JPH01244477A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of color slippage by a simple structure in multicolor development of elevating type by providing a groove for positioning the developing height of a developing device and restricting the vertical action of an elevator supporting body equipped with a developing device. CONSTITUTION:The elevator supporting body 15 is provided with plural developing devices 7a, 7b and is electronically elevated. It is also provided with a positioning lock groove 71 corresponding to developing devices 7b, 7c... and its vertical move is restricted by a lock member 80 inserted into the groove 71. The lock is detected by a switch 90 to turn off the driving means of the supporting body 15. In the image forming device of such a simple structure, the developing device stopping in an accurate height position develops and processes to prevent color slippage and a high quality multicolor image can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is mainly used in full-color copying machines and full-color printers.

(Prior Art) Full-color copying machines generally use four color developers to form color images.

Developing devices corresponding to each color are arranged within the apparatus, and there are three ways of arranging them.

■Stationary method: A method in which each developer is fixedly placed around the photoreceptor.

(2) Each developing device is attached to a rotating force type two-rotary support, and by rotating the rotary support to a predetermined position, the desired developing device is positioned at the developing position facing the photoreceptor.

- Lifting method: Each developing device is placed on a lifting support, and by moving the lifting support up and down to a predetermined position, the desired developing device is positioned at the developing position facing the photoreceptor.

The stationary method has the problem that when a photosensitive drum is used as a photosensitive member, its diameter becomes large, and because the position where the electrostatic latent image is formed and the development position differ depending on each color, the decay of the electrostatic latent image changes over time. This problem arises and requires correction.

The rotating system can solve the above-mentioned problems of the stationary system, but since the rotary support rotates, the developer is likely to spill out of the developing device (and the l/ner is only applied to the developing device at a predetermined rotational position). There is a problem that the I/toner replenishment performance is poor because the toner cannot be replenished.Furthermore, in the rotary type, there is a problem that it is difficult to constantly operate the toner stirring means in the developing device.

Although the elevating method requires a relatively large space in the vertical direction compared to the rotating method and has the problem of a longer travel distance, it has all the problems mentioned above for the stationary method and the rotating method. It has the advantage of being able to eliminate the

Japanese Patent Laid-Open No. 57-204567 discloses a full-color copying machine using an elevating method and having the above-mentioned features.

In this conventional example, after an elevating support body equipped with developing devices in multiple stages in the vertical direction is positioned at a predetermined height position, a horizontal drive means is activated to advance a predetermined developing device to substantially touch the photoreceptor. I try to stay in touch.

(Problems to be Solved by the Invention) In this conventional example, the developing height position of the developing device is determined by a threaded rod driven by a vertical movement motor. For this reason, if the rotation control of the motor becomes inaccurate, the developing roll of the developing device will not be able to contact the photoreceptor at the correct height position, and normal development will not be performed.

In addition, the positioning means for stopping the elevating support at the developing height position becomes complicated, and in order to accurately control the rotation of the motor, the configurations of both the bar 1' and the software I- become complicated. This results in increased costs.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention includes an elevating support body provided with developing units in multiple stages in the vertical direction, and a drive means for vertically moving the elevating support body. , in an image forming apparatus configured to supply developer to a photoreceptor from a developing device located at a developing height position, each developing device is positioned at a developing height position at a position corresponding to each developing device on the elevating support body; In addition, a locking member is provided on the device main body side to fit into the lock groove and restrain the vertical movement of the lifting support when the lifting support reaches a predetermined height position, and the locking member is fitted into the lock groove. The present invention is characterized in that a switch means is provided which detects the insertion operation and turns off the driving means based on this detection.

(Function) According to the present invention, by mechanically fitting the locking groove provided in the lifting support and the locking member provided on the apparatus main body, the lifting support and the development height position of a predetermined developing device are controlled. Therefore, even if the rotational control of the driving means (motor) is slightly inaccurate, the developing height position can be set accurately.

Further, by detecting the movement of the locking member fitting into the locking groove, the switch means turns off the driving means and the elevating support body is stopped at the developing height position, so a complicated positioning means is used. Moreover, there is no need for expensive hardware and software for accurately controlling the rotation of the drive means, which is advantageous in terms of cost.

(Embodiment) FIGS. 1 to 9 show a first embodiment in which the present invention is applied to a full-color copying machine.

