JPH07333678A - Focal plane shutter - Google Patents

Abstract

PURPOSE:To provide a very high speed focal plane shutter whose cost is low, whose durability is very high, and whose speed is >=1/8000 seconds. CONSTITUTION:As to this focal plane shutter constituted of at least four or five divided blades 11 to 14, 21 to 24, and driving mechanisms 19 and 29 driving the divided blades; the blade out of the divided blades 11 to 14 and 21 to 24, whose moving amount in the case of being driven by the driving mechanisms 19 and 29 is the largest, is made of magnesium and magnesium-lithium based alloy which contains >=11wt.% lithium, and the thickness of the blade is 130mum to 200mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical running focal plane shutter used in a camera (hereinafter, vertical running is omitted and simply referred to as a focal plane shutter).

[0002]

2. Description of the Related Art In recent years, there has been a demand for higher camera shutter speeds and flash sync speeds for reasons such as improved film sensitivity and the desire for new image expression.
High shutter speed up to 8000 seconds and synchronization speed 1 /
A camera (having a focal plane shutter) realizing 250 seconds is provided.

In such a focal plane shutter of a camera, a high shutter speed exceeding the flash synchronization speed starts moving the front curtain and the rear curtain with a timing shift, and the first blade of the front curtain and the first blade of the rear curtain are moved. This is realized by performing slit exposure while fixing the amount of the gap (slit) to a certain interval or changing it according to the speed.

This focal plane shutter comprises at least four or five divided blades (light-shielding blades) and a drive mechanism for driving them. The light-shielding blades are composed of a fiber-reinforced plastic plate (hereinafter referred to as FRP), an aluminum plate, two of the four blades that have a large amount of movement, the former, and two that have a small amount of movement. Some include the latter.

As disclosed in Japanese Patent Laid-Open No. 59-61827, FRP uses carbon fibers arranged in one direction as reinforcing fibers and epoxy resin as matrix resin. FRP is a precursor, prepreg sheet.
It is manufactured by laminating a plurality of t) (laminating such that the fiber directions thereof are orthogonal or substantially orthogonal to each other), and heating and curing the entire laminated body while pressing. The FRP material manufactured in this way is cut into the desired shape of the light-shielding blade. Cutting is generally punching with a press.

The light-shielding blade made of FRP (made of FRP) is lightweight but has high bending rigidity. for that reason,
Even with a shutter speed as high as 1/8000 seconds, the waviness of the blades during running and immediately after stopping is very small. Further, even if the wave is generated, the wavy (vibrating) state is settled more quickly than, for example, a blade made of aluminum. Therefore, when the light-shielding blade configured by the FRP is used, the blade is damaged by colliding with another blade or the aperture (which determines the angle of view) by performing the next shutter operation while the blade is wavy. It is possible to achieve extremely high durability performance without the shutter becoming inoperable.

However, the diameter of the carbon fiber is 3 to 8 μm.
m, and if the arrangement is poor, the number of fibers locally increases or decreases, causing variations in strength and deterioration of flatness (warpage). Also, some blades may warp after being used for some reason for a long time. Since such blades have a large variation in plate thickness, they are discarded in advance. In addition, products with a defective appearance such as failure in stacking or scratches are also discarded. Furthermore, some feathers will warp when painted. This also throws away the warped blade.

As described above, the FRP blade is very troublesome in quality control and has a low non-defective rate, that is, the cost is very high.
Further, in terms of performance, although it has the above-mentioned excellent points, its end surface becomes fluffy by punching with a press, which causes a problem of uneven exposure when performing the slit exposure. Although this can be improved by polishing or the like, it is very troublesome, and improvement is desired, for example, if too much polishing causes a defect.

Further, in order to realize a high-speed shutter of 1/8000 seconds or more, even when trying to cope with the situation by narrowing the slit interval, the problem of the end face causes a problem in practical use at present. is there. On the other hand, in the case of the blade made of aluminum, the problem of the end face is much smaller than that of the FRP, and the cost is considerably lower than that of the FRP.

