JP2010247523A - Label printer and method for preventing printing page from dropping out - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a label printer capable of performing downsizing, weight reduction and cost reduction, and preventing a printing page from dropping out. <P>SOLUTION: The label printer includes: a first counter 51 for measuring the amount of delivery of a paper drawn out from a roll 1 by a platen roller 3; a second counter 52 in which an estimated amount of delivery by the time when the tip of the paper reaches at a specified position is set and accompanies a delivery of the paper to decrement; and a history table 53 for recording the amount of delivery of the paper from the time when the tip of the paper reaches at the specified position to the time when the tip of the next paper reaches at the specified position. When the tip of the paper reaches at the specified position before the counter value of the second counter 52 reads zero, the counter value of the first counter 51 is recorded in the history table 53, and a value made by adding a specified margin to a counter value recorded in the history table 53 is set in the second counter 52 as the estimated amount of delivery. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for preventing the occurrence of missing printed pages and a label printer that prevents missing printed pages.

  In a label printer that feeds a mount from a roll made of a mount on which a sheet (label sheet) is loaded and prints on the label sheet, a paper leading edge detection sensor is used as a method for determining whether the label sheet has reached the print position start position. There are a method for detecting the paper leading edge mark and a method for making a determination based on the paper length information set / stored in the host application or printer without using the paper leading edge detection sensor.

  FIG. 16 shows a configuration of a main part of a label printer that detects a sheet leading end mark with a sheet leading end detection sensor. The paper drawn from the roll 11 is sandwiched between the print head 12 and the platen roller 13 and is conveyed by the rotation of the platen roller 13. A paper leading edge detection sensor 14 is provided on the paper conveyance path between the roll 11 and the print head 12 so that the paper leading edge mark can be detected.

When the paper leading edge detection sensor is used, the printing position is specified after the paper leading edge mark is detected, so that printing can be performed at an appropriate position even if there is a dimensional error of the label paper.
However, since the paper is transported until the paper leading edge mark is detected, there is a defect in the paper leading edge mark on a part of the label paper of the same roll, and if it cannot be detected by the paper leading edge detection sensor, the label paper is not printed. Will be conveyed and “print page omission” will occur.
Further, there is no problem if no paper slack occurs between the print head 12 and the paper leading edge detection sensor 14 as shown in FIG. 17 after back feed, but the print head 12 and the paper leading edge detection are detected as shown in FIG. If paper slack occurs between the sensor 14 and the paper leading edge sensor 14, the paper leading mark once passed through the sensor cannot be detected again.

  On the other hand, when the determination is made based on the paper length information, even if there is an abnormality in the paper leading edge mark or the paper is slackened due to the back feed operation, the print page missing does not occur. However, since the position of the leading edge of the paper is logically managed, line breaks are accumulated little by little every printing, and the printing position may be shifted. This print position deviation appears remarkably during continuous printing.

  There is an invention disclosed in Patent Document 1 as a technique related to prevention of a printing position shift in a label printer.

JP 2002-326408 A

  The invention disclosed in Patent Document 1 is a configuration that requires not only a paper leading edge sensor but also a paper trailing edge sensor. Therefore, it is difficult to cope with the reduction in size, weight, and cost of the label printer.

  SUMMARY An advantage of some aspects of the invention is that it provides a label printer and a printing page omission prevention method that can be reduced in size, weight, and cost and can prevent printing page omission.

  In order to achieve the above object, according to the first aspect of the present invention, as a first aspect, the first counter for measuring the transport amount of the paper drawn from the roll by the motor, and the expected transport amount until the leading edge of the paper reaches a predetermined position. Is set, and the second counter that is decremented as the paper is transported and the transport amount of the paper from when the leading edge of the paper reaches a predetermined position until the leading edge of the next paper reaches the predetermined position are recorded. If the leading edge of the sheet reaches a predetermined position before the counter value of the second counter reaches 0, the counter value of the first counter is recorded on the conveyance amount recording means. The label printer is characterized in that a value obtained by adding a predetermined margin to the counter value recorded in the carry amount recording means is set as the expected carry amount.

