JPS59131924A - Variable magnification optical device - Google Patents

Abstract

PURPOSE:To reset a scanner easily when a machine stops in the halfway of scanning operation owing to an accident such as a power failure and misoperation, by providing a pawl release blade which allows free enlargement and reduction. CONSTITUTION:When desired copy magnification is selected with a push-button switch, etc., and a solenoid 106 is turned on, a constant-point engagement pawl clutch 39, 40 or 41 corresponding to the magnification is engaged and a gear 12, 43 or 44 rotates together with a clutch shaft in one body. When the gear and a hook pawl 102 rotate by a specific angle, the extremity of the opposite side to the pawl is pressed down by a release pin 105 and a pawl 102a is disengaged from a groove 101a to free a clutch. If the power source is turned off during scanning operation, the solenoid 106 turns off and a blade driving lever 104 is frawn by a spring and displaced; and the external diameter of a pawl release blade 103 is increased to press up the pawl roll 102b of the hook pawl 102 and the pawl 102a is disengaged from the groove 101a of a wheel 101, so that a servomotor 29 for scan return is reset without any trouble.

Description

TECHNICAL FIELD The present invention relates to a variable magnification electrophotographic copying machine, and more particularly to a variable magnification optical device for a color variable magnification electrophotographic copying machine of a three-color separation image overlapping transfer system.

In a conventional color electrophotographic copying machine using a three-color separation image superimposition transfer method, an original is placed on a contact glass 2 provided on the top plate of the copying machine 1, as shown in FIG. 1, for example. 3 is irradiated with a slit by a light source 4, passes through a first mirror 5, a second mirror 6, a third mirror 7, an imaging lens 8, and a fourth mirror 9, and forms an image at a certain position on the photoreceptor drum 10 for exposure.

The same-magnification slit exposure using the above-mentioned optical device is performed by integrating the light source 4 and the first mirror 5 into the photoreceptor drum 10, as is well known.
This is carried out by moving the second mirror 6 and the third mirror 7 as one body in the same direction at a speed of 1/2·■ in the same direction.

Between the fourth mirror 9 and the photosensitive drum 10, blue, green,
Eight red color separation filters 11 are provided so as to be switchable and insertable into the optical path. Around the photoreceptor drum 10, following the exposure position, there are three developing units 12, each containing a developer containing toner of three colors: yellow, magenta, and cyan.
18.14 are arranged, and the latent images formed by being exposed to light passing through the front, green, and red color filters are yellow, magenta, and cyan color developers 12 and 18.14, respectively.
The toner images of three colors are sequentially formed. 3
A transfer drum 15 having the same outer diameter as the circumferential surface of the photoconductor drum IO is provided at a position after the two developing devices, and is in contact with the circumferential surface of the photoconductor drum IO, and rotates at the same circumferential speed in synchronization with the rotation of the photoconductor drum 10. At the contact position, they are rotated at a linear velocity in the same direction. A transfer paper 17 is fed to the transfer drum 15 from a paper feeder 16, and its leading end is clamped to a predetermined length by a mechanical clamper 18 and wound around the drum 15.
Each one-color toner image is transferred by the transfer charger 19 provided inside the transfer charger 19 for each rotation, and by rotating three times, the three-color toner images of yellow, magenta, and cyan are superimposed and transferred. . Thereafter, the transfer paper 17 is peeled off from the transfer drum 15, fixed by a fixing device 20, and discharged onto a paper discharge tray 21 to complete a full-size color copy.

Now, in a slit exposure scanning type copying machine, when copying a document by changing the magnification such as same size, reduction and/or enlargement, the lens and mirror of the exposure optical device are displaced according to the copying magnification, and It is necessary to change the document scanning speed.

