JP2004122402A - Thermal head holding mechanism - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact and inexpensive holding mechanism for a thermal head in which a stabilized print quality can be sustained even for print media of different thickness. <P>SOLUTION: The holding mechanism of a thermal head is arranged such that the thermal head is moved from a press contact release position to a waiting position through rotary movement when a ribbon cassette is replaced or a head is cleaned, and moved linearly from the press contact release position to a print position. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thermal head holding mechanism in a thermal transfer printer using a line type thermal head.
[0002]
[Prior art]
In a thermal transfer printer using a line type thermal head, the function of the thermal head holding mechanism is to control the following three positions. That is, first, at the time of printing, a function of pressing the thermal head to the print medium at the printing position via the ribbon. Next, when the print medium is supplied to the print unit having the thermal head and the platen roller, or at a position where there is no printing even during printing, the print head is separated from the print medium to perform a ribbon saving function for saving the ribbon. Function to separate the thermal head from the platen roller to the pressure release position. When the ribbon cassette is attached or detached or when the thermal head is cleaned, the thermal head is further separated from the platen roller to the standby position from the press-contact release position so that the operation can be facilitated. The conventional thermal head holding mechanism uses either a mechanism for rotating the thermal head about a shaft or a mechanism for moving the thermal head linearly with respect to the platen roller as means for achieving these functions. .
[0003]
[Problems to be solved by the invention]
In the case of a mechanism that rotates the thermal head about the shaft with respect to the platen roller, there is an advantage that the mechanism is compact.However, if the thickness of the print medium changes, the contact angle between the thermal head and the print medium changes. However, the printing quality is not stable. Also, in the case of a mechanism that moves the thermal head linearly with respect to the platen roller, even if the thickness of the print medium changes, the contact angle between the thermal head and the print medium does not change, so that print quality is stable. Although it has advantages, it has the disadvantage that the mechanism is large and the cost is high.
[0004]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a compact and inexpensive thermal head holding mechanism while maintaining stable printing quality even for printing media having different thicknesses. is there.
[0005]
[Means for Solving the Problems]
As a means for solving the above problems, the thermal head holding mechanism of the present invention moves the thermal head from the pressure release position to the standby position by a rotational movement when exchanging the ribbon cassette or cleaning the head. The linear movement is performed between the press release position and the printing position.
[0006]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0007]
FIG. 1 is an external perspective view of a thermal transfer printer to which the ribbon cassette device according to the present invention is applied. FIG. 2 is an external view of the printer with a printing unit cover removed. FIG. 3 is a schematic configuration diagram of the card-type paper transport mechanism. FIG. 4 is an external view of the printer with the ribbon cassette removed. Next, an outline of a printing operation of the thermal transfer printer will be described with reference to FIGS.
[0008]
First, when print data is transferred together with a print command from a computer connected via an interface (not shown) to the printer, the card-type paper feeding mechanism 6 is driven by the electronic circuit control unit 4 in the printer 1, and The transfer claw 7 at the lower part of the card type paper 5 stacked on the hopper part 2 moves in the direction of arrow B in FIG. 2, and only the lowermost one of the card type paper sheets 5 stacked on the hopper part is moved to the gate part. One sheet passes through a gap between the upper gate 11 and the lower gate 12 and is sandwiched between a card-type paper transfer belt 16 and a pinch roller 13 pressed by a spring (not shown).
[0009]
At this time, the front sensor 18 detects the leading end of the card-type paper, and the card-type paper is changed from the movement by the transfer claw 7 to the movement by the card-type paper transfer belt 16, pulled out from the hopper unit 2, and The transfer mechanism 8 starts the transfer operation to the printing unit.
