JPS60207125A - Forming device for image of variable magnification - Google Patents

Abstract

PURPOSE:To position highly precisely a lens through such simple constitution that the engaging dowel of a lens support base is pressed against the trapezoid notch part of a positioning arm and the both are engaged with each other by applying force slanting to the moving direction of the lens at two slanting parts of the trapezoid notch part. CONSTITUTION:Some variable magnification mode is selected, a cam ring 41 starts rotating, and a coupling member 38 begins to then, its quantity of oscillation is increased by a lever 22 and the lens support base 18 moves under the guidance of guide members 15 and 16. In this case, the engaging dowel 24 of the lens support base 18 presses the slanting surface of the trapezoid notch part of the positioning arm 25 against a spring 43 to move the arm 25, and when the cam ring 41 stops at the variable magnification mode position corresponding to the selected magnification, the dowel 24 enters one corresponding notch part, e.g. 29 among trapezoid notch parts 27-30 of the positioning arm 25 and the lens support base 18 is positioned by the positioning arm 25 at contacts (a) and (b) of the slanting part.

Description

[Detailed description of the invention] The present invention relates to a variable magnification image forming apparatus.

When projecting and forming an image of an original onto the photosensitive surface of an electrophotographic photoreceptor or solid-state image sensor, the imaging magnification can be changed by changing the position of the lens, which changes the optical path length between the original and the lens and the lens. , the ratio of the optical path lengths between the photosensitive surfaces must correspond to the selected magnification.

By the way, there is generally some play in the drive force transmission path that transmits the drive force from the drive source to the lens, and it is difficult to stop and position the lens at an accurate position until that point occurs. To solve this problem, in Japanese Patent Application Laid-Open No. 52-115217, the lens is positioned at a certain position only when the lens reaches that position from one specific direction. However, this has the disadvantage that it takes time to change the position of the lens. , also, JP-A-54-41723
In the Japanese Patent Publication No. 55-77762, after the lens is pressed against the stopper, the drive source continues to operate for a while, and a spring placed in the driving force transmission path is charged to ensure that the lens is pressed against the stopper elastically. The drive source is deenergized while the However, with this, the release of Gene's Charshika mentioned above is 1
A worm gear mechanism, one-way clutch mechanism, etc. is required to make the 4-way stop, which complicates the configuration of the device.

The present invention aims to solve the above-mentioned disadvantages.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is an explanatory diagram of an example of a variable magnification electrophotographic copying apparatus to which the present invention can be applied.

1 is an electrophotographic photosensitive drum that rotates in the direction of the arrow.

The drum 1 is first uniformly charged by the charger 2, and then a light image of the document 0 at a selected magnification of fl and 7 is slit exposed, thereby forming an electrostatic latent image. This latent image is developed using toner by a developing device 3, and the resulting toner image is transferred onto a transfer material 5 by a transfer charger 4, and then fixed onto this transfer material 5 by a fixing device (not shown).

After the transfer, the surface of the drum 1 is cleaned by a cleaning device 6. The present invention can also be applied to an apparatus in which the drum 1 is replaced with a solid-state image sensor such as a COD.

Original 0 is placed on transparent original table 7 and scanned. The document table 7 moves in the direction of the arrow in order to scan the document 0. Therefore, a rack 12 is fixed to the document table 7, and this rack 12
The pinion 13 is engaged with the pinion 13. The pinion 13 is rotationally driven via a transmission at a speed corresponding to the selected magnification, and moves the document table 7 in the direction of the arrow at a scanning speed equal to the circumferential speed of the drum 1 multiplied by the reciprocal of the selected magnification. .

When scanning of the original is completed, the pinion 13 is reversed.

The document table 7 is returned to the home position.

The present invention is applicable not only to the movable document table type, but also to the type in which the original is scanned by moving a mirror, and the type in which the original is held and conveyed by rollers or belts for scanning.

It is conventionally illuminated by a document lamp 8.

The original image is exposed onto the drum 1 by a projection optical system having identification mirrors 9 and 11 and a zoom lens 10. -F The zoom lens 10 is moved to a position corresponding to the selected magnification by a mechanism to be described later, thereby changing the ratio of the optical path lengths of the lenses. In conjunction with this movement, the focal length of the lens is also changed in accordance with the selected magnification. FIG. 2 is a perspective view of a main part of an embodiment of the present invention.

