JP2005111712A - Printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printer which can reduce printing misregistration even if a phase shift larger than an original phase shift occurs due to an error between first and second phase signals from an encoder when a malfunction occurs in the encoder or its slit, which can reduce unevenness in movement of a carrier and rotation of a paper feeder, and which can enhance printing accuracy. <P>SOLUTION: This printer is equipped with a printing control part 10 which counts the number of pulses with a predetermined frequency between respective edges of the first and second phase signals, which stores a previous count value in a count value storage register 26, which sets the previous stored count value as this timer value in a timer-value setting register 27, which sets this timer value by using the stored count value before the occurrence of the error, when the error occurs in either of the first and second phase signals, and which controls a motor and a printhead in accordance with the timer value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a printer that performs printing on recording paper by a print head.

Conventionally, in a printer, printing is performed on a recording sheet by controlling the motor and the print head according to a timer value generated based on a phase signal output from an encoder that detects the rotation speed of a motor that drives the carrier of the print head. It is configured as follows. The phase signal output from the encoder includes a first phase signal as a basic phase signal and a second phase signal that is 90 degrees out of phase with the first phase signal. A rising edge and a falling edge of the first phase signal and the second phase signal are detected, and a quadruple edge signal is output to generate a print timing signal having a quadruple resolution. And this printing timing signal is in one cycle of the edge signal obtained by the first phase signal and the second phase signal,
Correction control is performed so as to have a constant period according to a timer value based on a count value obtained by counting the number of pulses of a predetermined frequency.

FIG. 7 is a timing chart for explaining the operation of the print controller provided in the conventional printer. In FIG. 7 (1), P0, P1, P2, and P3 indicate carrier operating states. 7 (2) shows the phase signal A, and FIG. 7 (3) shows the phase signal B. The phase signal B is 90 degrees out of phase with the phase signal A. FIG. 7 (4) shows edge signals obtained by detecting edges of the phase signal A shown in FIG. 7 (2) and the phase signal B shown in FIG. 7 (3). FIG. 7 (5)
Indicates the count value counted by the counter. In FIG. 7 (5), for example, the numerical value 10
0 is a count value obtained by counting pulses of a predetermined frequency between the falling edge of the phase signal A and the falling edge of the phase signal B. FIG. 7 (6) shows each timer value set with the previous count value as the current timer value.

FIG. 7 (7) shows the state of carrier operation when an error occurs in the phase signal B. FIG. FIG. 7 (8) shows the phase signal A, and FIG. 7 (9) shows the phase signal B in which an error has occurred. FIG. 7 (10) shows edge signals obtained by detecting edges of the phase signal A shown in FIG. 7 (8) and the phase signal B shown in FIG. 7 (9). FIG. 7 (11) shows each count value obtained by counting the number of pulses of a predetermined frequency between the edges shown in FIG. 7 (10). FIG. 7 (12) is similar to FIG.
11) Each timer value set corresponding to each count value. FIG. 7 (13) is similar to FIG.
The print timing signal obtained corresponding to the timer value shown in 2) is shown.

FIG. 8 is a state transition diagram of a carrier provided in a conventional printer. This state transition diagram will be described with reference to the timing chart shown in FIG. First, when the rising edge of the phase signal A comes in the state P0, the state P1 is entered. Next, when the rising edge of the phase signal B comes in the state P1, the state P2 is entered. Further, when the falling edge of the phase signal A comes in the state P2, the state P3 is entered. Next, when the falling edge of the phase signal B comes in the state P3, the state P0 is entered. The state changes in this order because the motor rotates forward and moves in the positive direction (
Indicates that the print head is printing.

Here, for example, when the falling edge of the phase signal A comes in the state P1, the state moves to the state M0, and when the rising edge of the phase signal B comes in the state MO, the state moves to the state M3. Next, when the rising edge of the phase signal A comes in the state M3, the state moves to the state M2, and when the falling edge of the phase signal B comes in the state M2, the state moves to the state M1. The change of state in this order indicates that the motor rotates in the reverse direction and is operating in the reverse direction (such as returning the print head to the print start position).
Japanese Patent Laid-Open No. 5-24264 JP 2000-33739 A

Conventional printers only support forward or reverse operation, and control the rotation of the motor and the print timing of the print head based on the operations shown in the timing chart shown in FIG. 7 and the state transition diagram shown in FIG. However, when an error E1 occurs in the phase signal B as shown in FIG. 7 (9), the timer value becomes abnormal as shown in FIG. 7 (13). That is, when the phase signal B rises at the rising edge b1 and then falls at the falling edge b2, as shown in FIG. 7 (10), the edge signal becomes a pulse e generated by the rising edge b1.
1 and a subsequent pulse e2 by the falling edge b2 are generated, and the count value rapidly changes from “101” to “38” as shown in FIG. 7 (11). Along with this, the timer value also changes rapidly from “101” to “38” as shown in FIG.

