JPH02207283A - Transfer device - Google Patents

Abstract

PURPOSE:To preclude jamming and a transfer defect by providing a rotary material for transfer with contacts which connect electrically while an opening/ closing claw which chucks the front end of a transfer material is closed, and accurately detecting the abnormal state of the opening/closing claw. CONSTITUTION:A transfer drum 22 is formed by extending a dielectric film 37 on the surface of a drum frame body 220 and the front end of the transfer material is chucked by the chuck claw 38. The tip part 38b of the chuck claw 38 is put in opening/closing operation between the position where a contact A embedded in the peripheral surface of the drum frame body 220 is made and the position where the contact A is broken. Then the inside of each chuck claw 38 is connected electrically to the drum frame body 220 through a support pin 223 and grounded and the contact A, on the other hand, is connected electrically to a terminal B to constitute a detecting circuit, thereby deciding whether or not the chuck claw 38 is normal. Consequently, the jamming and transfer defect due to the edge folding, etc., of the transfer material can be precluded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer device installed in an image forming apparatus such as a color copying machine.

This type of transfer device is equipped with a plurality of chuck claws (opening/closing claws) as a means for holding a transfer material such as a transfer sheet on a transfer drum (rotating body for transfer) prior to the transfer process. Ru. That is, the transfer sheet conveyed to the position of the transfer device by the closing operation of the chuck claw is chucked and held on the transfer drum, and after the transfer process is completed, the chuck claw is opened to separate the transfer sheet from the transfer drum. .

In order to perform a highly accurate transfer process in such a transfer device, it is a prerequisite that a plurality of chuck claws arranged in parallel in the width direction of the transfer sheet are opened and closed accurately. That is, for example, if one of the plurality of chuck claws does not open or close properly, the corresponding position of the transfer sheet will not be chucked, causing the transfer sheet to have edges folded, causing jamming, and impairing transfer accuracy. occurs. Moreover, poor separation will occur.

Here, the opening/closing operation of the chuck jaws is generally performed by pressing a base portion of the chuck jaws, which are rotatably supported by a support bottle and biased toward closing by a spring member, with a push-up cam. The opening/closing abnormality of the chuck jaws occurs due to problems such as the support pin coming off, damage to the chuck jaws, and breakage of the spring member (hereinafter referred to as abnormal state of the chuck jaws).

Therefore, in order to prevent problems such as jamming and transfer failure, it is necessary to detect the open/closed state of the chuck jaws, thereby detecting an abnormal state of the chuck jaws, and to perform maintenance. Moreover, such an abnormal state is difficult to visually recognize from the outside even when the transfer drum unit is removed from the main body of the image forming apparatus. Therefore, it becomes even more necessary to be equipped with means for detecting abnormal conditions. Note that if all chuck jaws are abnormal, the transfer sheet cannot be chucked, so there is no need to detect whether the chuck jaws are open or closed.
Abnormalities can be determined.

However, conventionally, there has been no transfer device equipped with means for detecting such an abnormal state of the chuck jaws.

The present invention has been made in view of the current situation, and an object of the present invention is to provide a transfer device that can reliably detect an abnormal state of the chuck jaws and, as a result, prevent jamming and transfer defects. shall be.

The present invention is a transfer device that electrostatically attracts a transfer material to a transfer rotating body and electrostatically transfers a developed image formed on an image carrier to the transfer material, The transfer rotating body is provided with a plurality of opening/closing claws that chuck the leading edge of the transfer material and a plurality of contacts that are electrically connected when the opening/closing claws are closed. The device is characterized in that it has means for monitoring output changes, and determines whether the opening/closing claw is normal or abnormal based on the output changes.

In such a case, the abnormal state of the opening/closing claw can be accurately detected.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a front sectional view showing a color copying machine to which a transfer device according to the present invention is applied, and the general structure of this color copying machine will be described below with reference to FIG.

When a document (not shown) is placed on the document table glass 18 and a print switch (not shown) is turned on, the exposure lamp 17,
An image reader (UNIS) 10 consisting of a rod lens array 15, a CCD line sensor 16, etc. scans in the direction a in the figure, and the CCD line sensor 16 receives the reflected light of the light irradiated onto the original from the exposure lamp 17, that is, the exposure signal. It is read as three primary color signals of red, green, and blue. Next, these 3
An image processing circuit 19 comprising a color separation filter unit or the like converts the primary color signal into a three-value signal of yellow, magenta, and cyan or a four-value signal of yellow, magenta, cyan, and black, and outputs it to the laser optical system 11.