In the figure, a guide member 15.16 is fixed to the substrate 14, and this guide member 15.16 allows the zoom lens 10 to
A lens support stand 18 in which a lens barrel 17 containing a lens barrel 17 is internally defined is movably guided in a predetermined direction. This zoom ring 19 is a so-called zoom ring that changes the focal length of the lens 10 by rotating around the optical axis of the lens. Lotus bulkhead 20 fixed on substrate 14 through hole 21
The lenses are interlocked with each other, and zooming is performed in conjunction with the movement of the lens support stand 18.

Further, the lens support base 18 has a long hole 21 for a connecting pin, and the connecting pin 23 of the swing lever 22 is guided so that the long hole 21 and the connecting pin 23 are engaged. Lens support stand 18
There is an engaging dowel 24 below the elongated hole 21, and the dowel 24 is a trapezoidal notch 2 of the positioning stopper arm 25 whose swing center is the fixing pin 26 on the board 14.
It is in pressure contact with a magnification corresponding to a selected magnification of 7 to 30. The pressing force is applied by a tension spring 4SK applied to one end of the arm 25. The other end of the tension spring 43 is hung on a spring hook on the base plate 14.

FIG. 3 is a perspective view of the sliding guide portion of the substrate 14 and the lens support stand 1B. The guide member 15 on the substrate 14 is formed by thermally welding the guide groove 1 and the L half plate 15'', and then a conventional dowel 31.52 provided on the lower surface of the lens support base 18 is engaged with the groove. The grooves of the dowels 31 and 32 in the tank and the L half plate 15"
By.

An L half-plate shaped guide member 16 is located at a position apart from the 7f guide groove 15 configured to prevent the lens support stand 1B from moving upward.
, and engages and plays with the U-shaped portion 33 of the lens support stand 1B.

Returning to FIG. 2, the swing lever 22 is fixed to a connecting member 35 whose swing center is a fixed shaft S4. The connecting member 55 has a υ@56, which engages with the protrusion 39 of the other connecting member 3B, which swings about the fixed shaft 37. A pin 40 at one end of the connecting member 37 is loosely engaged with a cam groove 42 of a cam ring 41 that is interlocked with a transmission mechanism (described later) so that a gap of 0.4 to 0.5 mm may occur.

Therefore, after a certain variable magnification mode is selected, driving force is applied by rotation of a drive motor (not shown), and when the cam ring 41 starts rotating, the connecting member 58 starts swinging in either direction of the arrow. . Before the swing, the lens support base 18 is expanded by the lever 22 and moved. During the movement, the engagement dowel 24 on the lower surface of the lens support base 18 pushes the slope of the trapezoidal notch of the fσ compensation arm 25, thereby causing the arm 25 to swing around the shaft 26 against the spring 45. This causes the dowel 24 to come out of this notch. Then it enters the next trapezoidal notch. This operation continues until the cam @41 stops at the variable magnification mode position corresponding to the selected magnification. Stop position of cam ring 41 (groove 42 position t
Vt), lens position, and stop position ti of the pawl swing lever 22
! (The position of the connecting bin 25) only needs to be roughly adjusted. In other words, assuming that there is no arm 25 having each notch, the lens is selected by the magnification conversion operation and is located near the position corresponding to the specific magnification. In other words, the series of driving force transmission systems that move the lens support stand 18 have a backlash to the extent that the dowel 24 does not come out of the trapezoidal notch corresponding to the selected magnification of the positioning arm 25. This means that the design accuracy can be made more relaxed, and a little more care is required during assembly. Therefore, the final positioning is done by positioning arm 2.
This is done by the trapezoidal notch 5 engaging with the engaging dowel 24, and the lens position is reliably compensated by the tension spring 31.Of course, the position of the substrate 14 is adjusted and fixed in advance by optical adjustment, Where is the position of the board 14? There is no need to adjust other parts on the board 14 by just adjusting A.

