JP2000062232A - Image recording device - Google Patents

Abstract

(57) Abstract: The present invention relates to a thermal transfer type image recording apparatus, and more particularly to a method for driving an ink ribbon, which can reduce the amount of energy absorbed by a torque limiter when the printing speed changes significantly. I do. A winding shaft for winding an ink ribbon,
A motor for generating a driving force for rotating the winding shaft;
Driving means for driving the motor so that the number of rotations of the motor can be changed, torque limiting means for transmitting the driving force of the motor to the winding shaft by limiting the driving force to a predetermined magnitude,
Transport means capable of transporting the recording paper at a plurality of transport speeds, a thermal head that generates heat based on image data and urges the recording paper via the ink ribbon, and the transport speed based on the image data And control means for controlling the transport means and the drive means based on the determined transport speed.

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 image recording apparatus used to obtain an output image from a host computer such as a personal computer or a visual device such as a video or a television, and more particularly to an ink ribbon driving method. Regarding

[0002]

2. Description of the Related Art FIG. 5 is a relationship diagram between an ink ribbon and a thermal head in a thermal transfer type image recording apparatus.
In FIG. 5, the thermal head 11 and the platen 12 are
The ink ribbon R and the recording paper P are arranged so as to be sandwiched therebetween. Although not shown, the platen 12 is rotationally driven, for example, in the direction of the arrow shown by a paper feeding system motor. As a result, the recording paper P is conveyed in the direction of the arrow shown in the drawing at the printing speed of one line. The ink ribbon R on the supply reel 16a is wound in the direction of the arrow shown by the winding reel 16b.

The thermal head 11 generates a predetermined amount of heat according to the recording density of the image data to be printed, and heats the contact point (black circle in the figure) of the ink ribbon R with the recording paper P. As a result, the dye at the contact point of the ink ribbon R is transferred to the image receiving layer of the recording paper P by sublimation or melting, and an image having a desired density is recorded on the recording paper P. By the way, due to the heat generated by the thermal head 11, a phenomenon occurs in which the ink ribbon R adheres to the recording paper P at the contact points with black circles in the figure. This adhesion can be peeled off smoothly from the recording paper P by applying a constant tension to the ink ribbon R and winding it up.

Therefore, as shown in FIG.
Is configured such that a combination of the torque limiter 17 and the hoisting DC motor 18 causes the thermal head 11 to hoist while applying a constant tension. The winding mechanism of the ink ribbon R including a combination of the torque limiter 17 and the winding DC motor 18 is specifically configured as shown in FIG. 6, for example. Note that FIG.
6A is an external view, and FIG. 6B is a sectional view.

As shown in FIG. 6B, the central axes 50 and 62 of the torque limiter 17 and the reduction gear 60 are fixed to the base plate 61. Torque limiter 17
A drive rotation plane gear 51 and a support shaft rotation mechanism 52 are rotatably provided on the central shaft 50. The reduction gear 60 includes a large diameter gear 63 at one end of a central shaft 62 and a small diameter gear 64 at the other end.
The large-diameter gear 63 is screwed onto the rotating shaft of the hoisting DC motor 18, and the small-diameter gear 64 is screwed onto the drive rotary plane gear 51 of the torque limiter 17.

Support shaft rotating mechanism 52 of the torque limiter 17
Is composed of a first support portion 53, a second support portion 54, a coil spring 55, a third support portion 56, and a mounting portion 57. The first support portion 53 includes a support shaft rotatably supported by the center shaft 50 and a base plate 6 on the lower end side of the support shaft.
1 and a rotating disk provided in parallel with each other. The drive rotation plane gear 51, the second support portion 54, the third support portion 56, and the mounting portion 57, which are sequentially arranged from the rotation disk side of the first support portion 53 toward the upper end of the support shaft, are the first support portion 53. It is provided so as to be rotatable with respect to the support shaft. Between the upper surface of the rotary disc of the first support portion 53 (referred to as a support shaft rotation plane) and the lower surface of the drive rotation plane gear 51 (referred to as a drive rotation plane),
A felt material 17e having a large frictional force is provided.

The second supporting portion 54 also has a rotating disk of the same outer shape as the rotating disk of the first supporting portion 53. A felt material 17d having a large frictional force is similarly provided between the lower surface of the rotary disk (referred to as a support shaft rotation plane) and the upper surface of the drive rotation plane gear 51 (referred to as a drive rotation plane).

