JP3459356B2 - Aperture device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm for adjusting a light amount of an optical device, and more particularly to a diaphragm device suitable for an image processing apparatus such as an image scanner.

[0002]

2. Description of the Related Art When the image information of a document is read by a scanner, there is a case where the reflection type or the transmission type is selected depending on the form of the document. For example, for an image drawn on paper, the light from the light source is applied to the image and the reflected light is used to obtain image information, and for the image displayed on the transparent sheet or film, the light from the light source is used. An image is transmitted and image information is acquired from the transmitted light. Then, it becomes necessary to adjust the amount of light incident on the image pickup device or the like depending on whether it is the reflection type or the transmission type. Therefore, a diaphragm device is provided in the optical path leading to the image sensor.

FIG. 5 is a schematic front view of a conventional diaphragm device mounted on a scanner. This diaphragm device is incorporated in a diaphragm unit 1. A fixed diaphragm plate 2 is bent and formed on one edge of the base plate 1a of the diaphragm unit 1, and an opening 2a is formed in the center of the fixed diaphragm plate 2 about the optical axis S.
Two diaphragm blades 3 and 4 are arranged in front of the fixed diaphragm plate 2 with the optical axis S sandwiched therebetween, and these diaphragm blades 3 and 4 relatively move in the vertical direction and move away from each other. As a result, the opening area of the opening 2a is changed to adjust the light amount.

The operation of the diaphragm blades 3 and 4 is performed by receiving the rotational force of the drive motor 5. The drive motor 5 is formed by bending the edge portion of the base plate 1a to form the fixed diaphragm plate 2.
Is attached to a support plate 6 arranged side by side, and a pinion 7 is fitted to an output shaft 5a thereof. Aperture blades 3, 4
Each end of the interlocking arm 8 is rotatably rotatable about the shafts 8a and 8b at the end in the longitudinal direction of the drive motor 5 opposite to the drive motor 5 side. A drive gear 9 is connected to the end portion on the 5 side so as to be rotatable around shafts 9a and 9b. The interlocking arm 8 is rotatably supported by the fixed diaphragm plate 2 around the shaft 8c at the center of the shafts 8a and 8b, and the drive gear 9 is at the center of the shafts 9a and 9b.
Is rotatably supported by the fixed diaphragm plate 2. A parallelogram is formed by a straight line connecting the shaft 8a and the shaft 9a, the shaft 9b, and the shaft 8b.
4 and the interlocking arm 8 and the drive gear 9 constitute a parallel crank mechanism. A straight line connecting the axis 8c and the axis 9c (hereinafter, this straight line is referred to as "reference line") is orthogonal to the optical axis S. Further, the output rotation of the drive motor 5 is transmitted from the pinion 7 to the drive gear 9 via an appropriate gear train 10. The drive gear 9 may be a fan gear as shown in FIG.

In this conventional diaphragm device, the rotation of the output shaft 5a of the drive motor 5 is transmitted to the drive gear 9 to change the positions of the diaphragm blades 3 and 4 to adjust the opening of the opening 2a. I am doing it. FIG. 5 shows a state in which the opening 2a is opened at the maximum opening degree, and when the drive gear 9 rotates clockwise in this figure from this state, the shafts 9a and 9b also turn in the same direction. By the turning of the shafts 9a and 9b, the shafts 8a and 8b also turn in the same direction about the shaft 8c via the diaphragm blades 3 and 4. Since the diaphragm blades 3 and 4 form the opposing links of the parallel crank mechanism, the rotation of the shafts 9a, 9b, 8a and 8b reduces the distance between them while maintaining the parallel relationship. Therefore, the openings 2a are gradually blocked from the upper and lower sides, the opening is reduced, and the amount of light transmitted through the diaphragm device is reduced. Then, in the position where the drive gear 9 is rotated approximately 90 degrees from the state shown in FIG. 5, that is, when the shafts 9a and 9b are located on the reference line, the opening 2a has the aperture blades 3 and 4.
It will be closed by.

[0006]

However, the above-mentioned conventional diaphragm device has the following problems. In the conventional diaphragm device, as shown in FIG. 5, the shafts 9a and 9b connected to the drive gears 9 of the diaphragm blades 3 and 4 are located at positions where the straight line connecting the shafts 9a and 9b and the reference line are orthogonal to each other. In some cases it will be a maximum opening and will be closed if the axes 9a, 9b are located on the reference line. That is, a so-called small aperture is formed when the shafts 9a and 9b are close to the reference line. This is the optical axis S of the diaphragm blades 3 and 4.
This is because the opening is blocked by the side edge.

