JP2586014B2 - Thermal transfer printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ribbon winding mechanism of a thermal transfer printer and a head pressing / releasing mechanism.

[Prior art] In a conventional thermal transfer printer, as shown in Japanese Patent Publication No. 57-21471, a ribbon for winding a ribbon using a power for moving a carriage equipped with a thermal head, or a dedicated motor for an ink ribbon is used. There was something to wind up.
Further, it is common to use a solenoid plunger for switching the pressure contact force of the head as shown in Japanese Utility Model Application Laid-Open No. Sho 58-29438.

[Problems to be Solved by the Invention] The former method has a problem in that when a specified color is selected when using a color ink ribbon, the carriage must be moved, and the printing speed is reduced. However, the latter method has a disadvantage that the cost is increased.

Further, the solenoid plunger used for switching the pressure contact force of the head generates an impulsive sound, and it has alienated the largest feature of a thermal printer which has a value for its quietness.

Further, in the method using the ribbon winding mechanism as a single drive source, it is necessary to separately control the drive systems for switching the pressing force of the thermal head, so that the configuration of the drive control system becomes complicated and the cost increases. Had.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal transfer printer that eliminates such a conventional drawback and that can drive a ribbon traveling mechanism such as a ribbon winding mechanism and a head pressure switching mechanism by a motor that is a single drive source. is there.

Another object of the present invention is to provide a head pressure contact switching mechanism without impact sound.

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

Still another object of the present invention is to provide a head press-contact mechanism capable of selecting an optimum press-contact force even under various printing conditions such as a printing mode and printing paper.

Means for Solving the Problems The present invention provides a step motor, a rotating member rotatable in one direction by the step motor, and a movement that includes the rotating member and converts a circular motion of the rotating member into a reciprocating motion. A direction conversion mechanism, an elastic member that engages with the movement direction conversion mechanism and that urges the thermal head to press against the platen, and a rotation angle of the rotation member. A pressure contact force switching mechanism capable of setting two or more types of pressure contact forces of the thermal head by selecting the thermal head; and separating the thermal head from the pressure contact position when a predetermined position of the rotating member is selected by engaging with the thermal head. A release mechanism having a spring that urges the ink ribbon, a ribbon travel mechanism that travels the ink ribbon, and one of the rotations of the step motor to the rotating member. And a driving force transmission mechanism for selectively transmitting the stepping motor to the ribbon traveling mechanism, and a counter that counts the number of steps of the stepping motor, and rotates from the reference position when one of the stepping motors rotates. It is characterized in that an angle is set, switching of the pressure contact force of the thermal head and pressure contact / separation of the thermal head can be selected, and the ink ribbon can run when the other step motor rotates. It is a serial type thermal transfer pudding.

[Embodiment] FIGS. 1 (a), 1 (b), 2 and 3 are schematic views showing an embodiment of a thermal transfer printer according to the present invention. FIG. (A) and (b) are plan views, FIG. 2 is a perspective view, and FIG. 3 is a partially enlarged view. An embodiment will be described below in detail with reference to FIGS. 1 (a) and (b), FIGS. 2 and 3.

1 is a thermal head, 19 is a heat radiating plate which supports the thermal head rotatably around a shaft 21, and the shaft 21 is fixed to the carriage frame 20. Carriage frame 20
Are supported by a guide shaft 16 and are installed so as to be able to reciprocate in the directions of arrows E1 and E2. Reference numeral 4 denotes a step motor, which is a type of a motor provided at the lower portion of the carriage frame, and has a motor gear 8 fixed to a motor shaft 4a penetrating the carriage frame 20. A sun gear 9 meshes with the motor gear 8. The sun gear 9 has a planetary gear 11 and a third gear
The figure shows an enlarged sectional view of this part. Reference numeral 31 denotes a pin fixed to the carriage frame 20. A support arm 10 that supports the sun gear 9 and the planetary gear 11 is rotatably mounted on the pin 31 as an axis. The planetary gear 11 is rotatable about a shaft 32 erected on the support arm 10. Reference numeral 33 denotes a disc spring for transmitting the rotational movement of the gear 9 to the support arm 10, and presses the planetary gear 11 against the support arm 10.

Gears 12 and 13 transmit the rotation of the planetary gear 11 to the gear 14 engaged with the ink ribbon winding core 24. The sun gear 9 and the planetary gear 11 constitute a driving force transmission mechanism as basic elements. Such a configuration has a feature that only one of the rotation directions of the motor is independently transmitted to the corresponding driven gear.

FIG. 1A shows a state in which an ink ribbon take-up mechanism, which is a kind of ribbon traveling mechanism, is operating.

When the motor 4 rotates in the direction of the arrow A1, the sun gear 9 turns to the arrow
It rotates in the direction of B1, which is transmitted to the support arm 10, and the planetary gear 11 meshes with the gear 12. When the gear 13 rotates in the direction of the arrow C1, the gear 14 rotates in the direction of the arrow D1, and the core 24 rotates so that the ink ribbon 25 of a ribbon cassette or the like (not shown) passes through the thermal head 1, and then the inside of the ribbon cassette It is a mechanism that is wound around a spool. The gears 12 to 14 and the core 24 form a ribbon winding mechanism.