FIG. 2 shows the entire apparatus, and a color image of a document placed on a document glass 1 is read by a CCD line sensor 2 as color signals of three primary colors. Each color signal is processed by the image processing circuit as Y (yellow), M (magenta).
, C (cyan), and Bk (black), and the output signal is transmitted to the laser optical system 3.

From the laser beam generator 4 of the laser optical system 3, the Y,
Image-forming laser beams for each color based on M, C, and Bk signals pass through a reflecting mirror 5 to a photosensitive tram (photosensitive body).
6 is sequentially irradiated.

A latent image is formed on the surface of the photosensitive drum 6 rotating in the direction of the arrow by irradiation with the laser beam.

For the latent image formed based on the Y signal, yellow toner is supplied from the Y developing device 7y to the photosensitive drum 6, and a yellow toner image is formed on the photosensitive drum 6.

Similarly, for a latent image formed based on an M signal, a C signal, and a Bk signal, the toner of each color is
The toner is supplied to the photosensitive drum 6 from the developing device 7m, the C developing device 7c, and the Bk developing device 7b, and a magenta toner image, a cyan toner image, and a black toner image are respectively formed on the photosensitive drum 6''.

A paper feed cassette 9 is attached to the transfer drum 8 that rotates in the direction of the arrow.
The paper supplied from the conveyance roller 1.0.11 is wound around the conveyance roller 1.0.11. By rotating the transfer drum 8 a necessary number of times, the toner images of each color on the photosensitive drum 6 are sequentially transferred onto the paper wound around the transfer drum 8, thereby forming a full-color toner image. After the paper on which the full-color toner image has been formed is separated from the transfer drum 8, it is sent to a fixing roller 13 via a conveyance heald 12, where it is fixed, and then discharged to a paper discharge tray 14.

The developing units 7y, 7m, 7c, and 7b of each color are supported by the elevating support member 15 in a state where they are arranged in four stages in the vertical direction. As shown in FIG. 3, the lifting support 15 has side plates 16.
16 and four developing device support plates 17, each of the developing devices 7y, 7m, 7c, and 7b is guided and supported on each developing device support plate 17 so as to be movable back and forth. Both side plates 16 of the lifting support 15
．． A rail 18 is provided vertically on the outer surface of the device 16, and these are connected to a pair of fixing plates 19.1 fixed to the main body of the device.
It fits into a rail 20 attached to the inner surface of 9. By fitting these rails 18, 20, the lifting support 15 is guided and supported by the fixed plate 19, 19 so as to be able to move up and down.

A constant output balancer 21 is attached to the fixed plate 19, and a spring seat 2 of this constant output balancer 21 is attached.
2 is fixed to the side plate 16 of the elevating support 15. The constant output balancer 21 is one that balances the total weight of the lifting support 15, and is designed to maintain a balanced state at all times regardless of the vertical position of the lifting support 15.

At the rear edges of both side plates 16.16 of the elevating support 15, the developing units 7y, 7m, 7c, and 7b are positioned at the developing height positions corresponding to the respective developing units 7y, 7m, 7c, and 7b. A locking groove 71 is formed. This lock groove 71
Inclined guides 72a and 72b are formed above and below to introduce a lock roller 81, which will be described later.

A drive shaft 23 is horizontally suspended below the double-sided fixed plate 19, 19, and a drive gear 26 of a DC motor 25 (drive means) meshes with a gear 24 fixed to one end of the drive shaft 23.

Further, drive sprockets 27 are fixed to each of the drive shaft 23 near both ends thereof. A driven sprocket 28 is supported by a fixed plate 19 above the driving sprocket 27, and a chain 29 is wound between both sprockets 27 and 28. The chain 29 and the lifting support 15 are connected using a connecting tool 30, as shown in detail in FIG.

Thus, by 250 rotations of the DC motor, the lifting support 15
can be moved to a predetermined height position. Figure 2 shows
Although the bottom Y developing device 7y is shown at the developing height position facing the photosensitive drum 6, the other developing devices 7m,
It is also possible to determine the height position of the elevating support 15 so that each of 7b and 7c is at the developing height position by the rotation of the DC motor 25 and the action of the locking member 80 described below.