  In order to achieve the above object, according to the second aspect of the present invention, as a second aspect, the conveyance amount of the paper drawn from the roll as the motor rotates is measured as a first count value, and the leading edge of the paper is at a predetermined position. When the second count value for setting the expected transport amount until reaching the maximum value is decremented as the paper is transported, and the leading edge of the paper reaches a predetermined position before the second count value reaches zero, The present invention provides a print page omission prevention method that stores a first count value and sets a value obtained by adding a predetermined margin to the stored count value as a second count value.

  According to the present invention, it is possible to provide a label printer and a print page omission prevention method that can be reduced in size, weight, and cost and can prevent print page omission.

It is a figure which shows the structure of the principal part of the label printer which concerns on suitable embodiment of this invention. It is a figure which shows the flow of operation | movement of the label printer which concerns on suitable embodiment of this invention. It is a figure which shows the flow of operation | movement of the label printer which concerns on suitable embodiment of this invention. FIG. 6 is a diagram illustrating a state where a paper leading edge detection sensor has not detected a paper leading edge mark and has not exceeded a paper leading edge detection range. FIG. 6 is a diagram illustrating a state where a paper leading edge detection sensor has not detected a paper leading edge mark and has exceeded a paper leading edge detection range. FIG. 6 is a diagram illustrating a state in which a paper leading edge detection sensor detects a paper leading edge mark before exceeding a paper leading edge detection range. It is a figure which shows an example of operation | movement of a label printer. It is a figure for demonstrating the back feed of a label printer. FIG. 6 is a diagram for explaining an example of a paper jam that has occurred during printing. FIG. 6 is a diagram for explaining an example of a paper jam that has occurred during printing. It is a figure which shows the structure of the principal part of the label printer which concerns on other suitable embodiment of this invention. It is a figure which shows the flow of operation | movement of the label printer which concerns on other suitable embodiment of this invention. It is a figure which shows the flow of operation | movement of the label printer which concerns on other suitable embodiment of this invention. It is a figure which shows the flow of operation | movement of the label printer which concerns on other suitable embodiment of this invention. It is a figure which shows the flow of operation | movement of the label printer which concerns on other suitable embodiment of this invention. FIG. 3 is a diagram illustrating a configuration of a main part of a label printer that detects a paper front end mark with a paper front end detection sensor. FIG. 6 is a diagram illustrating a state in which no paper slack occurs between the print head and the paper leading edge detection sensor after backfeed. FIG. 6 is a diagram illustrating a state in which sheet slack has occurred between a print head and a sheet leading edge detection sensor after backfeed.

A preferred embodiment of the present invention will be described.
FIG. 1 shows a main configuration of a label printer according to this embodiment.
The paper drawn from the roll 1 is sandwiched between the print head 2 and the platen roller 3 and is conveyed by the rotation of the platen roller 3. The rotation of the platen roller 3 is controlled by the control unit 5. A paper leading edge detection sensor 4 is provided on the paper conveyance path between the roll 1 and the print head 2 so that the paper leading edge mark can be detected. Although FIG. 1 shows a configuration in which a light emitting unit and a light receiving unit are arranged across a paper conveyance path assuming a transmission type optical sensor, a reflection type optical sensor may be used. Needless to say.

  The control unit 5 includes a first counter 51, a second counter 52, a history table 53, a mark non-detection flag 54, and a printable flag 55. The first counter 51 is a counter that measures the number of driving of the platen roller 3 (number of steps) from the previously detected sheet leading edge mark to the next sheet leading edge mark. The first counter 51 indicates the sheet conveyance amount after the end of the previous printing. To express. The second counter 52 is a counter that manages the detection range of the leading edge mark. In the second counter 52, the platen roller driving number (paper front mark distance reference value) necessary for transporting paper from the paper front mark position detected last time to a position where detection of the paper front mark is expected is set. A value obtained by adding a predetermined margin is set and decremented as the paper is conveyed (driving the platen roller 3). The history table 53 stores the value of the first counter 51 when the paper leading edge detection sensor 4 detects a paper leading edge mark and the mark non-detection flag 54 is off. The mark non-detection flag 54 is turned on when the paper leading edge detection sensor 4 cannot detect the paper leading edge when the value of the second counter 52 becomes zero, and the value of the second counter 52 becomes zero. This flag is turned off when the paper leading edge detection sensor 4 has previously detected the paper leading edge. The printable flag 55 is a flag indicating that the next label can be printed.

