JPH02209252A - Printer - Google Patents

Abstract

PURPOSE:To enable printing to be performing by suitable pressing force by controlling the pressing force of a thermal head according to an indication of classification of printing paper by a method wherein energized force energizing the thermal head toward a platen is controlled according to the indication of the classification of the printing paper. CONSTITUTION:When a pressing cam part 16 is rotated in a CW direction with the CW direction rotation of a pulse motor 6, a sensor plate 21 swings to make a sensor turn ON, and this signal is detected to stop rotation of the pulse motor 6. At that time a pressing panel holder 17 is rotated in the CW direction, a pressing spring 19 presses a head holder 3, and a thermal head 2 comes to be pressed with a platen 1 via an ink ribbon and recording paper. When the pulse motor 6 is further rotated by an optional number of pulses in the CW direction from this state so that one end of the pressing spring holder 17 abuts against a second printing head pressure position of the pressing cam part 16b, an included angle B of the pressing spring 19 becomes less than an included angle A, and pressing force of the thermal head 2 becomes large. Therefore two kinds of pressing force are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a printing device, such as a thermal transfer printer, which performs printing by pressing a thermal head against a printing medium to generate heat.

2. Description of the Related Art In recent years, thermal transfer printers have been used as printers for word processors and personal computers due to their quietness and low cost, and are often used at home to print postcards such as New Year's cards and greeting cards.

A printing device having a conventional thermal head will be described below.

FIG. 7 is a plan view of a conventional thermal head pressing mechanism, and FIGS. 8 and 9 are plan views showing the thermal head in a non-printing position and a printing position, respectively. In the figure,
1 is a platen, 2 is a thermal head, and is fixed to a head holder 3.

A carriage base 4 is movable on a carriage shaft 5. The head holder 3 is swingably attached to the carriage base 4. 6 is a pulse motor mounted on the carriage base 4; 7 is a binion gear fixed on the shaft of the pulse motor 6; 8 is a reduction gear that meshes with the binion gear 7; 9 is a sun gear that meshes with the reduction gear 8;
0 is a planetary gear that meshes with the sun gear 9;
The planetary gear 10 is rotatably supported by a pendulum lever 11, and the pendulum lever 11 is attached to the carriage base 4 so as to be swingable about a shaft 12. This swinging motion of the pendulum lever 11 causes the planetary gear 10 to mesh with the ribbon winding gear 13 and the herad cam gear 14, thereby transmitting the power of the pulse motor 6 to each of them. The head cam gear 14 is rotatable about a shaft 15 on the carriage base 4 and has a pressing cam portion 16. Further, a pressure spring holder 17 is rotatable around a shaft 18, and one end thereof is in contact with the pressure cam portion 16 to hold the pressure spring 19. One end 19a of the pressure spring 19 is fixed to the pressure spring holder 17, and the other end 19b is rotatable about the shaft 18 and comes into contact with the head holder 3. Reference numeral 20 denotes a return spring whose end portions are attached to the head holder 3 and the carriage base 4, respectively, and act in a direction in which the thermal head 2 is released from the platen 1. Further, 21 is a sensor plate which is swingable about a shaft 22, one end of which is in contact with the pressing cam portion 16 by a sensor spring 23, and switches a sensor 24 attached to the carriage base 4.

The operation of the head pressing mechanism configured as above will be described below. When the binion gear 7, that is, the pulse motor 6 rotates in the clockwise direction indicated by the arrow in the figure (hereinafter referred to as the CW force direction), the reduction gear 8 rotates in the counterclockwise direction indicated by the arrow in the figure (hereinafter referred to as the CCW direction). Gear 9 rotates in the CW force direction. This rotation of the sun gear 9 causes a friction mechanism (not shown) between the sun gear 9 and the pendulum lever 11 to act, causing the pendulum lever to swing in the CW force direction. At this time, when the planetary gear 10 meshes with the herad cam gear 14, the planetary gear 10 starts rotating in the CCW direction, causing the head cam gear 14 to rotate in the CW force direction. Due to this rotation of the head cam gear 14, the pressing spring holder 17 rotates along the cam profile of the pressing cam portion 16 formed on the head cam gear 14, and the suppressing spring 19 is moved to the head holder 3.
to press the thermal head 2 onto the platen 1.

Although not shown in the diagram, the thermal head 2 and platen 1
An ink ribbon and recording paper are sandwiched between them. Furthermore, the sensor plate 21 also swings along the profile of the pressing cam portion 16 due to the rotation of the above-mentioned Herad cam gear 14, thereby performing a switching operation of the sensor 24.

