JPH0720787B2 - Image forming device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an image forming apparatus such as an LED printer, a laser printer, a copying machine, or the like.

[Prior art]

In conventional image forming apparatuses such as LED printers, laser printers, and copiers, printed characters and images are transferred from a paper feed cassette on a photosensitive drum, and the paper on which the characters and images are fixed is fixed by a fixing device. The paper is ejected to a paper ejection tray from a paper ejection unit provided on the side of the machine body.

[Problems to be solved by the invention]

However, in the image forming apparatus having the above structure, the paper discharged onto the paper discharge tray has the printing surface on which characters and images are printed facing upward, and therefore manual work is required to align the pages of the paper after printing. In particular, in a device such as a printer that continuously prints on a large number of sheets, there is a disadvantage that a lot of time is required for manual work for page alignment. Further, in the structure in which the paper discharge section is provided on the side of the machine body, the paper discharge tray must be provided in series with the paper discharge section, and the paper discharge tray largely protrudes from the machine body, resulting in the image forming apparatus There is a drawback that not only the size is increased, but also the installation area must be large.

In addition, the applicant of the present invention introduces a copy machine equipped with a paper discharge mechanism that guides a printed sheet, which has been transferred and fixed, to the upper part of the machine, and reverses and stores the sheet on a document holding plate on the upper part of the machine. Developed and filed (Japanese Patent Application No. 58-36747
-176758), Japanese Patent Application No. 58-36748 (Japanese Patent Laid-Open No. 59-176)
No. 759))]. In these copying machines, the above-mentioned problems can be solved, but when the page alignment is not necessary and the installation space of the image forming apparatus is sufficient, the image forming apparatus incorporating the paper discharge mechanism is costly. It had the drawback of becoming a high-quality copying machine.

The present invention has been made in view of the above points, eliminates the above problems, does not require downsizing and page alignment work, and when there is sufficient page alignment and installation space, remove the paper discharge mechanism. An object of the present invention is to provide an image forming apparatus that has versatility that can be used and that has a detection unit that can appropriately detect paper jam when the paper discharge mechanism is attached or removed.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention is an image forming apparatus such as an LED printer, a laser printer, and a copying machine. A unitized sheet discharging mechanism that guides the paper discharged from the unit to the outside of the machine to the upper side of the machine along the one side of the machine and stores it in a discharge tray provided on the upper side of the machine. Is detachably mounted on the machine, and first and second sensors for detecting the passage of the sheet are respectively provided at the opening of the machine and the discharge port of the paper discharge mechanism. No. 1 sensor is effective, and when the paper discharge mechanism is mounted on the machine, the second sensor is effective, and the jam is detected based on signals from the first and second sensors. A detection means was provided.

[Action]

By configuring the image forming apparatus as described above, when the unitized sheet discharge mechanism is mounted on the machine body, the sheet on which characters and images are printed is reversed and stacked on the sheet discharge tray. As described above, it is not necessary to manually perform page alignment, and since the paper discharge tray is not arranged on the side of the machine unlike the prior art, the printer can be downsized and its installation space can be reduced. Further, when page alignment is not necessary or when there is sufficient installation space, the unitized paper ejection mechanism can be used without mounting it on the machine body, so that versatility is widened and the selecting means is selected. As a result, it is possible to accurately detect a paper jam even when the paper discharge mechanism is attached or detached.

〔Example〕

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

FIG. 1 is a longitudinal sectional view showing the structure of a laser printer as an embodiment of the present invention. In the figure, 11 is a machine body of a laser printer, a laser beam scanning device 12, a photoconductor drum 13, and a fixing device 14 are provided in the machine body 11, and in the vicinity of the periphery of the photoconductor drum 13, A charging device 15, a developing device 16, a transfer device 17, a cleaning device 18, etc. are installed. A fan F is provided at the rear of the laser beam scanning device 12 to release heat generated by the laser beam scanning device 12 and the fixing device 14 to the outside of the machine body 11 and to remove ozone generated in the machine body 11 from an ozone filter (not shown). ) Is for absorption. It is like this.

