JP2004017473A - Printing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing device which can correctly grasp the number of printable remaining rows by setting a paper bottom sensor for detecting that a paper bottom passes at the upper stream side in a transfer direction than a printing unit. <P>SOLUTION: When an output of the paper bottom sensor 3 indicates a state of paper absence at the time of confirming the output of the paper bottom sensor 3, the paper sheet is sent in a reverse direction by switching a paper feed direction. A paper reverse feed amount until the paper bottom sensor 3 detects a state of paper presence is obtained. The paper reverse feed amount is a distance between a paper bottom 1a and the paper bottom sensor 3 before the paper sheet is sent in the reverse direction. A paper bottom position before the paper sheet is sent in the reverse direction can be correctly detected from the paper reverse feed amount, and the number of printable remaining rows can be correctly grasped accordingly. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention includes a printing unit that prints on a conveyed sheet, and a paper end sensor that is disposed upstream of the printing unit in the conveyance direction and detects that the end of the paper passes through the position. Printing device.
[0002]
[Prior art]
In a printing device such as a line printer, the paper feeding speed can be increased according to the paper feeding amount. For example, as shown in FIG. 2, the paper traveling speed (v) can be changed by the paper feed amount (line). Taking advantage of this characteristic, in a line printer, printing is performed by sending paper (continuous form) at a portion where there is no print data at a high speed, and sending paper at a low speed at a portion where there is print data.
[0003]
For printing devices such as line printers, the end of paper (paper exhaustion) is detected by arranging a paper end sensor upstream of the printing unit in the transport direction, and detecting that the paper end has passed the paper end sensor position. It is done by doing. When the end of the sheet is detected, the running and printing of the sheet are stopped before the end of the sheet reaches the printing section, and information indicating the end of the sheet is displayed.
[0004]
Here, if the end position of the sheet can be accurately grasped, the end of the sheet can be stopped immediately before the printing section. As a result, the sheet can be used without waste and the blank printing can be prevented. become.
[0005]
The running speed of paper such as a continuous form is about 100 inches / s at high speed. In the case where the control system includes a plurality of MPUs (Micro Processing Units), the detection signal output from the sheet end sensor reaches the MPU serving as the end position calculation unit via another MPU. Therefore, a delay of about several hundred μs occurs during that time. Therefore, the end position of the sheet at the time when the end position calculation unit receives the end-of-sheet detection signal advances ahead of the end-of-sheet sensor position, and the advance amount increases in proportion to the running speed of the sheet. I have.
[0006]
For this reason, when the time at which the end position calculation unit receives the sheet end detection signal is determined as the sheet end passage time on the sheet end sensor, the end position of the sheet is calculated, and the calculated end position of the sheet is determined by the traveling speed of the sheet. In the case of a printing apparatus that changes the traveling speed of a sheet, the detected end position of the sheet varies. In order to detect the end position of the sheet so as not to cause this variation, the hardware must be configured in a complicated manner, and an increase in cost is inevitable.
[0007]
Therefore, conventionally, the end of the sheet is not accurately detected by accurately detecting the end position of the sheet, and a sufficient amount of sheet feed is sent at a time with respect to the distance from the printing unit to the end detection sensor. The printing operation is defined as the maximum paper feed amount.
[0008]
More specifically, assuming that the distance from the end detection sensor to the printing unit is 14 inches, a margin is set, for example, to a maximum paper feed amount of 11 inches at a time, and the paper feed and printing are performed 11 inches at a time. To do. Then, before starting a new 11-inch paper feed and printing, the output of the end detection sensor is checked beforehand, and if it indicates that there is paper, it is determined that the end of paper has not occurred. When it is determined that the printing operation is started and the state of no paper is indicated, it is determined that the paper is ended at that time, and the printing operation of the next 11 inches is not performed.