However, the weight of the blade becomes considerably heavy, which not only causes an increase in charge energy, but also causes the ripple of the blade to become extremely large during traveling and immediately after stopping. Also, the wave (vibration) state does not easily settle. Therefore, the shutter using the blades made of aluminum is significantly inferior in durability to the shutter using the blades made of FRP.

[0011]

As described above, the present 1 /
The improvement of the shutter blade material that has achieved 8000 seconds has been awaited. Also, more recently, 1/8000
There is a demand for even faster ultra-high-speed shutters that exceed seconds. In order to meet such a demand, it is necessary to improve the blade member to be driven, that is, to reduce the weight and the rigidity, and to improve the quality and the cost.

An object of the present invention is to provide an ultra-high speed focal plane shutter of 1/8000 seconds or more which is low in cost and has extremely high durability.

[0013]

The inventors of the present invention who have thought that it is difficult to solve the above-mentioned problems are inherent in the conventional materials for shutter blades, such as FRP and aluminum, which have the above-mentioned drawbacks.
As a result of study focusing on magnesium-lithium alloys, ・ By adding lithium with a specific gravity of 0.53 to magnesium so that the composition of lithium is 11% by weight or more with respect to the entire alloy, the cold rolling property is improved. Further, if at least one kind of aluminum, zinc, silver and yttrium is added in a small amount, the rolling property (elongation) is further improved, and the plate thickness can be used as a blade material. It is possible that the specific gravity becomes very light as the added amount of is increased, and it is very difficult to dissolve lithium in magnesium, but the specific gravity is 1.0 depending on the composition.
The elastic modulus is about half that of aluminum, but in the case of a focal plane shutter, it is 4 to 5 as shown in FIG.
It is composed of a number of divided blades, and the blades that require strength and rigidity are only the blades that move a large amount.
The thickness may be 30 to 200 μm, particularly preferably 1
With a composition of magnesium-lithium alloy whose specific gravity is 1.0 or less when the thickness is 30 to 160 μm, the weight is equal to or less than the weight of the FRP blades.-Since the specific gravity is small, the charge energy increases even if the plate thickness is increased.・ When actually traveling at high speed, the blades of this alloy have small ripples during traveling and immediately after stopping, and the ripples (vibration) state immediately subsides, improving durability.・ The punching workability with a press is good, and the blade end surface is finished very neatly, so the slit can be made narrower, and it is easy to obtain a high-speed shutter speed. ・ When the blade shape is used, it is flat It has been found that there are many advantages that bad ones can be corrected and cost can be reduced.

Therefore, in order to solve the above-mentioned problems, the present invention firstly states, "A focal plane shutter comprising at least four or five divided blades and a drive mechanism for driving them is provided. Among them, the blade having the largest movement amount when driven by the driving mechanism is made of magnesium and a magnesium-lithium alloy containing 11% by weight or more of lithium, and the blade has a plate thickness of 13
A focal plane shutter (claim 1) characterized in that the focal plane shutter has a thickness of 0 μm to 200 μm.

Further, the present invention secondly relates to "a focal plane shutter comprising at least four or five divided blades and a drive mechanism for driving them, among the divided blades when driven by the drive mechanism. The first and second blades counting from the largest moving amount are made of magnesium-lithium alloy containing magnesium and 11% by weight or more of lithium, and the blade has a plate thickness of 130 μm-
A focal plane shutter having a thickness of 200 μm is provided.

Further, the present invention is thirdly "a focal plane shutter comprising at least four or five divided blades and a drive mechanism for driving them, among the divided blades when driven by the drive mechanism. The first and third blades counted from the largest moving amount are made of magnesium-lithium alloy containing magnesium and 11% by weight or more of lithium, and the slit forming blade has a plate thickness of 1
A focal plane shutter (claim 3) having a thickness of 30 μm to 200 μm is provided.

In a fourth aspect of the present invention, the composition of the magnesium-lithium alloy is 50 to 65% by weight of magnesium, 30 to 45% by weight of lithium, and 1 to 10% by weight of at least one of aluminum and zinc. %, The focal plane shutter according to claims 1 to 3 is provided. A fifth aspect of the present invention provides the focal plane shutter according to any one of claims 1 to 4, wherein the blade of the magnesium-lithium alloy has a plate thickness of 130 µm to 160 µm. To do.