[0010]
Next, the operation of the card-type paper transport mechanism 8 will be described. First, a toothed belt 17 wound around a pulley 21 attached to a card-type paper transport motor shaft 20 is driven by a card-type paper transport motor 19, and is driven by a pulley (not shown) at the other end to a frame 23. , The four card-type paper transport belt driving pulleys 14 attached to the shaft 22 rotate. A card-type paper transfer belt 16 is wound around each of the card-type paper transfer belt driving pulleys 14, and the other end of the card-type paper transfer belt 16 is driven by a driven shaft 24 supported by a frame 23. Are wound around four driven pulleys 15 attached to the motor. The frame 23 is supported by a support member 25 attached to the main body so as to be rotatable about the shaft 22, and the leading end of the card-type paper transfer belt 16 is moved downward by a belt retreat spring 26, that is, FIG. It is receiving a force falling in the direction of the middle arrow C '. On the other hand, a lever 27 is fixed to the frame 23, and the lever 27 is connected to a plunger 30 of a solenoid 29 via a link 28. A belt position sensor 31 is provided near the link 28. When the solenoid 29 is excited and the plunger 30 is sucked in the direction of arrow D 'in FIG. 4, the belt position sensor 31 is shielded by the link 28. When the excitation of the solenoid 29 is turned off and the plunger 30 is pulled out in the direction of arrow D in FIG. 4 by the force of the belt retracting spring 26, the belt position sensor 31 enters a transparent state. The belt position sensor 31 detects whether the card-type paper transfer belt 16 is in a raised transfer state or a lowered retreat state. At the time of feeding and transferring the card-shaped paper, the solenoid 29 is excited, the plunger 30 is sucked in the direction of arrow D 'in FIG. 4, and the belt 16 for transferring the card-shaped paper is moved upward, that is, in the direction of arrow C in FIG. It has become. When the leading end of the card type paper reaches the optical axis of the front sensor 19, the state of the front sensor 19 changes from transmission to shielding, and the card type paper is detected. Next, the card-type paper is moved by being sandwiched by a card-type paper transport belt 16 on the lower side and a pressing plate 34 pulled by a paper pressing spring 33 on the upper side. Thereafter, even if the card-shaped paper hits the stopper 35 and is bent, the posture is straightened by the stopper 35. At this time, the paper sensor 32 attached to the stopper 35 detects the leading end of the card-type paper, and stops the card-type paper transport motor 19. The stopper 35 moves in conjunction with the adjustment amount of the card-type paper feeding mechanism 6 that moves according to the paper size by half so that the center of the image is the same as the center of the paper. Next, the excitation of the solenoid 29 is turned off, and the card-type paper transport belt 16 is lowered toward the retracted position so that the card-type paper transport belt does not hinder the print conveyance.
[0011]
Then, the printing unit is operated, and the thermal head 36 is pressed against the card type paper via the ink ribbon 9 set in the ribbon cassette 10. Next, the platen roller 37 is driven to rotate, and the card type paper is transported to the front side in the front-rear direction of the printer body (the direction of arrow A in FIG. 1). Along with this transfer, the heating elements of the thermal head 36 are selectively operated based on the print data for one line developed by the electronic circuit control unit 4, and at the same time, the cassette driving mechanism 38 is operated to cause the ink ribbon 9 to be moved. While winding, the ink applied to the ink ribbon 9 is transferred to card-type paper to perform predetermined printing. When printing of one sheet is completed, the holding mechanism of the thermal head 36 is operated to release the pressure contact of the thermal head 36 pressed against the card-type paper via the ink ribbon 9 and to separate the thermal head 36 to the pressure release position. Then, the card type paper is configured to be discharged to the discharge unit.
[0012]
Next, a thermal head holding mechanism, which is a main part of the present invention, will be described with reference to FIGS. 5 (a) to 8 (b). FIG. 5A is a perspective view of a state where the ribbon cassette is removed when the thermal head is at the standby position, and FIG. 5B is a state where the ribbon cassette is removed when the thermal head is at the pressure release position. FIG. 6A is a front view showing a state in which the ribbon cassette is removed when the thermal head is at the standby position. FIG. 6B is a view showing the ribbon cassette when the thermal head is in the pressure release position. FIG. 7A is a front view showing a state in which the ribbon cassette is removed when the thermal head is at the pressure release position, and FIG. 7B is a front view showing the ribbon when the thermal head is in the printing position. FIG. 8A is a front view showing a state in which the cassette is removed, FIG. 8A is a link relation diagram when the thermal head is at the pressure release position, and FIG. 8B is a link relation diagram when the thermal head is at the printing position. is there.