FIG. 8 shows a non-printing state in which the thermal head 2 is separated from the platen l, and the sensor plate 21 is attached to the pressing cam part 1.
6, the sensor is separated from the sensor 24 by the action of
It is in FF state. From this state, when the head cam gear 14, that is, the pressing cam portion 16 rotates in the CW force direction due to the rotation of the pulse motor 6 in the CW direction, the pressing spring holder 17 rotates in the CW force direction as shown in FIG.
presses the head holder 3, and the thermal head 2 becomes pressed against the platen l via an ink ribbon (not shown) and recording paper (not shown). At this time, the sensor plate 21
The swing motion in the CCW direction turns the sensor 24 on. From this state, the head cam gear 14
When it is rotated in the CW force direction, the sensor 24 is turned off and the thermal head 2 begins to move away from the platen 1 and is located in a non-printing state as shown in FIG. In this way, when the sensor 24 is in the ON state, the thermal head 2 is in the printing state, and by rotating the Radcam gear 14 from the ON state to an arbitrary number of pulses, the thermal head 2 is located in the non-printing position, and the sensor 24 is turned OFF. This is to change the pressing force of the thermal head 2.

Further, when the pinion gear 7, that is, the pulse motor 6 rotates in the CCW direction, contrary to the above, the pendulum lever 11 is rotated in the CCW direction.
The planetary gear 10 swings in the W direction, and the ribbon winding gear 13
This causes the ribbon winding gear 13 to rotate in the CCW direction, thereby performing a ribbon winding operation.

Problems to be Solved by the Invention However, in the conventional mechanism described above, as shown in FIG.
30 and is pressed against the platen 1 by the thermal head 2 via an ink ribbon (not shown), the pressure of the thermal head 2 causes the recording paper 27 to be in the state shown by the broken line in the figure. Since the thermal head 2 is deformed in the direction of arrow C in the figure, the force required for the deformation is less than the pressing force of the thermal head 2. That is, the force required for the above deformation changes depending on the type of recording paper 27, and the pressing force of the thermal head 2 changes. When using a thin letter (such as PPC paper) with a small deformation force and a thick letter (such as a postcard) with a large thickness as recording paper, if the pressing force of the thermal head is adjusted to the thin letter, the pressing force will be smaller on the thick letter (this will result in printing problems). Another major problem is that if the pressing force is applied to thick letters, the pressing force becomes large on thin letters, resulting in printing smudges due to pressure transfer, which is one of the printing defects. Ta.

Means for Solving the Problem In order to solve this problem, the present invention includes a control means for controlling the urging force of the urging means for urging the thermal head toward the platen in accordance with an instruction of the type of printing paper. It becomes.

Operation With this configuration, the control means controls the pressing force of the thermal head according to the type of printing paper, whether it is thick paper or thin paper, and prints with an appropriate pressing force. Do this.

Embodiment FIG. 1 is a plan view of a thermal head pressing mechanism according to an embodiment of the present invention, FIG. 2 is an external perspective view of a carriage having the thermal head suppressing mechanism, and FIGS. 3, 4, and 5
Each figure is a plan view showing the thermal head in a non-printing state, a first print head pressure, and a second print head pressure. In Figures 1 and 2, 1 is a platen, 2
is fixed to the head holder 3 with a thermal head.

A carriage base 4 is movable on a carriage shaft 5. The head holder 3 is swingably attached to the carriage base 4. 6 is a pulse motor mounted on the carriage base 4; 7 is a binion gear fixed on the shaft of the pulse motor 6; 8 is a reduction gear that meshes with the binion gear 7; 9 is a sun gear that meshes with the reduction gear 8;
0 is a planetary gear that meshes with the sun gear 9;
The planetary gear 10 is rotatably supported by a pendulum lever 11, and the pendulum lever 11 is mounted on the carriage base 4 so as to be swingable about a shaft 12. This swinging motion of the pendulum lever 11 allows the planetary gear 10 to anastomose with the ribbon winding gear 13 and the helad cam gear 14, thereby transmitting the power of the pulse motor 6 to each. The head cam gear 14 is rotatable about a shaft 15 on the carriage base 4 and has a pressing cam portion 16. This pressure cam part 16 has a cam profile 16a for the first print head pressure and a cam profile 16b for the second print position.

Further, a pressure spring holder 17 is rotatable around a shaft 18, and one end thereof is in contact with the pressure cam portion 16 to hold the pressure spring 19. One end 19a of the pressure spring 19 is fixed to the pressure spring holder 17, and the other end 19b is rotatable about the shaft 18 and comes into contact with the head holder 3. Reference numeral 20 denotes a return spring whose end portions are attached to the head holder 3 and the carriage base 4, respectively, and act in a direction in which the thermal head 2 is released from the platen 1. Also, 2
Reference numeral 1 denotes a sensor plate which is swingable around a shaft 22, one end of which is brought into contact with the pressing cam portion 16 by a sensor spring 23, and a sensor 2 attached to the carriage base 4.
4 switching is performed. Further, 25 is an ink ribbon cassette which stores 26 ink ribbons. 27 is recording paper.

The operation of the thermal head pressing mechanism configured as above will be explained below.