[0009]
[Problems to be solved by the invention]
In the above-described conventional configuration, even if there is a variation in the detection of the end position of the sheet, blank printing does not occur, but a wide blank portion (unprinted portion) remains in front of the end of the sheet at the end of printing. In particular, if an operation to check the output of the end detection sensor is performed immediately after the end of the paper passes over the end of paper sensor, the paper ends at a position where the end of paper is near the end of paper sensor. A very wide blank space remains before the end position of.
[0010]
This blank portion is wasteful of paper, and its cost is high especially when the paper is a user form. Therefore, a user has requested to print as close to the end position of the paper as possible.
[0011]
SUMMARY OF THE INVENTION The present invention has been made to meet the above-mentioned demand, and a problem to be solved by the present invention is to realize a printing apparatus capable of accurately grasping the number of remaining printable lines. Another problem to be solved is to realize a printing apparatus capable of printing up to the vicinity of the end position of a sheet without causing blank printing.
[0012]
[Means for Solving the Problems]
The invention according to claim 1, which solves the above problem, is arranged such that a printing section for printing on a conveyed sheet and an upstream side of the printing section in the conveyance direction are provided, and the end of the sheet passes through the position. A paper end sensor for performing a predetermined number of lines of printing, the output of the paper end sensor is checked, and if the output of the paper end sensor indicates that there is paper, This is a printing device that determines that the paper end has not occurred and moves to the next printing operation. Then, when checking the output of the paper end sensor, if the output of the paper end sensor indicates that there is no paper, the paper feed direction is switched to perform paper feed in the reverse direction, and the paper end sensor is Is to determine the amount of paper feed in the reverse direction until the presence of paper is detected, and to determine the number of remaining printable lines based on the amount of paper feed.
[0013]
According to the present invention, when checking the output of the paper end sensor, if the output of the paper end sensor indicates that there is no paper, the paper feed direction is switched and the paper is fed in the reverse direction, and the paper end sensor is turned on. The paper feed amount in the reverse direction until the presence of paper is detected is determined. Since the paper feed amount in the reverse direction is the distance between the end of the paper before the paper feed in the reverse direction and the paper end sensor, the paper feed amount in the reverse direction is calculated from the paper feed amount in the reverse direction. The end position can be known accurately. Therefore, the number of remaining printable lines can be accurately grasped, and if necessary, printing can be continued to the vicinity of the end position of the sheet.
[0014]
According to a second aspect of the present invention, in the first aspect of the present invention, when checking the output of the sheet end sensor, if the output of the sheet end sensor indicates that there is no paper, the paper feeding direction is changed. Switch the paper feed in the reverse direction until the paper end sensor detects the presence of paper, and based on the amount of paper feed in the reverse direction, grasp the number of remaining printable lines and After the paper is fed, the paper is returned to a stop position before the reverse paper is fed, and thereafter printing is restarted within the remaining number of printable lines.
[0015]
According to the present invention, when checking the output of the paper end sensor, if the output of the paper end sensor indicates that there is no paper, the paper is fed in the reverse direction until the paper end sensor detects the paper present state. By doing so, the end position of the sheet is accurately known, and the number of remaining printable lines is determined. Next, the paper is returned to the stop position before the paper is fed in the reverse direction, and printing is restarted within the remaining number of printable lines. Therefore, printing can be performed up to the vicinity of the end position of the sheet without causing blank printing.
[0016]
The invention according to claim 3 is the invention according to claim 1 or 2, wherein the tractor is disposed downstream of the printing unit in the transport direction and transports the paper, and is disposed between the printing unit and the paper end sensor. A tension applying unit that applies tension to the sheet by pressing the sheet with a roller, and when the output of the sheet end sensor indicates that there is no sheet, the sheet feeding in the reverse direction is performed by the roller. And the tractor.
[0017]
According to the present invention, the roller in the tension applying section for ensuring good printing quality is also used as a means for feeding paper in the reverse direction, so that the configuration can be simplified.