The operation of the label printer according to this embodiment will be described. 2 and 3 show the flow of operations when the label printer according to the present embodiment conveys paper.
In the process of transporting the paper, after the platen roller 3 is driven one step (step S1), the paper leading edge detection sensor 4 tries to detect the paper leading edge mark (step S2).
If the paper leading edge detection sensor 4 does not detect the paper leading edge mark (step S3 / No), whether or not the paper leading edge detection range has been exceeded, in other words, whether or not the count value of the second counter 52 has become zero. Is determined (step S4).

  When the count value of the second counter 52 is not 0 (step S4 / Yes), the paper leading edge mark and the paper leading edge detection sensor 4 are in a positional relationship as shown in FIG. That is, since the next paper front end position has not yet been reached, the control unit 5 increments the count value of the first counter 51 by 1 to continue the paper length measurement (step S10), and continues detection of the paper front end mark. Therefore, the count value of the second counter 52 is decremented by 1 (step S11).

  When the count value of the second counter 52 becomes 0 (step S4 / No), the paper leading edge mark and the paper leading edge detection sensor 4 are in a positional relationship as shown in FIG. In this case, the control unit 5 operates assuming that the paper leading edge detection sensor 4 cannot detect the paper leading edge mark even if the next paper leading edge detection range is exceeded, and detects the paper leading edge in a pseudo manner. First, based on the value stored in the history table 53, the next paper leading edge mark distance reference value is obtained (step S5). At this time, the average value of the count values stored in the history table 53 is applied as the next paper leading edge mark distance reference value. Then, a value obtained by adding a predetermined margin (for example, 10%) to the paper front end mark distance reference value is set in the second counter 52 (step S6). Further, the control unit 5 clears the count value of the first counter 51 (step S7). Further, the printable flag 55 is turned on to make a printable state (step S8), and the mark undetected flag 54 is turned on (step S9).

  If the paper leading edge detection sensor 4 detects a paper leading edge mark in step S3 (step S3 / Yes), the paper leading edge mark and the paper leading edge detection sensor 4 are in a positional relationship as shown in FIG. In this case, the control unit 5 checks whether or not the mark undetected flag 54 is turned on (step S12). When the mark non-detection flag 54 is off (step S12 / No), the paper leading edge mark can be normally detected in the previous time, and the amount of paper transport until the current paper leading mark is detected can be regarded as the distance between the paper leading marks. Therefore, the control unit 5 stores the counter value of the first counter 51 in the history table 53 (step S13).

  If the mark non-detection flag 54 is on (step S12 / Yes), the paper leading mark was not normally detected last time, so the amount of paper transport until the current paper leading mark is detected is determined between the paper leading marks. The control unit 5 does not store the counter value of the first counter 51 in the history table 53.

  Thereafter, the control unit 5 clears the count value of the first counter 51 (step S14). Then, based on the value stored in the history table 53, the next paper leading edge mark distance reference value is obtained (step S15). At this time, the average value of the count values stored in the history table 53 is applied as the next paper leading edge mark distance reference value. Further, a value obtained by adding a predetermined margin (for example, 10%) to the paper front end mark distance reference value is set in the second counter 52 (step S16). Further, the printable flag 55 is turned on to make a printable state (step S17), and the mark non-detection flag 54 is turned off (step S18).

Since the label interval (paper leading mark interval) differs depending on the type of roll 1, the data stored in the history table 53 is preferably cleared when the roll 1 is replaced. This can be realized by providing a sensor (not shown) that supports the roll 1 to detect attachment / detachment of the roll 1 and inputting a detection result to the control unit 5.
In addition, when the user designates the type of the mounted roll 1 via a user interface (not shown) (for example, the model number of the roll 1 is input), the type of the roll 1 is selected from the data accumulated in the history table 53. It is also possible to selectively use data according to the above.

FIG. 7 shows an example of the operation of the label printer according to this embodiment.
In the second and third sheets from the left in the figure, since the detection of the leading edge mark was successful, the control unit 5 sets the print start position based on the detection result of the leading edge mark, and the distance between the leading edge marks ( The count value of the first counter 51) is stored in the history table 53.
For the fourth sheet from the left in the figure, since the detection of the sheet leading end mark has failed, the control unit 5 sets the printing start position based on the distance between the sheet leading end marks stored in the history table 53, and the mark has not been detected. The detection flag 54 is turned on.
For the fifth sheet from the left in the figure, since the detection of the leading edge mark was successful, the control unit 5 sets the printing start position based on the detection result of the leading edge mark. However, since the mark non-detection flag 54 is on, the paper non-detection flag 54 is turned off without storing the distance between the paper front end marks (the count value of the first counter 51) in the history table 53.
For the sixth sheet from the left in the figure, since the detection of the leading edge mark was successful, the control unit 5 sets the printing start position based on the detection result of the leading edge mark, and the distance between the leading edge marks (first The count value of the counter 51) is stored in the history table 53.