When the error E2 occurs after the phase signal B falls at the falling edge b4 and rises at the rising edge b5, as shown in FIG. 7 (10), the edge signal becomes a pulse e4 by the falling edge b4. Then, the subsequent pulse e5 by the rising edge b5 is generated, and the count value rapidly changes from “104” to “35” as shown in FIG. 7 (11). Along with this, the timer value also changes rapidly from “104” to “35” as shown in FIG.

Therefore, the print timing signal is a signal whose pulse generation cycle is not constant as shown in FIG. 7 (13), and the moving speed of the carrier and the print timing of the print head become unstable for a moment. That is, in the conventional printer, if there is a phase shift larger than the original phase shift due to an error between the phase signal A and the phase signal B from the encoder, the error detection of the phase signal and the interpolation of the print timing signal cannot be performed. When a phase shift larger than the original phase shift occurs, there is a problem in that a print shift occurs due to a shift in print timing, resulting in a decrease in print accuracy. In addition, a large phase shift due to the error causes uneven rotation of the motor, thereby causing uneven movement of the carrier and causing a decrease in printing accuracy.

In the prior art of Patent Document 1, a deviation from an average value is detected for the time interval of encoder output pulses from a speed detection encoder directly connected to a motor, and the deviation is corrected to generate a print timing. However, since no countermeasure is taken when an encoder output pulse error occurs, the problem as described above cannot be solved.

Further, in the prior art of Patent Document 2, when a recording timing signal having a period that is 1/8 of the previous period in the encoder output is generated and recording processing based on this is performed, it is caused by a change in the carriage speed or the like. Due to the fluctuation of the encoder cycle, the actual recording process is allowed to be executed with less time for the next encoder cycle, and the current recording start trigger is corrected based on this added time difference. Although the period is corrected, no measures are taken when an encoder output error occurs.
The above problems cannot be solved.

The present invention has been made to solve the above-described problems, and a problem occurs in the encoder and its slit, and between the first phase signal and the second phase signal from the encoder,
Even if there is a large phase shift due to an error than the original phase shift, the print shift can be reduced, and the uneven movement of the carrier and the uneven rotation of the paper feeder can also be reduced.
An object of the present invention is to provide a printer capable of improving printing accuracy.

In order to achieve the above object, the invention of claim 1 is characterized in that the driving means and the driving means according to a timer value generated based on a phase signal output from an encoder for detecting the speed of the driving means for driving the carrier of the print head. In a printer that controls a print head and prints on recording paper, the phase signal includes a first phase signal and a second phase signal that is 90 degrees out of phase with the first phase signal. Phase signal detection means for detecting a first phase signal and a second phase signal from the encoder; edge detection means for detecting edges of the detected first phase signal and second phase signal; Count means for counting the number of pulses of a predetermined frequency between each detected edge, and the previous count value counted by the count means is the drive means and the Timer value setting means for setting the current timer value for controlling the character head, storage means for storing the count value, current count value by the count means and the previous stored count stored in the storage means A comparator that outputs a correction signal when the current count value differs by a predetermined value or more compared to the previous stored count value, and a pre-error occurrence stored in the storage means when the correction signal is input. There is provided a printer comprising a print control unit having correction control means for setting a current timer value in the timer value setting means using a stored count value.

In this configuration, the first phase signal and the second phase signal from the encoder are detected by the phase signal detection means, and the edges of the detected first phase signal and second phase signal are detected by the edge detection means. Is done. The number of pulses of a predetermined frequency is counted by the counting means between the detected edges, and the count value is set in the timer value setting means as a timer value for controlling the driving means and the print head. The count value is stored in storage means. The current count value by the counting means and the previous stored count value stored in the storage means are compared by the comparing means, and the correction signal is output when the current count value differs from the previous stored count value by a predetermined value or more. Is output. The correction control means that has input this correction signal sets the stored count value before the error occurrence stored in the storage means in the timer value setting means as the current timer value. As a result, the driving means and the print head are controlled according to the set current timer value.