3- To explain this in more detail, in an optical device with a fixed document table and a moving scanner, the variable magnification function is to set the document to the desired magnification in the vertical direction (perpendicular to the scanning direction) and horizontal direction (scanning direction). It is important to match. When changing the magnification in the vertical direction with an exposure optical system that has the same lens and mirror arrangement as the optical system of the color copying machine shown in Figure 1, the second
As shown in the figure, with the light source 4 and the first mirror 5 fixed at the reference position, the second mirror 6, the third mirror 7, and the lens 8 are moved from the same magnification position shown by the solid line, for example, according to the magnification ratio. Displace it to the position shown by the chain line in the figure.

In that case, the second mirror 6 and the third mirror 7 are displaced to positions farther away from the first mirror 5 than at the same magnification (for example, positions indicated by 6/ and 7/) during both reduction and enlargement. For example, the lens 8 approaches the fourth mirror 9 during reduction.
', for example, 8, which approaches the third mirror 7 during magnification.
“ is displaced to the position.

FIG. 4-3 shows an example of a lens and mirror moving device that moves the second and eighth mirrors 6.7 and lens 8 in relation to each other in accordance with the magnification ratio as described above and scans an original. FIG. 3(a) shows a lens for variable magnification,
The mirror displacement mechanism is a mirror displacement mechanism in which a lens drive stepping motor 22 rotates a screw shaft 24 via a gear train 23, and a lens bracket 25 to which a lens 8 is fixed is moved leftward when zooming out and rightward when zooming in. When the lens is displaced by an amount corresponding to the magnification ratio, the cam plate 26 integrally attached to the lens bracket 25 is also moved left and right at the same time.

An arc-shaped slit cam 26a is formed on the cam plate 26, and this cam has an L rotatably supported on a fulcrum 27.
A cam follower 28a provided at one end of the letter-shaped variable power drive lever 28 is engaged. The locking position of the cam 26a at the same magnification is at the most downwardly protruding position in the figure, and the amount of protrusion decreases from there to the left and right. However, when the lens bracket 25 moves to the left or right during reduction or enlargement, the cam follower 28a is displaced upward in the figure, and accordingly, the variable power drive lever 2
8 rotates counterclockwise, and its upper end is displaced to the left from its position when magnified at 100%. As a result, when the light source 4 and the first mirror 5 are fixed by the arrangement of the rope and pulley shown in FIG. 3(b), the second and third mirrors 6.degree.7 are displaced to the left in the figure. (Note that the arrangement of lenses and mirrors in FIG. 8(b) is reversed from that in FIG. 2.) In this state, stop the lens drive stepping motor 22 and rotate the scan drive pulley 30. Accordingly, the light source 4 and the first mirror 5 are displaced at a certain speed, and the second and third mirrors 6.7 are synchronously displaced at half the speed in the same direction to perform exposure scanning.

Since the circumferential speed of the photosensitive drum cannot be changed by the process speed, it is necessary to always maintain it at a constant speed V regardless of the copying magnification, so the light source 4 and the first mirror are set to m. For this purpose, it is necessary to drive the scan drive pulley 30 shown in FIG. 8(b) at a rotation speed inversely proportional to the copying magnification. Note that the reference numeral 29 in FIG. 8(b) is a scan return servo motor.

The present invention relates to control of the rotational speed of the scan drive pulley 30 and the timing of its start/stop.

Conventionally, as a method for driving a scanner drive pulley according to the copying magnification of the variable magnification optical device of a variable magnification copying machine, (a) gear trains as many as the number of variable magnifications are provided between the drive source and the scanner drive pulley. , is switched and driven via an electromagnetic clutch, etc.

(b) A servo motor or pulse motor is used as a drive source, and the speed is switched and driven by an electric control means.

Such methods are known.

However, both of these methods require a switching step of an electromagnetic clutch or electrical control means, which inevitably causes a shift in the scanning start position for each imaging cycle.

Furthermore, control using an electromagnetic clutch or solenoid is not reliable in machines equipped with a high-voltage corona discharger, such as electrophotographic copying machines, as malfunctions are very common due to noise and the like.

