JPH10181055A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a peeling property of an ink ribbon during the printing, to reduce a noise, to raise a speed of conveying of the ribbon when setting the top of the ribbon and to convey the ribbon corresponding to a printing cycle during the printing. SOLUTION: After a paper is conveyed to an initial printing position (S11), a ribbon transporting motor is continuously driven to execute setting of a top of the ink ribbon (S12-S14). When printing, the ribbon transporting motor is intermittently driven and the driving is executed concurrently with driving of a paper transporting motor at a special timing in one printing cycle (S15-S17). As a result. a peeling property of the ink ribbon during the printing is improved so that it is possible to reduce a noise. A speed of transporting of the ribbon can be raised when executing the setting of a top of the ink ribbon. A clutch is not burdened by executing the transporting of the ribbon corresponding to the printing cycle during the printing. The printing is executed without generating slippage of the ribbon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer type printing apparatus for printing on a recording paper such as a card (postcard) by using an ink ribbon, and more particularly to a printing apparatus characterized by controlling the transport of the ink ribbon and the recording paper. Related to the device.

[0002]

2. Description of the Related Art In a thermal transfer type line printer, DC is used.
Printing is performed by feeding the ink ribbon in the sub-scanning direction of the print head using a motor. In this case, in the case of a multicolor ink ribbon coated with a plurality of colors of ink, it is necessary to perform cueing of the ribbon for each color before printing is performed. Nothing controlled the motor speed.

In printing, it is necessary to perform printing while controlling the transport of recording paper separately from the ink ribbon.
At that time, none of the methods specifically considered the timing of feeding the ink ribbon and the recording paper.

[0004]

As described above, there has been no conventional thermal transfer type line printer that controls the rotation speed of the DC motor between the start of the ink ribbon and the printing. For this reason, the DC motor is always driven at a constant rotation speed. For example, if an attempt is made to speed up the cueing of the ink ribbon using a DC motor having a high rotation speed, the feeding torque becomes excessive during printing. It was necessary to release the torque with the clutch. At this time, if there is too much difference in the number of rotations, a load is applied to the clutch, seizure failure and chattering noise are generated, and the ribbon tension increases,
There was a possibility that ribbon dragging (a phenomenon in which the ribbon was fed faster than each time printing was performed) might occur.

On the other hand, in order to solve such a problem,
If a DC motor having a low rotation speed is used, the cueing of the ink ribbon becomes slow, and problems such as slow printing operation occur. If the slip torque of the clutch is reduced in order to avoid dragging the ribbon, there is a possibility that the take-up torque will be insufficient at the time of cueing of the ink ribbon, and the ink ribbon will not be able to be fed to the end.

Conventionally, no special consideration has been given to the timing of feeding the ink ribbon and the recording paper, so that the ink ribbon may be peeled off from the recording paper after the ink cools down a little during printing. There was a problem that the ribbon peeling sound at that time caused noise.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a printing apparatus capable of improving peeling of an ink ribbon during printing and reducing noise.

In addition, the present invention provides a ribbon feeding device that speeds up the ribbon feeding at the time of ribbon cueing and performs the ribbon feeding in accordance with the printing cycle at the time of printing, so that no burden is imposed on the clutch and the ribbon is not dragged. It is an object to provide a printing device capable of performing printing.

[0009]

[Means for Solving the Problems]

(1) The present invention provides a printing unit including a printing head and a platen roller in which heating elements are arranged in a line, and conveys a recording sheet in the sub-scanning direction of the printing head according to printing of one line by the printing unit. And a DC for winding the used ink ribbon by moving the ink ribbon in the sub-scanning direction of the print head while conveying the recording paper by the conveying means.
Moving means using a motor as a drive source, pressing the recording paper and the ink ribbon between the print head and the platen roller and driving the print head to apply ink of the ink ribbon to the recording paper. A printing device for transferring, comprising motor control means for simultaneously switching the excitation signal of the step motor and applying the drive pulse of the DC motor at a specific timing during one printing cycle of the printing means. .

According to such a configuration, the feeding of the ink ribbon (DC motor) and the feeding of the recording paper (step motor)
Are performed simultaneously. Therefore, the ink ribbon can be sent before the ink transferred to the recording paper cools, and the ribbon peeling sound generated at that time can be reduced.