Figure 4 shows the positioning stopper arm 25 and lens support stand 1.
8 is shown in a plan view. Since the positions of the engaging dowel 24 of the lens support base 18 and the elliptical guide dowel on the same substrate are made by a single-component outsert molding method, it can be manufactured with high precision. In addition, the guide groove side wall surface 15' on the substrate 14 and the fixed pin 2
6 is similarly made using the single-piece outsert molding method. niJ ha dowel 24 and positioning stopper arm 25
The moving direction of the lens support stand 18 (
The position with respect to arrow B) is determined. The lens support 18, whose position in the direction perpendicular to the movement direction (arrow A) is defined by the member 1 and the dowels 31.52, is roughly adjusted by the above-mentioned device, and is Contact a.

b and contacts c and d to stop. Contact points a and b are points of contact between the dowel 24 and the remainder of the trapezoidal notch provided in the arm 25. In other words, the contact point a is the contact point between the first slope of the notch and the dowel 24, and the contact point A is the contact point of the second slope of the notch.
This is the point of contact between the slope and the dowel 24. Note E: The first and second slopes are separated r) in the direction of movement of the lens support base! These are surfaces that face each other as I and are inclined with respect to the direction of movement of the lens support. Thus, the arm 25 applies a force in a direction oblique to the movement of the lens support to the dowel 24 at two points a and b spaced apart in the direction of movement of the lens support. Since the resultant force of the forces applied at these two places a and b, that is, the load force of the spring 46, is in the direction of the arrow, the position of the lens support 18 is once determined by the trapezoidal notch corresponding to the selected magnification. If the magnification change driving force is not transmitted to the pin 23, the lens support stand 18 will not move, and the stand 18 will be accurately positioned at a position corresponding to the selected magnification. The lens position and its focal length are thus precisely mapped to the respective selected magnification.

In addition, the positioning stopper arm 250 trapezoidal notch 27
~30 yen, the more the engagement dowel 24 approaches the fixed pin 26, which is the swinging support shaft, the more the load that the engaging dowel 24 has to overcome over the notch increases. Angle θ formed by the first and second slopes of parts 27 to 30
increases as it approaches the fixed bin 26. Therefore, the relationships are θ, 〉θ, 〉θ, and 〉θ4.

In the above example, the arm 25 is provided with a plurality of notches each having a first and a second slope, but the lens support 18 has a plurality of notches which face each other and are inclined outwardly with respect to the movement direction of the table 18. 1. A notch (retaining part) having a second slope is provided, and the arm 25 is engaged with the notch. A plurality of dowels may be provided, each corresponding to a selected magnification.

Each dowel has a cutout above! The lens support is positioned by pressing against the first slope and the second slope of the lens support. Then each dowel @1
The forces applied to the first and second slopes are inclined with respect to the moving direction of the lens support base, and the resultant force of both is directed in the direction of the arrow as described above. Also, during the magnification changing operation, the notch part of the lens support base 18 is activated by the spring 43 due to the cam action of the first and second slope parts.
The process of climbing over the dowel of the arm 25 against the urging force of is the same as described above.

FIG. 5 shows an example of the drive mechanism for the cam 41. cam 4
1 is fixed to a shaft 44. This shaft 44 is connected to a gear 46 via a spring clutch 45. Rotational driving force from a motor (not shown) is transmitted to the gear 46 .

The spring clutch control unit 47 is provided with retaining portions 47 to 50 (only 47 and 48 are shown) corresponding to selectable magnifications, respectively. A control claw 5 is attached to either of these retaining parts.
1 comes into contact with the shaft 44, the action of the barbed clutch 45 is stopped, and the transmission of the rotational driving force of the gear 46 to the shaft 44 is stopped. Conversely, when the control pawl 51 is applied 1IfEtl from any of the above-mentioned retaining portions, the spring clutch 45 is activated, and the gear 45 and the shaft 4 are rotated until the selected retaining portion corresponding to the nine magnification comes into contact with the control pawl 51.
Rotate 4 as one unit. That is, rotating the cam 41,
The control claw 51 is provided at the tip of a lever 52 that is rotatable around a fixed shaft 53. A handle 54 is provided at the other end of the lever 54, and the operator cannot manually select this handle 54. By moving the control claw 51 to a position corresponding to the magnification, the control claw 51 is separated from the companion engagement claw that has been engaged to rL, and is moved to a position where it engages with the retaining portion corresponding to the selected magnification. 58 is a scale for adjusting the handle 54 to a desired magnification position.