A coil spring 55 is provided between the second support portion 54 and the third support portion 56. The mounting portion 57 is the first
It is fixed to the upper end side of the support shaft of the support portion 53. As a result, a spring force is generated in the coil spring 55, the second support portion 54 and the third support portion 56 are rotatably integrated around the central axis 50, and the second support portion 54 is driven by the drive rotary plane gear. The structure is pressed against the upper surface of 51. Although not shown, the winding reel 16b is mounted on the mounting portion 57 coaxially with the central axis 50 of the torque limiter 17.

In short, in the winding drive mechanism for the ink ribbon R configured as described above, the rotation of the rotating shaft of the winding DC motor 18 driven at a constant voltage drives the torque limiter 17 via the reduction gear 60. It is transmitted to the rotary plane gear 51, and the drive rotary plane gear 51 rotates. Then, in the torque limiter 17, the drive rotation plane gear 51
Is transmitted to the support shaft rotating mechanism 52 via the felt materials 17d and 17e, and the winding reel 16b mounted on the mounting portion 57 is driven with a predetermined torque. This allows
A constant tension is applied to the ink ribbon R.

Here, the printing time for one line is long when the number of gradations of the image to be printed is long, short when the number of gradations is low, and when a printed image of the same density is obtained. However, it may become longer or shorter depending on the type of the recording paper P or the ink ribbon R. The torque limiter 17 absorbs such a speed change on the friction surface formed between the drive rotation plane and the support shaft rotation plane by setting the drive rotation speed and the support shaft rotation speed to different speeds.
A constant torque is always generated.

That is, the torque generated by the torque limiter 17 is determined by the frictional force generated by the coil spring 55 between the drive rotation plane and the support shaft rotation plane via the felt members 17d and 17e. The support shaft rotation speed is set to be the same as the moving speed of the recording paper P because the ink ribbon R is adhered to the moving of the recording paper P and no slippage occurs.
The drive rotation speed is set to twice or more the support shaft rotation speed in order to maintain the amount of generated torque.

Specifically, the drive rotation speed is calculated as the speed for rotating the drive rotation plane from the printing speed of one line. Such a speed is obtained from the winding DC motor 18 rotating at a constant speed. It is obtained by determining the gear ratio of the reduction gear 60 so as to be obtained. Therefore, in the torque limiter 17, when the difference between the driving rotation speed and the support shaft rotation speed is large (when the printing speed is small), the slip on the friction surface becomes large,
On the other hand, when the speed difference is small (when the printing speed is high), the slip on the friction surface is reduced, so that the torque control of the ink ribbon R is performed.

[0013]

By the way, in recent years,
High-speed printing has become possible by changing the printing speed according to the gradation of the image, etc. However, when this is dealt with by the torque limiter described above, there are the following problems. The drive rotation speed is about twice as fast as the printing speed as described above, but the printing speed at low speed printing (high gradation printing) is about 1/2 of that at high speed printing. In time, the drive rotation speed during low-speed printing is about four times the printing speed, and the difference from the support shaft rotation speed is considerably large. That is, the absorbed energy on the friction surface becomes large.

Then, the large energy absorbed by the friction surface is converted into wear of the friction surface, vibration noise, heat, etc., resulting in deterioration of durability and performance. As a measure against this problem, it is possible to change the gear ratio according to the change in printing speed, but change the gear ratio so that it can flexibly respond to the printing speed that changes depending on the type of recording paper or ink ribbon and the number of gradations. Is difficult to do.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image recording apparatus provided with means capable of relaxing the amount of energy absorbed by the torque limiter when the printing speed changes greatly.

[0016]

According to another aspect of the present invention, there is provided an image recording apparatus including a winding shaft for winding an ink ribbon, a motor for generating a driving force for rotating the winding shaft, and the motor. Driving means for driving the motor so that the rotation speed of the motor can be changed, torque limiting means for limiting the driving force of the motor to a predetermined magnitude and transmitting it to the winding shaft, and recording paper at a plurality of transport speeds. A transporting unit capable of transporting, a thermal head that generates heat based on image data and urges the recording sheet through the ink ribbon, and the transport speed is determined based on image data, and is determined. It is characterized in that it is provided with control means for controlling the transport means and the drive means based on the transport speed.

An image recording apparatus according to a second aspect of the present invention is the image recording apparatus according to the first aspect, wherein the control means has: (a) the number of gradations of the image data is the first number of gradations. In the case of, the first transport speed is determined, and the drive means is controlled so as to drive the motor at the first rotation speed based on the first transport speed, and (b) the floor of the image data. When the number of tones is the second number of gray levels, which is larger than the first number of tones,
A second transport speed that is lower than the first transport speed is determined, and the motor is driven at a second rotation speed that is lower than the first rotation speed based on the second transport speed. It is characterized by controlling the driving means.