According to a fourth aspect of the present invention, in the invention according to the third aspect, the printing device is a dot line printer, and printing is performed only when the shuttle is moved to one side at least when printing is performed when the end of the paper exceeds the tension applying portion. And printing is continued within the range until the end of the sheet reaches the printing section.
[0018]
If the end of the sheet exceeds the tension applying section, the support by the tension applying section is lost, and the stability of the posture of the sheet is reduced. However, in the present invention, printing is executed only when the shuttle moves to one side, so the tension applying section Even without the support of the paper, high-quality printing can be performed up to just before the end of the sheet.
[0019]
Embodiment
(First Embodiment)
FIG. 1 is a diagram showing a first embodiment of the present invention. In FIG. 1, a sheet 1 on which printing (including the case of printing figures other than characters in this specification) is carried in the Y direction. The printing unit 2 includes a print head that prints on the paper 1. A paper end sensor 3 is disposed upstream of the printing unit 2 in the transport direction to detect that the paper end 1a passes through the position. Examples of the paper end sensor 3 include a transmission sensor that detects the end of the paper 1a by using light blocking / transmission, a reflection sensor that detects the paper end 1a by using the presence or absence of reflection of the light on the paper 1, and a paper. A microswitch that detects the end of the sheet 1a by using the contact with the sheet 1 is used.
[0020]
A pair of tractors 5 for transporting the paper 1 is disposed downstream of the printing unit 2 in the transport direction. A continuous form with sprocket holes is used as the paper 1, and a pin belt tractor that can fit in the sprocket holes of the paper 1 and convey the paper 1 not only in the Y direction but also in the opposite direction is used as the tractor 5. Can be Between the printing unit 2 and the paper end sensor 3, a tension applying unit 6 that applies tension to the paper 1 positioned between the tractor 5 and suppresses minute vibration of the paper 1 and improves printing quality is disposed. I have. The tension applying section 6 according to the present embodiment includes a tension roller (generally, a rubber roller) 6a that can slide on the paper 1 in a stopped state during a printing operation.
[0021]
The motor M1 is directly connected to the tractor 5, the motor M2 is directly connected to the tension roller 6a, and the tractor 5 starts / stops when the motor M1 is turned on / off, and the tension roller 6a starts when the motor M2 is turned on / off. / Stop. Usually, a stepping motor or a DC motor is used as the motors M1 and M2. The rotation control of the motors M1 and M2 is performed by the control unit 13 via the drivers 11 and 12, respectively. The printing unit 2 is also driven by the control unit 13 via the head control circuit 14, and the output of the sheet end sensor 3 is input to the control unit 13.
[0022]
M in FIG. 1 indicates a dimension between the printing unit 2 and the paper end sensor 3. S indicates the dimension between the printing unit 2 and the tension applying unit 6 where the application of tension is guaranteed. L indicates a dimension obtained by subtracting the dimension S from the dimension m. When printing is performed for this dimension L from the state in which the paper end sensor 3 detects the presence of the paper 1, the paper 1 must be straddling between the tractor 5 and the tension applying unit 6 during the printing period. Thus, printing is performed in a state where the application of tension is guaranteed.
[0023]
For example, when printing an address label or the like, the page length K is a dimension constituting one label (one page), and is a prescribed dimension L (maximum case) or an integer n / (L / L). n). Usually, the paper 1 is provided with intermediate perforations at intervals of the page length K. In the present embodiment, the output of the sheet end sensor 3 is checked every time printing of the page length K is completed, and if there is a sheet 1, the printing is shifted to the next page length K and the print quality is secured. While continuous printing is being performed. That is, the control unit 13 checks the output of the sheet end sensor 3 every time printing of the determined number of lines (page length K) is performed, and the output of the sheet end sensor 3 indicates a state with paper. Determines that the paper end has not occurred, and performs the next printing operation (page length K).
[0024]
On the other hand, when the output of the sheet end sensor 3 is checked and the output of the sheet end sensor 3 indicates that there is no paper as shown in FIG. Paper is fed in the reverse direction until the paper end sensor 3 detects the presence of the paper, and the remaining printable line number RMC is grasped based on the paper feed amount RC in the reverse direction.