By the way, the amount of light adjusted by the diaphragm depends on the opening area of the diaphragm opening, but in the diaphragm apparatus described above, the opening area changes depending on the distance between the edges of the diaphragm blades 3 and 4 on the optical axis S side. The distance between the edges of the diaphragm blades 3 and 4 on the optical axis S side varies depending on the rotation angle of the drive gear 9, but the drive gears start from the position where the shafts 9a and 9b are on a straight line orthogonal to the reference line. Even if 9 is rotated significantly, the amount of change in this distance is small. On the other hand, when the drive gear 9 rotates from the position where the shafts 9a and 9b are close to the reference line, the change amount of the distance becomes large even if the rotation angle is small. Therefore, when the aperture is small, even if the drive gear 9 is slightly rotated, the opening area is greatly changed and the light amount is greatly changed. However, the adjustment of the light amount requires a finer change when the aperture is small. In order to enable fine adjustment of the aperture area of the aperture when the aperture is small, the rotation angle of the drive motor 5 can be adjusted with high precision, and the gears forming the pinion 7 and the gear train 10 and the drive gear 9 can be adjusted. It becomes necessary to process the teeth with high accuracy to make them less susceptible to the effects of backlash, etc., which increases the component cost and the processing cost.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a diaphragm device which has a simple structure and can finely adjust the amount of light by finely adjusting the area of the diaphragm aperture at the time of a small diaphragm. I am trying.

[0009]

As a technical means for achieving the above object, in a diaphragm device according to the present invention, a pair of diaphragm blades constitutes an opposite side of a parallel crank mechanism, and the distance between the diaphragm blades is set to be equal. In the diaphragm device that adjusts the opening degree by changing, when the lines connecting the respective support shafts of the pair of diaphragm blades move in the directions approaching each other, the edge that adjusts the opening degree of the diaphragm blade is changed. Separate each other and connect the support shaft
Before and after the position where the line is farthest away,
If the amount of movement of the line connecting the spindles with respect to the rotation angle of
And the line connecting the support shafts is the furthest apart
It is characterized by the absence of root spacing .

For example, the pair of diaphragm blades are formed in a shape in which the central portion is U-shaped, the both ends of the U-shaped are bent outward to extend the support portion, and the end portions of the support portion are formed. The support shaft is provided to connect with an adjacent link. When the pair of diaphragm blades are positioned so that the inner sides of the U-shape are opposed to each other, the central portions of the U-shape of the pair of diaphragm blades are closest to each other with the diagonal lines of the parallel crank mechanism having the same length, or A part of the central portion will overlap. From this state, when one link of the parallel crank mechanism is rotated in an appropriate direction, the inner edge of the central portion of the U-shape moves while being separated from each other, and the edge between the pair of diaphragm blades A gap will be formed in this. When the diaphragm blade is located at a position where the optical axis passes through this gap, the diaphragm is closed when the central portions of the diaphragm blades overlap as described above with the diagonal lines having the same length. State, diagonal
When the difference between the lengths of the two is small , the throttle opening becomes the minimum. Then, when one link is rotated in an appropriate direction, the inner edge of the central portion is separated and the gap is gradually widened, so that the diaphragm is opened.

That is, with respect to a straight line that passes through the optical axis and is parallel to the straight line that connects the support shafts of one diaphragm blade, the diaphragm has the smallest aperture when the support shafts of the diaphragm blades are the farthest apart, and the support shafts are the closest The maximum opening is reached. Therefore, when the support shaft of the diaphragm blade is swung from the minimum diaphragm state, the movement amount of the diaphragm blade becomes smaller than the swivel angle, and the fine adjustment of the aperture size can be easily performed at the small diaphragm. it can.

When the force input portion for moving the parallel crank mechanism in parallel is applied to any member constituting the link, the amount of movement of the diaphragm blade is smaller than the turning angle of the support shaft of the diaphragm blade when the diaphragm is small. Although it becomes small and the aperture opening can be finely adjusted, it is desirable for the aperture device of the optical system to change the aperture area with respect to the optical axis. Therefore, in the diaphragm device according to a second aspect of the present invention, a pair of diaphragm blades constitute opposite sides of a parallel crank mechanism, and the aperture is adjusted by changing the interval between the diaphragm blades. The pair of links are rotatably provided on a part of a pair of links connecting the blades, which is located on a straight line which is parallel to the straight line connecting the support shafts of one diaphragm blade and passing through the optical axis. When a support shaft for supporting is provided, the support shaft is provided at an intermediate position of the support shafts of the diaphragm blades to which the link is connected, and when the lines connecting the support shafts of the pair of diaphragm blades move toward each other. , A state in which the edges for adjusting the opening degree of the diaphragm blades are separated from each other and the line connecting the support shafts is the farthest.
The rotation angle of the crank before and after the position
The amount of movement of the line connecting the spindles is minimized and
When the line connecting the axes is farthest away, there is no gap between the diaphragm blades.
It is characterized in that that.

