JPH06246986A - Electrophotographic printer - Google Patents

Abstract

PURPOSE:To keep high printing quality by starting the feed and transfer due to a feed control means by a printing control means when the negative length of the continuous form paper inputted by a negative length input means is equal to or shorter than the distance between a transfer position and a fixing position and opening and closing a pressure roller regardless of negative length by a contact and separation control means. CONSTITUTION:A printing control means 621 outputting a control signal to a transfer part 30 is provided and a feed control means 622 controlling the motor 11 of a feed part 10 on the basis of the negative length set from an operation part, the input from a detection part 20 and the presence of receiving data is provided and a separator contact and separation control means 623 performing the contact and separation of paper with respect to a photosensitive drum 31 in parallel to a transfer process is provided. A pressure roller contact and separation control means 624 opens a pressure roller 42 immediately before a perforation enters the nip part of a fixing part 40 and again closes the roller 24 immediately after the perforation passes through the nip part. The negative length of the paper used in a printer is three kinds of distance <s=La, Lb<<s and Lc>Ls from the transfer position due to a transfer device to the fixing position due to the fixing part 40.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to continuous form paper (hereinafter referred to as
Sometimes called paper. ) And using a heat roller fixing unit.

[0002]

2. Description of the Related Art In a conventional electrophotographic printer, every time one page of data is received and accumulated, it is output to operate the processes of exposure, development and transfer, and at the same time, the paper is conveyed and The pressure roller is opened immediately before the perforations on the front side of the page where the transfer is completed enter the nip portion of the fixing unit, and the pressure roller is closed immediately after the perforations pass through the nip portion.
When the rear perforation on the same page opens the pressure roller just before entering the nip part of the fixing unit, and if the data for the next page is received and accumulated before the transfer of the previous page is completed, the conveyance is continued. Then, control is performed to repeat transfer and opening / closing of the pressure roller, and when the data for the next page is not received, the paper with the back side perforation of the page being transferred is positioned at the transfer position. Control is performed to stop the conveyance and to open the pressure roller of the fixing unit.

The reason why the pressure roller of the fixing unit is opened while the perforation passes is that the minute deviation between the feed of the paper by the roller and the feed by the tractor is prevented from accumulating, and the paper is thereby peeled off at the tractor. This is to prevent the occurrence of paper stains and paper jams.

In the conventional electrophotographic printer described above, as shown in FIG. 1A, the distance between perforations (that is, the length of one page) La is from the transfer position of the transfer device 35 to the fixing unit 40. Only one type of paper 1A having a fixed distance Ls to the fixing position was used. In FIG. 1, 1, 1A, 1B and 1C are sheets, 31 is a photosensitive drum,
Reference numeral 35 is a transfer device, and 40 is a fixing unit including a heating roller 41 and a pressure roller 42 that is moved up and down.
Among a, 1b, and 1c, the shaded area represents the default attachment portion, the solid area represents the transferred / unfixed portion, and the chain area represents the untransferred portion.

[0005]

Recently, there has been a demand for a printer that can use papers having different page lengths (distances between perforations). However, when the data for the next page is not received when the transfer for one page is completed, according to the conventional control method of stopping the conveyance and opening the pressure roller of the fixing unit, the distance Ls between the transfer position and the fixing position is set. Page length L different from
When a paper having b, Lc (however, Lb <Ls, Lc> Ls) is used, various problems occur.

That is, as shown in FIG. 1 (b ₁ ), L
Last page received (1b) for paper 1B with b <Ls
If the conveyance is stopped at the end of the minute transfer, the previous page (1
When the paper conveyance is stopped in the middle of fixing a), the pressure roller 42
Since the opening of the fixing unit 40 is performed, uneven fixing occurs on the printing surface of the page (1a) that has passed through the fixing unit 40, or the fixing unit 4
There is a problem in that the unfixed toner on the page (1b) before passing 0 is scattered and the print quality is deteriorated.

Further, in order to avoid this problem, FIG.
_As shown in ₂ ), when the sheet is conveyed until the fixing of the page (1a) before the last page (1b) is completed, the transfer start of the data received after the waiting is started at the first position of the next page (1c). However, the paper must be discarded for one page (1c), which is a cost problem.

