unit approaches the other blade unit in the optical axis direction. A focal plane shutter, characterized in that: 2. The substrate, wherein the lower end of the shutter opening is gradually thicker in the optical axis direction and on the receiving plate side, and / or the upper end of the shutter opening is gradually thicker in the optical axis direction and on the substrate side. 2. The focal plane shutter according to claim 1, comprising both. 3. The substrate in which the upper end of the shutter opening is gradually thicker in the optical axis direction on the receiving plate side and / or the lower end of the shutter opening is gradually thicker in the optical axis direction on the substrate side. 2. The focal plane shutter according to claim 1, comprising both.