Magnesium-lithium alloys have the following advantages: ・ The cost of the metal is higher than that of aluminum. ・ The plate thickness must be increased to obtain the rigidity required for high-speed running. The shutter's blade chamber (the gap where the blades and arms travel) may be too narrow, and depending on the camera, the size of the shutter must be increased, and only after a major design change of the entire camera. However, there is a drawback that it may be difficult to apply, that is, it may be difficult to improve the function by changing only the material, so a highly durable and highly functional shutter can be easily provided. And to make it cheaper,
Use in combination with aluminum alloys (for example, aluminum / copper alloys such as duralumin, and the elastic modulus of which is more than twice that of magnesium / lithium alloys, so it is possible to reduce the plate thickness to make room in the blade chamber). Is more preferable.

Therefore, a sixth aspect of the present invention is "at least,
In a focal plane shutter including four or five divided blades and a drive mechanism for driving them, the divided blades are formed of the magnesium-lithium alloy blade according to claim 1 and an aluminum alloy. Focal plane shutter (claim 6) ".

Further, in order to suppress the blade shake during high speed traveling, it is effective to use the shutter for high speed traveling together with FRP. The problem of the slit end face can be solved by using a magnesium-lithium alloy, and it becomes possible to reduce the weight and improve the durability. Therefore, in a seventh aspect of the present invention, in a focal plane shutter including at least four or five divided blades and a drive mechanism for driving these, the divided blades are defined by claims 1 to 5.
And a blade made of the magnesium-lithium alloy described in 1 above, and a blade made of FRP. A focal plane shutter (claim 7) "is provided.

[0021]

Function: Generally, magnesium alloys have poor rolling properties and poor workability. Therefore, it is quite difficult to form a thin foil by cold rolling or the like. Also, it is very difficult to dissolve lithium in magnesium. This is because, when dissolved, lithium vaporizes even if a small amount of water is present.

However, in order to solve this problem, magnesium and aluminum (or zinc) are first melted in a high-frequency heating vacuum melting furnace filled with argon gas instead of air, and lithium is kept at a constant temperature. Melt in. Immediately after this, it was found that by adopting the method of lowering the temperature and pouring it into the mold, it becomes possible to add a high concentration of lithium, and it is possible to achieve good rollability and workability that are not possible with general magnesium alloys.

The composition ratio of magnesium-lithium alloy is 50-65% by weight of magnesium and 30% of lithium.
~ 45% by weight, at least one of aluminum or zinc
When the type is 1 to 10% by weight, the specific gravity is about 1.0, which is more preferable in terms of weight reduction. As an example, magnesium 57.4% by weight, lithium 37.6% by weight, aluminum 5% by weight
The specific gravity is 0.95 in the case of 56.5% by weight of magnesium, 38.5% by weight of lithium, and 5% by weight of zinc.
The weight can be significantly reduced compared to FRP and aluminum, and when the charge energy is at the same level as that of the conventional one (energy is not reduced), it is possible to increase the plate thickness to increase the rigidity.

Since the magnesium-lithium alloy is oxidized, it is desirable to perform anticorrosion treatment. For example, anodic oxidation improves the corrosion resistance, heat resistance, and wear resistance. The appearance of the anodic oxide film is a black matte opaque film, which is preferable because it also serves as a blade material to prevent reflection. In addition, black coating is generally applied to the blade material in order to impart wear resistance and lubricity, but in this case, it is preferable to perform anodization or chemical conversion treatment as a coating base.

The present invention will be described in more detail with reference to the following examples with reference to the drawings, but the present invention is not limited thereto.

[0026]

Embodiment 1 Hereinafter, referring to the drawings, etc.,
The present invention will be described in detail. 1 and 2 are views showing a first embodiment of a focal plane shutter according to the present invention, FIG. 1 is a front view, and FIG. 2 is an exploded view of split blades. The focal plane shutter of this embodiment includes a front curtain 10, a rear curtain 20, a shutter substrate 30 and the like.