Further, in the case of the paper Lc> Ls, (c
_As shown in ( ₁ ), there is a problem similar to that of (b ₁ ), and as shown in (c ₂ ), when fixing to the last page (1b), paper for 1 page (1c) is similarly formed. To be wasted.

The present invention has been made in view of the above points, and even if continuous form sheets having different page lengths are used, fixing can be performed for each page without causing fixing unevenness, and therefore high. An object of the present invention is to provide an electrophotographic printer that uses a heat roller fixing unit that can maintain print quality.

[0010]

In order to achieve the above object, in the present invention, a page length input means for inputting the page length of a continuous form sheet currently used, and a page length input by the page length input means. Is (a) the distance L from the transfer position to the fixing position
When La is equal to s or Lb shorter than Ls, transfer of the electrophotographic process is started at the same time when the conveyance control unit starts the forward conveyance of the sheet, and (b) When Lc is larger than Ls, the conveyance control is performed. If the page length input by the page length input means is (a) La, the print control means starts transfer of the electrophotographic process after the conveyance of the difference (Lc-Ls) between Ls and Lc by the means. At the same time when the transfer is started by the print control means, the paper conveyance is started, and if the received print data for the next page is present, the conveyance is continued in the forward direction. When it reaches (b) Lb, the paper is conveyed and stopped until just before the copy.
When the transfer of paper by the print control means is started, the paper conveyance is started. If the received print data for the next page is present, the forward conveyance is continued. After being conveyed in the forward direction until just before the nip portion and stopped, the sheet is conveyed in the opposite direction by the difference (Ls-Lb) between Ls and Lb and stopped, and when (c) Lc, electrophotography Before the transfer of the process is started, the sheet is conveyed in the positive direction by the difference between Ls and Lc (Lc-Ls), and at the start of the process, the perforated side of the front side of the transferred page passes through the fixing portion, and further, Ls and Difference of Lc (Lc-Ls)
After carrying the minute in the positive direction, if the received data for the next page is present, continue the carrying in the forward direction, if not, stop the carrying and carry the difference (Lc-Ls) in the opposite direction. Immediately after the rear side perforation of the page before the page transferred by the print control means has passed through the nip portion of the fixing portion, regardless of the conveyance control means that stops due to the size of the page length of the continuous form paper used. And a fixing control means for closing the pressure roller of the fixing unit and opening the pressure roller immediately before the rear perforation of the fixed page reaches the nip portion.

[0011]

When the data for the next page is continuously received during the transfer of one page, the paper conveyance is continued regardless of the size of the page length, and the transfer and the page length are adjusted. The opening and closing of the pressure roller of the fixing unit is repeatedly controlled.

When the page length is La which is equal to the distance Ls between the transfer position and the fixing position, and the data for the next page is not received at the time of transferring one page, the page currently being transferred is When the transfer is completed, the paper conveyance is stopped and the pressure roller is opened.
After that, when the data for the next page is received, the sheet conveyance is started, and fixing and transfer are started almost at the same time.

Next, when the page length is Lb smaller than Ls and the data for the next page is not received at the time of transferring one page, even after the transfer of the page currently being transferred is completed, It should be noted that the paper conveyance of the distance (Ls-Lb) is continued until the fixing of the previous page is completed, the conveyance is stopped at the end of the fixing, the pressure roller is opened, and the paper is reversely moved by the distance (Ls-Lb). Then, it is stopped and waits for the next page of data to be received. After that, when the data for the next page is received, the transfer in the forward direction is started and the transfer is started. When the distance (Ls-Lb) is advanced, the pressure roller of the fixing unit is closed.

When the page length is Lc larger than Ls and the data for the next page is not received at the time of transferring one page, the pressure of the fixing unit is applied at the end of fixing for the previous page. The roller is opened, and the conveyance is continued until the transfer of the page currently being transferred is completed, and when the transfer is completed, the conveyance is stopped and the paper is moved to the distance (Lc-
Ls) is conveyed in the reverse direction and stopped, and the next page of data reception is awaited. After that, when the next page of data is received,
Close the pressure roller, start the forward direction conveyance, and move the distance (Lc-
Ls) Start transcription when advancing.

