JPH0813563B2 - Printer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer using a cut sheet as a medium, and particularly to an electrophotographic printer.

[Prior Art] A general electrophotographic printer includes a pre-charger, a latent image forming device, a developing device for supplying toner powder to the surface of the photosensitive drum, a transfer device, and a removing device along the outer circumference of the rotating photosensitive drum. The elements forming the image forming / transferring area, which are an electric appliance and a cleaner, are sequentially arranged, while the paper is a pick roller for taking out the cut sheets stored in the paper hopper one by one,
A feed roller for feeding the taken-out paper to the image forming / transferring area, a fixing device including a heat roller and a back-up roller for heating and fixing the paper on which the image formed by the toner powder is transferred from the photosensitive drum to fix the paper, and The sheet after fixing is sent to the front by each of the discharge rollers for discharging the sheet out of the system.

[Problems to be Solved by the Invention]

In a conventional electrophotographic printer, generally, as shown in FIG. 19, a pick roller 11, a feed roller 12,
A magnetic clutch 18 is provided for each of the rotating bodies 2 and 5 such as a drum for image formation, the roller 14 of the fixing device, and the discharge roller 16, and the power from the motor as a drive source is turned on via the clutch 18. By turning on / off, each rotating part is independently controlled. However, since magnet clutches are expensive, using many of them increases the manufacturing cost of the entire device, and
Improvements have been demanded because they hinder the miniaturization of the device. Also, there has been a proposal to use one-way clutches acting in opposite directions for the pick roller 11 and the feed roller instead of the magnet clutch 18 (for example, Japanese Patent Laid-Open No. 61-226441). However, in this case, there is a problem that the next sheet cannot be fed out until the sheet is completely discharged.

An object of the present invention is to simplify the power transmission path for driving each rotating part, thereby realizing the downsizing of the entire apparatus and the low manufacturing cost.

[Means for solving the problem]

A printer according to the present invention introduces a rotating body of an image forming unit for forming and carrying an image of toner powder on a surface thereof, a pick roller for feeding a single-cut sheet from a hopper, and a fed sheet to a transfer area of the image forming unit. A feed roller, a roller of a fixing unit for fixing an image on paper, a discharge roller for discharging the fixed paper to the outside of the system, and a single forward / reverse rotation for driving each of these rotating elements. A motor, a first drive transmission system that transmits the power of the motor to the pick roller via a magnetic clutch, the feed roller via the one-way clutch, the roller of the fixing unit, and image formation. Drive transmission system for transmitting to the rotating body of the section, a third drive transmission system for always driving the discharge roller in a constant direction regardless of the rotation direction of the motor, and a rotation direction of the motor And a control unit that controls the entire apparatus including the control, characterized in that the provided.

[Action]

According to this configuration, first, the motor is rotated in one direction, the pick roller is driven to feed the paper, and then the motor is rotated in the opposite direction, so that the feed roller, the roller of the fixing device, and the image forming rotary unit are rotated. Printing is performed while driving to feed the paper. The motor is still rotated and then rotated in the reverse direction (first direction) for the next print operation. The discharge roller always rotates in a constant direction regardless of the rotation direction of the motor, so that the paper can be discharged even when the motor is rotated in the reverse direction (first direction) for the next printing operation. Then, the sheet feeding operation by the pick roller can be limited only to the rotation of the motor in one direction in the initial stage of the operation procedure, and the sheet subjected to the preceding printing operation is within the transfer area of the image forming unit. In this case, it is possible to prevent an accident in which a succeeding sheet is mistakenly fed and causes mutual interference.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS.

The printer of the present invention has an overall appearance as shown in FIG. 1, and as shown in FIG. 2, an upper frame unit 31 and a lower cover unit that can be separated into upper and lower parts by a clam structure.
It is composed of 32. In the figure, reference numeral 62 is a control panel for controlling the operation of the apparatus, and 63 is a stacker for receiving printed sheets.

As is apparent from the overall side view shown in FIG. 3 and the perspective view shown in FIG. 4, the upper frame unit 31 includes the fixing unit 36, the cooling fan 40, the entry sensor 41, and the discharge sensor.
42, a transfer unit 43, etc. are attached, and the first hopper 33 is further arranged from above.
a, the second hopper 33b is detachably attached. Pick rollers are provided in the first hopper 33a and the second hopper 33b, respectively.
34a and 34b are attached, and the feed rollers 35a and 35b provided on the upper frame unit 31 correspond to them.
These hoppers accommodate different types of cut sheets 10 and, when printing, use a magnetic clutch 29 as described later.
One of the hoppers is selected by the action of 5a and 298a. As shown in FIGS. 3 to 5, the fixing unit 36 has a heat roller 37, a backup roller 38, and a discharge roller 39 integrated therein.