(2) Further, according to the present invention, there is provided a printing means comprising a printing head in which heating elements are arranged in a line and a platen roller, and printing the recording paper in accordance with one-line printing by the printing means. A conveying means having a stepping motor for driving in a sub-scanning direction of a head as a driving source, and moving the ink ribbon coated with a plurality of colors of ink in the sub-scanning direction of the print head while conveying the recording paper by the conveying means. Moving means having a driving source of a DC motor for winding the used ink ribbon, and ink area detecting means for detecting each ink area of a plurality of colors of the ink ribbon. The recording paper and the ink ribbon are brought into pressure contact with each other at the same time. A plurality of inks of the ink ribbon are transferred onto the recording paper in a superimposed manner, and the DC motor is driven at a predetermined voltage value when cueing of the plurality of colors of ink is performed by the ink area detecting means. A voltage is continuously applied, and during printing by the printing means, the D
A motor control for intermittently applying the drive voltage of the predetermined voltage value to the C motor, and applying the drive voltage at a specific timing during one printing cycle of the printing means simultaneously with switching of the excitation signal of the step motor. Means.

According to such a configuration, in addition to the above (1), the speed of the DC motor is controlled at the time of ribbon cueing and at the time of printing. Therefore, when feeding the ribbon, the ribbon feeding can be accelerated as much as possible.On the other hand, when printing, the ribbon feeding is adjusted to the printing cycle, so that printing is performed without putting a burden on the clutch and causing the dragging of the ribbon. Can be.

(3) In the configuration of (1) or (2), the specific timing is set to one of the printing units.
It is set immediately after the temperature of the print head becomes highest in a printing cycle.

According to such a configuration, the DC motor is driven immediately after the temperature of the print head becomes highest. Therefore, noise at the time of peeling the ink ribbon can be reduced more effectively.

(4) In the configuration of (1) or (2), storage means for storing information on the amount of used ink ribbon wound by the moving means, and information stored in the storage means And a pulse width control means for increasing the width of the drive pulse applied to the DC motor as the used ink ribbon amount increases based on the above.

According to such a configuration, the DC motor is driven with a torque corresponding to the used amount of the ink ribbon.
Therefore, even when the diameter of the take-up spool of the ink ribbon cassette gradually increases and a larger torque is required, the DC motor can be driven with a torque corresponding to the torque. This makes it possible to always improve the peeling of the ribbon and reduce noise.

(5) In the configuration of (4),
The storage means comprises a non-volatile memory for storing the cumulative number of recording sheets printed by the printing means for each cassette accommodating the ink ribbon to be mounted and used in the printing apparatus, and the pulse width The control means includes a table for storing width data of a drive pulse applied to the DC motor corresponding to the accumulated number of printed sheets.

According to such a configuration, an increase in the diameter of the ribbon take-up spool is detected from the number of prints. Therefore, when the number of printed sheets increases, the DC motor can be driven with the torque corresponding to the number of printed sheets, so that the ribbon can always be peeled off better and the noise can be reduced.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a circuit configuration of a printing apparatus according to an embodiment of the present invention. This apparatus has a control unit 11, a ROM 12, a RAM 13, a key input unit 14, a paper sensor 15, and a ribbon sensor 16.

The control section 11 is composed of, for example, a CPU and controls the entire apparatus, and here executes a printing process as shown in FIG. The ROM 12 stores various data such as an operation program for a printing process. The ROM 12 also stores the cumulative number of recording paper sheets and the DC
A table 12a is provided which is associated with drive pulse width data applied to a motor (ribbon feed motor).

The RAM 13 stores various data necessary for the operation of the apparatus, and has a cumulative print number storage unit 13a for storing the cumulative print number of recording paper here.
The value of the accumulated print number storage unit 13a is cleared every time the ink ribbon cassette 31 shown in FIG. 2 is replaced. The key input unit 14 is provided with a power key, a print key for instructing printing, and the like.

The paper sensor 15 detects whether or not the paper is inserted into the apparatus main body, and is used for aligning the paper when performing multi-color printing while reciprocating the paper in color printing. Detect paper edges and marks on paper. The ribbon sensor 16 is used to perform cueing of the ink ribbon 32 shown in FIG. 2 for each of the colors Y (yellow), M (magenta), and C (cyan). A specific mark provided in the.