Note that this color copying machine does not have an image memory for three colors, and therefore, when forming an image for each color, the image reader unit 10 scans each time, reads the exposure signal sequentially, and outputs it to the image processing circuit 19. become.

The laser optical system 11 includes a polygon mirror 12, an Fθ lens 13, and the like, and optically scans the ternary or quaternary signal, and exposes the photosensitive drum 1 with the scanning light via the mirror 14. The photosensitive drum 1 is formed by coating a conductive drum frame with a selenium-based or other organic photosensitive layer, and is rotated in the counterclockwise direction indicated by the arrow by a driving means (not shown). There is. Note that the organic photosensitive layer used is one that exhibits high sensitivity near the laser emission wavelength of 780 nm.

The surface of the photosensitive drum 1 is uniformly negatively charged by a charger 2 prior to exposure, and an electrostatic latent image is formed in the exposed area. Then, a developing device 6 disposed on the left side of the photoreceptor drum 1 supplies negatively charged toner to this electrostatic latent image to visualize the toner image. The developing device 6 consists of a yellow developing device Y, a magenta developing device M, a cyan developing device C, and a black developing device B, which store toners of yellow, magenta, cyan, and blank colors, respectively, arranged from above, depending on the developing process. to supply each color of toner to the electrostatic latent image. That is, first, the first color is developed by the yellow developer Y, and then the second and subsequent colors are developed by the magenta developer M, the cyan developer C, and the blank developer B. A toner popper 7 is provided above the developing device 6 to supply toner of each color to the developing devices Y, M, C, and B, respectively.

A transfer drum 22 is provided below the photosensitive drum 1 to transfer a toner image onto a transfer sheet (not shown). The transfer sheet is supplied to the transfer drum 22 following the following conveyance path. That is, the paper feed roller 41 takes out transfer sheets stored in a stacked state in the paper feed cassette 40 one by one and feeds them to the transfer drum 22 side. A registration roller 20 is provided near the transfer drum 22. The registration roller 20 temporarily stops the transfer sheet conveyed to this position, forms a loop therein, performs skew correction, and registers the leading edge. Thereafter, the transfer sheet is supplied to the transfer drum 22 in synchronization with the rotation of the transfer drum 22.

The transfer drum 22 is formed by stretching a dielectric film 37 (described later in FIG. 2) on the surface of a drum frame 220, and uses a chuck claw 38 to grip the leading edge of the transfer sheet fed from the registration rollers 20. Chuck. and,
When the chucking operation is completed, the adsorption charger 23 provided inside the transfer drum 22 negatively charges the dielectric film 37, and at the same time, the counter electrode 24 provided outside the transfer drum 22 contacts the transfer sheet. The surface of this is electrically grounded. (Thus, the transfer sheet is electrostatically attracted onto the circumferential surface of the dielectric film 37.

Thereafter, the transfer charger 25 for positive charging provided inside the transfer drum 22 is discharged, and the toner image developed by the yellow developing device Y is transferred to the transfer sheet. When this first transfer (first color transfer) step is completed, the dielectric film 37 is positively charged, electrostatically attracts the transfer sheet, and performs the second transfer step, that is, transfer of the magenta toner image. become.

When the transfer process of the final color toner image is completed, the static elimination charger 26.2 is placed facing the dielectric film 37 in between.
7 is activated to eliminate static electricity from the dielectric film 37, and at the same time, a push-up cam 106 (see FIG. 2), which will be described later, causes the chuck claws 38 to perform an opening operation. Thus, the transfer sheet that has completed the transfer process is separated from the transfer drum 22, and is separated from the transfer drum 22 by a separating claw 28 provided downstream of the static elimination charger 26, 27 (downstream side in the rotational direction of the transfer drum 22, which rotates clockwise in the figure). Sanjeong transport unit 2 through
9 and then to the fixing device 3o. Then, after the fixing process is completed, the paper is discharged to the paper discharge tray 32.

Here, the static elimination charger 26 is a charger that mainly eliminates static electricity from the dielectric film 37, and has a function of reducing the electrostatic attraction force between the dielectric film 37 and the transfer sheet. On the other hand, the static elimination charger 27 mainly functions to eliminate static electricity from the surface of the transfer sheet at the time of separation, and also to suppress discharge accompanying the separation operation and prevent image blur from occurring.

Next, details of the transfer drum 22 will be explained based on FIGS. 2 and 3. However, FIG. 2 is a perspective view showing the transfer drum, and FIG. 3 is a cross-sectional view thereof.