As shown in FIGS. 2, 3, and 5, the lower cover unit 32 includes a process cartridge 52 and an LED array 5.
3 and a reversible motor 54 that is a drive source for the entire printer.

As shown in FIGS. 7a, 7b, and 8, the process cartridge 52 includes a developing device including a toner storage portion 70, an agitator 71, and a developing roller 72, a pre-charging device 74, a cleaning blade 73, Waste toner container 75 and photosensitive drum 55
The respective elements are integrated in a compact manner, and can be easily attached to and detached from the lower cover unit 32 by a push button operation. In this developing device,
The toner powder in the toner container 70 is stirred by the agitator 71 and at the same time is scraped up and supplied to the developing roller 72. The developing roller 72 is a core magnet roller 76 covered with a sleeve 77, and by relative rotation of the two, the toner powder is carried on the tip of a magnetic brush formed of iron powder applied to the sleeve surface, This is the photosensitive drum
The toner image corresponding to the electrostatic latent image formed on the surface of the drum is formed by carrying and transferring it to the surface of 55. Further, the cleaning blade 73 cleans the remaining toner powder transferred onto the paper from the surface of the photosensitive drum 2, and the pre-charger 74 uniformly charges the surface of the photosensitive drum 2 and the next image forming cycle. It is for preparing. The upper surface of the process cartridge 52 constitutes a guide 52 'for smoothly guiding the paper 10 to be fed, and a pinch roller 60a is provided at the tip edge thereof which contacts the photosensitive drum 55. The pinch roller 60a comes into contact with the guide roller 60 installed on the upper frame unit 31 side by the action of the leaf spring 52a to transfer the sheet 10 to the photosensitive drum 55 and the transfer unit.
It has the function of introducing into the image transfer area between 43 and.

The rotation from the motor 54 is transmitted to each rotating body in the lower cover unit 32 and the upper frame unit 31 via a gear box attached to the side surface of the lower cover unit 32.

FIG. 9 shows the appearance of the gear box with the cover removed, in which various gears and pulleys are combined on the bracket 90. The power from the motor 54 is transmitted to the gear 162 via the motor gear 110. A gear 163 is mounted coaxially with this gear 162, but both gears 162 and 163
Known one-way clutch using a spring between
162a is interposed and configured to transmit only the counterclockwise rotation of the gear 162 to the gear 163. Also, the pulley 149
The gear 151 and the gear 151 are mounted coaxially, but a one-way clutch 151a similar to the above-described one-way clutch 162a is provided between them.
Is installed and only rotates counterclockwise of the pulley 149 1
51 is configured to communicate.

In this figure, a gear 151 is for driving the photosensitive drum 55 of the process cartridge 52, and is biased in the direction of the arrow around the shaft A by a spring (not shown). Further, the gear 170 is the process cartridge 52.
Is for driving the developing roller 72 and is biased in the direction of the arrow about the shaft B by a spring (not shown). Further, the gear 161 is for transmitting power to a gear train for driving the rollers provided in the upper frame unit 31, and is similarly biased by the spring 80 in the direction of the arrow around the shaft C. There is. These gears 151, 161, 170 constitute terminals that output the power from the gearbox to the outside. This urging mechanism will be further described with reference to FIGS. 10a and 106 by taking the gear 161 as an example. The gear 161 and the gear 180 integrally mounted coaxially therewith are a U-shaped member. It is pivotally supported at one end of 93. The member 93 is rotatably supported at its center by a shaft C of a gear 179 meshing with a gear 180. Furthermore, the axis C is pivotally mounted on the bracket 90 forming a gearbox. The end of the member 93 opposite to the end where the gear 91 is attached is a bracket 90.
Has a pin 94 protruding rearward through an opening 95 provided in the pin 94. One end of a tension spring 80 (see FIG. 10b) is engaged with the pin 94 and the other end is fixed to a lower portion of a bracket 90. 96 engaged. With this configuration, the gear 161
Is always maintained in a state of being elastically biased in the direction of the arrow in FIG. Similar mechanisms are provided for the other gears 151 and 170. In this way, the gears engaging with the drive parts of each part are elastically biased upward, so that when the corresponding gears in the upper frame unit are applied from above, they mesh with each other. Will be certain.