The apparatus comprises a thermal head 17, a ribbon feed motor 18, a thermal head motor 19, a paper transport motor 20, and a drive circuit 2 for driving them.
1 to 24 and an I / O unit 25.

The thermal head 17 includes an ink ribbon 32
Is thermally transferred onto paper. Drive circuit 2
1 drives the thermal head 17 based on a strobe signal and a print data signal sent from the control unit 11. The ribbon feed motor 18 is a motor for feeding the ink ribbon 32, and is constituted by a DC motor. The drive circuit 21 controls the ribbon feed motor 18 under the control of the control unit 11.
(DC motor).

The drive circuit 21 of the ribbon feed motor 18 has a transistor (Tr), and applies a DC power supply voltage to the ribbon feed motor 18 (DC motor) by controlling ON / OFF of the Tr. In this case, if a pulse-like control signal is applied to the base of the Tr (at the time of ribbon cueing), the DC power supply voltage is intermittently applied to the ribbon feed motor 18, and the control signal is continuously applied to the base of the Tr. If (during printing), the DC power supply voltage is continuously applied to the ribbon feed motor 18. The control signal applied to the base of Tr is generated from the control unit 11 by software processing.

The thermal head motor 19 is a motor for pressing the thermal head 19 against the platen roller 36 shown in FIG. 2 or separating the thermal head 19 from the platen roller 36, and is constituted by a DC motor. The drive circuit 23 drives the thermal head motor 19 under the control of the control unit 11. The paper transport motor 20 is a motor for transporting the paper, and is constituted by a two-phase excitation type step motor. Drive circuit 24
Generates an excitation signal under the control of the control unit 11 to drive the paper transport motor 20.

The I / O section 17 is an interface with an external device. The I / O section 17 is connected to, for example, a digital camera and inputs image data captured by the digital camera.
FIG. 2 is a diagram illustrating a configuration of a printing mechanism unit according to the embodiment. This apparatus is a thermal transfer type line printer that prints on recording paper such as a card (postcard) using an ink ribbon.

In the figure, reference numeral 31 denotes an ink ribbon cassette.
The ink ribbon 32 is stored therein. The ink ribbon 32 is coated with three colors of ink in a predetermined width in the order of Y (yellow), M (magenta), and C (cyan) in the sub-scanning direction of the thermal head 17. A specific mark for identifying each color is provided at the head of each color. The ribbon sensor 16 includes an ink ribbon 32
The specific mark is detected at the time of cueing, and the detection signal is output to the control unit 11.

In the ink ribbon cassette 31, the ink ribbon 32 includes a supply spool 33 and a take-up spool 34.
Supported by. The take-up spool 34 is mounted on a take-up shaft (not shown), and the take-up shaft is provided with a clutch. By driving the ribbon feed motor 18 (DC motor), the take-up spool 34 rotates via a take-up shaft, and the ink ribbon 32 wound around the supply spool 33 is taken up by the take-up spool 34. In this case, the winding shaft is configured to rotate at a reduced speed via the gear train.

The thermal head 17 includes a platen roller 3
6 are provided. This thermal head 17
Is pressed against the platen roller 36 during printing by driving the thermal head motor 19. At that time, the sheet comes into contact with the ink ribbon 32 sent from the supply spool 33 and the paper 3
The ink on the ink ribbon 32 is transferred to the paper 35 by heat by being pressed against the platen roller 36 via the transfer roller 5.
The used ink ribbon 32 by this transfer is taken up by a take-up spool 34.

The paper 35 is sandwiched between a pair of transport rollers 37, and is transported in the sub-scanning direction of the thermal head 17 by the rotational force of the transport rollers 37. Transport roller 3
7 rotates by the drive of the ribbon feed motor 18 (step motor). In this case, the transport roller 37 is configured to rotate at a reduced speed by a gear train so as to feed the paper by one line.

The paper sensor 15 is provided at a conveyance port of the paper 35, detects whether or not the paper 35 has been inserted into the apparatus main body, and performs multi-color printing while reciprocating the paper 35 by color printing. At this time, an edge of the paper 35 for positioning the paper 35 and a mark attached to the paper 35 are detected, and a detection signal is output to the control unit 11.