The charger 15 uniformly charges the entire surface of the photoconductor drum 13 by corona discharge. Next, the photosensitive drum 13 is irradiated with the modulated and deflected laser beam from the laser beam scanning device 12.
By scanning the surface, an electrostatic latent image of printing characters or images is formed. The electrostatic latent image formed on the surface of the photoconductor drum 13 is visualized by the toner by the developing device 16 (in a laser printer, the toner must be attached to the exposed portion opposite to the copying machine. Since a toner having a charge of the same polarity as the chargeability of the photoconductor of the body drum 13 is used, the toner repels the charge of the unexposed portion and adheres only to the exposed portion). The toner image on the surface of the photoconductor drum 13 formed as described above is transferred to the photoconductor drum 13 and the transfer device by corona discharge having a polarity opposite to that of the toner by the transfer device 17.
It is transferred to the paper existing between 17 and. The toner remaining on the surface of the photoconductor drum 13 is cleaned by the cleaning device 18 in preparation for the next charging, exposure and transfer. In the laser printer having the above-described structure, for the paper fed from the paper feed cassette 19 by the paper feed mechanism 20 and reaching between the photoconductor drum 13 and the transfer unit 17 via the registration roller 21, the photoconductor drum 13 is transferred as described above. The toner image is transferred, and the sheet is passed through the fixing device 14, so that the toner image is fixed on the sheet by heating or the like, and the printing is completed. The paper printed as described above can be printed by the conventional laser printer.
In this embodiment, the sheet is discharged to the outside of the machine body 11 through the opening 11a provided on the side of the sheet, and in this embodiment, it is reversed to the discharge tray 25 provided on the top of the machine body 11 through the sheet discharge unit 24. And then stored.

FIG. 2 is a diagram showing a detailed structure of the paper discharge unit 24 of the laser printer. As shown, the paper discharge unit 24 is
Three drive rollers 26, 2 are provided in the housing 24a along the paper discharge path.
7, 28 and driven rollers 26a, 27a, 28a that rotate in association with the rotation of the drive rollers 26, 27, 28 are rotatably arranged, and further, between the drive rollers 26, 27, 28, printing is performed. This is a structure in which guide plates 29, 30, and 31 that are arranged to face each other and that guide the formed sheet are arranged. On the side of the paper discharge unit 24, there is formed a fitting portion 24b which is shaped to fit on the side of the machine body 11 of the laser printer. The distance between the drive rollers 26, 27 and 28 is at least the size of a business card (about 9 cm) or less. To secure the paper ejection unit 24 to the side of the machine 11,
This is performed by fitting the locking member 32b fixed to the 11 side to the locking member 32b from the fitting portion side of the paper discharge unit 24.
When removing the paper discharge unit 24 from the machine 11,
On the contrary, the locking member 32b is pulled out from the locking member 32a.

A first sensor S1 and a second sensor S2 for detecting passage of the paper X are provided near the opening 11a of the machine body 11 and the discharge portion 24c of the paper discharge unit 24, respectively. The sensors S1 and S2 are composed of, for example, a photocoupler including a photodiode and a phototransistor.

