JPS6392469A - Thermal transfer printer - Google Patents

Abstract

PURPOSE:To enable driving by using a motor as a single drive source, by driving a pressing force switching mechanism and a ribbon feeding mechanism through selective switching according to the rotating direction of the motor. CONSTITUTION:With a motor 4 rotated in the direction of an arrow A1, a sun gear 9 is rotated in the direction of an arrow B1, the rotation is transmitted to a support arm 10, and a planetary gear 11 is engaged with a gear 12. With a gear 13 rotated in the direction of an arrow C1, a gear 14 is rotated in the direction of an arrow D1, a core 24 is rotated, and an ink ribbon 25 is fed past a thermal head 1, before being taken up by a spool in a ribbon cassette. With a stepping motor 4 rotated in the direction of an arrow A2, the sun gear 9 is rotated in the direction of an arrow B2, the planetary gear 11 is engaged with a gear 7, and a cam 3 is rotated in the direction of an arrow G. The cam 3 can be rotated not less than 360 deg. in the direction of the arrow G, so that all cam positions can be selected through unidirectional rotation of the motor. Therefore, a drive source can be used in common as a driver source for a head-pressing force switching mechanism and a drive source for other mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a ribbon winding mechanism of a thermal transfer printer and
This relates to a head pressure contact/release mechanism.

[Prior Art] Conventional thermal transfer printers use power to move a carriage equipped with a thermal head to wind up a ribbon, as typified by Japanese Patent Publication No. 57-2 [471], or wind up an ink ribbon using a dedicated motor. There was one that was rolled up using a . In addition, for switching the pressure contact force of the head,
It was common to use a solenoid plunger, as seen in the 438.

[Problems to be solved by the invention] In the former method, when using a color ink ribbon,
When a designated color is selected, the carriage must be moved, resulting in a slow printing speed, and the latter method has the drawback of increasing costs.

Furthermore, the solenoid plunger that has been used to switch the pressure contact force of the head generates an impact noise, which detracts from the most important feature of thermal printers, which value quietness.

Furthermore, in the method of using the ribbon winding mechanism as a single driving source,
Since it is necessary to separately control the drive system for switching the pressure contact force of the thermal head, the structure of the drive control system becomes complicated and the cost increases.

An object of the present invention is to eliminate such conventional drawbacks and provide a thermal transfer printer in which a ribbon traveling mechanism such as a ribbon winding mechanism and a head pressure contact force switching mechanism can be driven by a single drive source, ie, a motor. be.

Another object of the present invention is to provide a head pressure contact force switching mechanism that is free from impact noise.

Still another object of the present invention is to provide a method in which a ribbon traveling mechanism can be driven independently without moving the carriage in a serial type thermal transfer printer in which a carriage carrying a head is movably installed. be.

Still another object of the present invention is to provide a head pressure contact mechanism that allows selection of the optimum pressure contact force under various different printing conditions such as print mode and printing paper.

[Means for Solving the Problems] The thermal transfer printer according to the present invention includes a motor, a rotating member rotatable by 360 degrees or more by the motor, and the rotating member, and converts circular motion of the rotating member into reciprocating motion. a motion conversion mechanism; a pressure force switching mechanism that engages with the motion conversion mechanism and is capable of setting two or more types of pressure force with which the thermal head is applied to the platen depending on the rotation angle of the rotating member; and a ribbon that runs the thermal transfer ink ribbon. The thermal transfer printer is characterized in that it has a running mechanism, and is driven by selectively switching between the pressure contact force switching mechanism and the ribbon running mechanism depending on the rotational direction of the motor.

[Embodiment] FIGS. 1(a) and 2(b), FIG. 2, and FIG. 3 are schematic diagrams showing an embodiment of a thermal transfer printer according to the present invention, showing the inside of a carriage part of a serial type thermal transfer printer. Figure (a
)(b) shows a plan view, FIG. 2 shows a perspective view, and FIG. 3 shows a partially enlarged view.

Examples are shown below in Fig. 1 (a) (1)), Fig. 2,
This will be explained in detail using FIG.

1 is a thermal head; 19 is a heat sink that supports the thermal head rotatably about a shaft 21; the shaft 21 is fixed to a carriage frame 20; The carriage frame 20 is supported by the guide shaft 16 and is installed so as to be able to reciprocate in the directions of arrows Ex and E2. Reference numeral 4 denotes a step motor, which is a type of motor installed at the bottom of the carriage frame, and a motor gear 8 is fixed to a motor shaft 4a that passes through the carriage frame 20. A sun gear 9 meshes with the motor gear 8. Sun gear 9 is planetary gear 1
1, and an enlarged sectional view of this portion is shown in FIG. 31. is a bin fixed to a carriage frame 20, and a support arm 10 for supporting a sun gear 9 and a planetary gear 11 is rotatably mounted around the bin. The planetary gear 1 is rotatable about a shaft 32 erected on the support arm 10. 33 is a disc spring for transmitting the rotational motion of the gear 90 to the support arm 10, and presses the planetary gear 11 against the support arm 10.