FIG. 3 is a diagram showing a drive waveform of the ribbon feed motor (DC motor) in the embodiment. FIG.
(A) shows the waveform at the time of ribbon cueing, and (b) shows the waveform at the time of printing. In the present invention, the driving method of the ribbon feed motor 18 composed of a DC motor is switched between when the ribbon is caught and when the ribbon is printed.

That is, at the time of ribbon cueing, FIG.
As shown in (a), by continuously applying a drive voltage of a predetermined voltage value (20 V) to the ribbon feed motor 18,
The cueing of the ink ribbon 32 is accelerated. On the other hand, at the time of printing, as shown in FIG. 3B, the predetermined voltage value (20) is synchronized with the printing cycle (15.2 ms).
By intermittently applying the drive voltage V) (chopper method), the number of rotations is reduced without generating a rotation ram of the DC motor.

FIG. 4 is a diagram showing the operation timing of the ribbon feed motor (DC motor) in the embodiment. FIG. 4A shows an applied signal of the thermal head 17, and FIG.
Is an excitation signal of the paper transport motor 20 (step motor),
FIG. 2C shows a drive signal of the ribbon feed motor 18 (DC motor), and FIG. 2D shows a temperature change of the thermal head 17.

In the present invention, the ribbon feed motor 1 is used for printing.
8 is driven at a specific timing during one printing cycle (15.2 mn), switching of the excitation signal of the paper transport motor 20 and application of the drive pulse of the ribbon feed motor 18 are performed at the same time. The peeling of the ink ribbon 32 is improved to reduce noise.

In consideration of the temperature of the thermal head 17, a drive pulse is applied to the ribbon feed motor 18 immediately after the temperature of the thermal head 17 becomes highest in the printing cycle, so that the ribbon peeling effect is enhanced. I have to. At this time, the drive pulse is generated at the following timing.
It is assumed that the optimum time has been set in advance by experiments.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 5 is a flowchart showing the operation of the printing process in the embodiment. When printing is instructed by operating a print key provided on the key input unit 14, the control unit 1
1 drives the paper transport motor 20 through the drive circuit 24, and transports the paper 35 to the initial printing position (step S1).
1). The paper transport motor 20 is a two-phase excitation type step motor, and the drive circuit 24 drives the paper transport motor 20 while switching the excitation signal. By the driving of the paper transport motor 20, the transport roller 37 shown in FIG. 2 rotates in the forward direction, and the paper 35 set in the paper transport port of the apparatus main body is transported to the initial printing position. The alignment of the paper 35 at this time is performed by detecting the edge of the paper 35 or a mark attached to the paper 35 by the paper sensor 15.

When the paper 35 is conveyed to the initial printing position, the control section 11 continuously drives the ribbon feed motor 18 through the drive circuit 22 to perform the cueing of the ink ribbon 32 (step S12). The ribbon feed motor 18 is DC
The drive circuit 2 consists of a motor.
2 continuously applies a drive voltage of a predetermined voltage value (20 V) to the ribbon feed motor 18 as shown in FIG.
The drive of the ribbon feed motor 18 causes the take-up spool 34 shown in FIG. 2 to rotate, and the ink ribbon 32 wound on the supply spool 33 is taken up by the take-up spool 34. In this case, since the ribbon feed motor 18 is continuously driven with a predetermined voltage value, the ink ribbon 32 is quickly fed.

The ink ribbon 32 is attached to the thermal head 17
Y (yellow), M (magenta), C
It has three color regions (cyan), and a specific mark for color identification is provided at the head of each color. When the ribbon sensor 16 detects this mark (the mark provided at the head of the Y area) while the ink ribbon 32 is being conveyed by the drive of the ribbon feed motor 18, the detection signal is output to the control unit 11 ( Ye of step S13
s). The control unit 11 stops driving the ribbon feed motor 18 by inputting the detection signal (step S14). As a result, the Y region of the ink ribbon 32 faces the thermal head 17, and a printable state of Y color is obtained.