[0025]
Since the reverse paper feed amount RC is the distance between the paper end 1a and the paper end sensor 3 before the reverse paper feed is performed, the reverse paper feed is performed from the reverse paper feed amount RC. The position of the preceding sheet end 1a can be accurately known. Therefore, the remaining number RMC of printable lines (RMC-S if the number of remaining printable lines is within the range in which tension application is guaranteed) can be accurately grasped.
[0026]
The control unit 13 returns the paper 1 to a stop position (the position shown in FIG. 3) before performing the reverse paper feed after the reverse paper feed, and thereafter, within the remaining number of printable lines (for example, RMC). Printing is restarted within the range of the number of lines corresponding to -S). The tension roller 6a is stopped during printing on the paper 1 and is started in reverse rotation in synchronization with the reverse rotation of the tractor 5 after the paper is fed in the reverse direction.
[0027]
Next, the operation of the above embodiment will be described. 4 and 5 are diagrams showing a specific control operation of the control unit 13. FIG. 4 shows the overall control operation, and FIG. 5 shows the control operation of paper end detection.
[0028]
First, as shown in FIG. 4, when a paper feed command is received from a higher-level device, processing is started (S1), a page length K (number of lines) is set in a page counter (PageC = K), and then a command from the higher-level device is issued. It is determined whether or not the supplied paper feed amount ln (the number of lines) is smaller than the specified dimension L (the number of lines) (S2). If it is smaller, that is, if the paper is fed within a range where printing can be performed without disturbing the subsequent printing result, ln instructed to the paper feed register is stored (S3), and Ln = ln. On the other hand, if it is larger than the specified dimension L, the specified dimension L (the number of rows) is stored in the paper feed register as the maximum value (S3 '), and Ln = L.
[0029]
Next, a paper feed command is issued to the mechanical unit (S4). The paper feed is performed in units of steps, and specifically, is performed by applying a drive pulse to a paper feed motor (stepping motor) not shown. After the command, it is checked whether or not the paper feed command operation is completed, and waits until the operation is completed (S5). In order to avoid a situation (hang-up) in which the paper feed command operation is not completed for some reason and the loop cannot be exited from S5 (a hang-up), timer monitoring is performed by a routine (not shown). Then, the processing is terminated by an interrupt.
[0030]
When the end of the paper feed command operation is confirmed, the value of the page counter is decremented by 1 to reach Page C-1 (S6). As described above, the initial value K of the PageC indicates the number of lines of the printing page being executed and one page, and is specified at the beginning of the job. In S6, the value Ln of the paper feed register is also decremented by 1 to Ln-1.
[0031]
Thereafter, it is checked whether the value PageC of the page counter has become 0 (S7). If it is 0, PageC is set again to the value (number of lines) K corresponding to the job (S8). Here, K indicating the page length takes a value of L / n (n is an integer of 1 or more) according to the job as described above, and if n is 2 or more, a small slip is included in L. n sheets will be included.
[0032]
Next, the output of the paper end sensor 3 is checked (S9). If the output of the paper end sensor 3 indicates that there is paper, it is determined that the paper end has not occurred, and the process proceeds to S10. Move on. In S10, it is determined whether or not the value Ln of the paper feed register is 0. If the value Ln is not 0, the process from S4 is executed again. If the value of PageC of the page counter is not 0 in S7, the process proceeds to S10, and if the value Ln of the paper feed register is not 0, the processes of S4 and thereafter are executed again. If the value Ln of the paper feed register is 0 in S10, the process is stopped in S11.