[0015]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 2 is a sectional view schematically showing the configuration of an electrophotographic printer that uses continuous form paper and uses a heating roller. This printer is provided in a main body 100 and is provided with a conveyance unit 10 for conveying a sheet 1, a detection unit 20 for detecting the leading end of the sheet 1 conveyed by the conveyance unit, and a sheet to be conveyed, which will be described later. The transfer unit 30 that prints data received from the outside via the communication control unit 70 by an electrophotographic method, the heat roller type fixing unit 40 that heats and fixes the toner image transferred on the paper, and the fixing unit Contact / separation unit 50 for contacting / separating the pressure roller 42 with respect to the heating roller 41
And a control unit 60 that controls the transport unit 10, the transfer unit 30, the fixing unit 40, and the contact / separation unit 50 according to the presence or absence of input data and received data from the detection unit 20.

The transfer section 10 includes a stepping motor (hereinafter simply referred to as a motor) 11 capable of reversing and a transfer section 3.
It is composed of tractors 12 and 13 arranged before and after 0, a conveyance roller (not shown) arranged between them, and a discharge roller 14 arranged on the paper discharge side. One feature of the present invention is that a reversible motor is used as the motor 11. The transfer unit 30 has the same configuration as the conventional one, and includes a photosensitive drum 31, and a charger 32, an exposure unit 33, a developing unit 34, a transfer unit 35, and a cleaning unit 36 arranged around the photosensitive drum 31. Further, 37 is a separator that contacts the paper 1 with respect to the photosensitive drum 31 during transfer and separates it during non-transfer.

The fixing section 40 comprises a heating roller 41 which is rotated in a predetermined direction by a motor (not shown) and a pressure roller 42 which faces the heating roller 41 and freely rotates. The pressure roller 42 is opened / closed with respect to the heating roller 41 by the contact / separation unit 50. The contact / separation part 50 is a Japanese Patent Application Sho 63
What was proposed by the specification of -306987 can be used. That is, the lever 52 is rotatably supported at one end thereof about the shaft 51 as a fulcrum, the pressure roller 42 is supported at the other end of the lever 52, and the roller 53 is rotatably provided at an intermediate portion of the lever 52. Then, a cam 54 corresponding to the peripheral surface of the roller 53 is provided on the upper side of the sheet conveying surface, and a spring 55 always urges the lever 52 upward so that a rotation source of the cam 54 is provided with a drive source (not shown). It is configured by connecting. The drive source is, for example, a rotary solenoid or a motor that rotates 180 ° when energized, and the cam 54 is set to 18 times each time a drive signal is input.
And a motor control circuit for rotating the motor until it is rotated by 0 °.

As shown in FIG. 2, the cam 54 is normally held in a state where the lower portion of the cam 54 contacts the roller 53, and therefore the pressure roller 42 is in pressure contact with the heating roller 41. However, when the drive source is driven by the control unit 60, which will be described later, the cam 54 is rotated by 180 ° and its high portion comes into contact with the roller 53.
Are moved downward and separated from the heating roller 41. At this time, the paper 1 is moved by the paper guide portion 56 having a long arcuate curved surface that abuts on the heating roller contact surface side.
Since it is pulled away from the heating roller 41,
It is separated from the heating roller 41 by a predetermined distance.

As shown in FIG. 3, the printer has a communication control unit 70 for receiving print data from a host computer, and an operating unit 80 such as a keyboard for inputting the page length of paper used in this printer. Have. The communication control unit 70, the operation unit 80, and the detection unit 20 include the control unit 6
It is connected to the CPU 62 via the 0 I / O unit 61. The CPU 62 also has a ROM 63 that stores a system program and an R that temporarily stores data.
A storage unit composed of AM 64 is connected, and further, a reversible motor 11 of the transfer unit 10 via an I / O unit 61,
The electrophotographic process unit of the transfer unit 30, the motor of the fixing unit 40, the heating roller 41, and the contact / separation unit 50 are connected.

