JPH07219062A - Zoom lens device - Google Patents

Abstract

(57) [Summary] [Object] To provide a zoom lens device capable of preventing deterioration of imaging performance even if the lens moves due to zooming. A zoom lens as a lens group for forming an image of a document on a surface of a photosensitive drum at an arbitrary magnification, a movable lens barrel which is a lens holding means for holding the zoom lens, and a lens movement for moving the movable lens barrel. Cam plate 26 as means
And a cam groove plate as a guide means for guiding the cam plate 26, and the movable lens barrel moves in the optical axis direction to change the focal length. A spring 35 is provided as a biasing member that biases each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens device used in, for example, an electrophotographic copying machine.

[0002]

2. Description of the Related Art Conventionally, there are zoom lens devices of this type as shown in FIGS.

FIG. 8 is a sectional view of a slit exposure type electrophotographic copying machine to which a conventional zoom lens device A'is applied. In the figure, the reflected light from the original 101 illuminated by the light source 105 in a slit shape is reflected by the lens unit 10.
An image is formed on the photosensitive drum 104 by 3, and the original 101 is sequentially moved and scanned from the end a'to the end b'at a constant speed to form a latent image on the photosensitive drum 104, which is further developed and transferred onto a transfer sheet. To be done. Since the movement of the optical system and the electrophotographic process are known techniques, their description is omitted.

FIG. 9 is a schematic view of the optical system of FIG. 8 taken out. In this optical system, the distance between the document surface and the surface of the photosensitive drum 104 is constant regardless of the magnification, and the optical system is simplified. When it is desired to make a copy of the same size as the image size of the original 101, the lens unit 103 is optically positioned approximately at the center of the distance between the original and the surface of the photosensitive drum 104. Further, when it is desired to obtain a copy larger than the original 101, the lens unit 103 moves toward the original, changes the focal length to an amount corresponding to the magnification, and forms the original image light flux on the surface of the photosensitive drum 104. When obtaining a reduced copy, the lens unit 103 is moved to the photosensitive drum 4 side.

FIG. 10 is a detailed view of the lens unit 103,
FIG. 11 is a perspective view of the main lens barrel, and each element configured below will be described.

A guide rail 106 for guiding the entire lens unit 103 and a cam groove plate 108 for guiding the cam plate 109 in communication are arranged on the lens base 107 of the copying machine. When obtaining magnified and reduced images, the lens unit 1
03 is moved by a distance corresponding to the magnification designated by a drive source such as a motor (not shown) while being guided by the guide rail 106.

A cam groove 109 is formed in the center of the cam plate 109.
a and 109b are arranged in the cam grooves 109a and 109b, and the pins 11 protruding from the lower portions of the lens barrels 113 and 114 are provided.
7, 118 are connected to each other (FIG. 11). The lens barrels 112, 113, 114, 115 have reference axes 119, 12
0 are arranged in a line, the lens barrels 112 and 115 are fixed, and 113 and 114 are the cam grooves 109a and 1a.
09b guides the lens barrel 11 on the reference shafts 119 and 120.
Reference holes 113a, 113b, 1 provided in 3, 114
14a and 114b slide and move. Lens barrel 112,1
Inside the lens 15, lenses G1 'and G8' are attached to the lens barrel 113,
Lens groups G2 ', G3', G4 'and G5', G6 ', G7' are fixed inside 114. A diaphragm plate 111 is arranged between the lens barrels 113 and 114.

When the lens unit 103 is guided by the guide rail 106 and moved to the designated magnification position by the drive source, the cam plate 109 is also guided and moved by the cam groove plate 108 and guided by the cam grooves 109a and 109b of the cam plate 109. The lens barrels 113 and 114 move between the lens barrels 112 and 115, the focal length of the lens unit 103 is changed, and the original surface and the photosensitive drum 104 surface are kept in a conjugate relationship for each magnification.
Get the enlarged / reduced screen.

[0009]

However, the lens barrel 1
Reference shaft 119 for moving 13, 114 by zooming, reference holes 113a, 113b, and reference shaft 120.
And the reference holes 114a and 114b have play, the lens barrel 1
There is a problem that the angles of 13 and 114 with respect to the reference axis 119 change due to zooming, which deteriorates the imaging performance.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object thereof is to provide a zoom lens device capable of preventing deterioration of image forming performance even if the lens moves due to zooming. To provide.

