JPH0136098B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic printer, and more particularly, the present invention relates to an electrophotographic printer that is particularly effective when recording (printing) recorded information on a long recording paper at high speed, such as in a computer printer. It is related to printers.

General electronic photo printers for office use use cut paper cut to a certain size as recording paper, but for example, electronic photo printers that need to record information at high speed, such as computer printers, Long recording paper such as roll paper or perforated folded paper is commonly used.

When recording information using this long recording paper, it is often the case that a predetermined length of the long recording paper is one page, and information is recorded on each page.

Therefore, once this type of printer has finished recording the commanded information, it is necessary to stop the running of the long recording paper, photosensitive drum, etc. page by page, and the printers often start and stop repeatedly. .

To explain the operation of the conventional printer, for example, after recording information on the first page, the running of the long recording paper, photosensitive drum, etc. is stopped, and in preparation for the next startup, the long recording is started from the photosensitive drum. The paper is released and at the same time it is fed backwards by a predetermined length. In this case, the predetermined constant length is the rising length required for the long recording paper to reach a predetermined constant speed after it starts to feed when the long recording paper is fed forward.

When starting up, start up the photosensitive drum,
When the photosensitive drum rotates until just before the transfer section where the photosensitive drum and the long recording paper come into close contact with each other, the photosensitive drum is moved backwards to the top position of the next page of the stopped long recording paper as described above. After alignment, a start signal is issued to the long recording paper, and at the same time, the long recording paper is brought into contact with the photosensitive drum. When the activated long recording paper reaches the transfer section, the speed of this long recording paper is
Recording is transferred from the photosensitive drum to a predetermined position on the next page of the long recording paper in accordance with the circumferential speed of the photosensitive drum.

In the printer mentioned above that operates like this,
The length required from start-up to stable running of the long recording paper is not always constant. The reason for this is that the inertia of a long recording paper is influenced by the thickness, width and characteristics of the long recording paper, for example, the frictional resistance of the guide bar etc. due to the surface characteristics.
Since the mechanical load on the drive system changes over time, the length of time from the start of the long recording paper until it stably runs becomes indeterminate, and the accuracy of the transfer position from the photosensitive drum to the recording paper becomes unstable. It has the disadvantage that it gets worse.
In addition, in order to improve the tracking accuracy of the long recording paper to the photosensitive drum, the mechanism for bringing the long recording paper into close contact with the photosensitive drum and the drive mechanism are required to have rapid rise characteristics. , the operation involves large shocks and lacks mechanical reliability. Furthermore, if there is an impact as mentioned above, the toner on the recording paper is not fixed immediately after transfer, so the toner and the recording paper are in an unstable bond, so even a small impact can disrupt printer quality and cause fogging. , resulting in quality defects such as blurring.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the conventional apparatus. To provide an electrophotographic printer that improves print position accuracy, can be reasonably designed, is highly reliable, and has excellent print quality.

To achieve the above object, the present invention includes a means for forming an electrostatic latent image of recorded information on the photosensitive drum, facing the photosensitive drum disposed so as to be rotatable, and along the rotational direction of the photosensitive drum; a means for transferring the visualized recorded information to a long recording paper, and a means for transferring the long recording paper to the transfer means discontinuously at the same speed as the circumferential speed of the photosensitive drum. and conveying means, and the conveying means, after stopping conveyance of the long recording paper upon completion of transfer, transports the long recording paper at least around the circumference of the photosensitive drum from the latent image forming position to the transfer position. It has a mechanism that reversely feeds the length plus the length required for the rising speed of the long recording paper to reach a steady state during normal feeding, and furthermore, when the long recording paper that has been reversed is fed forward again. The present invention is characterized by an electrophotographic printer having a mechanism for detecting the leading position of a page to be recorded, and a mechanism for transmitting a detection signal from the detection mechanism to the electrostatic latent image forming means.