The front curtain 10 is composed of four divided blades 11-14. The arms 15 and 16 are for supporting the respective divided blades 11 to 14, and these arms 15 and 16 are rotatably connected to the axes X ₁ and X ₂ planted in the shutter substrate 30. ing. The split vane 11-14, respectively caulking pin 17 _1-17
4 and the caulking pins 18 ₁ to 18 ₄ make the arms 15 and 1
6 is rotatably connected.

A drive shaft 31 is attached to the hole 16a of the arm 16, and the drive shaft 31 opens and closes the front curtain 10 in response to a drive force from a known shutter drive device when driving the shutter. Similarly, the trailing blade 20 is also composed of four divided blades 21 to 24. Arms 25, 26
Are for supporting the respective divided blades 21 to 24, and these arms 25 and 26 are provided for the shutter substrate 3
It is rotatably connected to the axes X ₃ and X ₄ which are planted at 0. The split blades 21 to 24 are attached to the arm 2 by the caulking pins 27 _{1 to} 27 ₄ and 28 _{1 to} 28 ₄ , respectively.
5 and 26 are rotatably connected.

A drive shaft 32 is attached to the hole 26a of the arm 26, and the drive shaft 32 opens and closes the rear curtain 20 by receiving a drive force from a well-known shutter drive device when the shutter is driven. These arms 15, 16, 2
₅ , 26, axes X _{1 to} X ₄ , caulking pins 17, 18, 2
7, 28 and drive shafts 31, 32 are divided blades 11 respectively.
Drive mechanisms 19 and 29 for moving 14 to 21 to 24.

Next, the shutter curtain of this embodiment will be described in more detail. Explaining the first curtain as an example, the split blades 11 to 14 are made of a magnesium / lithium alloy plate material having a plate thickness of 130 to 160 μm and an aluminum alloy plate material of a plate thickness of 50 to 70 μm. The composition of the alloy is 57.4 wt% magnesium, 37.6 wt% lithium, and 5 wt% aluminum.

First, the divided blades 11 and 12 having a large amount of movement required for strength and rigidity are made of a plate material having a thickness of 130 to 160 μm.
Then, the divided blades 13 and 14 having a small movement amount are set to 50 to 80
The aluminum alloy plate having a thickness of 3 μm is press-pressed, and then the entire surface of each of the divided blades 11 to 14 is subjected to anodic oxidation or chemical conversion treatment as a coating base, and a thickness of 3 to 6 μm is provided to impart wear resistance and lubricity. Apply the blackened coating.

Here, the non-defective rate was measured and is shown in Table 1. In this case, it is preferable that the blade shape is performed from the viewpoint of anticorrosion, but the blade shape may be obtained by performing anodizing or chemical conversion treatment and blackening coating on the plate material. However, it is preferable to apply anodization or chemical conversion treatment and blackening coating to the slit-side end surface of the slit forming blade.

The case of the divided blades 21 to 24 of the rear curtain is similar to that of the front curtain. Next, each divided blade 11-14 and 21-
The 24 is actually built into the shutter and the maximum speed is 1.
The results of running at / 8000 seconds are also shown in Table 1. For comparison, the result of measuring the non-defective rate of the conventional FRP and aluminum blades, and actually incorporating it in the shutter,
Table 1 also shows the result of running at the maximum speed of 1/8000 seconds.

As can be seen from Table 1, the shutter of the present embodiment has the same durability as the shutter using the FRP blade, but the non-defective rate of the blade constituting the shutter is the same as that of aluminum. It is now possible to improve durability at low cost. Also 1 /
It can also contribute to the practical application of ultra-high-speed shutters that exceed 8000 seconds.

[0035]

[Embodiment 2] In this embodiment, the composition of the magnesium-lithium alloy used for the dividing blades 11, 12 and the dividing blades 21, 22 is 56.5% by weight of magnesium and 3% of lithium.
Same as Example 1 except 8.5% by weight and 5% by weight zinc. Also for Example 2, the non-defective rate was measured, and Table 1
Described in.