Therefore, according to this configuration, a problem occurs in the encoder and its slit, and there is a larger phase shift due to an error than the original phase shift between the first phase signal and the second phase signal from the encoder. Even if there is, by correcting the timer value, the print timing of the print head can be corrected to reduce the printing deviation, and the uneven movement of the carrier and the uneven rotation of the paper feeder can also be reduced. Therefore, the printing accuracy can be improved.

According to a second aspect of the present invention, the drive means and the print head are controlled according to a timer value generated based on a phase signal output from an encoder that detects the speed of the drive means for driving the carrier of the print head, and the recording paper In the printer that performs printing, the phase signal includes a first phase signal and a second phase signal whose phase is shifted by a predetermined angle with respect to the first phase signal. The number of pulses of a predetermined frequency is counted between each edge of the second phase signal, and the previous count value is set as the current timer value for controlling the driving means and the print head, and the first phase signal and the When an error occurs in one of the second phase signals, the current timer value is set using the count value before the error occurs,
Provided is a printer comprising a printing control unit for controlling the driving unit and the printing head.

In this configuration, the number of pulses having a predetermined frequency is counted between the edges of the first phase signal and the second phase signal, and the previous count value is used to control the drive unit and the print head. When an error occurs in one of the first phase signal and the second phase signal, the count value before the error occurrence is used to set the current timer value. The driving means and the print head are controlled according to the current timer value.

Therefore, according to this configuration, a problem occurs in the encoder and its slit, and there is a larger phase shift due to an error than the original phase shift between the first phase signal and the second phase signal from the encoder. Even if there is, by correcting the timer value, the print timing of the print head can be corrected to reduce the printing deviation, and the uneven movement of the carrier and the uneven rotation of the paper feeder can also be reduced. Therefore, the printing accuracy can be improved.

According to a third aspect of the present invention, in the second aspect of the present invention, the print control unit receives the first from the encoder.
A phase signal detecting means for detecting the phase signal and the second phase signal, an edge detecting means for detecting an edge of the detected first phase signal and the second phase signal, and between the detected edges Counting means for counting the number of pulses at a predetermined frequency, timer value setting means for setting the previous count value counted by the counting means as a current timer value for controlling the driving means and the print head, The storage means for storing the count value, the current count value by the count means and the previous stored count value stored in the storage means are compared, and the current count value is greater than or equal to a predetermined value compared to the previous stored count value Comparing means for outputting a correction signal when different, and a storage count before the occurrence of an error stored in the storage means when the correction signal is input Correction control means for setting the current timer value in the timer value setting means using the value, so that when an error occurs in one of the first phase signal and the second phase signal, The current timer value can be set using the count value before the occurrence of the error, and therefore the driving means and the print head can be controlled in accordance with the set current timer value.

As described above, according to the present invention, the phase signal includes the first phase signal and the second phase signal that is 90 degrees out of phase with the first phase signal. A phase signal detection means for detecting a phase signal and a second phase signal; an edge detection means for detecting edges of the detected first phase signal and second phase signal; and between the detected edges Counting means for counting the number of pulses of a predetermined frequency; timer value setting means for setting a previous count value counted by the counting means as a current timer value for controlling the driving means and the print head; and The storage means for storing the count value, the current count value by the count means and the previous stored count value stored in the storage means are compared, and the current count value is The comparison means for outputting a correction signal when the difference differs from the delivery count value by a predetermined value or more, and the current timer value using the stored count value before the error occurrence stored in the storage means when the correction signal is inputted. Since it has a print control unit having a correction control means for setting the timer value setting means, a problem occurs in the encoder and its slit,
Even when there is a phase shift larger than the original phase shift between the first phase signal and the second phase signal from the encoder, the print timing of the print head is corrected by correcting the timer value. Is corrected, printing deviation can be reduced, carrier unevenness of movement and unevenness of rotation of the paper feed feeder can be reduced, and therefore the printing accuracy can be improved.