As shown in FIG. 4, the CPU 62 of the control unit 60 receives the print data sent from the host computer by the communication control unit 70 for each page and RAM.
A function of converting the print data into a font data string by using the character font data stored in the ROM 64 and stored in the ROM 63; and a function of outputting a control signal to the transfer unit 30 based on the converted font data string. Print control means
621, and the page length set from the operation unit 80,
It has a conveyance control means b622 for controlling forward rotation or reverse rotation of the motor 11 of the conveyance section 10 based on the input from the detection section 20 and the presence / absence of received data. Based on the separator contact / separation control means 623 for contacting / separating the sheet 31 and the input from the detection unit 20 and the number of pulses given to the reversible motor 11 for transport control, the perforation of the sheet 1 is determined by the fixing unit. From the time point of reaching 1/2 inch before the length of the non-printing area provided in front of and behind the sheet from the nip portion of 40 to the time point when the perforation passes 1/2 inch from the nip portion, the fixing unit It has pressure roller contact / separation control means 624 for opening the pressure roller 42 from the heating roller 41. The pressure roller contact / separation control means 624 opens the pressure roller 42 immediately before the perforations enter the nip portion of the fixing section 40, and closes the pressure roller 42 again immediately after the perforations pass through the nip portion. To control.

The operations of the print control means 621, the conveyance control means 622, the separator contact / separation control means 623, and the pressure roller contact / separation control means 624 of the CPU differ depending on the page length of the sheet currently used. This page length is input from the operation unit 80 after the printer is started up. However, if a perforation sensor capable of surely detecting perforations on the sheet is devised, the conveyance device is started, Between the time when the perforation sensor detects one perforation and the time when the next perforation is detected, the conveyance control means b of the control unit 60 causes the conveyance unit 10 to move.
The page length can be automatically set by the number of pulses applied to the motor 11.

The page length of the paper used in the printer according to the present invention, that is, the distance between perforations is La, Lb, Lc.
(However, if the distance from the transfer position of the transfer device 35 to the fixing position of the fixing unit 40 is Ls, La = Ls, L
b <Ls, Lc> Ls), next,
When the page length of the paper used is La, Lb, or Lc, the control unit 60 controls the transport unit 10 and the transfer unit 3.
0, the control for the contact / separation unit 50 and the operation by the control, schematic diagrams showing the sheet conveyance state of FIGS. 5 to 7 and FIGS.
A description will be given based on the flowchart.

[When Page Length is La (= Ls)] As shown in FIG. 8, when the printer power is turned on (started),
The control unit 60 executes the program to rotate the photosensitive drum of the transfer unit 30 (S11). When the page length of the used paper 1A is set to La equal to Ls shown in FIG. 5 (S1
2) checks whether or not there is received data to be printed in the storage unit (RAM 64) (S13), and if there is, print control means 621 starts exposure by the exposure device 33 at a predetermined timing (S14). , Separator contact / separation control means 62
3 causes the separator 37 to approach the photosensitive drum side, and the transport control means 622 starts transport (S15). Then, the conveyance amount (FL) of the sheet 1A is α, that is, as shown in FIG. 5 (a ₂ ), the distance of the non-printing area from the front perforation of page 1 (p ₁ ) to the leading end of the printing area (for example, 1 1/2 inch),
When it becomes equal to (Y in S16), the print control unit 62
When 1 starts transfer, the pressure roller contact / separation control unit 624 rotates the cam 5 of the contact / separation unit 50 to a predetermined angle to close the pressure roller 42 of the fixing unit and start fixing (S17). .

From this time point, it is judged whether or not the data for the next page has been received and accumulated between the end of exposure of the data for one page, that is, whether or not to continue printing (S1).
8) If it has been received, that is, if printing is to be continued (Y in S18), after the process control of the exposure, development, transfer, etc. by the transfer unit 30 (S19) is performed, it is conveyed from the conveyance control unit 621. From the number of pulses applied to the motor 11, it is determined whether the carry amount FL is La-α, that is, whether the trailing edge of the print area of the previous page has passed the fixing position of the fixing unit (S110), and fixing is performed. When passing through the position, the pressure roller contact / separation control unit 624 controls the contact / separation unit 50 to open the pressure roller 42 of the fixing unit (S111). Further, it is checked whether or not the carry amount has become La (S112). When it becomes La, that is, when one page length has been carried, the carry control means sets the carry amount count value FL to 0 when it becomes La. Then (S113), the process jumps to step S16.