The locking member 80 shown in FIGS. 1, 4, and 5 has a lower end pivotally supported on a support plate 83 via an ilK shaft 82, and an upper end that can be engaged with and detached from the lock groove 71. The lever part 84 includes a lever part 84 having a lock roller 81 that fits into the lever part 84, and a horizontal rod part 85 that is integrally formed with the lever part 84 and extends rearward. This horizontal rod portion 85 is urged upward by a spring 86, and an eccentric cam 87 is in pressure contact with the rear upper surface of the horizontal rod portion 85. This eccentric cam 87 is driven by a cam drive shaft 88, and when it is in the position shown in FIG. 4, the lock roller 81 is removed from the lock groove 71, and when it is in the position shown in FIG. is the lock groove 7
The lock member 80 is swung so that it can be fitted into the lock member 80. The rotation of the cam drive shaft 88 is controlled by a motor and a clutch (not shown). The horizontal rod portion 85
A detection plate 89 is attached to the device, and an optical switch (switch means) 9 made of a photocoupler is mounted on the main body side of the device.
0 is provided, and when the detection area of the optical switch 90 is shielded from light by the detection plate 89 as shown in FIG.
is activated to turn off the drive of the DC motor 25 and stop the vertical movement of the lifting support 15.

Each of the developing units 7y, 7m, and 7C17b is forced rearward by a spring 31 and positioned at a predetermined retreat position.

Further, a plate spring 32 bent in a dogleg shape is attached to the rear end of these parts i-1 with its upper end fixed. FIG. 8(c) shows a state in which the lowermost Y developing device 7y is at a developing height position facing the photosensitive drum 6.
Behind the developing device 7y, the Y developing device 7y is advanced toward the photosensitive tram 6 and is substantially brought into contact with it, so that enough developer from the developing roll 48'' is supplied to the surface of the photosensitive tram 6. A guide means 33 is provided to bring the object close to the object at a distance of about 100 degrees. Even when the other developing devices 7m, 7b, and 7c are at the developing height position, the guide means 33 performs the same function.

As shown in FIGS. 7 and 8, the guide means 33c includes a solid frame 34 fixed to the main body of the device, a movable cam 35 guided and held by the fixed frame 34 so as to be movable back and forth, and a movable cam 35 that moves back and forth. It is provided with an eccentric drive body 36 for moving.

Guy F circumferential holes 37 and 38 are formed in the downward direction in the two parts and the lower part of both side plates of the fixed frame 34, respectively, and guide bins 39. 4
0 engages, the movable cam 35 moves to the fixed frame 34.
Guidance is supported. The front surface of the moving cam 35 includes an upper inclined surface 41, a middle vertical surface 42, and a lower inclined surface 43.

Further, the movable cam 35 has a hollow portion 145 that is pressed against the eccentric drive body 36, and moves back and forth as the eccentric drive body 36 rotates. Note that the moving cam 35 is urged rearward by a spring 44. The eccentric drive body 36 is fixed to a cam drive shaft 46, and the rotation of the cam drive shaft 46 is controlled by a motor and a clutch (not shown).

The upper inclined surface 41 of the moving cam 35 is connected to the lifting support 15.
The developing units 7y, 7m, which come to the developing height position by lowering the
7c, 7b gradually move toward the photosensitive drum 6 along with the downward movement.
It acts to advance towards.

The lower inclined surface 43 of the moving cam 35 is connected to the lifting support 15.
The developing units 7y, 7m, which come to the developing height position by the rise of
7c and 7b gradually move toward the photosensitive drum 6 along with the upward movement.
It acts to advance towards. The eccentric drive body 36 functions to move the developing units 7y, 7m, 7c, and 7b back and forth in a short period of time. To determine the forward position of the developing units 7y, 7m, 7c, and 7b, developing gap setting rollers 56 are provided in the developing units 7y, 7m, 7c, and 7b concentrically with the developing roll 48, and this roller 56 is connected to the photosensitive drum 6. This is done by contacting both end surfaces of the When the forward position is determined in this manner, the developing roll 48 and the photosensitive drum 6 come closest to each other, substantially contacting each other, and developing units 7y, 7m, 7
A state is reached in which toner (developer) can be supplied to the photosensitive drum 6 from C17b.

Next, the operation of this apparatus during color copying will be explained.