Now, 59 is a turret plate fixed to 1li144, and supports a plurality of stepped gears 61 to 64 (only 61 and 62 are shown) between it and the opposing turret plate 6o. Each stepped gear corresponds to a selectable magnification, and one gear portion of each gear is always in mesh with a gear 65 loosely fitted on the shaft 44, while the other gear portion of each stepped gear is This gear 6 meshes with gear 66 when it comes to the operating position.
6 transmits the driving force to the pinion 13 described in FIG. 1.

Driving force from a drive motor (not shown) is transmitted to the gear 65. Thus, the gear 66 receives the driving force of the gear 65 via the stepped gear that has come to the operating position, and at this time, the gear 66 is rotated at a speed corresponding to the gear ratio between one gear part and the other gear part of the stepped gear. Driven. In other words) rA a is scanned at a speed corresponding to the selected magnification.

Turret plate 59 supporting each stepped gear as described above
is fixed to the shaft 44 like the cam 41. Manual operation of handle 54 therefore brings the stepped gear corresponding to the selected ratio into an operating position in which it meshes with gear 66.

In the embodiment shown in FIG. 5, the welfare cam 41 was rotated in conjunction with the speed switching operation of the transmission. If the lens is moved and the focal length is changed in conjunction with the speed switching operation of the transmission in this way, the number of four driving sources will be reduced and the configuration will be simplified. However, it is not always necessary to link the two; The camera and the lens may be driven by separate drive sources.

As described above, according to the present invention, a considerable amount of error such as wobbling is allowed in the means for moving the lens, and highly accurate positioning can be achieved with a simple configuration regardless of the factors.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a variable #r copying system to which the present invention can be applied, and FIG. 2 is an explanatory diagram of essential parts of an embodiment of the present invention. Due to
FIG. 4 is an explanatory diagram of a part of FIG. 2, and FIG. 115 is an explanatory diagram of the transmission. 0 is the original 1, the photoreceptor 10 is the lens 18, the lens support 22 is the lever 24, the dowel 25 is the positioning stopper 27 to 30 are trapezoidal notched grooves. Applicant Canon Co., Ltd.

Claims (4)

[Claims] (1) A lens that forms an original image on a photosensitive surface, a movable support means that supports this lens, and a guide means that guides this movable support means along a predetermined path. In order to change the magnification of the document (I), a drive means for moving the movable support means; a stopper receiver provided on the movable support means; and a stopper receiver provided in pressure contact with the movable support means to select the movable support means. means for positioning a stopper at a position corresponding to a magnification determined by W, the stopper receiver being pressed against the first and second parts as soon as they are separated in the direction of movement of the movable support means; and a stopper means for applying a force to the stopper receiver in a direction oblique to the moving direction of the movable support means.The stopper means is elastically attached to the stopper receiver. A variable magnification image forming device comprising: a biasing means for biasing the image. (2) The stopper receiver is a protrusion, and the stopper means is a recess that engages with the protrusion, and the first portion has a first slope that engages with the protrusion, and the second 2. The variable magnification image forming apparatus according to claim 1, further comprising a recessed portion having a second slope that engages with the protrusion at a portion thereof. (3) The stopper means has a protrusion that engages with the stopper receiver, the stopper receiver has a recess, and a first slope that engages with the protrusion at the first portion; 2. The variable magnification image forming apparatus according to claim 1, wherein the second portion is a recessed portion having four sides that engages with the protrusion. (4) The variable magnification image forming device includes an original scanning means and a speed changing means for moving the original scanning means at a speed corresponding to the selected magnification, and the driving means controls the speed changing operation of the speed changing child actor. A variable magnification image forming apparatus according to any one of claims 1 to 3, comprising a cam that is interlocked with the cam and a transmission element that transmits the displacement force of the cam to the movable support means.