 Next, the operation of this gear box will be described.

When the motor is driven clockwise, power is transmitted to the gear 162 via the motor gear 110, causing it to rotate counterclockwise, as shown in Figure 11a. Therefore, this rotation is transmitted to the gear 163, and passes through the gear train 171, 172, 173 and the gear 170.
Rotate in the direction of the arrow. On the other hand, the rotation of the motor gear 110 is transmitted to the gear 161 via the gear trains 174, 178, 179, 180,
Rotate this in the direction of the arrow. Further, the motor gear 110
The rotation of the gear rotates the gear 151 in the arrow direction via the pulley 175 coaxial with the gear 174, the belt 49, and the pulley 149. Here, a mechanism composed of a pulley and a belt is used to rotate the gear 151, because the photosensitive drum driven by the gear 151 rotates smoothly to improve print quality.

On the other hand, when the motor 54 is driven counterclockwise,
As shown in FIG. 11b, the gear 162 rotates in the clockwise direction, and this rotation is caused by the action of the one-way clutch 162a.
It is not transmitted to 163 and gear 163 remains stationary, so gear 170 downstream thereof does not rotate. The rotation of the gear 110 is transmitted to the gear 161 through the gear trains 174, 178, 179, 180, and rotates it in the direction of the arrow opposite to the previous direction. Although the pulley 149 rotates in the clockwise direction opposite to the previous time by the above-mentioned path, this rotation is not transmitted by the action of the one-way clutch 151a, and the gear 151 remains stationary.

As a result, each rotating body in the process cartridge 52 is driven only when the motor rotates in the clockwise direction, and stops when rotating in the counterclockwise direction. 7a, 7b, 8 described above
This will be described in more detail with reference to the figures and Figures 12a and 12b.

Details of the drive gears L to Q of the process cartridge 52, a part of which is omitted in FIGS. 7a and 7b, are described below.
This is as shown in FIGS. 12a and 12b. Gear L is a developing roller
72 is fixed to the shaft end of the sleeve 77, and the gear Q is fixed to the shaft end of the magnet roller 76. The gear M is composed of three gears M1, M2 and M3 which are coaxially integrated, and the gear N
Is composed of two gears N1 and N2 that are coaxially integrated. The gear M1 meshes with the gear 170 in the gear box, transmits the rotation thereof to the gear Q via the gear B2, and drives the magnet roller 76. The rotation of this gear M2 is
It is transmitted to the gear L through the gears M3, N1, N2, P and drives the sleeve 77. The gears M, N, P are each pivotally supported on the side wall of the cartridge. Referring to FIG. 7b, a gear C provided coaxially with the magnet roller 76 at the other end meshes with and drives a gear F fixed to the shaft of the agitator 71.

Next, the gear train installed in the upper frame unit 31 will be described.

This gear train has a central gear 28, as shown in FIG.
1 is the gear box gear in the lower cover unit 1
It is designed to mesh with 61.

First, the transmission path from the gear 281 to the left will be described. Power is transmitted through gears 237, 282, 286, 287 and meshes with the gear R at the shaft end of the heat roller 37 of the fixing device to drive it. Since the one-way clutch 287a that transmits only the rotation of the gear 286 in the clockwise direction is interposed between the gears 287 and 286 provided coaxially here, the heat roller 37 is counterclockwise, which is the traveling direction of the paper. It can only rotate in the direction.

The gear 286 further transmits power to the gear 211 that drives the discharge roller 39 via the gears 283, 284, 285a or 285b, 278.
As shown in the partially enlarged views of FIGS. 14a and 14b, the gear 28
The gear 5a is attached to one end of an L-shaped lever 285 pivotally supported about the same axis X as the gear 284, and a gear 285b having the same number of teeth is attached to the other end of the lever. When the gear 283 rotates clockwise as shown in FIG. 14a, the gear 284 is driven counterclockwise, and the lever 285 also rotates counterclockwise accordingly, and as a result, it is attached to the end in one direction. The gear 285a engages with the gear 278, and the other gear 285a becomes free. This gives the gear 211 a counterclockwise rotation indicated by the arrow. This direction coincides with the traveling direction of the paper. Conversely, when the gear 283 rotates counterclockwise as shown in FIG. 14b, the lever 285 rotates clockwise and the gear 285b engages the gear 290, which results in the gear 211 still Driven counterclockwise. That is, the lower cover unit
Regardless of whether the direction of rotation transmitted from the 32 gear box to the gear 281 is forward or reverse, the discharge roller 39 always rotates in the direction of advancing the paper.