Since the link connecting the diaphragm blades rotates about the support shaft, the support shaft of the diaphragm blade rotates about the support shaft and the central portion of the diaphragm blade maintains a parallel positional relationship. Make a turning motion. Moreover, the intersection of the diagonal lines of the parallel crank mechanism is located on a straight line passing through the support shafts of the pair of links, and the central portion of the pair of diaphragm blades is a straight line passing through the support shafts, that is, a straight line passing through the optical axis. Since they are always at the same distance from each other, the aperture opening changes with the optical axis as a reference.

Furthermore, if the intersection of the diagonal lines of the parallel crank mechanism and the optical axis are made to coincide with each other, the central portion of the diaphragm blade will make a point-symmetrical swivel motion about the optical axis, and the central portion will be horizontal. In both the vertical direction and the vertical direction, the movement can be performed with the optical axis as a reference, and the diaphragm aperture can be changed around the optical axis.

The diaphragm device according to the invention of claim 3 is
One of the links connecting the pair of diaphragm blades is used as a drive gear.

Input to the parallel crank mechanism in which a part of the links is constituted by diaphragm blades may be applied to any of the links, or may be input by a piston rod or the like which makes a linear reciprocating motion. If one of the links is used as a drive gear, it is not necessary to separately provide a component for inputting to the parallel crank mechanism, and the number of components can be reduced. Moreover, if the position of the shaft of the drive gear is matched with the position of the support shaft of claim 2, the structure of claim 2 can be easily obtained.

Further, the diaphragm device according to the invention of claim 4 is characterized in that a fixed diaphragm plate is provided in which a fixed diaphragm is formed by an opening centered on the optical axis.

Although the diaphragm opening may be formed by the link of the parallel crank mechanism, if the aperture of the fixed diaphragm is adjusted by the movement of the pair of diaphragm blades, the shape of the diaphragm opening of the diaphragm blade is adjusted. Since it changes only depending on the position, the diaphragm aperture can always be maintained in a line-symmetrical shape.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION The diaphragm device according to the present invention will be specifically described below based on the preferred embodiments shown in the drawings. FIG. 1 is a schematic front view showing this diaphragm device.
Similar to the structure shown in FIG. 5, the rotation of the output shaft 5a of the drive motor 5 attached to the support plate 6 is driven by the drive gear through the pinion 7 fitted to the output shaft 5a and an appropriate gear train 10. 9 has been transmitted. Further, the fixed aperture plate 2 arranged in parallel with the support plate 6 is formed with an opening 2a which is a fixed aperture and is formed in an appropriate rectangle around the optical axis S. Since these configurations are similar to those shown in FIG. 5, they are designated by the same reference numerals.

The drive gear 9 constitutes a part of the link,
A part of the drive gear 9 and a support shaft 9c for the drive gear 9.
A shaft 9a rotatably connected to an upper diaphragm blade 20 forming a part of the link at a position of 180 degrees on the circumference centered on
And a shaft 9b that is rotatably connected to the lower diaphragm blade 30 that forms a part of the link. A support shaft 8c is supported by the fixed diaphragm plate 2 at a position symmetrical to the support shaft 9c with the optical axis S interposed therebetween, and the support shaft 8c is rotatably linked about the support shaft 8c. The central portion of the interlocking arm 8 that constitutes a part of is supported. That is, the support shaft 9c, the optical axis S, and the support shaft 8c are arranged on the reference line.

The upper diaphragm blade 20 and the interlocking arm 8 are rotatably connected by a shaft 8a at a position symmetrical to the shaft 9a about a plane including the optical axis S and orthogonal to the reference line. The lower diaphragm blade 30 and the interlocking arm 8 are rotatably connected by a shaft 8b at a position symmetrical to the shaft 9b. That is, the shaft 9a and the shaft 8a are the upper diaphragm blades.
It becomes the support shaft of 20, the shaft 9b and the shaft 8b become the support shaft of the lower diaphragm blade 30, the distance between the shaft 9a and the shaft 8a and the distance between the shaft 9b and the shaft 8b are equal, and the shaft 9a and the shaft 9b are the same. Since the distance and the distance between the shaft 8a and the shaft 8b are equal, the interlocking arm 8, the drive gear 9, the upper diaphragm blade
A parallel crank mechanism is constituted by 20 and the lower diaphragm blade 30. Moreover, the support shaft 9c is in a position that bisects the distance between the shaft 9a and the shaft 9b, and the support shaft 8c is in a position that bisects the distance between the shaft 8a and the shaft 8b.