The image recording apparatus according to a third aspect of the present invention is the image recording apparatus according to the first aspect, wherein the motor is a DC motor and the driving means is the DC.
The number of revolutions is changed by changing the voltage applied to the motor. An image recording apparatus according to a fourth aspect of the present invention is the image recording apparatus according to the first aspect, wherein the motor is a DC motor, and the drive means changes the drive time of the DC motor. The number of rotations is changed according to.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an image recording apparatus of an embodiment corresponding to claims 1 to 4. In FIG. 1, the image recording apparatus 1 is composed of a mechanism unit 10 and a drive unit 20. In the mechanism section 10, a photo interrupter 14 is provided in the conveyance path of the recording paper P, in addition to the above-mentioned thermal head 11, platen 12, paper feed system motor 13, and the thermal head 11 is provided with a temperature sensor 15. To be

In the mechanism section 10, the supply system for the ink ribbon R includes the supply reel 16a, the winding reel 16b, the torque limiter 17, and the winding DC motor 1 described above.
8, a photo interrupter 19 and the like are provided. In the drive unit 20, the IF circuit 2 is added to the central processing unit (CPU) 21.
2, image memory (RAM) 23, program memory (R
The OM) 24, the paper feed system motor driver 25, the DC motor driver 26, the thermal head driver 27, the temperature sensor 15, and the photo interrupters 14 and 19 are connected. I
A host computer 30, for example, is connected to the F circuit 22. The paper feed motor 13 is connected to the paper feed motor driver 25. The paper feeding system motor 13 is a pulse motor. The winding DC motor 18 is connected to the DC motor driver 26, and the thermal head 11 is connected to the thermal head driver 27.

Next, FIG. 2 is a structural example of the DC motor driver 26 shown in FIG. The DC motor driver 26
Either the drive time changing type (FIG. 2A) or the applied voltage changing type (FIG. 2B) is used. The drive time changing type (FIG. 2 (a)) uses the PWM (pulse widt) from the CPU 21.
hW-dulation) PW that receives setting and on / off control
P waveform from the M waveform generator 41 and the PWM waveform generator 41
Based on M waveform, fixed power supply and hoisting DC motor 18
And a drive circuit 42 for connecting and disconnecting the connection with.

The applied voltage changing type (FIG. 2B) is a CPU
A D / A converter 44 for D / A converting the voltage value (digital value) set and output by 21 into an analog signal, and an amplifier 45 for amplifying the analog signal output by the D / A converter 44.
And the on / off control from the CPU 21, and the amplifier 45
Drive circuit 46 for driving the hoisting DC motor 18 based on the output of

Correspondence between the above configuration and claims 1 to 4 is as follows. The central shaft 50 (see FIG. 6) corresponds to the winding shaft. The hoisting DC motor 18 corresponds to the motor. The drive means is a CPU
21 corresponds to the DC motor driver 26. The torque limiter 17 and the reduction gear 60 correspond to the torque limit means. The thermal head 11 corresponds to the thermal head. The CPU 21 corresponds to the control means.

The operation of this embodiment will be described below with reference to FIGS. Note that FIG. 3 is a voltage control flowchart of the DC motor. FIG. 4 is a relationship table between the rotation speed of the DC motor and the drive ratio. In the figure, CP
When a print command and image data are input from the host computer 30 via the IF circuit 22, the U21 stores the image data in the RAM 23 and controls the drive mechanism of the supply reel 16a of the ink ribbon R and the winding reel 16b. The ribbon R is fed, and the photo interrupter 19
The ink ribbon R is cued by using the detection signal of (1) (FIG. 3: S1). The CPU 21 takes in the type of the ink ribbon R by this cueing operation.

Next, the CPU 21 controls the paper feed system motor driver 25 to rotate the paper feed system motor 13 so that the platen 12 conveys the recording paper P to the position of the thermal head 11. The CPU 21 detects that the recording paper P has reached the print start position by relying on the detection signal of the photo interrupter 14 (FIG. 3: S2). When the recording paper P is set at the print start position, the CPU 21 causes the type of the ink ribbon R acquired in S1, the type of the recording paper P input separately, and the RAM2.
The printing time is determined from the number of gradations of the image data stored in 3 (FIG. 3: S3). Specifically, the rotation speed of the paper feed system motor 13 (that is, the printing speed) and the one-line printing time of the thermal head 11 are determined. For example, when printing on standard recording paper with gradation a, the printing time for one line is "A" ms.
Then, the paper feed motor 13 is set to "B" pps (pulse per seco
nd), the number of gradations is four times (a × 4) O
For printing on HP paper, printing time per line is "A x 4" m
Therefore, the paper feed system motor 15 is driven at "B / 4" pps. That is, when the printing time is increased by n times, the paper feed system motor 15 is driven with a pulse cycle that is 1 / n times as high.