Further, the guide roller 60 is rotated by the gear 237.

Next, regarding the transmission path from the gear 281 to the right, the 13th
Description will be made with reference to FIGS. 15, 15 and 16. Power from the motor is transmitted from the gear 281 to the gear 215 via the gear 279. This gear 215 is attached to the shaft end of the feed roller 35a for the first hopper via a one-way clutch 215a,
The rotation of the gear 215 for driving the pick roller described later is not transmitted to the feed roller 35a, but is configured to transmit only the rotation in the opposite direction, that is, the rotation in the direction in which the feed roller 35a advances the sheet. ing. Feed roller 35a
A gear 217 is fixed to the other end of the gear and is configured to transmit the rotation to a gear 294 fixed to the shaft end of the feed roller 35b for the second hopper via gear trains 291 to 293. That is, both feed rollers 35a and 35b always rotate simultaneously regardless of the selection of the hoppers 33a and 33b. A press roller (not shown) that is pressed against the feed roller to move the paper forward is driven by a gear (not shown) fixed to the feed roller.

On the other hand, the gear 215 meshes with a gear 297 coaxial with a gear 295 having a magnet clutch 295a, and a gear train 241,242,
A gear 298 having a second magnet clutch 298a and a gear 299 coaxially fixed thereto are engaged with each other via 241. The magnet clutch gear 295 is configured to mesh with the hopper gear 296 of the first hopper 33a shown in FIG. 17, and can transmit power to the pickup roller 34a via the gear train. One magnet clutch gear 298
Also, the power can be transmitted to these pickup rollers 34b by meshing with the hopper gear of the second hopper 33b having exactly the same configuration. Only one of the magnetic clutches 295a and 298a is selectively energized when the paper is fed, and the rotation is transmitted to the gear 295 (298) of the pick roller 34a (34b). With this mechanism, it becomes possible to feed out the sheet 10 from the selected hopper 33a (33b) by the pick roller 34a (34b) by operating an arbitrary magnetic clutch.

The operation of the printer having the above-described configuration will be described. Since the plurality of hoppers 33a, 33b are provided, first, the magnetic clutch 295a of the selected hopper, for example 33a, is operated to form a power transmission path to the hopper 33a. Of course, the other magnet clutch 298a is deactivated.
Next, the motor 54 is rotated in the direction in which the pick roller 34a feeds the paper 10 (see FIG. 18a). When the entrance sensor 41 detects the arrival of the sheet, the magnet clutch 295a is disengaged, and then the motor 54 is stopped.

Next, the motor 54 rotates in the reverse direction, and all the rollers except the pick rollers 34a and 34b rotate in the direction shown in FIG. 18b to advance the paper 10. The sheet 10 passes along the upper surface of the photosensitive drum 55, and when the discharge sensor 42 detects the trailing edge of the sheet, the motor 54 is stopped and the printer waits for the next print command.

Here, the guide roller 60 rotates in the opposite direction to the print operation when the pick roller operates to feed the paper,
At this point, there is no sheet in the image forming area, so there is no problem even if the sheet is rotated in the reverse direction. Further, the feed roller 35a or 35b attached to the hopper not selected also rotates, but there is no problem because the paper is not in contact with the feed roller not selected. Further, since the discharge roller 39 always rotates in a constant direction regardless of the rotation direction of the motor, the motor 54 is rotated in the reverse direction to discharge the paper,
You can feed the next sheet.

〔The invention's effect〕

As described in detail above, according to the present invention, a single reversible motor is used to drive each rotating part of the printer, and a magnet clutch and a one-way motor are provided in a drive transmission path leading to each rotating part. With a clutch interposed, the pick-up of the paper by the pick roller and the printing work by the synchronous operation of other rotating parts are performed by switching the forward and reverse rotation of the motor,
Further, since the discharge roller is always rotated in a constant direction regardless of the rotation direction of the motor, the time required from supply to discharge of the printer can be shortened, and the printer structure can be simplified and downsized. It became possible to do.

In addition, each roller for paper transport is housed in the upper frame unit, while the motor is housed in the lower cover unit, and both units can be separated by the clam system, so when the paper jams, etc. By lifting the frame unit, the drive transmission system of each roller can be completely separated from the motor, and the rollers can be lightly turned by hand to handle the jam of paper.