7- In a color electrophotographic copying machine using a three-color separation image superimposition transfer method, the most important thing is the alignment of the transferred images, so the variable magnification drive method described above is inappropriate for a color copying machine. For this reason, the reality is that a color electrophotographic copying machine of the overlapping transfer method with a variable magnification mechanism has not yet been realized.

Note that although this is not a variable magnification copying machine, there is one that uses a fixed point engagement clutch as an optical scanning drive means that does not cause positional deviation.

By the way, a fixed point meshing clutch conventionally used in an optical system scanning drive device of a copying machine has a meshing groove provided on a rotating disc that is rotationally driven by a drive source, and rotates in conjunction with an optical system scanning drive pulley. The pawl portions of the engaging pawls, which are pivotally supported on a member that rotates freely, are urged by a spring or the like so as to press against the circumferential surface of the rotating disk, and when the engaging grooves of the rotating disk come to the position of the pawls, they engage with each other. When the clutch is engaged and optical scanning is completed, a release pin installed at a predetermined position on the machine is used to push down the end of the engaging pawl opposite to the pawl, and the connection between the pawl and the groove is made against the force of the spring. The bond had been removed.

8- Therefore, if the power is turned off due to a power outage or erroneous operation during optical scanning, or if the machine stops operating due to some kind of failure, the clutch's engaging pawl and engaging groove will remain engaged. The method of resetting the scanner becomes very complicated.

Purpose: In view of the above-mentioned circumstances of conventional variable-magnification copying machines and optical scanning drive clutches, the present invention is applicable not only to monochrome copying machines but also to color copying machines using an overlapping transfer method, and which is applicable to electrophotographic machines. The variable magnification optical device allows stable scanning without being affected by unavoidable electrical noise, and allows the scanner to be easily reset in the event that the mechanical operation stops mid-scanning. The purpose is to provide.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to embodiments shown in the drawings.

FIG. 4 is a perspective view showing a scanning speed switching unit that enables variable magnification copying in the color electrophotographic copying machine of the type previously explained with reference to FIG. In the embodiment shown in the figure, the copying magnification m can be switched to three types: 1.1.148.0.7647, as an example.

The scanning speed switching device section includes an input shaft 31 and a clutch shaft 32.
, three shafts of the drive shaft 33 are provided parallel to the axis of the photoreceptor drum 10 and supported by a side plate (not shown).

The input shaft 31 is provided with an input pulley 35 and two gears 86 and 87, which are driven by the main motor of the copying machine via a timing belt (toothed belt) 34.

The clutch shaft 32 includes a gear 38 that can obtain a speed ratio such that the above-mentioned gear 36 and the dog clutch shaft 32 have the same rotational speed as the photosensitive drum 10, and three fixed point dog claw clutches 8.
9, 40, 41, and gears 42, 4 that rotate integrally with the clutch shaft 32 when these clutches are engaged.
3.44 is provided.

The other gear 37 provided on the input shaft 31 includes a gear 46 fixed to the shaft 45 of the photoreceptor drum 10 .
and 38 mesh at the same speed ratio. The gear provided at one end of the photoreceptor drum 10
A gear provided at one end of the transfer drum 15 having the same diameter as the photoreceptor drum 10 and the transfer drum 1 is engaged with each other.
5 is rotated by the main motor in synchronization with the clutch shaft 32 at the same rotational speed.

The structure of the fixed point meshing pawl clutches 89, 40, 41 will be explained with reference to FIGS. 5 and 6.

This clutch is swingably supported at one point on each side of a wheel/I/101 fixed to the clutch shaft 32 and having a meshing groove 101a around it, and gears 42, 48, and 44 that are pivotally supported on the clutch shaft 32. The hook has a claw portion 102a at one end that can be held in the groove 101a, and the hook has a claw roller 10 provided near the claw 102a of the claw 102.
A claw release blade 103 whose outer diameter is expandable and retractable, and a blade drive lever 104 which switches the outer diameter of the claw release blade 10311- between an enlarged state and a contracted state, and an engaging groove. The release pin 105 releases the catch claw 102 rotated together with the gear at a predetermined position when the claw 102a engages with the release pin 101a.