[0033]
On the other hand, when the output of the sheet end sensor 3 is confirmed in S9 and the output of the sheet end sensor 3 indicates a state of no paper, the process proceeds to Sbox processing described later (S20). The Sbox process is a process for detecting the current position of the sheet 1 (the interval between the sheet end sensor 3 and the end position of the sheet 1) as illustrated in FIG. In this process, first, the value RC (the number of lines) of the reverse line feed number counter is set to 0 (S21). Next, a reverse line feed command is issued (S22). In this case, the reverse line feed (paper feed in the direction opposite to Y) is a unit that can reliably detect the change from the absence of paper to the presence of paper in the paper end sensor 3 by reverse line feed, for example, 1/120 inch, 20/120. It is performed in inches or the like. This paper feeding is performed by reversing the tractor 5 and the tension roller 6a. Each time a reverse line feed command is issued in S22, the value RC of the reverse line feed number counter is incremented by 1 to RC + 1 (S23).
[0034]
Wait for the end of the operation instructed in S22 (S24). When the operation is completed, the output of the sheet end sensor 3 is checked (S25). If the output of the sheet end sensor 3 does not indicate that there is a sheet, the operation proceeds to S22. The processing shifts to this processing, and this operation is repeatedly executed until a paper present is found in S25.
[0035]
If the output of the sheet end sensor 3 has changed to the state with paper in S25, the process proceeds to S26, and the number of remaining lines is calculated. At this point, the value RC of the reverse line feed number counter is the total number of steps for returning the sheet 1 and represents the dimension from the position of the sheet end 1a where the sheet 1 was initially stopped to the sheet end sensor 3 ( (See RC in FIG. 3). Therefore, the value RC of the reverse line feed number counter is subtracted from the dimension m from the printing unit 2 to the sheet end sensor 3. As shown in FIG. 3, this value RMC represents the dimension from the sheet end 1a to the sheet end sensor 3 at the position where the sheet 1 is initially stopped (the units of m, RMC, and RC are the same). .
[0036]
Next, the size of the value RMC corresponding to the number of remaining lines is examined, and if printing is continued, it is determined whether or not there is a blank portion where printing can be continued while the paper 1 is pressed by the tension applying unit 6. (S27). For example, it is determined whether RMC-S is positive (or not less than a certain value) (S27). If this value is positive, it means that there is a blank area on the paper 1 where printing can be continued while being pressed by the tension applying unit 6, and the process proceeds to S30. If RMC-S is 0 or negative, the flow shifts to S28 to turn on the paper end status, and stops the processing in S11.
[0037]
In the remaining line number grasping process up to S26, since the sheet 1 is fed in the reverse direction until the sheet end sensor 3 detects the presence of the sheet, it is necessary to return the sheet 1 to the position where it was initially stopped. The process after S30 is a process for this. In S30, RMC is stored in the paper feed register, and Ln = RMC is set (S30). Next, a forward direction paper feed command is issued to the mechanism unit (S31). After this command, it is checked whether or not the paper feed command operation has been completed, and the process waits until the operation is completed (S32). When the step of the paper feed command operation is completed, the value of the value Ln of the paper feed register is decremented by 1 to Ln-1 (S33). Thereafter, it is determined whether the value Ln of the paper feed register is 0 (S34). If the value Ln is not 0, the processes after S31 are executed again. If the value Ln of the paper feed register is 0 in S34, the process is stopped in S11.
[0038]
With the above processing, the Sbox processing has been completed, and the position where the sheet 1 was initially stopped can be accurately grasped as the value of the number of remaining lines RMC. Thereby, printing can be continued before entering the print non-guaranteed area (the state in which the sheet 1 does not straddle between the tractor 5 and the tension applying section 6), and printing is stopped immediately before entering the print non-guaranteed area. can do.
[0039]
In the conventional processing, in FIG. 4, there is no Sbox processing in S20, and when no paper is detected in S9, it is determined that there is no paper. However, in the present embodiment, the Sbox processing is performed to accurately grasp the position of the paper 1. And printing is continued. As this printing is performed, the trailing end 1a of the paper reaches the tension applying section 6 in due course. Therefore, printing is not performed after the arrival timing. Such control is possible because the position of the sheet 1 is accurately grasped. Therefore, printing can be performed up to the vicinity of the end position of the sheet 1 without causing blank printing. Further, if the printing is performed within the range as in the present embodiment, the paper 1 being printed is under tension, and the printing quality is improved. Further, such control does not require additional hardware, and thus can be easily realized without increasing the cost.