Reference numeral 3 denotes a cam, which is a kind of a rotating member.
Can rotate more than 0 degree. This cam 3 has at least three cam positions with different radii to the outer circumference. The position of r1 having the smallest radius is the cam position 3a, the position of the maximum radius r3 is the cam position 3c, and the position of the intermediate radius r2 is the position r2. This is the cam position 3b. A reflection section 6 is provided on the upper surface of the cam, and the reference position of the rotation position of the cam can be detected by the reflection type photo sensor 5. With this reflection part 6,
The photo sensor 5 forms cam position detecting means. In the present embodiment, the photo sensor 5 detects the reflection section 6 and selects the cam position 3a having the radius r1.

A spring supporting member, which is a kind of an engaging member, is provided on an outer periphery of the cam 3.
18 are in contact. The spring support member 18 has a receiving portion 18a integrally formed and is installed so as to be rotatable around the guide shaft 16. A compression coil spring 2, which is a kind of an elastic member, is indirectly engaged with the cam 3 and supported by the spring support member 18. 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. And can receive a pressing force. When the cam 3 is in contact with the spring supporting member 18 at the cam position 3a, a pulling coil spring, which is a kind of releasing means, is used.
With the force of 15, the thermal head 1 moves in the direction of arrow F2 and separates from the platen 17, so that the ink ribbon 25 and printing paper (not shown) can be inserted between the platen 17 and the ink ribbon 25. When the cam position 3c is selected during printing, the pressing force of the thermal head 1 becomes maximum, and at the cam position 3b, the pressing force becomes small.

FIG. 1B is a diagram showing a state in which the pressing force switching function is driven by the step motor 4.

When the step motor 4 rotates in the direction of arrow A2, the sun gear 9 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. Since the outer peripheral portion of the rotating motion of the cam 3 has at least two radii having different radii, the member abutting on the outer peripheral portion can reciprocate, and the cam 3 and the spring supporting member 18 move in the moving direction. It constitutes a conversion mechanism. Although the spring supporting member 18 is set so that the coil spring 2 maintains its position, the coil spring 2 may be directly contacted. The coil spring 2 engages with the movement direction conversion mechanism to obtain a pressing force for pressing the thermal head 1 against the platen 17, but it is possible to obtain two or more pressing forces by selecting the cam position.

In a thermal transfer printer, it is generally known that the printing density and printing quality are affected by the pressing force of a thermal head. For bond paper or plain paper having a low surface smoothness, the print quality is better when the pressure of the head is larger, and for print-only paper, the print quality is better when the pressure is smaller. When the pressing force is further large, the energy for moving the carriage on which the thermal head is mounted becomes large. For this reason, it is very convenient to change the pressing force according to the printing mode, and in this embodiment, the head pressing force switching mechanism also functions as a head pressing / releasing function as it is.

When the photo sensor 5 detects the reflection part 6, the number of steps of the step motor 4 is controlled using the reflection part 6 as a reference position.
It is possible to determine the rotation angle of the cam 3 and select a predetermined cam position. The cam 3, which is a rotating member, moves in the direction of arrow G
It can rotate 360 degrees or more, and has a structure in which all cam positions can be selected by one-way rotation of the motor. This makes it possible to share the drive source of the head pressure contact switching mechanism with another drive source, and to switch the pressure contact force of the head without having a sound source such as a plunger.

FIG. 4 is a schematic diagram showing the configuration of the thermal transfer printer according to the present invention, and the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals and description thereof is omitted.

Reference numeral 1a denotes a heating resistor which is a kind of a heating element arranged on the surface of the thermal head 1, 1b denotes a flexible cable serving as an electrode of the thermal head 1, 31 denotes a head driving circuit, and 32 denotes light emission and reception for driving the reflection type photo sensor 5. Circuit, a first motor drive circuit 33 for driving the step motor 4; 37, a carriage motor for moving the carriage frame 20 in the column direction; 38, a second motor drive circuit as its drive circuit;
Is a CPU for overall control of the entire thermal transfer printer, 34 is a control program of the CPU 30, and the number of rotation steps from the reference position of the cam 3 to each cam position is described.
M and 35 are RAMs having a counter 36 for counting the number of steps of the step motor 4 and the like. Reference numeral 39 denotes an interface for inputting print data.