As described above, the label printer according to the present embodiment performs printing at a position expected to be the leading end of the sheet when the leading end mark cannot be detected even when the sheet is conveyed by a predetermined amount. For this reason, it is possible to prevent the occurrence of missing print pages even when there is an abnormality in the leading edge mark of the sheet or when the sheet is slackened due to back feed.
In addition, since the measurement distance between the paper front end marks is managed by the history table, the same operation can be realized even if a plurality of papers exist between the paper front end detection sensor and the print head. For example, when there is a gap of several centimeters between the paper leading edge detection sensor and the print head and the paper length is several millimeters, there are a plurality of sheets between the paper leading edge detection sensor and the printing head. Even in such a case, the leading edge of the sheet can be accurately positioned.

Next, another preferred embodiment of the present invention will be described.
A case where the leading edge mark cannot be detected even when the sheet is conveyed by a predetermined amount may be caused by the occurrence of a sheet jam in the feed after the sheet back feed in addition to the sheet slack.

FIG. 8 shows a label printer provided with a paper discharge port 6 for discharging paper, which is fed forward to discharge printed paper P1 (FIG. 8 (a)), and after paper P1 is discharged, back feed ( FIG. 8B is a diagram for explaining the start of printing on the paper P2. The paper P1 discharged from the paper discharge port 6 may be automatically cut by a cutter (not shown) provided at the paper discharge port, or may be cut by the user using the cutter. It may be discharged by being automatically cut by a cutter (not shown) provided between the discharge port 6 and the platen 2.
FIG. 8C shows a state immediately after the completion of the back feed.

Next, printing of the paper P2 is started. Here, a case (paper jam) in which the leading edge of the paper P2 does not enter the paper discharge port 6 and is jammed and the paper does not advance can be considered. FIG. 9 is a diagram for explaining an example of a paper jam.
As described above, when a cutter is provided between the paper discharge port 6 and the platen 2 (not shown), a case where the cutter does not enter the cutter port is also assumed.

  In addition, as a case where the paper does not advance (paper jam), there may be a case where the paper jam occurs when the leading edge of the paper comes off from the platen roller 3 after back feeding (FIG. 10A). As a cause of detachment, it may occur when the leading edge mark of the next sheet is accidentally cut when the sheet is cut (see FIG. 10B [problem]).

  For this reason, in this embodiment, when a paper leading edge mark cannot be detected, a paper jam is determined, and notification to that effect is used to avoid printing by predicting the paper leading edge position when a paper jam occurs and to prevent a print page from missing. Can be prevented.

FIG. 11 shows a main configuration of the label printer according to the present embodiment.
The control unit 25 of the label printer according to the present embodiment has the configuration of the control unit 5 of the main configuration of the label printer shown in FIG. It has the structure which further had. The back feed counter 56 is a counter that measures a sheet conveyance amount (back feed amount) when back feed is performed. The paper jam determination counter 57 is a counter for determining paper jam. The paper jam determination counter 57 is set with a value obtained by combining the back feed amount of the paper and the reference value of the leading edge mark distance, and is decremented as the paper is conveyed (driving the platen roller 3). The back feed immediately after flag 58 is a flag indicating that it is immediately after the completion of back feed.

The operation of the label printer according to this embodiment will be described. 12 to 14 show the flow of operations when the label printer according to the present embodiment conveys paper.
First, the flow of the back feed operation will be described with reference to FIG.
A motor for controlling the platen roller 3 is driven and the roller is rotated in the reverse direction to back feed the paper (step S20). The control unit 5 increments the count value of the backfeed counter 56 by 1 to measure the backfeed amount (step S21). When the backfeed is completed (step S22 / Yes), the immediately after backfeed flag 58 is turned ON. (Step S23).