[0013]
First, the operation of the first mechanism that moves the thermal head 36 by rotation between the standby position and the pressure release position, which is the intermediate position, will be described. When the thermal head 36 is at the standby position, the head lock lever 39 is in a substantially horizontal state as shown in FIGS. 5A and 6A. When the head lock lever 39 attached to the head lock lever shaft 40 is rotated, the head pressing lever 41 coaxially attached is rotated about the head lock lever shaft 40 as a fulcrum, and attached to the pins on both sides of the head pressing lever 41. When the pressed pressing roller 42 presses the upper surface of the head frame 45 on which the head unit 43 is mounted while rotating, the head unit 43 rotates about the head block rotation shaft 44 as a fulcrum and approaches the platen roller 37. . On the other hand, one end of a spring 48 hung on a pin 47 attached to the frame 46 is also hung on the head frame 45. The spring 48 extends when the head unit 43 approaches the platen roller 37, and 43 is returned to the standby position. On the opposite side of the head lock lever 39 across the head lock lever shaft 40, a detection lever (not shown) is also attached to the head lock lever shaft 40, and rotates with the rotation of the head lock lever 39. Then, as shown in FIGS. 5 (b) and 6 (b), when the detection lever presses a micro switch (not shown) in a position where the head lock lever 39 is vertical, the head lock lever 39 has moved to the pressure release position. Is detected. At this time, the pressing roller 42 enters a hole (not shown) provided in the upper part of the head frame 45, and resists the force of returning the spring 48 to the standby position, so that the pressing roller 42 is fixed at the pressure release position. The pressure release position is a state in which the preparation of the printer is completed, and is a position where the card-type paper is fed out, the ribbon is saved, and the card after printing is ejected. When returning the thermal head 36 from the pressure release position to the standby position, first, the head lock lever 39 is rotated in a direction to return from the vertical position to the horizontal position. Then, the pressing roller 42 comes out of a hole (not shown) provided in the upper part of the head frame 45, is pulled by the spring 48, and the head unit 43 rotates about the head block rotating shaft 44 as a fulcrum, and the standby position. Return to As described above, the rotation of the head lock lever 39 causes the thermal head 36 to reciprocate between the standby position and the pressure release position. This operation is a rotational motion about the head block rotating shaft 44 as a fulcrum.
[0014]
Next, the operation of the second mechanism for linearly moving the thermal head 36 between the intermediate position shown in FIG. 7A, which is the pressure release position, and the printing position shown in FIG. 8 will be described. When the thermal head 36 is moved from the pressure release position to the print position, the pulse motor 51 is rotated counterclockwise. Then, the disk 52 attached to the pulse motor shaft and the roller 53 attached to the disk 52 also rotate, pulling the arm 56 via the link A 54 and the link B 55, and the pusher 58 rotated about the shaft 57 pushes the spring 59. . At this time, the spring 59 pushes down the head fixing block 60 without being compressed. A head bracket 61 and a thermal head 36 are attached to the head fixing block 60, and the thermal head 36 is simultaneously pushed down. The thermal head 36 abuts on the platen roller 37 via a recording medium such as an ink ribbon or card-type paper and stops. When the pulse motor 51 is further rotated, the spring 56 is compressed. As the compression amount of the spring 59 increases, the pressure at which the thermal head 36 is pressed against the platen roller 37, that is, the printing pressure, increases. The control of the printing pressure is performed as follows. First, when the disk 52 attached to the pulse motor shaft rotates together with the rotation of the pulse motor 51, the slit portion 62 provided on the disk 52 rotates, so that the sensor 63 is shielded from transmission. The printing pressure is controlled by counting a predetermined number of pulses based on the point in time when the detection of the sensor 63 changes from transmission to shielding. When the printing pressure is increased, the number of pulses to be counted is increased, and when the printing pressure is decreased, the number of pulses to be counted is decreased. By appropriately setting the number of pulses of the pulse motor 51 for compressing the spring 59, good print quality can be obtained. The movement between the pressure release position and the printing position by the pulse motor 51 is carried out by a center of the head unit 43 supported by a guide shaft 49 attached to the head frame 45, and a corner (not shown) on both sides of the head frame 45. The roller 50 in the hole guides the up and down movement, so that a linear movement is performed. When returning the thermal head from the printing position to the pressure release position, the pulse motor 51 is rotated clockwise to perform the reverse operation of the movement sequence from the pressure release position to the print position.