[0040]
Further, in the present embodiment, since the tension roller 6a in the tension applying section 6 for ensuring good print quality is also used as a means for feeding paper in the reverse direction, the configuration can be simplified.
(Second embodiment)
When the end 1a of the sheet exceeds the tension applying section 6, the support by the tension applying section 6 is lost, and the sheet 1 is dragged in the horizontal direction by a dot line printer shuttle or a printing belt, an ink ribbon, or the like. If printing is continued as it is, the printing quality deteriorates because the stability is lowered. However, depending on the user, there is a demand that the printing is continued because the paper (user form) 1 is expensive even if the printing is slightly disturbed. In this case, by performing slow paper feed operation or printing only in one-way movement with a shuttle type line printer, etc., it is possible to print to some extent clear even in the print non-guaranteed area. It is possible.
[0041]
FIG. 6 is an example of an embodiment for providing a mechanism for improving the print quality when printing continues on the paper (form) beyond the tension imparting section 6 of the paper transport system of the line printer in FIG. Specifically, this printing apparatus is a dot line printer, and at least when the end of the sheet 1a exceeds the tension applying section 6, when the shuttle is moved to one side (to the left or right). And printing is continued within the range until the end of the sheet 1a reaches the printing unit 2.
[0042]
FIG. 6 shows only the main steps, and does not show the operation until the control unit 13 detects that the output of the sheet end sensor 3 is in a paper-out state. These operations are the same as in the first embodiment. In FIG. 6, when the control unit 13 detects that the output of the sheet end sensor 3 is in a state of no paper (S51), as shown in FIG. The process proceeds to Sbox processing (S52), and the position of the sheet 1 is accurately grasped. Then, printing is continued. Eventually, the sheet end 1a reaches the tension applying section 6.
[0043]
In S53, it is determined whether or not the sheet end 1a has passed through the tension applying section 6. If it does not exceed, there is no change in the printing control, but if it does, it shifts to the one-way printing mode. In order to improve the printing quality, the printing direction is fixed in one direction, that is, in the case of a oscillating shuttle type line printer, the printing direction of one line is fixed in one direction (right → left or left → right). This one-way printing mode continues until the end of the sheet 1a reaches the printing unit 2 (S55). Then, when the sheet end 1a reaches the printing section 2, the true printing is terminated and the printing operation is stopped (S56).
[0044]
As described above, in the present embodiment, after the sheet end 1a has passed through the sheet end sensor 3, the position of the sheet end 1a is accurately grasped by the Sbox process, and when the sheet end 1a has passed through the tension applying unit 6, The printing direction is set to one direction, and when the end of the sheet 1a reaches the printing unit 2, printing is stopped.
[0045]
When the sheet end 1a exceeds the tension applying section 6, the support by the tension applying section 6 is lost, and the posture stability of the sheet 1 is reduced. In the present embodiment, printing is executed only when the shuttle moves to one side. Therefore, the paper 1 is printed in a state of receiving a force from the shuttle or the like only in one of the left and right directions, and the printing quality can be maintained until just before the paper end 1a. Therefore, even when the print quality exceeds the guaranteed print area, expensive paper (form) is not wasted, and printing can be performed to the end while maintaining print quality.
(Other Embodiments)
The present invention is not limited to the configuration of the above embodiment. For example, instead of driving the tractor 5 and the tension roller 6a with the individual motors M1 and M2, a one-way clutch is connected to the motor M1 directly connected to the tractor 5, so that the motor M1 rotates in the reverse direction and the tension roller 6a rotates at the same time. With this configuration, the motor M2 can be omitted.