According to the present invention, the phase signal includes a first phase signal and a second phase signal whose phase is shifted by a predetermined angle with respect to the first phase signal. The number of pulses of a predetermined frequency is counted between each edge of the second phase signal, and the previous count value is set as the current timer value for controlling the driving means and the print head, and the first phase signal and the When an error occurs in any one of the second phase signals, a print control unit is provided that sets the current timer value using the count value before the error occurs, and controls the drive means and the print head. Therefore, even if there is a problem with the encoder or its slit and there is a phase shift between the first phase signal and the second phase signal from the encoder that is larger than the original phase shift, an error occurs. By correcting the value, the print timing of the print head can be corrected to reduce print misalignment, and the carrier movement unevenness and the rotation of the paper feed feeder can be reduced, thus improving the printing accuracy. Can be planned.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a printer according to an embodiment of the present invention. In FIG. 1, 1 is a motor as drive means, 2 is an encoder for detecting the rotational speed of the motor 1, 3 and 4 are pulleys coupled to the motor shaft, 5 is a belt provided between the pulleys 3 and 4, 6 Is a carrier driven left and right by the belt 5, 7 is a print head mounted on the carrier 6, 8 is a platen, 9
Is a recording sheet, 10 is a print control unit, 11 is a motor drive circuit for driving the motor 1, 12 is a print head drive circuit for driving the print head 7, and 13 is a print buffer for temporarily storing dot data to be output. is there.

The print control unit 10 controls the motor drive circuit 11 to start up the motor 1, drives the carrier 6 in a steady state via the pulley 3 and the belt 5, reads dot data from the print buffer 13, and print head drive circuit 12 is supplied. An encoder 2 is directly connected to the shaft of the motor 1, and a phase signal output from the encoder 2 is supplied to the print head drive circuit 12 and used for dot drive timing of the print head 7. The phase signal includes a phase signal A (first phase signal) and a phase signal B (second phase signal) that is 90 degrees out of phase with the phase signal A.

FIG. 2 is a block diagram showing a characteristic configuration of the print control unit 10 in FIG. The print control unit 10 includes a phase signal detection circuit 21 as a phase signal detection unit that detects the phase signal A and the phase signal B from the encoder 2, and the motor 1 based on the detected phase signal A and phase signal B. A forward / reverse detection circuit 22 that detects whether (see FIG. 1) is a forward rotation state or a reverse rotation state, and edge detection as an edge detection means that detects edges of the detected phase signal A and phase signal B A circuit 23 and a counter 25 as counting means for counting the number of pulses having a predetermined frequency between the detected edges are provided.

The print control unit 10 also includes a timer value setting register 27 as a timer value setting means for setting the previous count value counted by the counter 25 as the current timer value for controlling the motor 1 and the print head 7. The count value storage register 26 as the storage means for storing the count value, the current count value by the counter 25 and the previous stored count value stored in the count value storage register 26 are compared, and the current count value is A comparison circuit 24 serving as a comparison means for outputting a correction signal when the stored count value differs from the stored count value by a predetermined value or more, and a stored count value before occurrence of an error stored in the count value storage register 26 when the correction signal is input. Correction control as correction control means for using and setting the current timer value in the timer value setting register 27 And a road 28.

FIG. 3 is a timing chart for explaining the operation of the print control unit 10. FIG.
In 1), P0, P1, P2, and P3 indicate the operating states of the carrier 6 (see FIG. 1).
3 (2) shows the phase signal A, and FIG. 3 (3) shows the phase signal B. The phase signal B is 90 degrees out of phase with the phase signal A. FIG. 3 (4) shows each count value counted by the counter 25. In FIG. 3 (4), for example, in the state P3, the numerical value 100 is a count value obtained by counting pulses of a predetermined frequency from the falling edge of the phase signal A to the falling edge of the phase signal B.

FIG. 3 (5) shows the operation state of the carrier 6 when an error occurs in the phase signal B.
FIG. 3 (6) shows the phase signal A, and FIG. 3 (7) shows the phase signal B in which an error has occurred.
FIG. 3 (8) shows edge signals obtained by detecting edges of the phase signal A shown in FIG. 3 (6) and the phase signal B shown in FIG. 3 (7). FIG. 3 (9) shows the count values obtained by counting the number of pulses of a predetermined frequency between the edges shown in FIG. 3 (8) by the counter 25. FIG. 3 (10) shows each count value including a count value partially corrected. FIG. 3 (11) shows each stored count value stored in the counter value storage register 26 corresponding to the previous value of the count value shown in FIG. 3 (10). FIG. 3 (12) shows each timer value stored in the timer value setting register 27 corresponding to each stored count value shown in FIG. 3 (11). FIG. 3 (13) shows the corrected printing timing signal.