Here, the speed reduction ratio of the reduction gear 60 is the drive rotation speed calculated from the 1-line printing time as before.
Rotation speed of DC motor 18 for hoisting (rotation speed; rp
m) is set to a reduction ratio that can be obtained. That is, in the present embodiment, the change of the printing time is dealt with by changing the rotation speed rpm of the hoisting DC motor 18 in a state where the speed reduction ratio of the reduction gear 60 is a constant value as before. .

That is, the CPU 21 determines the rotation speed r of the winding DC motor 18 according to the printing time determined in S3.
pm is determined (FIG. 3: S4). For example, if the rotation speed of the hoisting DC motor 18 is "C" rpm when the 1-line printing time is "A" ms, the 1-line printing time is "A x
When it becomes 4 "ms, the hoisting DC motor 18
It will be driven at "C / 4" rpm.

Changing the rotation speed of the hoisting DC motor 18 from "C" rpm to "C / 4" rpm is as follows.
This can be realized by changing the drive voltage of the hoisting DC motor 18. As a method of changing the drive voltage, in the present embodiment, a method of changing the drive time by setting the PWM value of the hoisting DC motor 18 (FIG. 2A) is adopted (FIG. 3: S5, S6). In addition, there is a method (FIG. 2B) of changing the voltage applied to the hoisting DC motor 18.
In any case, the relationship table between the rotation speed and the drive ratio of the DC motor shown in FIG. 4 is used.

The table data shown in FIG. 4 is stored in the CPU 21.
Of the DC motor rotation,
The horizontal axis is the drive ratio. When the hoisting DC motor 18 is driven at a certain rotation speed less than the rated rotation speed, the drive ratio on the horizontal axis is the drive voltage {PWM
Value or applied voltage} indicates the percentage of the drive voltage at which the rated rotation speed is obtained.

Such table data is obtained by collecting relational data between various drive voltages {PWM value or applied voltage} and the rotation speed (rotation speed) of the hoisting DC motor 18.
It is obtained by dividing the drive voltage obtained at each rotation speed by the drive voltage at the rated rotation speed to obtain each drive ratio. Figure 2
In (a), the CPU 21 sets the "on / off control signal" to "on" to activate the PWM generator 41, and also sets the rotation speed of the hoisting DC motor 18 to "C ÷".
The drive ratio for 4 "rpm is obtained from the table shown in FIG. 4, and the corresponding PWM value is output to the PWM generator 41 (FIG. 3: S5).

The PWM generator 41 outputs a pulse signal having a duty according to the drive waveform of the input PWM value to the drive circuit 42. The drive circuit 42 turns on / off the output voltage of the fixed power source according to a pulse signal of a predetermined duty input from the PWM generator 41, and winds the DC motor 1
8 is applied. When the hoisting DC motor 18 is driven by a signal that turns on and off at a certain cycle, the hoisting DC motor 18 operates in the same manner as when it is driven by its average voltage, and the rotation speed changes in proportion to the duty of the drive waveform. It can be driven at a desired rotation speed “C / 4” rpm (FIG. 3: S6)).

Next, referring to FIG. 2B, the winding D
In the method of changing the voltage applied to the C motor 18, the CPU
Reference numeral 21 sets the “on / off control signal” to “on” to activate the drive circuit 46, and at the same time, the hoisting DC motor 1
The drive ratio for setting the rotation speed of 8 to "C / 4" rpm is obtained from the table shown in FIG. 4, and the corresponding applied voltage is output to the D / A converter 44 (FIG. 3: S5).

The D / A converter 44 converts the input digital voltage value into an analog voltage value. D / A converter 4
The analog voltage signal output by 4 is amplified by the amplifier 45 and applied to the hoisting DC motor 18 via the drive circuit 46. The rotation speed of the hoisting DC motor 18 is
Since it changes in proportion to the applied voltage, it can be driven at a desired rotation speed “C / 4” rpm as well (FIG. 3: S).
6)).