The pawl release blade 103 has a rotation center 103C at one end as shown in FIG. 6(e), and a blade roller 103 at the other end.
As shown in FIG. 6(C), two unit blades 103a having a diameter of
Each plate is rotatably attached to the center of rotation 103C with a pin. A mounting pin and a blade roller 108dld of the unit blade 103a provided on the side opposite to the blade drive lever 104; an oblong relief hole 108e provided in the unit blade 103a on the side of the blade drive lever;
It penetrates through and projects toward the grade drive lever 104.

As shown in FIG. 6(f), the blade drive lever 104 has four grooves 1 on its periphery in which the blade rollers 103d engage.
048 and one arm 104b that protrudes in the radial direction, and the plunger of the solenoid 106 and the spring 107 are provided at the tip 12- of the arm 104b.
are connected.

Therefore, when the solenoid 106 is energized, the arm 104b of the blade drive lever 104 is pulled and the grade drive lever 104 is rotated through an angle, thereby causing the groove 1
The grade roller 108d that engages with the clutch shaft 3
As shown in FIG. 6(d), the outer periphery of the claw release grade 103 changes from the position shown by the chain line to the position shown by the solid line, and the outer diameter is reduced. When the pawl release grade 108 is in the swollen state, the pawl roller 102b is pushed out by the outer periphery of the pawl release grade 103, and the toe 102a is retracted from the outer periphery of the wheel 101, as shown in FIG. Even if 101 rotates, the catch is claw 1
02 is stationary together with the gear that supports it, but when the outer diameter of the pawl release grade 103 is reduced, as shown in Fig. 6 (
As shown in b), the claw roller 102b of the claw 102 approaches the wheel/L/101, and the toe 102a approaches the wheel 1.
01, and when the groove 101a rotates, it engages with the groove 101a, and the catch is the claw 102 and the gear 42 to which it is attached.
43 or 44 rotates integrally with the wheel 101. In other words, the clutch engages.

When the claw 102 of the gear and the hook rotates by a predetermined angle, the end of the hook 102 opposite to the claw is pushed down by the release pin 105, and the hook 102a and the groove 101a of the wheel 101 are pressed down.
The clutch is disengaged and the clutch is disengaged.

As described above, as the clutch shaft 32 rotates, the wheel tL/101 of each clutch rotates at the same rotational speed in synchronization with the photosensitive drum IO. The deviation angle θm of the pawl retaining groove 101a of the clutch wheel from the reference position of the wheel corresponding to the reference position of the photosensitive drum IO for each copying magnification m is proportional to the copying magnification m, as shown in FIG. The settings are as follows.

Each groove 101a of the wheel 1v101 of each clutch is connected to the photosensitive drum 10 because it is fixed to the shaft 32 via gears 46, 87, 86.88 fixed to each shaft 45, 31.82, respectively. Since each groove 101a always corresponds to a certain position on the photoreceptor drum, the photoreceptor drum 10 and the clutch wheel 101 always rotate in synchronization. On the other hand, winter melon 102 meshes with each clutch wheel 101.
are waiting as their respective home positions with respect to the starting point on the manuscript table depending on the respective magnification ratios, and the waiting home positions of the winter melon and each groove 10 of each wheel 101 are
The declination angle from the reference position of 1a is the same for each magnification ratio m, and the declination angle θm is as follows.

Copy magnification (,?+) 0m1
14.824°0.7647 10.953°1.141
16.872° As shown in FIG. 4, gears 47 and 48 mesh with the gears 42° and 48.44 connected to the clutch shaft 32 by the clutches 89 and 40, respectively.
．． 49 is provided integrally with the drive shaft 33. gear 42
The gear ratios of 47.43, 48.44, and 49 are set as follows.