[Brief description of drawings]

FIG. 1 is a perspective view showing the appearance of a printer according to an embodiment of the present invention, FIG. 2 is a perspective view of the printer according to the embodiment showing a state in which an upper frame unit and a lower cover unit are separated, and FIG. FIG. 4 is a perspective view showing a configuration of an upper frame unit, FIG. 5 is a perspective view showing a configuration of a fixing unit, and FIG. 6 is a perspective view showing a configuration of a lower cover unit. FIGS. 7a and 7b are perspective views showing the structure of the process cartridge, FIG. 8 is a schematic side view showing the structure of the process cartridge, and FIG. 9 is a perspective view showing the structure of the gear box attached to the lower cover unit. Fig. 10a is a plan view of a mechanism for ensuring engagement between the gears in the gear box and the gears in the upper frame unit, and Fig. 10b is a partially enlarged side view of the same, Figs. 11a and 11b. The illustration shows Fig. 12a is a side view of a gear box showing the transmission of power according to the rotation direction of the rotor, Fig. 12a is a plan view showing a gear mechanism for driving a rotating element in the process cartridge, Fig. 12b is the same side view, and Fig. 13 is A side view showing a gear train attached to the upper frame unit, FIGS. 14a and 14b are partially enlarged side views of the gear train showing the drive system of the discharge roller, and FIG. 15 is a view for driving the feed roller. FIG. 13 is a side view of the gear train seen from the opposite direction to FIG. 13, FIG. 16 is a plan view showing the gear train for driving the feed roller and the pick roller, and FIG. 17 is a side view showing the configuration of the hopper. 18a and 18b are side views showing the rotation of each rotary element of the printer of the embodiment according to the rotation direction of the motor, and FIG. 19 is a view for explaining the rotation control of the rotary element of the conventional printer. 10 ... Paper, 33a, 33b ... Hopper, 34a, 34b ... Pick roller, 35a, 35b ... Feed roller, 36 ... Fixing device, 37 ...
Heat roller, 39 Eject roller, 54 Motor, 55
...... Drum, 72 …… Developing roller, 151a, 215a, 287a …… One-way clutch, 285 …… Swing lever, 285a, 285b …… Gear, 295a, 295b …… Magnet clutch.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B65H 29/22 Z G03G 15/00 550

Claims (4)

[Claims] 1. A rotating body (55) of an image forming unit for forming and carrying an image of toner powder on a surface thereof, and pick rollers (34a, 34b) for feeding a single-cut sheet (10) from a hopper (33a, 33b). , Feed rollers (35a, 35b) that introduce the fed paper (10) into the transfer area of the image forming unit, and rollers (37) of the fixing unit that fix the image on the paper.
And a discharge roller (39) that discharges the fixed paper (10) out of the system
And a single forward / reverse rotatable motor (54) for driving each of these rotating elements, and the power of the motor (54) is applied to the magnetic clutch (295a, 295a).
b) via a first drive transmission system for transmitting to the pick rollers (34a, 34b) and the power of the motor (54) by a one-way clutch (215a, 287a, 15).
A second drive transmission system for transmitting to the feed rollers (35a, 35b), the roller (37) of the fixing unit, and the rotating body (55) of the image forming unit via 1a), and rotation of the motor (54) Control of the entire device including control of the rotation direction of the third drive transmission system (285, 285a, 285b) that always drives the discharge roller (39) in a constant direction regardless of the direction, and the rotation direction of the motor (54) A printer provided with a control unit. 2. A component including the rotating elements is housed in a clam-type housing which is divided into an upper frame unit (31) and a lower cover unit (32) and hinged to each other so as to be openable and closable. The cover unit (32) accommodates the motor (54), a gear box forming a part of the drive transmission system, and a rotating body (55) of an image forming unit, while the upper frame unit (31) is provided. The other rotating elements (34a, 34b, 35a, 35b, 37) for transporting the paper are accommodated, and when both units (31, 32) are separated, the motor (54) and the upper frame unit ( The printer according to claim 1, wherein the transmission of torque to each of the rotating parts in 31) is completely cut off. 3. One of the clutches of the magnet, each of which includes a pick roller (34a, 34b) and includes a plurality of hoppers (33a, 33b) connected via a magnetic clutch (295a, 298a). By operating
3. The printer according to claim 1, wherein only the pick roller of any hopper is selectively operated. 4. A rotating body (55) of the image forming unit is integrated with a developing device (70, 71, 72) as a process cartridge (52), while the fixing device (36) is a cooling fan (4).
The printer according to claim 1, wherein the printer is integrated as a fixing unit (36) with the printer (0).