As shown in FIG. 1, the upper diaphragm blade 20 is formed in a substantially U-shape with its central portion being biased toward the lower diaphragm blade 30, and the diaphragm plate forming the central portion of the U-shape. The inner edge 21a of the portion 21 is located closer to the optical axis S than the straight line connecting the axes 8a and 9a. Further, the lower diaphragm blade 30 is formed in a substantially U-shape with its central portion being biased toward the upper diaphragm blade 20, and the inner edge 31a of the diaphragm plate portion 31 forming the central portion of the U-shape is an axis. It is located closer to the optical axis S than the straight line connecting 8b and 9b. Then, as shown in FIG. 1, with the diaphragm blades 20 and 30 in a position where the straight line connecting the axes 9a and 9b is orthogonal to the reference line, the inner edge 21a is slightly closer to the axis 8 than the reference line.
It is desirable that the inner edge 31a is located on the sides of a and 9a, and the inner edge 31a is located slightly on the sides of the axes 8b and 9b from the reference line.

The drive gear 9 has a position in which the straight line connecting the shafts 9a and 9b is orthogonal to the reference line, and the shaft 9a of the upper diaphragm blade 20.
Is rotated toward the optical axis, and the shaft 9a is rotated within a range of an appropriate position that approaches the reference line and does not reach the reference line. In addition, stopper means (not shown) for restricting the rotation in this range is provided.

The diaphragm blades 20 and 30 described above are incorporated in the diaphragm unit 15, and this diaphragm unit 15 is incorporated in a predetermined position of the image processing apparatus.

The operation of the embodiment of the diaphragm device according to the present invention constructed as above will be described below.

FIG. 1 shows a state in which the opening 2a of the fixed diaphragm 2 is closed. In this state, the straight line connecting the shaft 9a and the shaft 9b provided on the drive gear 9 is substantially orthogonal to the reference line. There is. When the drive motor 5 is operated from the position in this state to rotate the drive gear 9 in the clockwise direction in FIG.
The shaft 9a and the shaft 9b turn about the support shaft 9c in the same direction.
Since the drive gear 9 constitutes a parallel crank mechanism together with the upper diaphragm plate 20, the lower diaphragm plate 30, and the interlocking arm 8, the rotation of the drive gear 9 causes the upper diaphragm plate 20 and the lower diaphragm plate 30 to be separated from each other. Move in parallel. The upper diaphragm plate 20 and the lower diaphragm plate 30 are shown in FIG.
From the position shown in (1), the inner edge 21a in the central portion of the upper diaphragm plate 20 and the inner edge 31a in the central portion of the lower diaphragm plate 30 also move while rotating in a clockwise direction. From the position shown in FIG. 1, the inner edge 21a of the upper diaphragm plate 20 moves below the optical axis S across the reference line, and the inner edge 31a of the lower diaphragm plate 30 moves.
a moves above the optical axis S across the reference line. Then, after the inner edge 21a and the inner edge 31a are misaligned, a gap is formed between them, and the opening 2a of the fixed diaphragm plate 2 is gradually opened by this gap. Become. If the inner edge 21a and the inner edge 31a are formed at the same distance from the reference line, they are misaligned on the reference line, and the opening 2a is gradually opened around the reference line. Become. Then, as shown in FIG. 4, when the drive gear 9 is rotated to a position where the shafts 9a and 9b are close to the reference line, the inner edge 21a and the inner edge 31a move the upper edge and the lower edge of the opening 2a. Crossing will open the entire opening 2a. That is, the opening 2a is changed depending on the rotation angle of the drive gear 9.
The opening area of is to be adjusted.

Then, when the drive gear 9 starts to rotate from the position shown in FIG. 1, the opening 2a is slightly opened, which is a so-called small aperture state. In this state, even if the rotation angle of the drive gear 9 is large, the upper diaphragm blade
Since the amount of movement of 20 and the lower diaphragm blade 30 is smaller than the size of the rotation angle, fine adjustment of the opening area can be easily performed.

When the drive gear 9 is rotated counterclockwise from the position shown in FIG. 4, the opening area is gradually reduced. From the state shown in FIG. 4, even if the rotation angle of the drive gear 9 is small, the amount of movement of the diaphragm blades 20 and 30 is large, so that the opening area changes greatly.