Next, the label printer operation during printing will be described with reference to FIG.
In the process of transporting paper, if the flag immediately after back feed is not ON (step S30 / No), printing is performed (step S33), and the motor is driven to feed the paper forward (step S34).
If the flag immediately after the back feed is ON (step S30 / Yes), the paper jam judgment counter is updated (step S31), and the flag immediately after the back feed is turned OFF (step S32), and printing is performed (step S33). ), The platen roller 3 is driven one step (step S34).

  Here, the update of the paper jam determination counter in step S31 is the sum of the value of the back feed counter 56 storing the back feed amount measured in step S21 of FIG. 12 and the paper leading edge mark distance reference value. This is newly stored in the paper jam determination counter.

  In the process of transporting paper (discharging by forward feed), after the platen roller 3 is driven one step (step S34), whether or not the feed for the back feed has been completed, in other words, the back feed counter value (back feed amount) is set. It is determined whether it is 0 (step S35). If it is not 0, it is decremented by 1 (step S36).

Next, the paper leading edge detection sensor 4 tries to detect a paper leading edge mark (step S37).
If the paper leading edge detection sensor 4 does not detect the paper leading edge mark (step S38 / No), whether or not the paper leading edge mark detection range has been exceeded, in other words, whether the count value of the second counter 52 has become zero. It is determined whether or not (step S39).

  When the count value of the second counter 52 is not 0 (step S39 / Yes), the paper leading edge mark and the paper leading edge detection sensor 4 are in a positional relationship as shown in FIG. That is, since the next paper front end position has not yet been reached, the control unit 5 uses the first counter 51 (the platen roller 3 from the previously detected paper front end mark to the next paper front end mark to continue the paper length measurement. 1 is incremented by 1 (step S48), and the count value of the second counter 52 is decremented by 1 (step S49) in order to continue detecting the leading edge mark.

  When the count value of the second counter 52 becomes 0 (step S39 / No), the paper leading edge mark and the paper leading edge detection sensor 4 are in a positional relationship as shown in FIG. 9) or the positional relationship in which the paper front end mark cannot be detected due to loose paper, or the positional relationship as shown in FIG. 9 or 10 (the paper front end mark cannot be detected because it has not passed). Is assumed. In this case, the control unit 5 operates assuming that the paper leading edge detection sensor 4 cannot detect the paper leading edge mark even if the next paper leading edge detection range is exceeded, and detects the paper leading edge in a pseudo manner.

  The control unit 5 clears the count value of the first counter 51 (step S40), and obtains the next paper front end mark distance reference value based on the value stored in the history table 53 (step S41). At this time, the average value of the count values stored in the history table 53 is applied as the next paper leading edge mark distance reference value. Then, a value obtained by adding a predetermined margin (for example, 10%) to the paper front end mark distance reference value is set in the second counter 52 (step S42). Further, the mark undetected flag 54 is turned on (step S43).

  As a feature of this embodiment, it is next determined whether or not the paper jam determination counter 57 has a value, in other words, whether or not the count value of the paper jam determination counter 57 is 0 (step S44). When the count value of the paper jam determination counter 57 is 0 (No in step S44), the back feed has never been performed so far, and the paper jam determination counter has not been updated or is normal after the back feed. When the leading edge of the paper is detected (step S38 / Yes, S56 paper jam judgment counter clear).

  If the count value of the paper jam determination counter 57 is not 0 (step S44 / Yes), the paper jam determination counter 57 is decremented by 1 (step S45). When the paper jam determination position is reached, in other words, when the value of the paper jam counter 57 becomes 0 as a result of decrementing the paper jam determination counter (step S46 / Yes), the back feed amount and the paper leading mark distance Even if the feed for the reference value is completed, the paper leading edge mark is not detected, so it can be determined that the paper is jammed. Therefore, notification of paper jam (for example, notification to the display unit, notification by voice, notification via the network to the information processing apparatus that made the print request) is stopped, and the motor drive is stopped (step S47).

As described above, the label printer according to the present embodiment avoids continuing the printing by detecting the leading edge of the paper in a case where the leading edge mark is not detected due to the paper jam, and eliminates the paper jam early. Can prompt the user.
If no paper jam is determined, it is determined whether the forward feed of printing by detecting the leading edge of the paper is completed (step S57). If the forward feed for printing has not been completed (step S57 / No), the processing from step S30 is repeated. When the print forward feed is completed (step S57 / Yes), the process ends (END).