As described above, the transfer drum 22 is made up of a drum frame 220 and a dielectric film 37 stretched around the circumferential surface of the drum frame 220.

The drum frame 220 is manufactured by cutting out a predetermined portion of a cylinder as follows. That is, as shown in the figure, the cylinder is manufactured by cutting out both side parts 220a, 220a and a part of the circumferential surface by an appropriate width. The remaining portion of the circumferential surface is a band-shaped connecting portion 221 whose both ends are connected to both side portions 220a, 220a.
It has become.

The drum frame body 220 is rotatably supported on a rotating shaft 228 in a centered state by three support rollers 227, 227, and 227 provided on the inner surface of the drum frame body 220.

A dielectric film 37 is stretched over a portion of the drum frame 220 excluding the band-like connecting portion 221. As the dielectric film 37, for example, a polyester film having a thickness of 70 to 120 μm, a polyester net or a nylon net having a thickness of 50 to 80 mm is used.

A notch 222 that is long in the axial direction of the drum frame 220 is provided in a part of the band-like connecting portion 221, and four chuck claws 38, 38, 38, and 38 are provided within this notch 222. These four chuck jaws 38, 38, 38, 38 are rotatably supported by support pins 223 provided in the notch 222, and springs 224, 224, 224, 22.
4 are biased towards the surface side of the band-shaped connecting portion 221 so as to close freely.

Furthermore, as shown in FIG. 3, a push-up cam 225 is provided on the inner surface of the transfer drum 22 to push open the chuck claws 38 against the biasing force of a spring 224. The push-up cam 225 is eccentrically supported by a support shaft 226 1, and when the support shaft 226 is rotated by a drive means (not shown), four push-up cams 2 (only one is shown in the drawing) are activated.
25 rotates eccentrically, and the base end portion 38a of each chuck claw 38 is pressed by the amount of eccentricity at that time.

The driving means is controlled by the CPU 50 (see FIG. 4). The CPU 50 also controls the above series of steps of this color copying machine.

Thus, the chuck claw 38 opens and closes between the closed position where the tip 38b closes the contact (contact terminal) A recessed in the circumferential surface of the drum frame 220 and the open position where the contact A is opened. Become. The inside of each chuck claw 38 is electrically connected to the drum frame 220 via a support pin 223 and grounded. On the other hand, contact A
is electrically connected to terminal B which is pulled up to 5V,
These constitute a detection circuit as shown in FIG. As shown in FIG. 4, terminal B is connected to CP via input port 51.
Connected to U50.

In this detection circuit, when the push-up cam 225 causes the chuck claw 38 to perform an opening operation and opens the contact A as shown in FIG. The CPU 50 reads this state as a high level. On the other hand, the chuck claw 38
performs a closing operation, and as shown in Fig. 4(b), contact A
When closed, the output is grounded, so the CPU 50 reads this state as a low level.

Therefore, when such a detection circuit is used, it is possible to determine whether the chuck jaws 38 are in a normal or abnormal state. That is,
For example, if all the chuck jaws 38, 38, 38, 38 are opened normally, the detection signal will be at a high level, but if at least one chuck jaw 38 has an abnormality, it is not opened normally. If not, the level will be low compared to a predetermined threshold level, so an abnormality can be determined.

In addition, a reference position sensor S (see FIG. 1) consisting of a closed type optical sensor is provided in the rotation area of the transfer drum 22.
When a marker section (not shown) provided on the transfer drum 22 comes to the installation position of the reference position sensor S, the marker section blocks the transmitted light and the reference position sensor S is turned on. Reference position sensor S
When turned on, a pulsed position detection signal (
(see FIG. 6(a)), and receives the output from the CPU 50.
performs a predetermined calculation based on the position detection signal, calculates the rotational position of the transfer drum 22, and then controls the opening/closing operation of the chuck claws 38, which will be described later, based on this calculated data.

Next, the control contents of the CPU 50 will be explained based on FIGS. 5 and 6. However, FIG. 5 is a flowchart showing the opening/closing control operation of the chuck claw 38, and FIG. 6 is a timing chart showing the transfer operation.

First, the CPU 50 determines whether the control timing is a chucking mode in which the chuck claws 38 are closed and the copy sheet 100 is gripped, based on the rotational speed of the transfer drum 22 from the start of the copying operation (Sl). Transfer drum 2
The number of rotations No. 2 is calculated based on the position detection signal. If it is determined that the chucking mode is selected, the process proceeds to step S2; on the other hand, if it is determined that the chucking mode is not present, the process proceeds to a separation mode in which the chuck claws 38 are opened to separate the transfer sheet from the transfer drum 22 (S13). )
.