Here, when printing is performed, the control unit 1
1 sets the width data of the drive pulse applied to the ribbon feed motor 18 with reference to the table 12a of the ROM 12 (step S15). The table 12a is associated with the cumulative number of recording sheets printed and the width data of the drive pulse applied to the DC motor (ribbon feed motor).
As the diameter of the take-up spool 34 of the ink ribbon cassette 31 gradually increases, a larger torque is required.
Therefore, an increase in the diameter of the take-up spool 34 is detected based on the number of prints, and the pulse width is controlled by the table 12a. The number of prints is stored in the accumulated number of prints storage unit 13a of the RAM 13.
Is stored in Initially, the number of prints is “0”
It is. Therefore, the pulse width corresponding to the number of prints is the minimum.

When the pulse width to be applied to the ribbon feed motor 18 is set, the control section 11 conveys the paper 35 in the forward direction one dot at a time while switching the excitation of the paper conveyance motor 20 through the drive circuit 24. At this time, the controller 11 applies a drive pulse having the set pulse width to the ribbon feed motor 18 through the drive circuit 22 to intermittently drive the ribbon feed motor 18 to move the ink ribbon 32 in the same manner as the paper feed. While one line is being sent, printing for one line is executed (step S1).
6). At this time, as shown in FIG. 3B, since a drive voltage of a predetermined voltage value (20 V) is intermittently applied to the ribbon feed motor 18 (chopper method), the time from when the ribbon is caught to when it is printed is determined. When switching to the state, the rotation speed of the ribbon feed motor 18 can be reduced without causing rotation unevenness. Thus, printing can be performed without imposing a load on the clutch and without inducing the dragging of the ribbon or the like.

When printing is started, the thermal head 17 is pressed against the platen roller 36 via the ink ribbon 32 by driving the thermal head motor 19. Paper 35 is interposed between the ink ribbon 32 and the platen roller 36. Therefore, by causing the thermal head 17 to generate heat based on the print data, the ink of the ink ribbon 32 is transferred onto the paper 35 according to the print data.

In this case, since the paper feeding and the ribbon feeding are performed simultaneously, the ink ribbon 32 can be fed before the ink transferred to the paper 35 cools, and the ribbon peeling sound generated at that time is reduced. be able to.
Further, as shown in FIG. 4, if a drive pulse is applied to the ribbon feed motor 18 immediately after the temperature of the thermal head 17 becomes the highest, the effect of reducing the ribbon peeling sound can be further enhanced. . Note that the generation timing of the driving pulse at this time is set in advance to an optimal timing by an experiment.

When printing of one color is completed while feeding the paper 35 and the ink ribbon 32 (step S1).
7), the control unit 11 drives the sheet transport motor 20 in the reverse direction through the drive circuit 24, thereby
5 is conveyed backward to the printing initial position (steps S18, S1
9).

Thereafter, similarly, the processing from step S12 is repeated, and Y (yellow), M (magenta), C
Printing for three colors is performed in the order of (cyan). Then, after printing for three colors is completed (Yes in step S18), the control unit 1
1 updates the number-of-printed-sheets data stored in the accumulated-printed-number storage 13a of the RAM 13 by +1 (step S20), and discharges the sheet 35 by driving the sheet conveying motor 20 (step S21).

When printing is continuously performed on another sheet while the same ink ribbon cassette 31 is mounted, the print number data in the cumulative print number storage unit 13a is updated every time the printing is performed, and the same data is updated. , The pulse width of the drive signal for the ribbon feed motor 18 is set to be large. As a result, as the number of prints increases, a larger torque can be generated, the peeling of the ribbon can be always improved, and the noise can be reduced. When the ink ribbon cassette 31 is replaced, the data of the number of prints is cleared.

As described above, the rotation speed of the ribbon feed motor 18 (DC motor) is controlled at the time of ribbon cueing and printing. By doing so, the ribbon can be fed as fast as possible at the time of cueing the ribbon, and the ribbon can be fed according to the printing cycle at the time of printing, so that printing can be performed without imposing a burden on the clutch and without causing dragging of the ribbon. Become like

Further, by driving the ribbon feed motor 18 at the same time as the paper transport motor 20 (step motor) during printing, it is possible to improve peeling of the ink ribbon during printing and reduce noise. .

[0050]

As described above, according to the present invention, since the ribbon feed and the paper feed are performed simultaneously, the ink ribbon is easily peeled off during printing, and noise can be reduced.