Next, embodiments of the present invention will be described with reference to the drawings. In the figure, a photosensitive drum 1 has a photoconductive layer of selenium, cadmium sulfide, or the like on the surface of a metal drum, and is rotated in the direction of the arrow by a drive source (not shown). 2 is a charger such as a corona discharger that uniformly charges the surface (photoconductive layer) of the photosensitive drum 1.

The electrostatic latent image forming means includes a laser tube 4 that exposes a light pattern of recorded information on the photosensitive drum 1, such as a laser light pattern 3, and a laser light modulation deflector 5. The charge on the photosensitive drum 1 disappears in accordance with the laser beam pattern 3 of the recorded information, and an electrostatic latent image of the recorded information is formed.

The electrostatic latent image developing means includes a developing device 6 and brings toner (developer) into contact with the electrostatic latent image on the photosensitive drum 1 to visualize it.

The transfer means, that is, the means for transferring visualized recorded information onto the long recording paper 7, has a charger 8 such as a corona discharger, and the photosensitive drum 1 is inserted between the charger 8 and the photosensitive drum 1. Visualized recorded information on the photosensitive drum 1 is transferred onto a long recording paper 7 that is brought in so as to be in close contact with the drum 1. This transfer means moves in the direction of arrow A when transferring onto the long recording paper 7.
When the long recording paper 7 is fed backwards, it is moved in the direction of arrow B by the eccentric cam 9.

On the other hand, the recorded information transferred to the long recording paper 7 is
After the toner is fixed by a fixing device such as a heater (not shown) and transferred, remaining toner on the surface of the photosensitive drum 1 is wiped off by a cleaning brush 10.

The conveying means for carrying the long recording paper 7 into and out of the transfer means has an upper tractor 11, a lower tractor 12, and a carriage tape 13 that detects the movement of the long recording paper 7, and is connected to each drive system 15, 16 by a motor 14.
and 17. The upper tractor 11 and the lower tractor 12 are formed in a kind of sprocket shape, and each of these pins engages with small holes drilled in the longitudinal direction at both ends of the long recording paper 7 at equal intervals. Then, the long recording paper 7 is stably conveyed in the direction of the arrow or in the opposite direction.

That is, the long recording paper 7 is fed forward and backward, and the forward feeding mechanism receives a drive command 19 from the printer controller 18 in response to a print command 34 from the computer 30, which will be described later. It has a motor drive pulse calculation oscillator 21 that emits a rotation signal 20. The reverse feed mechanism receives a drive command 19 from the printer controller 18 and includes the motor drive pulse calculation transmitter 21 which issues a reverse rotation signal 22 to the motor 14 , and the motor 14 .
An encoder 23 that is directly connected to and detects its rotation.
, a pulse counter 25 that counts the signal 24 from the encoder 23, and a signal system 26 that sends the counted pulses to the calculation transmitter 21.
It has

When the long recording paper 7 that has been fed backwards is fed forward again, a mechanism that detects the leading position of the paper surface to be recorded and sends this detection signal to the electrostatic latent image forming means is operated by a motor 14 together with a lower tractor 12. It has a rotating carriage tape 13, a carriage tape optical detector 27, a character transmission signal control transmitter 28, a character generator 29, a computer 30, and signal lines transmitted from each of these devices as shown in the figure. ing.

The carriage tape 13 is an endless tape having a length proportional to the cycle length to be recorded on the long recording paper 7, for example, the length from the leading position of a page to be printed to the leading position of the next page. It is. A small hole through which light passes is provided at one location of the carriage tape 13, and the position of the long recording paper 7 is detected by the carriage tape optical detector 27.