In step S2, it is determined whether the reference position sensor S has changed from the off state to the on state. When it is confirmed that the reference position sensor S has changed to the on state, timers TII to T4 are started (S3), and the process returns to the main flow. . Timers T1° to TI4 are used for chucking timing and C for terminal B.
This is for setting the reading timing of the PU 50, and time limits are set as shown in FIGS. 6(b) and 6(c), respectively.

On the other hand, if the reference position sensor S does not change from the off state to the on state, that is, for example, the position detection signal is
If it is the period from when 0 is input to when the next position detection signal is input, it is determined whether the time limit of timer T has expired or not (S4), and when it is confirmed that this time limit has expired, , the detection signal from terminal B is read at the timing shown in FIG. 6(C). Then, it is determined whether the detection signal is at a high level or not (S5), and if it is at a high level, an abnormal condition such as breakage has occurred in the chuck jaw 38 as shown in FIG. 3(b). It is determined that the copying machine is in an abnormal trouble mode (S6), and the copying operation is stopped, and a trouble message is displayed on the display section (not shown) of the copying machine main body. Thereafter, the process returns to the main flow.

In addition, FIG. 6(f) shows the detection signal when the chuck claw 38 is normal, and FIG. 6(g) shows the detection signal when the chuck claw 38 has an abnormality and does not open. h)
1 and 2 show detection signals when the chuck claw 38 is broken.

Here, in the chucking mode, the chuck claw 38
is normal, the chuck claw 38 closes contact A,
Since the detection signal is at a low level, if a high level is detected, it can be determined that an abnormality has occurred in the chuck jaws 38.

If the time limit of the timer T has not expired in step S4, and if the detection signal is not at a high level in step S5, the process proceeds to step S7, and the timer T1
It will be determined whether the time limit □ has expired or not. When it is confirmed that the timer TI□ has expired, the push-up cam 225 is driven at the timing shown in FIG. 6(b) to cause the tick pawl 38 to perform an opening operation (S8).
, set to chucking standby state.

Next, the process proceeds to step S9, and it is determined whether or not the time limit of the timer TI3 has expired. When this is confirmed, the detection signal of the terminal B is read at the timing shown in FIG. 6(C), and the detection signal is at a low level. 510
), if it is not at a low level, that is, if it is confirmed that the chuck claw 38 is reliably opened, the process proceeds to step 311, and it is determined whether or not the time limit of the timer T+a has expired. When it is confirmed that the timer TI4 has expired, the chuck claw 38 is caused to perform a closing operation at the timing shown in FIG. 6(b) to chuck the leading edge of the transfer sheet (512), and the process returns to the main flow.

In this way, the transfer sheet held by the chuck claws 38 is
is wound around the transfer drum 22, and then the counter electrode 24
are brought into pressure contact at the timing shown in FIG. 6(d), and the surface of the transfer sheet is brought into contact with the ground. Next, the transfer charger 25 discharges at the timing shown in FIG. 6(e), and the first color, second color, and third color transfer steps are sequentially performed.

On the other hand, if the detection signal is at a low level in step 310, it means that the chuck jaws 38 have not opened even though they have been caused to open, that is, an abnormality has occurred in the chuck jaws 38. The abnormal trouble mode similar to step S6 is executed and the process returns to the main flow.

Note that in step S7, if the time limit of the timer TI2 has not expired, the process proceeds to step S9. Further, in step S9, if the time limit of the timer TI3 has not expired, the process proceeds to step S11, and in step Sll, if the time limit of the timer TI4 has not expired, the process returns to the main flow.

Next, the separation mode will be explained. If the separation mode is confirmed in step 313, step 3
14, it is determined whether the reference position sensor S has changed from the off state to the on state. When it is confirmed that the state has changed to the on state, the timers TRI to TZ4 are activated (315), and the process returns to the main flow. Here, the timers T21 to T24 are the timers T, to T14.
Similarly, the chaffing timing and CPU for terminal B
This is only for setting the reading timing of 50.

On the other hand, if the reference position sensor S does not change from the OFF state to the ON state in step S14, step 31
6, it is determined whether or not the time limit of the timer TZ+ has expired, and when it is confirmed that the time limit has expired, the chuck jaw 38 is caused to perform the opening operation at the timing shown in FIG. 6(b).
S17). Next, it is determined whether or not the time limit of timer T2□ has expired (318), and when it is confirmed that the time limit has expired,
The detection signal at terminal B is read and it is determined whether the detection signal is at a low level (319).