[0046]
【The invention's effect】
As described above, according to the first aspect of the present invention, when checking the output of the paper end sensor, if the output of the paper end sensor indicates that there is no paper, the paper feed direction is switched to the reverse direction. Is performed, and the paper feed amount in the reverse direction until the paper end sensor detects the presence of the paper is obtained. Since the paper feed amount in the reverse direction is the distance between the end of the paper before the paper feed in the reverse direction and the paper end sensor, the paper feed amount in the reverse direction is calculated from the paper feed amount in the reverse direction. The end position can be accurately known, and if necessary, printing can be continued to the vicinity of the end position of the sheet.
[0047]
According to the second aspect of the present invention, when the paper is fed in the reverse direction, the paper is fed in the reverse direction until the paper end sensor detects the presence of the paper, so that the end position of the paper can be accurately known and printing can be performed. The remaining number of lines, return the paper to the stop position before feeding the paper in the reverse direction, and resume printing within the remaining number of printable lines. Printing can be performed up to the vicinity of the end position.
[0048]
According to the third aspect of the present invention, since the roller in the tension applying section for ensuring good print quality is also used as a means for feeding paper in the reverse direction, the configuration can be simplified.
[0049]
According to the fourth aspect of the present invention, printing is performed only when the shuttle moves to one side in printing when the end of the sheet exceeds the tension applying section. Printing with high printing quality can be performed until just before.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a paper feed speed.
FIG. 3 is a view showing another operation state of the embodiment shown in FIG. 1;
FIG. 4 is a flowchart showing an overall control operation of the embodiment shown in FIG. 1;
FIG. 5 is a flowchart showing a control operation of Sbox processing in FIG. 4;
FIG. 6 is a flowchart showing main operations in another embodiment of the present invention.
[Explanation of symbols]
1 paper
1a End of paper
2 Printing section
3 Paper end sensor
5 Tractor
6 Tension applying part
6a tension roller
11,12 driver
13 Control unit
14 Head control circuit
M1, M2 motor

Claims (4)

A printing unit that performs printing on the conveyed paper, and a paper end sensor that is disposed upstream of the printing unit in the conveyance direction and detects that the end of the paper passes through the position,
The output of the end-of-paper sensor is checked each time printing is performed for a predetermined number of lines. If the output of the end-of-paper sensor indicates that paper is present, it is determined that the end of paper has not occurred. A printing device that moves to the next printing operation,
When checking the output of the paper end sensor, if the output of the paper end sensor indicates that there is no paper, the paper feed direction is switched and the paper is fed in the reverse direction, and the paper end sensor is turned on by the paper end sensor. A printing apparatus characterized in that a paper feed amount in a reverse direction until a presence state is detected is obtained, and the number of remaining printable lines is determined based on the paper feed amount. When checking the output of the paper end sensor, if the output of the paper end sensor indicates that there is no paper, switch the paper feed direction until the paper end sensor detects the paper present state. Perform paper feeding in the reverse direction, and based on the paper feeding amount in the reverse direction, grasp the number of remaining printable lines, and after the paper feeding in the reverse direction, to the stop position before performing the paper feeding in the reverse direction. 2. The printing apparatus according to claim 1, wherein the sheet is returned, and then printing is restarted within the remaining number of printable lines. A tractor that is arranged downstream of the printing unit in the conveyance direction to convey the paper, and a tension applying unit that applies tension to the paper by pressing the paper with a roller disposed between the printing unit and the paper end sensor. With
3. The printing apparatus according to claim 1, wherein the paper feeding in the reverse direction is performed by the roller and the tractor when the output of the paper end sensor indicates that there is no paper. The printing device is a dot line printer, and at least in the case where the end of the paper exceeds the tension applying section, printing is performed only when the shuttle moves to one side, and the printing is performed within the range until the end of the paper reaches the printing section. 4. The printing apparatus according to claim 3, wherein printing is continued.

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