FIG. 3 is a view showing the structure of the drive system of the paper discharge unit 24. As shown in the drawing, the drive system of the paper discharge unit 24 is provided with drive sprockets 26 ', 27', 28 'corresponding to the drive rollers 26, 27, 28 and giving a drive force to the drive rollers 26, 27, 28,
The driven rollers 26a, 27a are pressed against the drive rollers 26, 27, 28 by springs 35, 36, and follow and rotate. Although the relationship between the drive roller 28 and the driven roller 28a is not shown, the driven roller 28a is pressed against the drive roller 28 by a coil spring. The drive sprocket 28 'includes the drive sprocket 2
The drive gear 28 ″ is formed integrally with 8 ′, and the drive gear 28 ″
The driven gear 33 is arranged to be driven by the driving force of. A chain 34 for transmitting a driving force to the drive sprockets 26 ', 27', 28 'is guided and suspended by the support rollers 40, 41, 42 on the drive sprockets 26', 27 ', 28'. The chain 34 is also suspended on a drive sprocket 39 that gives a driving force to the chain 34. The drive sprocket 39 is integrally provided with a drive gear 39 ″, the drive gear 39 ″ meshes with the gear 38, and the gear 38 meshes with the gear 37. The gears 37 and 38 are gears that are driven by the fixing device 14 provided on the machine body 11 side. Further, the gear 38 is rotatably supported by a support plate 43 which is rotatably supported by a support shaft 39 'of a drive gear 39. The support plate 43 is biased downward by a coil spring 44, and the gear 38 is pressed against the gear 37. The gear 37 is adapted to rotate in association with the drive mechanism of the fixing device 14, that is, the paper transport mechanism in the machine body 11.
When the paper discharge unit 24 configured as described above is inserted into the side of the machine body 11 and the locking member 32b is inserted and fixed to the locking member 32a, the drive mechanism of the fixing device 14 and the sheet transfer mechanism in the machine body 11 are formed. Drive sprocket 26 ', 2 in the paper discharge unit 24
A drive system composed of 7 ', 28', a drive gear 39, a chain 34, etc. is also driven via the gears 37, 38 to drive the drive roller 2
It also drives the paper transfer mechanism consisting of 6,27,28 and driven rollers 26a, 27a, 28a.

In this state, the printed sheet discharged from the fixing device 14 has a gap between the guide plates 29 and 29, a gap between the driving roller 26 and the driven roller 26a, a gap between the guide plates 30 and 30, and a driving roller 27 and the driven roller 27a.
Between the guide plates 31 and 31, and between the driving roller 28 and the driven roller.
It is accommodated in the paper discharge tray 25 through a discharge port 24c provided at the upper part of the paper discharge unit 24 through the space between 28a. At this time, the sheets are reversed during the transfer process in the sheet discharge unit 24 and are stacked in the sheet discharge tray 25 with the printing surface facing down, so that the page order is obtained, and it is not necessary to perform page alignment again.

FIG. 4 is a vertical sectional view showing a state in which the paper discharge unit 24 is not attached to the side portion of the machine body 11. By mounting the paper discharge tray 45 in the opening 11a through which the printed paper of the machine body 11 is discharged and storing the paper discharged from the fixing device 14 in the paper discharge tray 45, there is no conventional page alignment function. It can be used as a normal laser printer.

FIGS. 5A and 5B are circuit diagrams showing the circuit configuration of a detector that detects a jam of the paper X when the paper discharge unit 24 is attached to the machine body 11 and when it is removed. In FIGS. 11A and 11B, SK is a socket for mounting and connecting the paper discharge unit 24 to the machine body 11. The paper ejection unit 24
The socket SK is automatically connected by mounting it on 11, and when the power switch E is turned on and the selection switch SW1 is tilted to the b side, the second sensor S2 on the paper discharge unit 24 side becomes effective. When the laser printer starts printing in this state and the second sensor S2 detects the paper X within a predetermined time, an output is issued from the terminal T and it is determined that the paper X is not jammed.
If the second sensor S2 does not detect the paper X within the predetermined time, no output is generated from the terminal T, and the paper X is the machine body.
It is determined that the paper discharge mechanism in 11 or the paper transport path of the paper discharge unit 24 is clogged.

When the paper discharge unit 24 is detached from the machine body 11, the selection switch SW1 is tilted to the a side and the first sensor S1 is made effective. When the laser printer starts printing in this state and the first sensor S1 detects the paper X within a predetermined time, an output is output from the terminal T and the paper X is not jammed in the paper ejection mechanism in the machine body 11. If it is determined that it is not detected, it is determined that it is clogged.