The case where the leading edge mark is detected in step S38 (step S38 / Yes) will be described with reference to the flowchart of FIG.
When the paper leading edge detection sensor 4 detects the paper leading edge mark in step S38 (step S38 / Yes), the paper leading edge mark and the paper leading edge detection sensor 4 are in a positional relationship as shown in FIG. In this case, the control unit 5 checks whether or not the mark undetected flag 54 is turned on (step S50). When the mark non-detection flag 54 is off (step S50 / No), the paper leading edge mark can be normally detected in the previous time, and the amount of paper transport until the current paper leading mark is detected can be regarded as the distance between the paper leading marks. Therefore, the control unit 5 stores the counter value of the first counter 51 in the history table 53 (step S51).

  If the mark non-detection flag 54 is on (step S50 / Yes), the paper leading mark was not normally detected last time, so the amount of paper transport until the current paper leading mark is detected is determined between the paper leading marks. The control unit 5 does not store the counter value of the first counter 51 in the history table 53.

  Thereafter, the control unit 5 clears the count value of the first counter 51 (step S52). Then, based on the value stored in the history table 53, the next paper leading edge mark distance reference value is obtained (step S53). At this time, the average value of the count values stored in the history table 53 is applied as the next paper leading edge mark distance reference value. Further, a value obtained by adding a predetermined margin (for example, 10%) to the paper front end mark distance reference value is set in the second counter 52 (step S54). Further, the mark non-detection flag 54 is turned off (step S55), and the paper jam determination counter is cleared (step S56).

Next, a paper jam notification when a paper jam occurs when a paper is discharged by forward feed will be described.
The operation of the label printer according to this embodiment is shown in the flowchart of FIG.

  In the process of transporting paper (discharging by forward feed), after the platen roller 3 is driven one step (step S60), whether or not the back feed has been fed, in other words, is the back feed counter value 0? Judgment is made (step S61), and if it is not 0 (step S61 / No), it is decremented by 1 (step S62).

Next, the paper leading edge detection sensor 4 tries to detect the paper leading edge mark (step S63).
If the paper leading edge detection sensor 4 detects a paper leading edge mark (step S64 / Yes), the paper jam determination counter 57 is cleared (step S69).
If the paper leading edge detection sensor 4 did not detect the paper leading edge mark (Step S64 / No), whether the paper leading edge mark passed but could not be detected, or the paper leading edge mark could not be detected because it was loose. It is assumed that the leading edge mark is not passed and cannot be detected due to a paper jam.

  Accordingly, it is next determined whether or not the paper jam determination counter 57 has a value, in other words, whether or not the count value of the paper jam determination counter 57 is 0 (step S65). When the count value of the paper jam judgment counter 57 is 0 (No in step S65), the back feed has not been performed so far, and the paper jam judgment counter has not been updated or is normal after the back feed. (Step S38 / Yes, S56 paper jam judgment counter clear, or steps S64 / Yes, S69 paper jam judgment counter clear).

  When the counter value of the paper jam determination counter 57 is not 0 (step S65 / Yes), the paper jam determination counter 57 is decremented by 1 (step S66). When the paper jam determination position is reached, in other words, when the value of the paper jam counter 57 becomes 0 as a result of decrementing the paper jam judgment counter (step S67 / Yes), the back feed amount and the paper leading mark distance reference Even if the feed for the value is completed, the paper leading edge mark is not detected, so it can be determined that the paper is jammed. Therefore, a notification of paper jam is sent (for example, a notification to the display unit, a notification by voice, a notification to the information processing apparatus that made the print request via the network), and the motor drive is stopped (step S68).

As described above, the label printer according to the present embodiment avoids detecting the paper leading edge in a pseudo manner when the paper leading edge mark is not detected due to paper jamming and continuing printing, and eliminates the paper jam early. Can prompt the user.
If no paper jam is determined, it is determined whether the forward feeding of the discharge is completed (step S70). When the forward feed of the discharge is not completed (Step S70 / No), the processing from Step S60 is repeated. When the forward feed of the discharge is completed (Step S70 / Yes), the process ends (END).

In addition, the said embodiment is an example of suitable implementation of this invention, and this invention is not limited to this.
For example, in the above embodiment, the configuration for detecting the leading edge mark of the paper is taken as an example, but the same effect can be obtained even in the configuration for detecting the boundary between the mount and the label paper.
As described above, the present invention can be variously modified.