[0011]

In order to achieve the above object, in the present invention, a lens group for forming an image of a document on a display means at an arbitrary magnification, a lens holding means for holding the lens, A lens moving means for moving the lens holding means, and a guide means for guiding the lens moving means,
In the zoom lens device in which the focal length is variable by moving the lens holding means in the optical axis direction, a biasing member for biasing the lens holding means and the lens moving means to each other is provided. .

On the other hand, a lens group for forming an image of a document on the surface of the photoconductor at an arbitrary magnification, a lens holding means for holding the lens, a lens moving means for moving the lens holding means, and a guide for the lens moving means. In the zoom lens device having a variable focal length by moving the lens holding means in the optical axis direction, the biasing means biases the lens holding means and the lens moving means to each other. Is provided.

Further, it is preferable that the lens holding means and the lens moving means have a portion in contact with each other, and the urging means urge in a direction in which the pressure of the contacting portion increases.

Further, the lens holding means is provided with an engaging member attached via the lens moving means, a flange portion is provided on the engaging member, and the flange portion is provided between the lens moving means. It is preferable that a biasing unit is installed and the flange and the lens moving unit are biased in a direction in which they are separated from each other.

The lens moving means has a guide hole through which the engaging member penetrates to move the lens holding means, and the urging means is urged in a direction perpendicular to the direction in which the engaging member penetrates. It is preferable that there is a biasing component, and the biasing component does not coincide with the normal line direction of the inner peripheral surface of the guide hole.

[0016]

In the zoom lens device constructed as described above, since the lens holding means and the lens moving means are provided with the urging means for urging each other, there is a play between the lens holding means and the lens moving means. To be prevented.

Further, there is a portion where the lens holding means and the lens moving means come into contact with each other, and the biasing means biases the lens holding means and the lens moving means by pushing in a direction in which the pressure at the abutting portion becomes high. The looseness is further prevented.

The lens holding means is provided with an engaging member attached via the lens moving means, the engaging member is provided with a flange portion, and the biasing means is provided between the flange portion and the lens moving means. Since the flange portion and the lens moving means are biased in the direction in which they are separated from each other, the biasing means can be easily installed not between the lens holding means and the lens moving means.

The lens moving means has a guide hole through which the engaging member penetrates to move the lens holding means, and the urging means has a component for urging in a direction perpendicular to the direction in which the engaging member penetrates. However, since this urging component does not coincide with the normal line direction of the inner peripheral surface of the guide hole, the outer peripheral surface of the engaging member is in contact with one inner peripheral surface of the guide hole, and the lens holding means. Will be moved.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

(First Embodiment) FIGS. 1 to 3 show a first embodiment of the present invention. FIG. 1 is a sectional view of a slit exposure type electrophotographic copying machine to which a zoom lens device A of the present invention is applied. In the figure, the reflected light from the document 1 illuminated by the light source 5 in a slit shape is imaged by the zoom lens 21 on the photosensitive drum 4, which is a photoconductor, and the document 1 is sequentially moved at a constant speed from the end a to the end b. Is moved and scanned to form a latent image on the photosensitive drum 4, which is further developed and transferred onto a transfer paper. Since the movement of the optical system and the electrophotographic process are known techniques, their description is omitted.

FIG. 2 is a detailed sectional view of a zoom lens 21 portion as a lens group in the zoom lens device A, and FIG. 3 is a perspective view of the zoom lens 21 portion. In FIGS. 2 and 3, reference numeral 24 is a lens holder, which is moved onto the guide 8'by a driving source (not shown). Reference numerals 22 and 23 denote fixed lens barrels, in which a G1 lens is incorporated in 22 and a G8 lens is incorporated in 23. The fixed barrels 22 and 23 are fixed to the lens holder 24, and the fixed barrel 22 holds one ends of the reference shaft 27 and the guide shaft 28. Reference axis 2
7 and the other end of the guide shaft 28 are supported by the lens holder 24. Reference numerals 30 and 31 denote movable lens barrels as lens holding means, in which G2 to G4 and G5 to G7 lenses are incorporated, respectively.