In Example 2 as well, the shutter was actually incorporated into the shutter to run at a maximum speed of 1/8000 seconds. The results are also shown in Table 1. As can be seen from Table 1, good results were obtained as in Example 1.

[0037]

[Embodiment 3] In this embodiment, the composition of the magnesium-lithium alloy used for the dividing blades is the same as that in Embodiment 1, but the dividing blades 11, 13 and 21, 23 are 130-1.
From 60μm magnesium-lithium alloy plate material,
Then, the divided blades 12, 14 and 22, 24 are set to 50 to 80.
Example 1 except that the blades 11 to 14 and 21 to 24 were formed by punching out from a sheet of aluminum alloy having a thickness of μm.
Is the same as. Also in Example 3, the non-defective rate was measured and is shown in Table 1.

Also in Example 3, the shutter was actually incorporated and the vehicle was run at a maximum speed of 1/8000 seconds. The results are also shown in Table 1. As can be seen from Table 1, good results were obtained as in Example 1. In this case, the charge energy was slightly higher than that in the cases of Example 1 and Example 2.

[0039]

[Embodiment 4] In this embodiment, the composition of the magnesium-lithium alloy used for the dividing blades is the same as that in Embodiment 1, but the dividing blades 11 and 21 only have 130 to 150 μm.
Of the magnesium-lithium alloy, and the dividing blades 13 and 23 are made of an aluminum alloy plate material having a thickness of 80 to 100 μm, and the dividing blades 12, 14 and 22, 2,
4 is press-punched from a plate material of an aluminum alloy of 50 to 80 μm to form divided blades 11 to 14 and 21 to 24, which is the same as the first embodiment. Also in Example 4, the non-defective rate was measured and is shown in Table 1.

Also in this case, the charge energy was slightly higher than that in the case of Example 1 or 2. In Example 3 as well, the shutter was actually incorporated into the shutter to run at a maximum speed of 1/8000 seconds. The results are also shown in Table 1. As can be seen from Table 1, good results were obtained as in Example 1.

The present invention is not limited to the embodiment described above, and it is possible to use FRP blades instead of aluminum alloy blades. In this case, although there is a drawback that the cost becomes high, since the vibration damping property is high, the durability can be further improved. Further, it is also a good method to increase the plate thickness of the FRP to increase the non-defective rate and reduce the cost. Further, it is preferable to use a plate material made of a magnesium-lithium alloy having a thickness of 70 to 100 μm because the weight can be further reduced and a vibration damping effect can be expected although it is not as great as FRP.

Further, for example, when the plate thickness of the plate material used for each divided blade is used more finely, the composition of the magnesium-lithium alloy is changed, or the material composition (plate thickness, composition) of the front curtain and the rear curtain. The present invention also includes the case of changing.

[0043]

[Embodiment 5] In this embodiment, all the divided blades 11 to 1 are used.
No. 4, 21 to 24 with the same composition as in Example 1 and a plate thickness of 130 to 1
The same as Example 1 except that a 60 μm magnesium-lithium alloy was used. Also in this example, the non-defective product ratio was measured, and the product was actually incorporated into a shutter and allowed to run at a maximum speed of 1/8000 seconds. The results are shown in Table 1.
Described in. As can be seen from Table 1, good results were obtained as in Example 1.

[0044]

[Embodiment 6] In this embodiment, the composition of the magnesium-lithium alloy used for the divided blades is the same as that in Embodiment 1. In addition, only the divided blades 11 and 21 have plate thicknesses of 130 to 16
It is formed by using a magnesium-lithium alloy of 0 μm, and the divided blades 12 to 14 and 22 to 24 have a plate thickness of 90 to 12.
It is the same as Example 1 except that it was formed by using a 0 μm FRP plate material.

In this embodiment, since the blade made of FRP having a large plate thickness is used, the reduction of the non-defective rate is suppressed, and the FR rate is further reduced.
The vibration damping ability of P can be effectively used. Maximum speed of 1/8000 seconds and 1/1 when actually installed in the shutter
It ran for 2000 seconds. The results are shown in Table 1.
As can be seen from Table 1, good results were obtained.