When setting the long recording paper 7 on the upper tractor 11 and the lower tractor 12, set the beginning position of the recording cycle of the long recording paper 7 to the length corresponding to L in the figure, and forward the long recording paper 7. When the recording paper 7 is started for this purpose, it is set at a distance from the transfer position by a distance equal to the distance that the long recording paper 7 travels from when it starts up until it reaches a steady speed. Then, when the long recording paper 7 is started to be fed forward, the long recording paper 7 reaches a steady speed from the start up, and the leading position of the page to be printed moves from the transfer position to the position corresponding to L in the figure. Once reached, the carriage tape optical detector 27 detects the leading position of the page to be printed through the small hole of the carriage tape 13, and sends this signal 31 to the character transmission signal control transmitter 28, from which characters are generated. A character generation command 32 is sent to the device 29. The character generator 29 is then connected to the computer 30
A laser beam modulation polarization signal 35 is emitted to the laser beam modulation polarizer 5 in response to a character generation signal 33 from the .
In this way, a character signal is emitted onto the photosensitive drum 1, and the photosensitive drum 1 rotates in the direction of the arrow, advances by a distance L, and reaches the transfer position of the charger 8. On this occasion,
Since the long recording paper 7 is moving in the direction of the arrow from the position corresponding to L in the figure on the photosensitive drum 1 at the same speed as the circumferential speed of the photosensitive drum 1, the long recording paper 7 is synchronized with the photosensitive drum 1. and reaches the transfer position of the charger 8. While these are moving by a distance L, the charger 8
The eccentric cam 9 moves slowly forward in the direction of the arrow A, and the long recording paper 7 and the photosensitive drum 1 are brought into close contact with each other and run at the same speed by this transfer means to prepare for transfer.

Therefore, even if there is an unfixed print that was previously transferred to the long recording paper 7, there is no misalignment between the long recording paper 7 and the photosensitive drum 1, and the charger 8 operates slowly and can be used for long periods of time. Since the length recording paper 7 and the photosensitive drum 1 are brought into close contact, there is no impact and unfixed prints are not damaged.

Then, as described above, the photosensitive drum 1 is transferred to the long recording paper 7, which has been prepared for transfer, by the action of the transfer means.
However, since the leading position of the page to be printed on the long recording paper 7 coincides with the exposed part at the beginning of the photosensitive drum 1, the recorded information is transferred onto the long recording paper 7 with accurate positioning. transcribed.

Next, when the transfer ends, that is, when the character generation ends, the exposure of the character signal to the photosensitive drum 1 by the laser beam pattern 3 ends, but there is no untransferred material on the surface of the photosensitive drum 1, which is indicated by the distance L in the figure. Recorded information remains. Therefore, the photosensitive drum 1 and the motor 14
does not stop immediately, but continues to rotate until the untransferred recorded information on the photosensitive drum 1 is completely transferred. This rotation time is calculated in advance from the circumferential speed of the photosensitive drum 1 and stored in the printer controller 18. When the transfer is finally completed in this way, the motor 14 stops;
immediately starts reverse rotation, and the long recording paper 7 is reversely fed by the upper tractor 11 and the lower tractor 12 via the drive systems 15 and 16. The signal 24 generated from the encoder 23 when the motor 14 reverses is sent to the pulse counter 25, and the signal 26 counted here is sent to the motor drive pulse arithmetic calculator 21.
send to This arithmetic calculator 21 calculates the sum of the distance L shown in the figure and the distance traveled by the long recording paper 7 from when it starts to feed forward until it reaches a steady speed. , is received as a reverse signal with a pre-calculated number of pulses, and when the predetermined number of pulses is reached, the motor 14 is stopped. If the long recording paper 7 does not stop immediately and overruns, the length due to this overrun is further added to the above-mentioned reverse feeding length.

Therefore, due to these effects, even if the stop position during forward rotation described above changes each time due to differences in the load on the long recording paper 7, changes over time, etc., the reverse rotation of the long recording paper 7 The stopping position after feeding can be fixed and accurately determined.

In addition, just before starting to reverse feed the long recording paper 7,
The photosensitive drum 1 is stopped, and the charger 8 is slowly retreated from the photosensitive drum 1 in the direction of arrow B by the eccentric cam 9 to be in a standby state.