A diaphragm plate 34 is provided between the movable lens barrels 30 and 31 to limit the thickness of the light beam. Reference numeral 26 denotes a cam plate as a lens moving means, which is movably held by the lens holder 24 and is connected to a cam groove plate 8 as a guiding means at a protruding portion 26d provided at one end. The cam plate 26 is attached to the lens holder 24 by the two springs 29.
It is pressed against the abutting part of and is positioned without play.

Also, a gap between the projection 26d and the cam groove plate 8 is removed by a spring 26c (FIG. 4). The pressing direction F of the cam plate 26 is such that the cam plate 26 is pressed in the same direction as the moment M due to the sliding friction with the cam groove plate 8 with respect to the moving direction X of the zoom lens 21.

Cam grooves 26a and 26b are formed in the cam plate 26, and movable lens barrels 30 and 31 are formed in the cam grooves 26a and 26b.
Pins 32 and 33 as more protruding engaging members are pressed by a spring 35 as a biasing means along the inside of the cam grooves 26a and 26b. In this embodiment, the spring 35 is made of metal, but may be made of an elastic material such as resin or rubber as long as it can prevent looseness between the lens holding means and the lens moving means, and may be a coil spring, a leaf spring, or the like. But it's okay.

Here, as can be seen from the enlarged view of the cam groove 26a, the pin 32, and the spring 35 in FIG. 6A, the normal direction h to the inner peripheral surface of the cam groove 26a at the contact point 26e between the pin 32 and the cam 26 is h. And the urging force direction g of the spring 35 do not match. This biasing force is applied to the pins 32 and 33, respectively, and a moment about the Z axis in FIG. 3 is generated depending on the strength and the like. This prevents looseness on the outer peripheral surface of the pin 32, the inner peripheral surface of the cam groove 26a, and the outer peripheral surface of the pin 33 and the inner peripheral surface of the cam groove 26b, respectively. It is possible to prevent backlash between the shaft 28 and the movable lens barrels 30 and 31.

Further, the spring 35 has rising portions 35a and 35b as shown in FIG. 6B, and since it also has a biasing force in the vertical direction, the movable lens barrels 30 and 31.
Flange portions 32a, 33 of more protruding pins 32, 33
3a is urged downward in FIG. 3, and the contact pressure of a roller or the like (not shown) in the sliding contact portion inside is increased to prevent backlash. This is merely an example, and any shape may be used as long as it can provide a biasing force that can prevent looseness around the three axes of X, Y, and Z shown in FIG.

As described above, the flanges are provided on the pins 32 and 33 projecting from the lower portion of the moving lens barrel, and the flanges are urged downward in the direction of urging the cam grooves 26a and 26b of the cam plate 26. By using at least one spring member, the movement of the movable lens barrel shown in FIG. 3 around the X, Y, and Z axes can be suppressed, and the change in posture during zooming can be reduced.

(Second Embodiment) FIG. 7 shows a second embodiment of the present invention.

In FIG. 7, 1 is a microfilm as an original, 2 is a screen as a display means, and 3 is a screen.
Is a mirror, 5 is a light source, 6 is a condenser lens, 7 is a reflecting mirror, A
Is a zoom lens device.

The second embodiment also has the same structure as the zoom lens device A in the first embodiment, and can be applied to the display on the screen 2.

(Other Embodiments) The spring 35 is used for the movable lens barrel 3
The two directions of urging 0 and 31 to the cam groove and the direction of urging vertically downward are performed as one, but two bodies may be urged separately.

Further, even when the cam plate 26 is arranged at a position different from that of the embodiment, the pin 3 protruding from the movable lens barrel is used.
The same effect can be obtained by changing the shape of the spring 35 so as to urge the flange portions 32a and 33a of the Nos. 2 and 33.

[0034]

According to the present invention having the above-described structure and operation, since the lens holding means and the lens moving means are provided with the urging means for urging each other, the space between the lens holding means and the lens moving means is increased. Backlash can be prevented, a change in posture during zooming can be reduced, and imaging performance can be improved.