12 and 13 are gears that transmit the rotation of the planetary gear 11 to the gear 14 engaged with the core 24 for winding up the ink ribbon.

FIG. 1(a) shows a state in which an ink ribbon winding mechanism, which is a kind of ribbon traveling mechanism, is in operation.

When the motor 4 rotates in the direction of arrow A1, the sun gear 9 rotates in the direction of arrow B1, this is transmitted to the support arm 10, and the planetary gear]1 meshes with the gear 12.

When the gear 13 rotates in the direction of arrow 01, the gear 14 rotates in the direction of arrow D1, the core 24 rotates, and the ink ribbon 25 of a ribbon cassette or the like (not shown) is transferred to the thermal head]
After passing through the ribbon, it is wound onto a spool inside the ribbon shaft. The gears 12 to 14 and the core 24 form a ribbon winding mechanism.

3 is a kind of cam which is a rotating member, and 3 is rotated around the shaft 3d.
Can be rotated more than 60 degrees. This cam 3 has at least three cam positions with different radii to the outer circumference,
The position of the smallest radius rl is the cam position [3a, the maximum radius r3 is the cam position w13c, and the intermediate radius r2
This is the cam position 3b. On the top of this cam,
A reflective section 6 is installed, and the reflective photosensor 5 can detect the reference position of the rotational position of the cam.

This reflecting section 6 and the photosensor 5 form a cam position detecting means. In this embodiment, the photosensor 5
detects the reflecting portion 6, and the cam position 3a having the radius r1 is selected.

A spring support member 1, which is a type of engagement member, is provided on the outer periphery of the cam 3.
8 is in contact. The spring support member 18 has a receiving portion 18a integrally formed with the spring support member 18, and is rotatably installed around the guide shaft 16. A compression coil spring 2, which is a kind of elastic member, is supported by a spring support member 18 and indirectly engages with a cam 3, and by selecting the position of the cam 3, the thermal head 1 is moved from behind to the platen 17 in the direction of arrow F1. can be biased and receive pressure contact force. When the cam 3 is in contact with the spring support member 18 at the cam position 3a, the thermal head 1 moves in the direction of arrow F2 by the force of the tension coil spring 15, which is a kind of release means, and is separated from the platen 17, and the ink ribbon 25 Also, printing paper (not shown) can be inserted between the platen 17 and the platen 17.

Further, when the cam position 3c is selected during printing, the pressure contact force of the thermal head 1 becomes maximum, and the pressure contact force becomes small at the cam position 3b.

FIG. 1(b) is a diagram showing a state in which the pressure contact force switching mechanism is driven by the step motor 4. As shown in FIG.

When the step motor 4 rotates in the direction of arrow A2, the sun gear 6 rotates in the direction of arrow B2, the planetary gear 11 engages with the gear 7 integrally formed with the cam 3, and the cam 3 rotates in the direction of arrow G. The outer circumferential portion of the circular motion of the cam 3, which is a rotating member, has at least two different radii, so that the member in contact with the outer circumferential portion can be reciprocated,
The cam 3 and the spring support member 18 constitute a motion direction changing mechanism. Although the spring support member 18 is installed so that the coil spring 2 maintains its position, the coil spring 2 may be brought into direct contact with the spring support member 18 . The coil spring 2 engages with a motion direction changing mechanism to obtain a pressing force that presses the thermal head 1 against the platen 17, and it is possible to obtain two or more types of pressing forces by selecting the cam position.

It is generally known that print density and print quality of thermal transfer printers are affected by the pressure force of the thermal head. For bond paper and plain paper with low surface smoothness, the higher the pressure contact force of the head, the better the print quality, and for transfer paper, the lower the pressure contact force, the better the print quality. Furthermore, when the pressure contact force is large, the energy required to move the carriage on which the thermal head is mounted becomes large. For this reason, it is extremely convenient to change the pressure force depending on the printing mode.
In this embodiment, the head pressure contact force switching mechanism also functions as a head pressure contact/release mechanism.

When the photo sensor 5 detects the reflective portion 6, it is possible to control the number of steps of the step motor 4 using the reflective portion 6 as a reference position, determine the rotation angle of the cam 3, and select a predetermined cam position. The cam 3 is 3 in the direction of the arrow G.
It can be rotated by more than 60 degrees, and all cam positions can be selected by rotating the motor in one direction. This allows the drive source of the head pressure contact force switching mechanism to be shared with another drive source, and also allows the head pressure contact force to be switched without having a sound source such as a plunger.

FIG. 4 is a schematic diagram showing the structure of a thermal transfer printer according to the present invention. Components that are the same as those in FIGS. 1 and 2 are designated by the same numerals and their explanations will be omitted.

1a is a heating resistor which is a type of heating element arranged on the surface of the thermal head 10, 1b is a flexible cable which is an electrode of the thermal head l, 31 is a head drive circuit, 32
33 is a light emitting light receiving circuit that drives the reflective photosensor 5;
is a first motor drive circuit that drives the step motor 4; 37 is a carriage motor that moves the carriage frame 20 in the digit direction; 38 is a second motor drive circuit that is its drive circuit; 30 is a motor drive circuit that drives the entire thermal transfer printer. The CPU 34 for overall control is the CPU 30 (1) In addition to the i control program, there is a ROM that stores the number of rotation steps from the reference position of the cam 30 to each cam position;
35 is a RAM, which includes a counter 36 for counting the number of steps of the step motor 4, and the like. Reference numeral 39 indicates an interface for inputting print data.