[0029]

As described above, according to the diaphragm device of the present invention, the state in which the straight line connecting the respective support shafts of the diaphragm blades is orthogonal to the reference line is the closed or small diaphragm state. Therefore, since the diaphragm is gradually opened in accordance with the rotation of the support shaft, the increase amount of the opening area is smaller than the rotation angle. For this reason, it is possible to easily perform fine adjustment of the opening area when the aperture is small.

Moreover, since the drive mechanism and the like of the conventional diaphragm device can be used only by changing the shape of the diaphragm blade, the cost of the product is not increased.

According to the diaphragm device of the second aspect of the present invention, the link connected to the diaphragm blades is rotatably supported at an intermediate position of a straight line connecting the support shafts of the diaphragm blades, and the support shaft is supported. Is arranged on a straight line parallel to the straight line connecting the support shafts of one diaphragm blade through the optical axis, so that the diaphragm blade moves based on the above straight line passing the optical axis. Therefore, the diaphragm opening is opened and closed with the optical axis as a reference, and a symmetrical diaphragm opening can be obtained.

According to the throttle device of the third aspect of the present invention, since the drive gear constitutes one link of the parallel crank mechanism of the throttle device, a separate member for inputting power to the link is required. Without doing so, the structure can be simplified. Particularly, since it is easy to match the rotation shaft of the drive gear with the support shaft, the configuration of claim 2 is easy.

Further, according to the diaphragm device of the fourth aspect of the invention, the diaphragm aperture is determined by the outer shape of the fixed diaphragm, and the diaphragm aperture always centered on the optical axis is irrespective of the position of the diaphragm blades. can get.

[Brief description of drawings]

FIG. 1 is a front view of a diaphragm unit incorporating a diaphragm device according to the present invention, showing a state in which a diaphragm aperture is closed.

FIG. 2 is a plan view of a diaphragm unit incorporating the diaphragm device according to the present invention.

FIG. 3 is a right side view of a diaphragm unit incorporating the diaphragm device according to the present invention.

FIG. 4 is a front view of a diaphragm unit incorporating a diaphragm device according to the present invention, showing a state in which a diaphragm aperture is opened.

FIG. 5 is a front view of a diaphragm unit incorporating a conventional diaphragm device, showing a state in which a diaphragm aperture is opened.

[Explanation of symbols]

2 Fixed diaphragm plate 2a opening 5 drive motor 6 Support plate 8 interlocking arms 8a, 8b axis 8c support shaft 9 drive gear 9a, 9b axes 9c support shaft 15 Aperture unit 20 Upper diaphragm blade 21 diaphragm plate 21a inner edge 30 Lower diaphragm blade 31 Aperture plate 31a inner edge S optical axis

Claims (4)

(57) [Claims] 1. A diaphragm device in which a pair of diaphragm blades constitute opposite sides of a parallel crank mechanism, and an opening degree is adjusted by changing a distance between the diaphragm blades, wherein a spindle of each of the pair of diaphragm blades is connected. When the lines move toward each other, the edges for adjusting the opening degree of the aperture blades are separated from each other, and before and after the position where the line connecting the support shafts is in the most separated state.
The line connecting the spindles with respect to the rotation angle of the crank.
The amount of movement is minimized and the line connecting the support shafts is the farthest away.
A diaphragm device in which the gap between the diaphragm blades disappears in the open state . 2. A diaphragm device in which a pair of diaphragm blades constitute opposite sides of a parallel crank mechanism, and an opening degree is adjusted by changing an interval between the diaphragm blades, wherein a pair of links connecting the pair of diaphragm blades is used. A support shaft that rotatably supports the pair of links is provided in a part that is located on a straight line that passes through the optical axis and that is parallel to a straight line that connects the support shafts of one diaphragm blade. A support shaft is provided at an intermediate position of a support shaft of the diaphragm blade to which the link is connected, and when the lines connecting the support shafts of the pair of diaphragm blades move in directions toward each other, the opening degree of the diaphragm blade is increased. Before and after the position where the edges that adjust are separated from each other and the line connecting the support shafts is the most separated
The line connecting the spindles with respect to the rotation angle of the crank.
The amount of movement is minimized and the line connecting the support shafts is the farthest away.
A diaphragm device in which the gap between the diaphragm blades disappears in the open state . 3. The driving gear is one of the links connecting the pair of diaphragm blades.
A diaphragm device described in. 4. The diaphragm apparatus according to claim 1, further comprising a fixed diaphragm plate having a fixed diaphragm formed by an opening centered on the optical axis.