DESCRIPTION OF SYMBOLS 1 Roll 2 Print head 3 Platen roller 4 Paper front end detection sensor 5, 25 Control part 51 1st counter 52 2nd counter 53 History table 54 Mark undetected flag 55 Printable flag 56 Back feed counter 57 Paper jam determination counter 58 Flag just after backfeed

Claims (14)

A first counter for measuring a conveyance amount of paper drawn from the roll as the motor rotates;
A second counter that sets an expected transport amount until the leading edge of the sheet reaches a predetermined position and is decremented as the sheet is transported;
A conveyance amount recording means for recording a conveyance amount of the sheet from when the leading end of the sheet reaches the predetermined position until the leading end of the next sheet reaches the predetermined position;
When the leading edge of the sheet reaches a predetermined position before the counter value of the second counter reaches 0, the counter value of the first counter is recorded in the transport amount recording unit, and the transport amount is recorded. A label printer characterized in that a value obtained by adding a predetermined margin to a counter value recorded in a recording means is set as the expected transport amount. A flag that is turned on when it is not possible to detect that the leading edge of the sheet has reached a predetermined position even if the counter value of the second counter becomes 0;
When the flag is on, even if the leading edge of the sheet reaches a predetermined position before the counter value of the second counter becomes 0, the counter value of the first counter is recorded in the transport amount recording. 2. The label printer according to claim 1, wherein the label printer is not recorded. A paper jam determination counter in which a value obtained by adding a back feed amount, which is a paper conveyance amount when the paper is back-fed, and a counter value recorded in the conveyance amount recording unit, is decremented as the paper is conveyed. Have
3. The label according to claim 2, wherein when the flag is ON and the counter value of the paper jam determination counter becomes 0, notification of paper jam is notified and conveyance of the paper is stopped. Printer.   3. The label printer according to claim 2, wherein when the leading edge of the sheet reaches a predetermined position before the counter value of the second counter reaches 0, the flag is turned off.   5. The apparatus according to claim 1, wherein a plurality of counter values are recorded in the transport amount recording unit, and a value obtained by adding the predetermined margin to the average value is set as the expected transport amount. Label printer.   2. The optical sensor detects a mark formed on the sheet or a boundary between the sheet and a mount holding the sheet to detect that the leading edge of the sheet has reached a predetermined position. 6. The label printer according to any one of items 1 to 5.   7. The label printer according to claim 1, wherein the count value recorded in the transport amount recording unit is cleared when the roll is exchanged.   The label printer according to claim 1, wherein the motor pulls out the paper from the roll by rotating a platen roller that sandwiches the paper with a print head. Measure the transport amount of the paper drawn from the roll as the motor rotates as the first count value,
Decrementing a second count value for setting an expected conveyance amount until the leading edge of the sheet reaches a predetermined position as the sheet is conveyed;
When the leading edge of the sheet reaches a predetermined position before the second count value becomes 0, the first count value is stored, and a predetermined margin is added to the stored count value. A print page omission prevention method, characterized in that a value is set as a second count value. A flag is turned on when it is not detected that the leading edge of the paper has reached a predetermined position even if the second count value becomes 0;
When the flag is on, the first count value is not stored even when the leading edge of the sheet reaches a predetermined position before the second count value becomes zero. Item 10. A method for preventing missing printed pages according to Item 9. A paper jam determination count value, which is a combination of a back feed amount, which is a paper conveyance amount when the paper is back fed, and a counter value recorded in the conveyance amount recording unit, is decremented as the paper is conveyed;
The print page missing according to claim 10, wherein when the flag is ON and the paper jam determination count value becomes 0, a notification of paper jam is given and the conveyance of the paper is stopped. Prevention method.   11. The method for preventing missing printed pages according to claim 10, wherein the flag is turned off when the leading edge of the sheet reaches a predetermined position before the second count value becomes 0. 11.   10. The optical sensor detects a mark formed on the paper or a boundary between the paper and a mount that holds the mark to detect that the leading edge of the paper has reached a predetermined position. 13. A method for preventing missing printed pages according to any one of items 1 to 12.   14. The method for preventing missing printed pages according to claim 9, wherein the count value recorded in the transport amount recording unit is cleared when the roll is exchanged.

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