In FIG. 1, the pinion gear 7, that is, the pulse motor 6 moves in the clockwise direction indicated by the arrow in the figure (hereinafter referred to as the CW force direction).
, the reduction gear 8 rotates counterclockwise as shown by the arrow in the figure (hereinafter referred to as CCW direction), and the sun gear 9 rotates CW.
Rotates in the direction of force. This rotation of the sun gear 9 causes a 7-reaction mechanism (not shown) between the sun gear 9 and the pendulum lever 11 to act, causing the pendulum lever to swing in the CW force direction. At this time, when the planetary gear 10 meshes with the head cam gear 14, the planetary gear lO starts rotating in the CCW direction, and the head cam gear 1
4 in the CW force direction. Due to this rotation of the head cam gear 14, the pressing spring holder 1 is moved along the cam profile of the pressing cam portion 16 formed on the head cam gear 14.
7 rotates, and the suppression spring 19 presses the head holder 3 and presses the thermal head 2 against the platen 1. Although not shown in the figure, an ink ribbon and recording paper are sandwiched between the thermal head 2 and the platen l. Furthermore, the sensor plate 21 also swings along the profile of the pressing cam portion 16 due to the rotation of the above-mentioned Herad cam gear 14, thereby performing a switching operation of the sensor 24.

FIG. 3 shows a state in which the thermal head 2 is separated from the platen 1 and is in a non-printing state, and the sensor plate 21 is separated from the sensor 24 by the action of the pressing cam part 16.
The sensor is in the OFF state. From this state, when the head cam gear 14, that is, the pressing cam portion 16 rotates in the CW direction due to the rotation of the pulse motor 6 in the CW direction, the sensor plate 21 swings in the CCW direction as shown in FIG. 4, turning the sensor 24 into the ON state. Detecting this signal, the pulse motor 6
stop rotating. At this time, the press spring holder 17 rotates in the CW force direction and stops in contact with the first print head pressure position of the press cam part 16a, the press spring 19 presses the head holder 3, and the thermal head 2 presses the ink ribbon. (not shown) and recording paper (not shown) are pressed against the platen 1. From this state, if the pressing cam part 16, that is, the pulse motor 6, is further rotated by an arbitrary number of pulses in the CW force direction so that one end of the pressing spring holder 17 comes into contact with the second print head pressure position of the pressing cam part 16b, the fifth
As shown in the figure, the included angle B of the pressing spring 19 is smaller than the included angle A in FIG. greater than the pressing force of one print head pressure (
Therefore, two pressing forces are obtained. Further, at this second print head pressure, the sensor 24 is in the OFF state, but the output signal of the sensor 24 has no relation because it is managed by the number of rotation pulses of the pulse motor 6 after the ON signal of the sensor 24. The distinction between the first print head pressure and the second print head pressure is determined by the control of a host (not shown) to which a printing device having a carriage equipped with the present thermal head pressing mechanism is connected. For example, the printing format of a word processor has options for thin paper and thick paper, and the operator selects thick paper or thin paper. The rotation angle of the cam is controlled according to this selection result. As shown in FIG. 6, in the case of a thin letter in which the deformation force of the recording paper 27 due to the pressing operation of the thermal head 2 is small, printing is performed in the first printing head pressure state where the pressing force is small; In the case of letters, printing can be performed using the second print head pressure state with a large pressing force. Also this fifth
When the rad cam gear 14, that is, the pulse motor 6, is further rotated in the CW force direction from the state where the thermal head 2 is at the second print head pressure shown in the figure to an arbitrary number of pulses, the thermal head 2 becomes a non-printing state as shown in FIG. It will be located at In this way, the thermal head 2 is switched between the no-print state, the first print head pressure state, and the second print head pressure state, and responds to the difference in deformation force due to the difference in the type of recording paper, that is, the decrease in the pressing force. By changing the pressing force of the thermal head 2, printing can always be performed with an appropriate pressing force regardless of the type of recording paper, and good print quality can be obtained.

Further, when the pinion gear 7, that is, the pulse motor 6 rotates in the CCW direction, contrary to the above, the pendulum lever 11 is rotated in the CCW direction.
The planetary gear 10 swings in the W direction, and the ribbon winding gear 13
This causes the ribbon winding gear 13 to rotate in the CCW direction, thereby performing a ribbon winding operation.

Effects of the Invention The present invention controls the pressing force of the thermal head in accordance with the type of printing paper by using the urging force of the urging means that urges the thermal head toward the platen. Since printing is performed with appropriate settings, the printing quality is improved on both thick paper such as postcards and plain paper.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a printing device in an embodiment of the present invention;
FIG. 2 is an external perspective view of the carriage of this embodiment, FIG. 3 is a plan view showing the thermal head in a non-printing state, FIG. 4 is a plan view showing the first print head pressure state, and FIG. 6 is a sectional view showing the conveyance of recording paper relative to the thermal head and platen; FIG. 7 is a plan view of the thermal head pressing mechanism of a conventional printing device; FIG. 9 is a plan view showing a conventional printing device in a non-printing state, and FIG. 9 is a plan view showing a printing state of the conventional printing device. l: 6: 17: 21; 27: Platen pulse motor pressure spring holder sensor board recording paper 2: 16; 19: 24= Thermal head pressure cam part pressure spring sensor

Claims (1)

[Scope of Claims] A thermal head having a heating element; a platen provided opposite to the heating element of the thermal head; urging means for urging the thermal head toward the platen; 1. A printing device comprising: control means for controlling the biasing force of the biasing means in accordance with an instruction of the type of printing paper.