If the detection signal is at a low level, even though the chuck jaws 38 have performed the opening operation, the chuck jaws 38
Since the opening claw 38 is not opened, the same abnormal trouble mode as described above is executed (520), and then the process returns to the main flow.

On the other hand, if the time limit of the timer T2□ has not expired in step S18 and if the detection signal is not at a low level in step S19, that is, if there is no abnormality in the chuck jaws 38 and the chuck jaws 38 are opened normally, , the process proceeds to step S21, and it is determined whether or not the time limit of the timer T23 has expired (S21). After confirming that this time limit has expired, Fig. 6(b)
At the timing shown in , let the chuck jaws perform the closing action,
The next chucking operation is awaited (S22).

As shown in FIG. 6(b), the separation operation of the transfer sheet I is performed from the time when the timer T21 expires until the timer T23 expires.

Next, it is determined whether or not the time limit of the timer T24 has expired (523). When the time limit has been confirmed, the detection signal is read and it is determined whether the detection signal is at a high level (S24). If the level is not high, the chuck claw 38 is reliably closed, so the process returns to the main flow and waits for the next copying operation. on the other hand,
If the level is high, an abnormality has occurred in the chuck jaw 38, so the process advances to step S20 and an abnormal trouble mode is executed.

FIG. 7 is a perspective view showing a modification of the present invention, and FIG. 8 is a cross-sectional view thereof. In this modification, a cleaning member 229 is provided on a part of the circumferential surface of the drum frame 220, and the counter electrode 24 is cleaned by the cleaning member 229.
A configuration is adopted to prevent stains from forming on the surface of the transfer sheet.

That is, as shown in the figure, the belt-shaped connecting portion 2 of the drum frame body 220
A cleaning member 229 made of felt or the like is embedded in a portion of 21 located on the opposite side from the notch 222. This buried position is selected upstream of the chuck claw 38 (upstream in the rotational direction of the transfer drum 22).

The cleaning member 229 is in a state of slightly protruding from the surface of the band-like connecting portion 221.

When such a cleaning member 229 is provided, the image quality can be improved without causing stains on the surface of the transfer sheet. That is, in a copying machine, the counter electrode 24 is damaged by toner spilled from the developing device 6, toner rising in a plume, or by the dielectric film outside the sheet area when passing a small-sized transfer sheet. Since the surface is smeared by the toner adhering to 37, when transferring to the next transfer sheet, the surface will be smudged and the image quality will be impaired. However, cleaning member 2
29, when it comes into pressure contact with the counter electrode 24, it cleans the dirt on the counter electrode 24, thereby improving the image quality.

The cleaning member 229 is brought into pressure contact with the counter electrode 24 before the transfer sheet is chucked, and specifically, the cleaning member 229 is brought into pressure contact with the counter electrode 24 at the timing shown in FIG. 6(d). Note that this timing is set by the CPU 50 based on the detection result of the position detection signal.

4. In the above embodiments, the case where the transfer device of the present invention is applied to a color copying machine has been described, but it is needless to say that the present invention is not limited to a color copying machine.

Highlights (1) In the present invention, abnormal conditions of the opening/closing claw can be accurately detected, so jamming and transfer defects caused by folded edges of the transfer material can be reliably prevented. Moreover, poor separation can also be prevented.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view showing a color copying machine to which a transfer device according to the present invention is applied, FIG. 2 is a perspective view showing a transfer drum,
FIG. 3 is a cross-sectional view thereof, FIG. 4 is a circuit diagram showing the detection circuit, FIG. 5 is a flowchart showing the opening/closing control operation of the chuck jaws 38, FIG. 6 is a timing chart showing the transfer operation, and FIG. A perspective view showing a modified example, and FIG. 8 is a cross-sectional view thereof. 38...Chuck jaw, 50...cpu, 225...
・Push-up cam, 229...Cleaning member, A...
・Contact, B...terminal.

Claims (1)

[Claims] (1) A transfer device that electrostatically attracts a transfer material to a transfer rotating body and electrostatically transfers a developed image formed on an image carrier to the transfer material, the transfer device including a plurality of devices that chuck the leading edge of the transfer material. The transfer rotating body is provided with opening/closing claws and a plurality of contacts that are electrically connected when the opening/closing claws are closed, and means for monitoring output changes of the contacts during the transfer process; A transfer device characterized in that whether the opening/closing claw is normal or abnormal is determined based on the change.