As shown in FIG. 5 (a ₃ ), 1 of the paper 1A
The data for the next page (pn + 1) has not been received between the start of the transfer of the page (pn) and the end of the transfer (N in S18
In the case of), when the conveyance amount FL becomes La-α for the page (pn) currently being transferred (S114) (S115), that is, the front perforation of the transferred area is α more than the fixing position.
When the pressure roller comes close to this side, the pressure roller contact / separation control means 62
4 separates the pressure roller 42 from the heating roller 41 in the contact / separation part 50. That is, the fixing unit is opened (S116).
). When the carry amount FL becomes La (Y in S117), the carry control means 621 stops the carry, and at the same time, the separator contact / separation control means 623 separates the separator 37 from the photosensitive drum, and the carry control means carries the carry. The quantity count value (FL) is set to O and the process returns to step S13 to wait for reception of data for the next page.

[When Page Length is Lb (<Ls)] As shown in FIG. 9, when the printer power is turned on (started),
When the control unit 60 executes the program to rotate the photosensitive drum of the transfer unit 30 (S21) and the page length of the used paper 1B is set to Lb smaller than Ls shown in FIG. 6 (S2).
2) checks whether or not there is received data to be printed in the storage unit (RAM 64) (S23), and if there is received data, the print control means 621 starts exposure by the exposure device 33 at a predetermined timing (S23). Simultaneously with S24), the separator contact / separation control unit 623 brings the separator 37 closer to the photosensitive drum side, and the conveyance control unit 622 starts conveyance, (S2
5) At the time when the sheet conveyance amount (FL) becomes equal to α, that is, the distance of the non-printing area from the front perforation of one page to the tip of the printing area, the print control means 621 starts the transfer, and The pressure roller contact / separation control means 624 is the contact / separation unit 5.
Operation of rotating the cam 54 of 0 to a predetermined angle, closing the pressure roller 42 of the fixing unit, and starting fixing (S
21 to S27), when the page length is La (S11 to S1)
Same as 7).

Then, the sheet conveyance amount FL is (Ls-Lb)
When it becomes + α, the pressure roller contact / separation control means 624 closes the pressure roller 42 of the fixing portion and starts fixing. If the data for the next page has been received and accumulated by the time the exposure of the data for one page is completed (Y in S210), process control of exposure, development, transfer, etc. by the transfer unit 30 (S).
After the step 211) is performed, whether the carry amount FL is Lb based on the number of pulses given to the carry motor 11 from the carry control means 621,
That is, it is determined whether or not one page length has been conveyed (S21
2) When Lb is reached, the transport control means 621 sets the transport amount count value FL to 0 (S213), and further transport amount F
When L becomes (Ls-Lb) -α, that is, when the trailing edge of the printing area of the previous page reaches the fixing position, the pressure roller contact / separation control unit 624 controls the contact / separation unit 50. , The pressure roller 42 of the fixing unit is opened (S215), and then step S26
To jump to. The operation up to this point is a case where print data is continuously received and paper conveyance is continued.
Since it is almost the same as the case a, the illustration is omitted in FIG.

Then, as shown in FIG. 6, for example, Pn-
While fixing one page, before the exposure of Pn page is completed, the next page (Pn + 1)
If no minute received data (N in S210), after the completion of the exposure control (S216) for Pn page FIG 6 (b ₂₎
As shown in (4), when the carry amount FL reaches Ls-α (Y in S217), that is, when the end of the print area of the previous page (Pn-1) reaches the stationary position, the separator contact / separation is performed. The control unit 623 separates the separator 37 from the photosensitive drum 31 to end the transfer, the pressure roller contact / separation control unit 624 separates the pressure roller 42 of the fixing unit from the heating roller 41, and the conveyance control unit. 622 stops the transportation (S218).