Further, in the same figure (b), when the paper discharge unit 24 is attached to the machine body 11, the curl socket SK is connected and when the power source E is turned on, the power source E is input to the terminal 1 of the AND circuit AND1 via the socket SK. Therefore, the AND circuit AND1 becomes valid, while the power supply E is connected to the terminal 1 of the AND circuit AND2.
Is inverted and input via the inverter IN1,
AND circuit AND2 becomes invalid. In this state, the laser printer starts printing, and when the second sensor S2 detects the paper X within a predetermined time, a detection signal is input to the terminal 2 of the AND circuit AND1 and the AND circuit AND1 via the OR circuit OR1. It is determined that the output is not output and the paper X is not jammed. On the contrary, when the paper X is not detected within the predetermined time, it is determined that the paper X is jammed. When the paper discharge unit 24 is not attached to the machine body 11, the AND circuit AND2 becomes valid and the AND circuit AND1 becomes invalid. Therefore, when the first sensor S1 detects the paper X within the predetermined range, the paper X may not be jammed. On the contrary, if the paper X is not detected within the predetermined time, it is judged that the paper X is jammed.

In the above embodiments, the laser printer has been described as an example, but the present invention is not limited to the laser printer and can be widely used in image forming apparatuses such as LED printers and copying machines. Further, in a copying machine or the like, a discharge tray for storing discharged paper may be provided above the so-called document pressing plate provided on the top of the machine body 11.

If the paper discharge unit 24 is sold as an accessory separate from the machine body 11, the user can purchase only the image forming apparatus main body or both the image forming apparatus main body and the paper discharge unit depending on the purpose of use. It is also possible to do.

〔The invention's effect〕

As described above, according to the present invention, the paper discharge tray is not arranged on the side of the machine as in the conventional case, so that the printer can be downsized and its installation space can be reduced. In addition, the first and second sensors for detecting the passage of the paper are provided at the opening of the machine and the discharge port of the paper discharge mechanism, and when the paper discharge mechanism is detached from the machine, the first sensor is made effective, and When the paper mechanism is mounted on the machine body, the selecting means for activating the second sensor and the jam detecting means for detecting the jam of the paper based on the signals from the first and second sensors are provided. By selecting, it is possible to obtain an excellent effect that the paper jam can be accurately detected when the paper discharge mechanism is attached or detached.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing the structure of a laser printer according to the present invention, and FIG. 2 is a vertical sectional view of a paper discharge unit thereof.
FIG. 3 is a view showing a drive system of the paper discharge unit, FIG. 4 is a vertical sectional view showing a state in which the paper discharge unit is not attached to the machine body, and FIG.
(A) and (b) are diagrams showing the circuit configuration of the paper jam detector, respectively. In the figure, 11 ... Airframe, 12 ... Laser beam scanning device, 13 ...
Photoconductor drum, 14 …… Fixing device, 15 …… Charger, 16 ……
Developing device, 17 ... Transfer device, 18 ... Cleaning device, 19
…… Paper feed cassette, 20 …… Paper feed mechanism, 21 …… Registration roller, 22 …… Reflector, 23 …… Lens, 24 …… Paper ejection unit, 25 …… Paper ejection tray, 26,27,28… … Drive roller, 26a,
27a, 28a ...... driven roller, 26 ', 27', 28 ', 39 ...... drive sprocket, 29, 30, 31 ...... guide plate, 32 ...... locking member, 33
...... Drive gear, 35,36,44 …… Coil spring, 37,38 …… Gear, 28 ″, 39 ″ …… Drive gear, 40,41,42 …… Support roller, 43 …… Support plate, S1, S2 …… Sensor, SW1 …… Selection switch, SK …… Socket.

Claims (1)

[Claims] 1. A sheet of paper, which is fed from a paper feed cassette, is transferred and fixed, and is discharged to the outside of the machine body through an opening provided on one side of the machine body along the one side of the machine body to the upper side of the machine body. A unitized paper discharging mechanism for reversing and storing the paper in the paper guiding tray is detachably provided on one side of the machine body, and detects passage of paper at the opening of the machine body and the discharge port of the paper discharging mechanism. 1 and a second sensor are provided, and the first sensor is effective when the paper discharge mechanism is detached from the machine body, and the second sensor is effective when the paper discharge mechanism is attached; An image forming apparatus comprising: a jam detecting unit that detects jam of the sheet based on signals from the first and second sensors.