Further, since the speed of the DC motor at the time of ribbon cueing and printing is controlled, no load is imposed on the clutch and the ribbon is not dragged.
Printing can be performed.

When the DC motor is driven at the time of printing, the timing is determined in consideration of the temperature of the head, so that noise at the time of peeling the ribbon can be reduced more effectively.

Further, as the diameter of the take-up spool of the ink ribbon cassette is gradually increased, a larger torque is generated, so that the peeling of the ribbon can be always improved and the noise can be reduced.

Since the increase in the diameter of the take-up spool is detected based on the number of prints, a larger torque can be generated as the number of prints increases. Thus, noise can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of a printing apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a printing mechanism unit in the embodiment.

FIG. 3 is a diagram showing a drive waveform of a ribbon feed motor (DC motor) in the embodiment.

FIG. 4 is a view showing the operation timing of a ribbon feed motor (DC motor) in the embodiment.

FIG. 5 is an exemplary flowchart showing the operation of print processing in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Control part 12a ... Table 13a ... Cumulative print number storage part 14 ... Key input part 15 ... Paper sensor 16 ... Ribbon sensor 17 ... Thermal head 18 ... Ribbon feed motor 19 ... Thermal head motor 20 ... Paper transport motor 31 ... Ink ribbon cassette Reference numeral 32: ink ribbon 33: supply spool 34: take-up spool 35: paper 36: platen roller 37: transport roller

Claims (5)

[Claims] 1. A printing means comprising a print head and a platen roller in which heating elements are arranged in a line, and a step of conveying recording paper in the sub-scanning direction of the print head in accordance with one-line printing by the printing means. A transport unit using a motor as a drive source, and a DC motor that winds the used ink ribbon by moving the ink ribbon in the sub-scanning direction of the print head while transporting the recording paper by the transport unit. A printing device for transferring the ink of the ink ribbon to the recording paper by driving the print head while pressing the recording paper and the ink ribbon between the print head and a platen roller. Switching of the excitation signal of the step motor and driving of the DC motor at a specific timing during one printing cycle of the printing means. Printing apparatus comprising: a motor control means for applying a pulse at the same time. 2. A printing means comprising a printing head and a platen roller in which heating elements are arranged in a line, and a recording paper is conveyed in the sub-scanning direction of the print head in accordance with one-line printing by the printing means. A transport unit having a stepping motor as a drive source, and a transporting unit that transports the recording paper by the transport unit and moves an ink ribbon coated with a plurality of colors of ink in the sub-scanning direction of the print head. A moving means having a DC motor as a drive source for winding the ink ribbon; and an ink area detecting means for detecting each ink area of a plurality of colors of the ink ribbon, wherein the recording paper and the ink are interposed between the print head and a platen roller. The print head is driven by pressing the ribbon while pressing the ink areas of the plurality of colors with the ink area detecting means. A printing apparatus for superimposing and transferring a plurality of colors of ink of the ink ribbon on paper, wherein a continuous drive voltage of a predetermined voltage value is continuously applied to the DC motor when cueing of the plurality of colors of ink is performed by the ink area detecting means. During the printing by the printing means, the driving voltage of the predetermined voltage value is intermittently applied to the DC motor, and the application of the driving voltage is performed at a specific timing during one printing cycle of the printing means. A printing apparatus, comprising: a motor control unit that performs the switching simultaneously with the switching of the excitation signal of the step motor. 3. The printing apparatus according to claim 1, wherein the specific timing is set immediately after the temperature of the print head becomes highest in one printing cycle of the printing unit. Printing device. 4. A storage means for storing information on a used ink ribbon amount wound by said moving means, and said DC as the used ink ribbon amount increases based on the information stored in said storage means. The printing apparatus according to claim 1, further comprising a pulse width control unit configured to increase a width of a driving pulse applied to the motor. 5. The storage means comprises a non-volatile memory for storing the cumulative number of recording sheets printed by the printing means for each cassette containing an ink ribbon to be mounted and used in the printing apparatus. 5. The printing apparatus according to claim 4, wherein the pulse width control means includes a table for storing width data of a drive pulse applied to the DC motor corresponding to the accumulated number of printed sheets.