Subsequently, the transport control means 622 is operated by the motor 11
6 is reversed (S219), and when the reverse conveyance amount FL becomes (Ls-Lb)-. Alpha. As shown in FIG.
When Y in 220), that is, when the front perforation of the next page (Pn + 1) is fed back to the position matching the transfer position, the feeding is stopped and the carry amount FL is set to 0 (S221), and then the process proceeds to step S23. It jumps and waits for data reception for the next page.

When data is received next (Y in S23)
As shown in (b ₄ and b ₅ ) of FIG. 6, exposure is started again (S24), the separator 37 is approached, and conveyance is started (S2).
5) is performed, and transfer to the Pn + 1 page is started when the carry amount becomes α (S26, 27), and as described above, when the transfer amount becomes (Ls−Lb) + α, the transfer to the previous page (Pn) is performed. Fixing is started (S28, 29).

[When Page Length is Lc (> Ls)] When the page length is Lc which is larger than the distance Ls between the transfer position and the fixing position, the sheet 1C is on the front side of the page before the first page to be printed. Wait for reception with the perforations aligned with the fixing position.
Then, after the page length is set to Lc (S32) and print data is received (Y in S33), the separator 37 is brought close to the photosensitive drum 31 and conveyance is started (S3).
4). Then, when the carry amount FL becomes α (Y in S35), the pressure roller 42 is closed, and fixing to the previous page is started (S36). After that, the exposure is started by matching the preset carry amount (S37), and the transfer is started when the carry amount FL is (Lc-Ls) + α (S39), and then the next page is received. The presence or absence of data is determined (S310),
If there is, the exposure control for that page is continued (S311),
When the carry amount is Lc-α (Y in S212), that is, immediately before the rear perforation of the previous page during fixing reaches the nip portion of the fixing portion (when the end of the printing area reaches the nip portion). ), The pressure roller 42 is opened (S313). Then, when the carry amount is Lc, that is, when the page length for one page is carried, the carry amount count value FL of the carry control means 621 is cleared to O, and the process jumps to step S35 to perform similar printing on the next page. Continue operation.

On the other hand, when printing is not continued in step S310 (print data for the next page is not received), exposure control for the page currently being transferred (S316) is performed.
), When the conveyance amount FL becomes LC-α, that is, as shown in FIG. 7 (c ₁ ), the currently fixed page (pn
When the end of the print area of -1) has passed the fixing position of the fixing unit 40 (Y in S317), the pressure roller 42 is opened (S31).
8) When the carry amount reaches Lc (S320),
When the carry amount count value FL is set to 0 and then the carry amount FL again becomes (Lc-Ls) -α (Y in S321),
That is, as shown in (c ₂ ) of FIG. 7, when the end of the print area of the page (Pn) currently being transferred has passed the transfer position and the transfer has been completed, the conveyance of the paper 1C is stopped and the separator 3
7 is separated from the photosensitive drum (S322).

Subsequently, the conveyance control means 621 reversely controls the motor 11 of the conveyance section to reversely feed the sheet (S323).
When (S324) to the opposite direction conveying amount becomes {(Lc-Ls) -α} , i.e., as shown in FIG. 7 (c _3),
Reverse feeding is stopped while the leading edge of the printing area of the page (Pn) for which transfer has been completed coincides with the fixing position, and the carry amount count value FL is cleared to 0 (S325).
It jumps to 3 and waits for the reception of the next data.

[0034] Then when print data is received, the process proceeds to step S34, as already described, subjected to approach and conveyance start of the separator, and as shown in FIG. 7 (c ₄₎ and (c ₅₎ , When the leading edge of the print area of the page (Pn) before the page (Pn + 1) to which the data is transferred reaches the fixing position (S
At 315, the fixing unit is closed to start fixing, and the exposure of the data is started (S37). When the leading edge of the print area of the next page Pn + 1 reaches the transfer position (Y at S38), transfer is started. After starting (S39), the same operation as described above is repeated.