FIG. 4 is a state transition diagram of the carrier 6. This state transition diagram will be described with reference to the timing chart shown in FIG. First, when the rising edge of the phase signal A comes in the state P0, the state P1 is entered. Next, when the rising edge of the phase signal B comes in the state P1, the state P2 is entered. Further, when the falling edge of the phase signal A comes in the state P2, the state P3 is entered. Next, when the falling edge of the phase signal B comes in the state P3, the state P0 is entered. The change of state in this order indicates that the motor 1 is rotating forward, and that the carrier 6 is moving the print head 7 in the printing direction.

Here, for example, when the falling edge of the phase signal A comes in the state P1, the state moves to the state M0, and when the rising edge of the phase signal B comes in the state MO, the state moves to the state M3. Next, when the rising edge of the phase signal A comes in the state M3, the state moves to the state M2, and when the falling edge of the phase signal B comes in the state M2, the state moves to the state M1. The change of state in this order indicates that the motor 1 is rotating in the reverse direction, and that the carrier 6 is moving in a direction to return the print head 7 to the print start position.

FIG. 5 is a state transition diagram for explaining a correction process when an error occurs in the phase signal B. This correction process will be described with reference to the timing chart of FIG.

At the rising edge a1 of the phase signal A, the state P0 is shifted to the state P1, and when the rising edge b1 of the phase signal B comes at the state P1, the state P2 is shifted to. In this state P2, an error E1 occurs in the phase signal B, the phase signal B falls earlier than the original period, and the state shifts to the state n1 at this falling edge b2. In this state n1, the comparison circuit 24 of the print control unit 10
For example, it is detected that the count value has suddenly changed from “101” to “38”.
For example, since it is less than half of “101”, it is determined that the phase signal B is abnormal, and the last stored count value stored in the count value storage register 26 is not used as the current count value. To control the motor 1 and the carrier 6 using “101” as a timer value,
The correction control circuit 28 performs correction processing from state n2 to state n3 described below until time t1.

That is, from the state P2 to the state P0, the state n2 and the state n3 related to the correction process are connected by a bypass path. In state n2, the count value replacing the count value “38” is set to the previous stored count value “101” stored in the count value storage register 26, and in state n3, the count value replacing the count value “62”. Also, the previous stored count value “101” stored in the count value storage register 26 is set. As a result, the timer value also becomes “101” as shown in FIG. 3 (12), and the motor 1 and the carrier 6 are normally controlled despite the error E1 of the phase signal B.

A similar correction process is performed for the next error E2. Falling edge b of phase signal B
4 shifts from the state P3 to the state P0. In this state P0, when the error E2 occurs in the phase signal B and the phase signal B rises earlier than the original period, when the rising edge b5 is detected, the process proceeds to correction processing.

That is, in the state P0, the comparison circuit 24 of the print control unit 10 determines that the count value is, for example, “
A sudden change from “104” to “35” is detected. Since “35” is, for example, half or less of “104”, it is determined that the phase signal B is abnormal, and the current count value is “ 35
”Without using the previous stored count value“ 104 ”stored in the count value storage register 26.
Is corrected by the correction control circuit 28 until time t2.

FIG. 6 is a flowchart for explaining the operation for setting the timer value of the print control unit 10 provided in the printer of this embodiment. The operation of setting the timer value of the print control unit 10 will be described with reference to this flowchart.

In the print controller 10, the phase signal detection circuit 21 detects the phase signal A and the phase signal B from the encoder 2 (step S1), and then the forward / reverse detection circuit 22 detects the falling edge of the phase signal A. Then, it is determined whether or not the count value at that time is positive (step S2). If the count value is correct, it is determined that the motor 1 is rotating forward (step S3). In this case, the carrier 6 has moved the print head 7 in the printing direction. In step S3, after determining that the motor 1 is rotating forward, the process returns to step S1.

On the other hand, if the count value is not correct (step S2), the comparison circuit 24 determines whether or not the count value is, for example, half or less of the stored count value stored in the count value storage register 26. (Step S4), if the count value is not less than half of the stored count value, the forward / reverse detection circuit 22 detects the fall of the phase signal B, and the motor 1 is rotating in the reverse direction. A determination is made (step S5), and the process returns to step S1, but if the count value is half or less of the stored count value, a process for correcting the timer value is performed (step S6).