Before copying starts, the lifting support 15 is at the highest position,
The lowest Y developing device 7y is located slightly above the developing height position. Further, at this time, the Y developing device 7y is in the retracted position and is located diagonally rearward and above the photosensitive drum 6. When copying starts, a latent image is formed on the photosensitive drum 6 based on the Y signal, and at the same time, the Y developing device 7y moves downward and forward as shown in FIG. That is, as shown in FIG. 8(a), the cam drive shaft 46 rotates, and the eccentric drive body 3
6 moves the moving cam 35 forward (imaginary line -
)solid line). Concurrently with this, the DC motor 25 rotates to lower the elevating support 15, and along with this, the Y
The developing device 7y also moves down.

As the Y developing device 7y descends, the plate spring 32 first comes into contact with the partially inclined surface 41 of the movable cam 35 in the forward position, and then is guided by this partially inclined surface 41 and moves diagonally downward and forward. . Therefore, the Y developing device 7y gradually moves forward as it descends, and reaches the position shown in FIG. 8(b). At this time, plate 3
2 is in elastic contact with the middle vertical surface 42 of the movable cam 35. Further, while the Y developing device 7y descends and reaches the developing height position shown in FIG.
The developing device 7y still advances slightly. Immediately before reaching the developing height position, the rotation of the DC motor 25 is reduced to a low speed, and the eccentric cam 87 is rotated half a rotation, thereby swinging the locking member 80 from the state shown in FIG. 4 in the training direction. As a result, the lock roller 81 comes into pressure contact with the inclined guide 72b, and is guided by this and fits into the lock groove 71 as shown in FIG. 5, positioning the elevating support 15 at the developing height position, and in this state to restrain. When the locking member BO swings to the position shown in FIG. 5, the optical switch 90 operates to turn off the drive of the DC motor 25, and the lifting support 15 stops.

Note that the lowering of the lifting support 15 from FIGS. 8(b) to 8(c) is performed by inertia. Also, by operating the optical switch 90 a little before the lock roller 81 fits into the lock groove 71, the DC motor 25
Stopping will be smoother. Further, as shown in FIG. 8 ((7)), the gap setting roller 56 is connected to the photosensitive drum J.
, 5, the Y developing device 7y substantially contacts the photosensitive drum 6.

In this manner, with the Y developing device 7y set in the position shown in FIG. 8(c), toner is supplied to the photosensitive drum 6.
The latent image on the photosensitive drum 6 is developed into a yellow toner image. This yellow 1-toner image is also transferred from the photosensitive tram 6 to the paper on the transfer drum 8.

When the development with the yellow toner is completed, the next step is to develop with the magenta I toner.

First, the lock member 80 swings to the state shown in FIG. 4, the lock roller 81 is disengaged from the lock groove 71, and in conjunction with this, the one C monitor 25 is rotated by the action of the optical switch 90. As a result, the lowering of the lifting support 15 is started,
The Y developing device 7y gradually retreats, and then the moving cam 35
is retracted to its original position by half a rotation of the eccentric drive body 36. FIG. 9(a) shows the movement locus of the developing roll 48 of the Y developing device 7y. Note that each developing device 7y, 7m, 7c,
7b is short and there is not enough time for the movable cam 35 to advance and retreat, the movable cam 35 is moved backward as the lock part +A80 is released, and after the developing unit is moved by the spring 31, the vertical movement is performed. You can also do it. 9th
Figures (b) and (c) show the developing roll 4 in this case.
8 shows the movement trajectory of No. 8.

The moving state of the M developing device 7m in the developing process using magenta toner is also the same as the moving state of the Y developing device 7y, which is not shown in FIGS. 8 and 9. And it has already been exposed to light by the M developing device 7m positioned at the same position as in FIG. 8(c)]
A latent image formed on the ram 6'2 based on the M signal is visualized, and then a magenta toner image is transferred from the photosensitive tram 6 onto the paper.

The development process with cyan I/toner and the development process with black toner are also similar, and at the final stage, the paper is
The colored toner images are transferred so as to overlap, resulting in a full-color copy.