[0035]

As described above, according to the present invention, even if continuous form papers having different page lengths are used, fixing can be performed for each page without causing unevenness in fixing, and therefore high print quality can be obtained. Can be held.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a relationship between a page length of a sheet and a conveyance position, for explaining a problem when a control method in a conventional electrophotographic printer is used.

FIG. 2 is a cross-sectional view showing a configuration of a general electrophotographic printer.

FIG. 3 is a schematic configuration diagram illustrating a control system.

FIG. 4 is a block diagram illustrating functions of a control unit that realizes the present invention.

FIG. 5 is a schematic diagram for explaining the control content when the page length of the paper is equal to the distance between the transfer position and the fixing position in the printer of the present invention.

FIG. 6 is a schematic diagram for explaining the control contents when the page length of the paper is smaller than the distance between the transfer position and the fixing position in the printer of the present invention.

FIG. 7 is a schematic diagram for explaining the control content when the page length of the paper is larger than the distance between the transfer position and the fixing position in the printer of the present invention.

FIG. 8 is a schematic flowchart for explaining the operation of the printer of the present invention when the page length of the paper is equal to the distance between the transfer position and the fixing position.

FIG. 9 is a schematic flowchart for explaining the operation of the printer of the present invention when the page length of the paper is smaller than the distance between the transfer position and the fixing position.

FIG. 10 is a schematic flowchart for explaining the operation of the printer of the present invention when the page length of the paper is larger than the distance between the transfer position and the fixing position.

[Explanation of symbols]

 100 printer body 10 transport unit 20 paper detection unit 30 transfer unit 40 fixing unit 50 contact / separation unit 60 control unit 70 communication control unit 80 operation unit 62 CPU 621 print control unit 622 transport control unit 623 separator contact / separation control unit 624 pressure roller Contact / separation control means

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI Technical indication location G03G 15/20 107 (72) Inventor Masatake Satake 4-3 Jonai, Hanamaki-shi, Iwate Inside Shinko Seisakusho Co., Ltd. (72 ) Inventor Masaetsu Shirato 4-3 Jouchi, Hanamaki-shi, Iwate Prefecture Shinko Seisakusho Co., Ltd.

Claims (1)

[Claims] 1. An electrophotographic printer using continuous form paper and a heat roller type fixing device, comprising: (a) page length input means, print control means, conveyance control means, and contact / separation control means. (B) The page length input means is for inputting the page length of the continuous form paper currently used, and (c) the print control means is for the page length input from the page length input means. (A) When La is equal to the distance Ls between the transfer position and the fixing position, or Lb shorter than Ls, the transfer of the electrophotographic process is started at the same time when the transfer control unit starts the forward transfer of the sheet, and (b) L greater than Ls
At the time of c, the difference (L
The transfer of the electrophotographic process is started after the conveyance of (c-Ls), and (d) the conveyance control means, when the page length input from the page length input means is (a) La, At the same time when the transfer is started by the print control means, the paper conveyance is started, and if the received print data for the next page is present, the conveyance is continued in the forward direction. When (b) Lb, the conveyance of the paper is started at the same time when the transfer by the print control means is started, and when the received print data for the next page is present, the conveyance is continued in the forward direction. If not, the front perforation of the transferred page is conveyed in the forward direction until it stops just before the fixing device, and then stopped in the reverse direction by the difference (Ls-Lb) between Ls and Lb. , And (c) Lc, the electrophotographic professional Before the transcription of the process, the difference between Ls and Lc (Lc-L
s) in the positive direction, the front perforation of the transferred page passes through the fixing section at the start of the process, and then the difference between Ls and Lc (Lc-Ls) is further conveyed in the positive direction. After that, if there is received data for the next page, the transport in the forward direction is continued, and if not, transport is stopped and the difference (Lc-Ls) is transported in the reverse direction and stopped. (E) The contact / separation control means is irrespective of the size of the page length of the continuous form paper used, and immediately after the back side perforations before the page transferred by the print control means passes through the fixing portion. An electrophotographic printer, characterized in that the pressure roller of the fixing unit is closed, and the pressure roller is opened immediately before the rear perforation of the fixed page reaches the fixing unit.