Further, the lens holding means and the lens moving means have a portion in contact with each other, and the urging means urges the lens holding means and the lens moving means in a direction in which the pressure of the abutting portion increases. It is possible to further prevent backlash, further reduce the change in posture during zooming, and improve the imaging performance.

The lens holding means is provided with an engaging member attached via the lens moving means, the engaging member is provided with a flange portion, and the urging means is provided between the flange portion and the lens moving means. Since the flange portion and the lens moving means are urged in the direction away from each other, the urging means can be easily installed and assembled not between the lens holding means and the lens moving means. Also, the installation state can be easily confirmed.

The lens moving means has a guide hole through which the engaging member penetrates to move the lens holding means, and the urging means has a component for urging in a direction perpendicular to the direction in which the engaging member penetrates. However, since this urging component does not coincide with the normal line direction of the inner peripheral surface of the guide hole, the outer peripheral surface of the engaging member is in contact with one inner peripheral surface of the guide hole, and the lens holding means. It is possible to prevent backlash in multiple directions between the lens holding means and the lens moving means, to significantly reduce posture changes during zooming, and to improve the imaging performance.

[Brief description of drawings]

FIG. 1 is a sectional view showing a slit exposure type electrophotographic copying machine according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a zoom lens that is an embodiment of the present invention.

FIG. 3 is a perspective view showing a zoom lens that is an embodiment of the present invention.

FIG. 4 is a top view showing a zoom lens that is an embodiment of the present invention.

FIG. 5 is a rear view showing a zoom lens that is an embodiment of the present invention.

6 (a) and 6 (b) are respectively a rear view of a main part and a perspective view of a spring alone showing a mounted state of a spring in a zoom lens according to an embodiment of the present invention.

FIG. 7 is a schematic view showing a second embodiment of the present invention.

FIG. 8 is a sectional view showing a general slit exposure type electrophotographic copying machine to which a conventional zoom lens device is applied.

FIGS. 9A, 9B, and 9C are schematic diagrams illustrating lens movement according to a set magnification.

FIG. 10 is a top view of a conventional zoom lens.

FIG. 11 is a rear perspective view of a conventional zoom lens.

[Explanation of symbols]

 A, A'zoom lens device 1, 101 original 2 screen (display means) 4, 104 photosensitive drum (photoconductor) 5 light source 8 cam groove plate (guide means) 21 zoom lens (lens group) 24 lens holder 26 cam plate ( Lens moving means) 26a, 26b Cam grooves (guide holes) 26e Contact points 30,31 Moving lens barrel (lens holding means) 32, 33 Pins (engaging members) 32a, 33a Flange portion 35 Spring (biasing means)

Claims (5)

[Claims] 1. A lens group for forming an image of a document on a display means at an arbitrary magnification, a lens holding means for holding the lens, a lens moving means for moving the lens holding means, and a lens moving means. In the zoom lens device, wherein the lens holding means moves in the optical axis direction to change the focal length, and the lens holding means and the lens moving means bias each other. A zoom lens device characterized by being provided with. 2. A lens group for forming an image of a document on a photoconductor surface at an arbitrary magnification, a lens holding unit for holding the lens, and a lens moving unit for moving the lens holding unit.
In the zoom lens device, which has a guide unit for guiding the lens moving unit, and which makes the focal length variable by moving the lens holding unit in the optical axis direction, the lens holding unit and the lens moving unit are attached to each other. A zoom lens device characterized in that a biasing means for biasing each other is provided. 3. The lens holding means and the lens moving means have a portion in contact with each other, and the urging means urges in a direction in which the pressure of the contacting portion increases. 2. The zoom lens device according to item 2. 4. An engaging member attached to the lens holding means via the lens moving means, a flange portion being provided on the engaging member, and the flange portion and the lens moving means. 4. The zoom lens device according to claim 1, wherein an urging means is installed to urge the flange portion and the lens moving means in directions away from each other. 5. The lens moving means has a guide hole through which the engaging member penetrates to move the lens holding means, and the biasing means has a direction perpendicular to a direction in which the engaging member penetrates. The zoom lens device according to claim 4, wherein the zoom lens device has a component for urging the lens, and the component for urging does not coincide with the normal direction of the inner peripheral surface of the guide hole.