When the computer 30 issues a print command 34 to the printer controller 18 from this state, the printer controller 18 receives this command.
sends the drive command 19 to the calculation transmitter 21, and from this sends the forward rotation signal 20 to the motor 14, causing the motor 1 to
4 is rotated in the normal direction, and the long recording paper 7 is normally fed to be synchronized with the circumferential speed of the photosensitive drum 1 as described above.

Therefore, even if there is an unfixed print on the long recording paper 7 that is fed normally, there is no misalignment between the long recording paper 7 and the photosensitive drum 1, and the movement of the transfer means is made slow. This allows the recording information to be newly printed to be placed on the long recording paper 7 with accurate positioning accuracy, without damaging the unfixed prints.
can be transferred to

Incidentally, since the movement of the transfer means in the direction of the arrow A-B may be slow, an actuator such as a rotary solenoid can be used.

Also, when transferring to the long recording paper 7, it is possible to print from the top of the page to any position within the page, but if there is no recorded information to print, from the top of the page. Needless to say, exposure to laser light does not start immediately.

As described above, according to the present invention, the long recording paper starts and stops repeatedly, and the inertia of the long recording paper is caused by the frictional resistance of the guide bar etc. due to its thickness, width and surface characteristics. Even if it is influenced by the mechanical load of the drive system and changes over time in the mechanical load of the drive system, if the long recording paper is fed live, printing of the long recording paper will be performed after it reaches a stable running state. Since the leading position to be printed and the leading position of image formation on the photosensitive drum can be synchronized, the accuracy of the printing position is always high. Therefore, no blank pages will be left on the long recording paper.

In addition, when moving the transfer means in the semi-longitudinal direction of the photosensitive drum, within the time it takes for the long recording paper to move by a distance (L in the figure) corresponding to the circumferential length of the photosensitive drum from the latent image forming position to the transfer position. Since it is only necessary to move the transfer means, the movement of the transfer means can be made slow.

Therefore, unlike the conventional apparatus, the apparatus of the present invention is free from quality defects such as disturbances in print quality, fogging, and blurring, and can significantly improve printer quality.

Additionally, the present invention has many advantages, such as being able to provide a highly reliable device with a flexible design, and its effects are significant.

[Brief explanation of drawings]

The drawing is a schematic front view showing an embodiment of the electrophotographic printer of the present invention. 1... Photosensitive drum, 2... Charger, 3... Laser light pattern, 4... Laser tube, 5... Modulation deflector, 6... Developer, 7... Long recording paper, 8... Charging device, 9... Eccentric cam, 10... Cleaning brush, 11... Upper tractor, 12... Lower tractor, 13... Carriage tape, 14... Motor, 15, 16, 17... Drive system, 18... ...Printer controller, 19... Drive command, 20...
Forward rotation signal, 21... Calculation transmitter, 22... Reverse rotation signal, 23... Encoder of motor 14, 24...
Signal, 25... Pulse counter, 26... Signal system, 27... Carriage tape optical detector, 28
... Signal control transmitter for character transmission, 29 ... Character generator, 30 ... Computer, 31, 32 ... Signal, 33 ... Character generation signal, 34 ... Print command, 35 ... Laser light modulation polarization signal .

Claims (1)

[Claims] 1. A means for forming an electrostatic latent image of recorded information on the photosensitive drum facing the rotatably arranged photosensitive drum and along the direction of rotation of the photosensitive drum, and a means for visualizing the electrostatic latent image; comprising means for transferring visualized recorded information onto a long recording paper, and means for discontinuously conveying the long recording paper to the transfer means at the same speed as the circumferential speed of the photosensitive drum; In addition, after stopping the conveyance of the long recording paper upon completion of the transfer, the conveying means transports the long recording paper at least along the circumference of the photosensitive drum from the latent image forming position to the transfer position. It has a mechanism to reverse feed by the length required for the rising speed to reach a steady state during forward feed, and furthermore, when the long recording paper that has been reverse fed is fed forward again, the top of the page to be recorded is Mechanism for detecting position,
An electrophotographic printer having a mechanism for transmitting a detection signal from the detection mechanism to the electrostatic latent image forming means.