[0015]
【The invention's effect】
As described above, the thermal head holding mechanism of the present invention moves the thermal head from the pressure release position to the standby position by rotational movement when replacing the ribbon cassette or cleaning the head, and moves the thermal head from the pressure release position to the standby position. Since the movement is performed linearly up to the printing position, compact and stable printing quality can be provided.
[Brief description of the drawings]
FIG. 1 is an external view of a printer according to an embodiment of the present invention.
FIG. 2 is an external view of the printer according to the embodiment of the present invention with a printing unit cover removed.
FIG. 3 is a schematic configuration diagram of a card-type paper transport mechanism of the printer according to the embodiment of the present invention.
FIG. 4 is an external view of the printer according to the embodiment of the present invention in a state where a ribbon cassette is removed from a main body.
FIG. 5A is a perspective view illustrating a state in which a ribbon cassette is removed when a thermal head of a printer according to an embodiment of the present invention is at a standby position, and FIG. It is a perspective view (b) of the state where it did.
FIG. 6A is a front view of the printer according to the embodiment of the present invention in a state where the thermal head is at a standby position and a ribbon cassette is removed, and FIG. It is a front view (b) of a state.
FIG. 7A is a front view of the printer according to one embodiment of the present invention in a state where the ribbon cassette is removed when the thermal head is at the pressure release position, and the ribbon cassette is removed when the thermal head is at the printing position. It is a front view (b) of a state.
8A and 8B are a link relation diagram when the thermal head of the printer according to the embodiment of the present invention is at the pressure release position and a link relation diagram when the thermal head is at the printing position, respectively.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Printer 2 Hopper 3 Printing part cover 4 Electronic circuit control part 5 Stacked card type paper 6 Card type paper feeding mechanism 7a, 7b Transfer claw 8 Card type paper transfer mechanism 9 Ink ribbon 10 Ribbon cassette 11 Upper gate 12 Lower gate 13 Pinch roller 14 Card-type paper transport belt drive pulley 15 Follower pulley 16 Card-type paper transport belt 17 Toothed belt 18 Front sensor 19 Card-type paper transport motor 20 Card-type paper transport motor shaft 21 Pulley 22 Shaft 23 Frame 24 Follower Shaft 25 support member 26 belt retracting spring 27 lever 28 link 29 solenoid 30 plunger 31 belt position sensor 32 paper sensor 33 paper press spring 34 press plate 35 stopper 36 thermal head 37 platen roller 38 case Drive mechanism 39 head lock lever 40 head lock lever shaft 41 head pressing lever 42 pressing roller 43 head unit 44 head block rotating shaft 45 head frame 46 frame 47 pin 48 spring 49 guide shaft 50 roller 51 pulse motor 52 disk 53 roller 54 link A
55 Link B
56 arm 57 shaft 58 pusher 59 spring 60 head fixing block 61 head bracket 62 slit section 63 sensor

Claims (1)

A thermal head holding mechanism that positions the thermal head at a printing position when printing, and retracts the thermal head to a standby position when not printing,
Providing an intermediate position between the standby position and the printing position,
A first mechanism for rotating the thermal head between the standby position and the intermediate position by rotational movement;
A second mechanism for linearly moving the thermal head between the intermediate position and the printing position.

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