That is, in step S6, for example, when an error E1 occurs in the phase signal B as shown in FIG. 3 (7), instead of the count values “38” and “62” as shown in FIG. Using the previous stored count value “101” stored in the storage register 26, FIG.
Is corrected to the timer value “101” as shown in (Steps S7 and S8), and the timer value “1” is corrected.
01 ”is set in the timer value setting register 27. Thereafter, the process returns to step S1 and the same processing is performed.

If such a process is performed, even if a malfunction occurs in the encoder 2 or its slit, the abnormal count value at that time can be ignored, and the stored count value before the error can be used as the timer value. Thus, the printing timing signal at the time of error can be interpolated, and the printing timing signal can be output correctly.

As described above, according to the above-described embodiment, a problem occurs in the encoder 2 and its slit, and the phase between the phase signal A and the phase signal B from the encoder 2 is larger than the original phase shift due to an error. Even if there is a deviation, by correcting the timer value, the printing timing of the print head 7 can be corrected, the printing deviation can be reduced, and uneven movement of the carrier and uneven rotation of the paper feeder can be reduced. Therefore, the printing accuracy can be improved.

1 is a block diagram illustrating a configuration of a printer according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a characteristic configuration of a print control unit in FIG. 1. 6 is a timing chart for explaining an operation of the print control unit. It is a state transition diagram of a carrier provided in the printer of the embodiment. FIG. 6 is a state transition diagram for explaining correction processing when an error occurs in the phase signal B in the printer of the embodiment. 6 is a flowchart for explaining an operation for setting a timer value of the print control unit. It is a timing chart for demonstrating operation | movement of the printing control part with which the conventional printer is equipped. It is a state transition diagram of a carrier provided in a conventional printer.

Explanation of symbols

1 Motor (drive means)
2 Encoder 6 Carrier 7 Print Head 10 Print Control Unit 21 Phase Signal Detection Circuit (Phase Signal Detection Means)
23 Edge detection circuit (edge detection means)
24 Comparison circuit (comparison means)
25 Counter (Counting means)
26 Count value storage register (storage means)
27 Timer value setting register (timer value setting means)
28 Correction control circuit (correction control means)

Claims (3)

In a printer that controls the drive means and the print head according to a timer value generated based on a phase signal output from an encoder that detects the speed of the drive means for driving the carrier of the print head, and prints on a recording sheet. The phase signal includes a first phase signal and a second phase signal that is 90 degrees out of phase with the first phase signal. The first phase signal and the second phase signal from the encoder A phase signal detecting means for detecting the edge, an edge detecting means for detecting edges of the detected first phase signal and the second phase signal, and counting the number of pulses of a predetermined frequency between the detected edges. Counting means, and the previous count value counted by the counting means as the current timer value for controlling the driving means and the print head The timer value setting means to set, the storage means for storing the count value, the current count value by the count means and the previous stored count value stored in the storage means are compared, and the current count value is A comparison unit that outputs a correction signal when the stored count value differs by a predetermined value or more, and a current timer value by using a stored count value stored in the storage unit before an error occurs when the correction signal is input. A printer comprising a print control unit having correction control means for setting the timer value setting means. In a printer that controls the drive means and the print head according to a timer value generated based on a phase signal output from an encoder that detects the speed of the drive means for driving the carrier of the print head, and prints on a recording sheet. The phase signal includes a first phase signal and a second phase signal whose phase is shifted by a predetermined angle with respect to the first phase signal, and each of the first phase signal and the second phase signal. Count the number of pulses of a predetermined frequency between edges,
If the previous count value is the current timer value for controlling the drive means and the print head, and an error occurs in either the first phase signal or the second phase signal, the error is not detected. A printer comprising a print control unit that sets a current timer value using the count value of the control unit and controls the drive means and the print head. The print control unit detects phase signal detection means for detecting a first phase signal and a second phase signal from the encoder, and detects edges of the detected first phase signal and second phase signal. Edge detection means, count means for counting the number of pulses of a predetermined frequency between the detected edges, and a previous count value counted by the count means for controlling the drive means and the print head Timer value setting means for setting the timer value, storage means for storing the count value, and comparing the current count value by the count means with the previous stored count value stored in the storage means. A comparison means for outputting a correction signal when the value differs by a predetermined value or more compared to the previous stored count value, and the case when the correction signal is input. The printer according to claim 2, characterized in that it comprises a correction control means for setting the current timer value to the timer value setting means using the stored count value prior to the occurrence of the error stored in the unit.

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