15- Gear Copy magnification (m) Gear ratio 42.47
1 1 48, 48 1.148 1/1.14
844, 49 0.7647 110.7
647, that is, the gear ratio of each gear train is inversely proportional to the copying magnification m.

A scanning drive pulley 30 is fixed to the drive shaft 33.
The mirror drive wire shown previously in FIG. 3(b) is wound. This drive wire is the servo motor 2 for scanning return.
It is also wound around a pulley provided on the shaft of 9.

The operation of the variable magnification drive device configured as described above will be explained below.

When the copying machine is turned on and a desired copying magnification is selected using a pushbutton switch or the like, the lens 106 corresponding to the selected magnification is turned on, and the above-mentioned action causes the fixed point meshing pawl clutch 89, 40 corresponding to that magnification to be activated. Or 41 is engaged and gear 42, 48 or 44 rotates integrally with the clutch shaft. As a result, the drive shaft 33 rotates at a rotation speed of 16 times, which is inversely proportional to the copying magnification m, and the wire rope wound around the scanning drive pulley 30 moves the first mirror and the light source lamp to 1 of the scanning speed V at the same magnification. / m, and the second and third mirrors are driven at half that speed. In this way, scaling of the document in the lateral direction (scanning direction) is achieved.

Generally, when the scanner starts scanning, it is unavoidable that the scanner vibrates, so as shown in FIG. The starting position of the photosensitive drum 10 is shifted from the image forming reference position by LDrn, as shown in FIG.

In this embodiment, LS=15 m is set, and LDrn=LS=15 trrm when copying at the same size.

Copy magnification m = 1, m = 0.7647, m
= Clutch wheel/L corresponding to each of 1.148
/ The position of the engaging groove 101a provided on 101 is θm = 14.0 for m = 1 as described above.
824゜m = 0.7647 ・ 〃 θm
= 10.953゜m' = 1.148''
θm=16.872°, and the diameter of the photosensitive drum 1o and the diameter of the scanning drive pulley 30 are both set to 120wn. Since the photosensitive drum 10 and the clutch shaft 32 rotate synchronously and at the same rotational speed, the following is obtained for each magnification in the circumferential length LD from the start position of the photosensitive drum to the image leading edge reference position.

LD,, = 15mmX (0m/14.824
°) Copy magnification (→ LDrn1
15 Satoshi O, 764
711,47 scream],,148 17.154
Breathing, or LDtn, is proportional to the magnification m.

However, since the scanning drive pulley 30 rotates at a speed inversely proportional to the magnification m, Ls = LD,, / m, and L
s is always kept at a constant value of 15 smoke. Therefore, the distance Ls between the scanner start position and the document reference edge position does not need to be changed depending on the magnification, and the image leading edge position (reference position) on the photosensitive drum remains the same regardless of the magnification.

In the present invention, a constant point engaging pawl clutch is used as a variable power clutch.Since the present invention employs a constant point engaging pawl clutch as a variable power clutch, the timing at which the clutch engages for the selected magnification is extremely accurate, and the photoconductor drum The leading edge position of the upper image does not shift (V). Therefore, of course monochrome copying,
Variable magnification copying is also possible for color copying using the three-color separation/superposition method.

Now, when the clutch corresponding to the selected magnification is engaged and the gear corresponding to the clutch is rotated by a predetermined angle, the tail of the claw 102 is pressed by the release pin 105, and the hook is released into the groove 101a of the wheel zl/101. The rotation of the drive shaft 33 and scanning drive pulley 30 is stopped.

At this time, the hook 102 turns on a microswitch (not shown) to turn on the scan return servo motor 29,
The mirror driving wire rope is driven in the opposite direction to the scanning direction to return the scanner to the scanning start position.

The scanning length of the scanner that scans the document table varies depending on the magnification type (
Since the copying magnification differs depending on the type of magnification, it is necessary to provide the same number of release pins 105 as the number of magnification types at positions corresponding to the scanning length of the scanner for each magnification.