The second action has been described for the case where the elevating support 15 is sequentially lowered to position the developing units 7y, 7m, 7c, and 7b, but it is also possible to use only some of them. If there is sufficient capacity, or by raising the elevating support 15, each developing device 7y, 7
It goes without saying that the above-mentioned device can also be applied to the case of positioning the parts M, 7c, and 7b. -1- When positioning for raising and lowering, the lock roller 81 is guided by the upper inclined guide 72a when it is fitted into the lock groove 71.

In this way, the developing height position of the elevating support member 15 can be determined in either vertical movement, which is advantageous in shortening the developing device switching time.

The second embodiment shown in FIG. 10 and FIG.
This embodiment differs from the first embodiment in that after the developing heights corresponding to the developing units 7y, 7m, 7c, and 7b are positioned, the contact positions are determined by the forward movement of the developing units 7y, 7m, 7c, and 7b. ing.

The development height position of the elevating support member 15 is determined by the functions of the locking member 80, the locking groove 71, etc., as in the first embodiment.

The movable cam 35a is swingably supported on a pivot shaft 49 at its lower part, and its front surface is a pushing surface 42a, and its rear surface 5 is a pushing surface 42a.
0 is in pressure contact with the eccentric drive body 36.

44a is a spring for pressing the moving cam 35a against the eccentric drive body 36, and 31a is a spring for urging the developing devices 7y, 7m, and 7C17b backward. By the action of the pushing surface 42a of the movable cam 35a and the eccentric drive body 36, the developing devices 7y, 7m, 7c, and 7b are positioned according to the movement locus shown in FIG. When the developing process shown in FIG. 10(b) is completed, the moving cam 43a swings to the retracted position as shown in FIG. 10(a), and the developing units 7y, 7m, 7c
, 7b also retreat in a short time. The configuration other than that described above is the same as that of the first embodiment. The parallel movement type moving cam 35 of the first embodiment has the problem that the guide mechanism for moving it in parallel becomes complicated, and there is a risk that twisting may occur during parallel movement, so smooth movement cannot be ensured. There is a problem that it is difficult to
The second embodiment has the advantage of being able to solve these problems.

In addition to the embodiments described above, the present invention can also be applied to copying machines and printers having two or three developing devices.

(Effects of the Invention) According to the present invention, in an image forming apparatus that switches developing devices by an elevating method, the developing height of the elevating support can be improved without complicating the control of the driving means or using a complicated positioning means. position can be set accurately.

[Brief explanation of the drawing]

1 to 9 show a first embodiment of the present invention.
Figure 2 is a perspective view showing the locking member, Figure 2 is a cutaway side view schematically showing the entire device, Figure 3 is a perspective view of the main parts, and Figures 4 and 5 each illustrate the action of the locking member. 6 is a perspective view of a portion connecting the lifting support and the chain, FIG. 7 is a perspective view of the guide means, and FIG. 8 is a side view showing the relationship between the developing device and the guide member. FIG. 9 is a schematic diagram showing the movement locus of the developing device. 10 and 11 show a second embodiment of the present invention, FIG. 10 is a side view showing the relationship between the developing device and the guide member, and FIG. 11 is a schematic diagram showing the movement locus of the developing device. . 6−−−−−−−−−−−−−−−−−−−−−−−−
-- Photoreceptor 7y, 7m, 7c, 7b-1 -----
-----Developer 15----11---------
------ Lifting support body 25 ------------------------
1---------Driving means 71--1~=----
−−−−−−−−−−−−−−Lock groove 80−−−−−
−−−−−−−−−−−−−−−− Lock member 9
0−−−−−−−−−−−−−−−−−−−−−−−−
Switch means agent Patent attorney Masaru Ishihara: Mistake ii1:: d≧Umizawa [88

Claims (1)

[Claims] (1) An elevating support body equipped with developing devices in multiple stages in the vertical direction;
In an image forming apparatus that includes a driving means for vertically moving the elevating support and is configured to supply developer to the photoconductor from a developing device located at a developing height position, a drive means that corresponds to each developing device of the elevating support is provided. A lock groove for positioning each developing device at a developing height position is provided at the position, and when the elevating support member reaches a predetermined height position on the apparatus main body side, the elevating support member is fitted into the lock groove to restrain vertical movement of the elevating support member. An image forming apparatus comprising: a lock member; and a switch means that detects an operation in which the lock member is fitted into a lock groove, and turns off the driving means based on the detection.