Print data is CP tJ 30 from Inkface 39
, the print mode is determined, and the first motor drive circuit is operated to rotate the step motor 4 in the direction of arrow A2, thereby selecting the head pressure contact force switching mechanism side and press the thermal head 1 to a predetermined pressure. Press it against the platen with force. At this time, the CPU 30 drives the first motor so that the number of steps of the step motor stored in the ROM 34 and the value of the counter 36 that counts the number of driving steps from the reference position obtained by the light emitting light receiving circuit 32 are the same. The cam 3 is rotated by a predetermined rotation angle by a circuit. After this, the cam 3 maintains the selected position by reversing the step motor 4 in the direction of the arrow A. Next, by further reversing the stepper motor 4, this drive source engages the ribbon winding mechanism and begins the ribbon winding operation. At the same time, the motor 37 is driven by the second motor drive circuit, and the printing operation is performed while moving the carriage frame in the column direction. When the printing operation is completed, the step motor 4 is rotated again in the direction of arrow A1, the cam position 3a with the smallest rotation radius is selected, and the thermal head 1 is separated from the platen. Thereafter, the carriage motor 37 is driven to return the carriage to the printing start position.

There is a slip mechanism inside the core 24 to wind up the ink ribbon 25 without slack, and the step motor 4 winds up the ink ribbon 25 faster than the speed at which the ink ribbon 25 is discharged from the thermal head 1 in the direction of arrow H. U1
It is turning m1 at high speed.

In this embodiment, a step motor is used as the drive source motor for the head pressure contact force switching mechanism and the ink ribbon winding mechanism, but even if it is a DC motor, the DC motor has rotation detection so that 30 rotation angles of the cam can be detected. It is possible to use a DC motor by attaching a device or the like or by installing a reflecting part corresponding to each cam position of the cam 3. The detector may be a mechanical switch in addition to the photodetector shown in the embodiment.

In addition to the cam used in this embodiment, a link mechanism may also be used as the motion direction conversion mechanism for changing rotational motion into reciprocating motion.

Furthermore, in this embodiment, the power transmission means in the rotational direction is performed by a sun gear having a planetary gear, but a one-way spring clutch installed on both the ribbon winding device and the rotating member can also be used to transmit the power in the rotation direction of the motor that serves as the drive source. It is possible to take out one of the two.

In addition to normal printers that use the heating elements shown in the examples, the present invention also applies to current-type thermal transfer printers that use electrodes as heating elements and generate heat and transfer ink using a resistance layer on the back side of a thermal transfer ribbon. It is applicable and widely applicable.

Furthermore, although the ribbon traveling mechanism has been described as a ribbon winding mechanism that winds up a disposable ink ribbon, it can be applied to a recycling type thermal transfer printer that remanufactures ink ribbons by changing to a ribbon traveling mechanism.

[Effects of the Invention] As detailed above, according to the present invention, the pressure contact force of the head is switched by the forward rotation of the motor, and the ink ribbon is wound by the reverse rotation, so it is not necessary to use separate motors as in the conventional example. Compared to the installation method, the configuration is simpler and the cost can be reduced by eliminating the motor.

Furthermore, since the ink ribbon can be wound up without moving the carriage, it is possible to cue the color ink ribbon for a given color in the standby state before printing starts, which is advantageous for speeding up color thermal transfer printers. It is.

[Brief explanation of the drawing]

FIGS. 1(a) and 3 are schematic diagrams showing an embodiment of a thermal transfer printer according to the present invention, and FIG.
)(b) is a plan view of the inside of the carriage part, FIG. 2 is a perspective view, and FIG. 3 is a partially enlarged sectional view. FIG. 4 is a diagram showing the configuration of a thermal transfer printer according to the present invention. 1...Thermal head 2...Elastic member (coil spring) 3...Rotating member (cam) 4...Motor (step motor) 15...Release means (coil spring) 24... Ribbon winding core 1 Figure 2 Figure 3

Claims (1)

[Claims] In a thermal transfer printer that transfers ink from an ink ribbon placed between the thermal head and the platen onto recording paper while pressing a thermal head equipped with a heat generating element against a platen placed opposite to the thermal head, a motor is used. a rotating member rotatable by 360 degrees or more by the motor; a motion converting mechanism that includes the rotating member and converts circular motion of the rotating member into reciprocating motion; A pressure contact force switching mechanism that can set the pressure contact force of the thermal head to two or more types depending on the rotation angle of the rotary member using an elastic member that urges the thermal head to come into pressure contact with the platen, and a ribbon running mechanism that causes the ink ribbon to run. , a thermal transfer printer characterized in that the pressing force switching mechanism and the ribbon traveling mechanism are selectively switched and driven depending on the rotational direction of the motor.