If there is a power outage or the power is accidentally turned off during the scanning operation, the solenoid 106 is turned off, the blade drive lever 104 is pulled by the spring 107 and displaced, and the outer diameter of the pawl release blade 108 is expanded. Since the hook pushes up the claw roller 102b of the claw 102 and disengages the claw 102a from the groove 101a of the wheel 101, the reset by the scan return servo motor 29 is performed without any problem.

Effects As described above, according to the present invention, the release of the clutch during the image forming process is performed by the release pin fixedly provided on the machine frame, so that the specified release is ensured as long as the release pin is not damaged. The clutch is released at this position. Additionally, this release is achieved by engagement between an engaging pawl that is swingably attached to a member that rotates at a constant speed on the drive source and a release pin that is fixedly implanted in the machine frame, so electrical noise and clutches are avoided. It is completely unaffected by phenomena such as friction plate slippage, and can always perform stable scanning without positional deviation. As a result, it has become possible to perform not only single-color copying, but also variable-magnification copying for color electrophotographic copying machines that use color separation image superimposition, where the occurrence of positional misregistration is the most problematic, making it possible to obtain color copies without color misregistration. This makes it possible to easily reset the scanner even if the machine stops due to an accident such as a power outage or erroneous operation during scanning.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the schematic configuration of a known color separation image superimposition type color electrophotographic copying machine, and FIG. A schematic diagram illustrating the variable power system. FIG. 3(a) is a side view showing the main parts of the lens and mirror drive system of the variable power system shown in FIG. 2, and FIG. 3(b) is a diagram showing the entire mirror drive wire system. FIG. 4 is a perspective view schematically showing the configuration of the variable magnification scanning drive section of the present invention, and FIG. 5 is an exploded perspective view showing an example of a constant-point engagement pawl clutch used in the device of the present invention. , FIG. 6 is an exploded view showing the constituent members of the clutch, FIG. 7 is a schematic diagram showing an example of the position of the pawl of the clutch and its engaging groove, and FIG. 8(a) is a starting point of the scanner according to the present invention. (b) is a diagram illustrating the relationship between the position and the document placement reference position, and (b) is a diagram illustrating the relationship between the image forming reference position and the start position of the photoreceptor drum. .40.41... Constant point mesh clutch 42.47
;48,48;44.49...Gear train 101...Wheel/l/102...Catch is claw 10B...Claw release blade 104...Grade drive lever 105...Release pin 106.・・Solenoid 23- 131- -134- 2m

Claims (2)

[Claims] (1) A variable magnification electrophotographic copying machine that changes magnification in the scanning direction by moving an optical scanner in the scanning direction via a wire rope using one scanning drive pulley at a speed inversely proportional to the copying magnification during the image forming process. The magnification optical device includes a number of gear trains corresponding to the number of magnification ratios provided between a scanning drive source and the above-mentioned scanning drive pulley, and disconnects and disconnects each of these gear trains from the above-mentioned drive source. In a variable magnification optical device equipped with a constant point engagement clutch, the constant point engagement clutch is connected by energizing a solenoid, whereby the engagement claw provided on the rotating member interlocked with the scanning drive pulley and the drive source are connected. This is done through engagement with an engagement groove provided at a fixed point on a rotating member, and the engagement and disengagement of the above-mentioned fixed point engagement clutch during the image forming process is performed by a release bin fixedly provided to the machine frame. This is done by engaging the engaging pawl and disengaging the engaging pawl from the engaging groove, and releasing the engagement of the constant point engaging clutch in the event of an abnormality is performed by de-energizing the solenoid. A variable magnification optical device that is characterized by being distorted. (2) The above-mentioned release pins are arranged one at a position corresponding to the scanning length of the optical scanner at each magnification ratio for each of the fixed point engagement clutches provided in a number corresponding to the number of the above-mentioned magnification ratios. A variable magnification optical device according to claim 1, further comprising a variable power optical device.