Further, since the slit forming blade is not made of FRP, polishing of the end face becomes unnecessary, and the cost can be reduced.

[0047]

[Embodiment 7] In this embodiment, a split blade 14 is formed by pressing a plate material of an aluminum alloy having a plate thickness of 50 to 80 μm.
24 is the same as Example 6 except that 24 is formed. Also in this embodiment, the maximum speed 1 /
It was run for 8000 seconds and 1/12000 seconds. The results are shown in Table 1. As can be seen from Table 1, good results were obtained.

Further, by using an inexpensive aluminum alloy for the largest blade, the amount of FRP, which is an expensive material, can be suppressed, which leads to cost reduction.

[0049]

[Table 1]

[0050]

As described in detail above, according to the focal plane shutter of the present invention, the non-defective rate of the magnesium-lithium alloy blades constituting the shutter is about the same as that of the aluminum blades. And 1
Even though it is a super high-speed shutter that exceeds / 8000 seconds,
With respect to the number of times of durability, it was possible to realize extremely high durability at a low cost, which is equivalent to that of a shutter composed of FRP blades.

Further, by using a magnesium / lithium alloy and an aluminum alloy in combination for the blades of the focal plane shutter, it has become possible to realize even lower costs. Further, according to the focal plane shutter of the present invention, it is possible to reduce the charge energy. Therefore, it is possible to spend electric capacity in areas other than the shutter, which makes it easy to add new functions.

[Brief description of drawings]

FIG. 1 is a front view showing a state where a front curtain of a first embodiment of a focal plane shutter according to the present invention is developed to cover an exposure window.

FIG. 2 is an exploded view showing the divided blades of the front curtain of the focal plane shutter according to the first embodiment.

[Explanation of symbols]

10 front curtain 20 curtain 11-14 split vane 15,16,25,26 arms 17, 18, 27 and 28 semi-tubular rivet 19, 29 drive mechanism 31 drive shaft X ₁ to X _4-axis than on

Claims (7)

[Claims] 1. A focal plane shutter comprising at least four or five divided blades and a drive mechanism for driving the divided blades, of which blades have the largest movement amount when driven by the drive mechanism. Is a magnesium-lithium alloy containing magnesium and 11 wt% or more of lithium, and the blade has a plate thickness of 130 μm to 200 μm. 2. A focal plane shutter comprising at least four or five divided blades and a drive mechanism for driving the divided blades, wherein the divided blades are counted in descending order of movement amount when driven by the drive mechanism. The first and second blades are made of a magnesium-lithium alloy containing magnesium and 11% by weight or more of lithium, and the blade thickness is 1
A focal plane shutter having a thickness of 30 μm to 200 μm. 3. A focal plane shutter comprising at least 4 or 5 divided blades and a drive mechanism for driving them, wherein the divided blades are counted in descending order of movement amount when driven by the drive mechanism. A focal plane shutter characterized in that the first and third blades are made of a magnesium-lithium alloy containing magnesium and 11% by weight or more of lithium, and the slit-forming blades have a plate thickness of 130 μm to 200 μm. 4. The composition of the magnesium-lithium alloy is 50-65 wt% magnesium and 30-lithium.
45% by weight, and at least one kind of aluminum or zinc is 1 to 10% by weight.
The focal plane shutter described in 3). 5. The focal plane shutter according to claim 1, wherein the blade of the magnesium-lithium alloy has a plate thickness of 130 μm to 160 μm. 6. A focal plane shutter comprising at least 4 or 5 divided blades and a drive mechanism for driving them, wherein the divided blades are made of the magnesium-lithium alloy according to claim 1. And a blade made of an aluminum alloy. 7. A focal plane shutter comprising at least 4 or 5 divided blades and a drive mechanism for driving them, wherein the divided blades are made of the magnesium-lithium alloy according to claim 1. A focal plane shutter comprising: a blade and a blade made of FRP.