When print data is input to the CPU 30 from the interface 39, the print mode is determined. First, the first motor drive circuit is driven and the step motor 4 is rotated in the direction of arrow A2 to select the head pressure contact force switching function side. Then, the thermal head 1 is pressed against the platen with a predetermined pressing force. At this time, the CPU 30 operates the first motor drive 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 drive steps from the reference position obtained by the light emitting and receiving circuit 32 become the same. The circuit rotates the cam 3 by a predetermined rotation angle. Thereafter, the cam 3 is maintained at the selected position by reversing the step motor 4 in the direction of the arrow A1. Next, by further reversing the stepping motor 4, this drive source engages with the ribbon winding mechanism and starts 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 beam direction. When the printing operation is completed, the step motor 4 is again rotated in the direction of arrow A1, and the cam position having the smallest turning radius is set.
Select 3a and separate the thermal head 1 from the platen. Thereafter, the carriage motor 37 is driven to return the carriage to the print start position.

There is a slip mechanism inside the core 24 and the ink ribbon
The step motor 4 moves the ink ribbon 25 from the thermal head 1 with an arrow H.
It rotates at a high speed so that it can be wound faster than the speed of discharging in the direction.

In this embodiment, a stepping motor is used as a driving source motor for the head pressure contact force switching mechanism and the ink ribbon take-up mechanism. However, even a DC motor is rotated by the DC motor so that the rotation angle of the cam 3 can be detected. Attach detectors, etc.
The DC motor can be used by installing the reflecting portions corresponding to each of the cam positions of the cam 3.
As the detector, a mechanical switch may be used in addition to the photo detector shown in the embodiment.

Further, as the movement direction converting mechanism for changing the rotational movement to the reciprocating movement, not only the cam used in the present embodiment but also a link mechanism can be considered.

Further, in the present embodiment, the power transmission means in the rotational direction is performed by the sun gear having the planetary gears. However, the rotation of the motor serving as the driving source can be performed by a one-way spring clutch or the like installed on both the ribbon winding device and the rotating member. Can be taken out.

The present invention is applicable not only to the thermal printer using the heating element shown in the embodiment but also to an energizing type thermal transfer printer that uses an electrode as a heating element and generates heat by using a resistance layer on the back surface of a thermal transfer ribbon to transfer ink. It is widely applied.

Also, the ribbon running mechanism has been described as a ribbon winding mechanism for winding a disposable ink ribbon, but in a recycle type thermal transfer printer for remanufacturing an ink ribbon,
It can be applied by changing to a ribbon traveling mechanism.

[Effects of the Invention] As described in detail above, in the serial type thermal transfer printer according to the present invention, the ribbon traveling mechanism and the mechanism for traveling the recording paper are independent of each other. In one line of printing, the pressing force of the thermal head can be conveniently converted according to the color of the ink ribbon or the type of character. This allows
For example, lowercase letters where ink is generally not good,
By increasing the pressure of emphasized characters that you want to partially emphasize, you can increase the expressiveness of printing in one line and correct variations in color development for each color of the ink ribbon. Expression becomes possible.

Further, according to the configuration of the present invention, it is possible to obtain a head press-contact / release mechanism using the cam used for switching the press-contact force as it is.

Further, a predetermined pressing force can be quickly set by means for detecting the position of the cam and a counter for counting the rotation angle of a step motor for rotating the cam. In this case, high-speed printing can be performed when the ink ribbon switching operation is involved.

Furthermore, since the ink ribbon can be wound up regardless of the movement of the carriage, it is possible to locate a predetermined color of the color ink ribbon in a standby state before starting printing, which is advantageous for speeding up the color thermal transfer printer. is there.

[Brief description of the drawings]

FIGS. 1 (a), (b), 2 and 3 are schematic views showing an embodiment of a thermal transfer printer according to the present invention, and FIGS. 1 (a) and (b) are plan views of the inside of a carriage unit. FIG. 2 is a perspective view, and FIG. 3 is a partially enlarged sectional view. FIG. 4 is a diagram showing the configuration of the thermal transfer printer according to the present invention. DESCRIPTION OF SYMBOLS 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

Claims (1)

(57) [Claims] 1. A serial type thermal transfer printer which mounts a thermal head having a heating element on a carriage and transfers ink on an ink ribbon to recording paper while running along a platen opposed to the thermal head. A stepping motor, a rotating member rotatable in one direction by the stepping motor, a movement direction conversion mechanism that includes the rotating member and converts a circular motion of the rotating member into a reciprocating movement, and a reference position of the rotating member. Position detecting means for detecting, an elastic member which engages with the movement direction converting mechanism and urges the thermal head to press against the platen, and a pressing force of the thermal head by selecting a rotation angle of the rotating member. A pressing force switching mechanism that can be set in two or more types, and a predetermined position of the rotating member is selected by engaging with the thermal head. A release mechanism having a spring for urging the thermal head away from the pressure contact position, a ribbon traveling mechanism for traveling the ink ribbon, and one of the rotations of the step motor to the rotating member and the other to the ribbon traveling mechanism. A driving force transmitting mechanism for selectively transmitting the driving force mounted on the carriage, and a counter for counting the number of steps of the step motor; setting a rotation angle from the reference position when one of the step motors rotates; A serial type thermal transfer printer, wherein switching of head pressure contact force, pressure contact and separation of the thermal head can be selected, and the ink ribbon can be run when the other step motor rotates.