After that, the CPU 21 executes the printing process instructed by the host computer 30. That is, C
The PU 21 drives the paper feed system motor 13 at "B / 4" pps to rotate the platen 12 in the direction of the arrow shown in the figure. As a result, the recording paper P moves in the direction of the arrow shown in the drawing in accordance with the printing speed of one line. At the same time, CPU2
Reference numeral 1 denotes image data taken out from the RAM 23 and applied to the thermal head 11, and while being monitored by the output of the temperature sensor 15, causes the thermal head 11 to generate a predetermined amount of heat according to the recording density of the image data, and to record with the ink ribbon R. The contact point (black circle in the figure) of the paper P is heated. Further, the CPU 21 drives the winding DC motor 18 at “C ÷ 4” rpm to wind the ink ribbon R to which a predetermined tension is applied to the winding reel 16b.

As a result, the dye at the contact point of the ink ribbon R is transferred to the image receiving layer of the recording paper P by sublimation or melting, and at the same time, the adhesion between the recording paper P and the ink ribbon R is smoothly released, and recording is performed. An image having a desired density is recorded on the paper P. When the print process is completed, the CPU 21 turns “ON / ON”.
The "off control signal" is turned "off" to stop the PWM generator 41.

At this time, in the torque limiter 17, in synchronization with the printing speed of the recording paper P becoming "B / 4" pps, the rotation speed of the winding DC motor 18 corresponds to "C / 4". Since the rotation speed is “rpm”, the relationship between the support shaft rotation speed and the drive rotation speed is maintained almost twice as high as the support shaft rotation speed. Therefore, it is possible to prevent unnecessary energy from being generated on the friction surface of the torque limiter 17.

[0037]

As described above, in the present invention, the number of revolutions of the motor can be changed according to the number of gradations, so that it is possible to prevent the torque limiter from generating useless energy. Therefore, a vibrating noise is not generated by the torque limiter, and printing processing with excellent durability can be performed.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an image recording apparatus of an embodiment corresponding to claims 1 to 4.

FIG. 2 is a configuration example of a DC motor driver. (A) is a circuit example of a drive time changing type, and (b) is a circuit example of an application time changing type.

FIG. 3 is a voltage control flowchart of a DC motor.

FIG. 4 is a relationship table between the number of rotations of a DC motor and a drive ratio.

FIG. 5 is a relationship diagram between a thermal head and an ink ribbon.

FIG. 6 is a configuration diagram of an ink ribbon winding drive mechanism. (A) is an external view and (b) is a sectional view.

[Explanation of symbols]

1 Image recording device 10 Mechanical part 11 Thermal head 11 12 Platen 13 Paper feed motor 14, 19 Photointerrupters 15 Temperature sensor 16a supply reel 16b winding reel 17 Torque limiter 18 Winding DC motor 20 Drive 21 Central Processing Unit (CPU) 22 IF circuit 23 Image memory (RAM) 24 Program memory (ROM) 25 Paper feed motor driver 26 DC motor driver 27 Thermal head driver 30 host computer 30 41 PWM generator 42,46 drive circuit 44 D / A converter 45 amplifier 50 central axis 51 Drive rotation plane gear 52 Support shaft rotation mechanism 53 First support part 54 second support 55 coil spring 56 Third support part 57 Attachment 60 reduction gear P recording paper Q ink ribbon R

Claims (4)

[Claims] 1. A winding shaft for winding an ink ribbon, a motor for generating a driving force for rotating the winding shaft, a driving unit for driving the motor so that the rotation speed of the motor can be changed, and the motor. Torque limiting means for limiting the driving force of the recording paper to a predetermined magnitude and transmitting it to the take-up shaft, conveying means capable of conveying recording paper at a plurality of conveying speeds, and heat generation based on image data. A thermal head for urging the recording paper via an ink ribbon; and a control means for determining the transport speed based on image data and controlling the transport means and the drive means based on the determined transport speed. An image recording apparatus comprising: 2. The image recording apparatus according to claim 1, wherein the control unit has (a) the number of gradations of the image data is first.
When the number of gradations is 1, the first transport speed is determined and
The drive means is controlled so as to drive the motor at a first rotation speed based on the conveyance speed of the second floor, and (b) a second floor in which the gradation number of the image data is larger than the first gradation number. In the case of a key number, a second transport speed lower than the first transport speed is determined, and the motor is driven at a second rotation speed lower than the first rotation speed based on the second transport speed. An image recording apparatus, characterized in that the driving means is controlled so as to drive the image recording apparatus. 3. The image recording apparatus according to claim 1, wherein the motor is a DC motor, and the drive unit changes the rotation speed by changing a voltage applied to the DC motor. An image recording device characterized by. 4. The image recording apparatus according to claim 1, wherein the motor is a DC motor, and the drive unit changes the rotation speed by changing a drive time of the DC motor. Characteristic image recording device.