JP3667532B2 - Thermal transfer printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal transfer printer, and more particularly to a thermal transfer printer that can obtain an appropriate pressure of a thermal head against a platen depending on the type of recording medium or ink ribbon.
[0002]
[Prior art]
A conventional thermal transfer printer supports a recording medium such as paper and an ink ribbon of a desired color in front of a platen, and a thermal head in which a plurality of heating elements are aligned reciprocates along the platen together with the carriage. Then, the heat generating element of the thermal head is selectively heated based on the print data, and the ink ribbon ink is transferred to a recording medium to print a desired image.
Such thermal transfer printers are widely used as output devices for computers, word processors, and the like for reasons such as high print quality, low noise, low cost, and ease of maintenance.
[0003]
In the thermal transfer printer as described above, a lever having the thermal head attached to one end side via a spring member and a cam member having a cam groove engaged with a roller attached to the other end side of the lever are disposed. Has been. The lever is rotatable about a support shaft at a substantially central portion.
When the rotation of the drive source is transmitted and the cam member rotates, the roller of the lever moves along the cam groove of the cam member and the lever rotates, so that the thermal head is raised / lowered with respect to the platen. It is supposed to be.
The thermal head lowered by such an operation can print a desired image on the recording member by sandwiching the ink ribbon and the recording member between the platen and the platen with a predetermined pressure contact pressure.
[0004]
As shown in FIG. 7, the cam member 21 has a gear formed on its outer peripheral portion, and a cam groove 22 having a predetermined depth and width having an outer wall 22a and an inner wall 22b is formed on one side surface. . A roller 23 indicated by a two-dot chain line rotatably supported on the other end of the lever (not shown) is engaged in the cam groove 22.
The roller 23 is moved in the cam groove 22 by the rotation of the cam member 21, and the lever is rotated by the movement in the cam groove 22 so that the thermal head is moved up / down.
The cam groove 22 has first, second, third, and fourth cam positions 21a, 21b, 21c, and 21d at predetermined rotation angles and different radial dimensions r1, r2, Each of r3 and r4 is formed.
The cam diagram of the cam groove 22 having the respective cam positions 21a, 21b, 21c, and 21d as shown in FIG. 8 shows that the portions of the respective cam positions 21a, 21b, 21c, and 21d are flat. The first, second, and third inclined surfaces 21e, 21f, and 21g are formed between the cam positions 21a, 21b, 21c, and 21d.
[0005]
The movement of a thermal head (not shown) when the cam member 21 having the cam diagram as described above is rotated will be described.
First, when the roller 23 is positioned at the fourth cam position 21d, the thermal head is in an up state, and the roller 23 is in contact with the inner wall 22b of the cam groove 22. While the roller 23 is moving in the fourth cam position 21d, the thermal head remains in the up state and cannot move in the platen direction.
[0006]
Next, when the cam member 21 shown in FIG. 7 is rotated counterclockwise, the roller 23 located at the fourth cam position 21d moves on the third slope 21g of the cam diagram shown in FIG. Located at the third cam position 21c. At this time, the thermal head (not shown) is in a down state and is brought into pressure contact with the surface of the platen (not shown) with a first pressure.
When the cam member 21 is further rotated counterclockwise and the roller 23 is moved along the second inclined surface 21f shown in FIG. 8, the roller 23 is positioned at the second cam position 21b. Then, the thermal head can press the platen surface with a second pressure contact pressure larger than the first pressure contact pressure.
[0007]
Further, when the cam member 21 is further rotated counterclockwise and the roller 23 is moved along the first inclined surface 21e shown in FIG. 8, the roller 23 is positioned at the first cam position 21a. Then, the thermal head can press the platen surface with a third pressure contact pressure that is larger than the second pressure contact pressure.
That is, the conventional thermal transfer printer rotates the cam member 21 and moves the roller 23 in the cam groove 22 from the fourth cam position 21d to the third cam position 21c, thereby lowering the thermal head to the platen. The first pressure contact pressure is used. Thereafter, the roller 23 is moved from the third cam position 21c to the second cam position 21d and the first cam position 21a, so that the pressure contact pressure on the platen of the thermal head is changed from the first pressure contact pressure to the third pressure contact pressure 3. It can be changed to the size of the stage.
Therefore, the pressure of the thermal head against the platen can be controlled in three stages depending on the type of the recording medium or the ink ribbon, and a high-quality image can be printed.
[0008]
[Problems to be solved by the invention]
However, in the conventional thermal transfer printer as described above, the cam diagrams of the respective cam positions 21a, 21b, and 21c after the thermal head is lowered are formed by horizontal parallel portions . The gradients of the first, second, and third inclined surfaces 21e, 21f, and 21g connecting 21a, 21b, 21c, and 21d are increased, and the rotational load on the cam member 21 is increased. When the rotational load of the cam member 21 becomes large, a drive source for rotationally driving the cam member 21 is required to have a high torque, and the drive source has to be enlarged. Therefore, it has been an obstacle to miniaturization of the conventional thermal transfer printer.
[0009]
Since the cam positions 21a, 21b, and 21c are formed of parallel portions, the cam member 21 increases when the number of cam positions is increased, and the number of cam positions decreases when the cam member 21 is decreased. There is a problem that the pressure contact pressure of the thermal head cannot be varied at any time according to the type of ink ribbon.
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems and to provide a thermal transfer printer capable of continuously changing the pressure contact pressure of a thermal head against a platen with a small driving source.
[0010]
[Means for Solving the Problems]
As a first means for solving the above problems, a thermal transfer printer of the present invention includes a platen, a thermal head that can be raised / lowered with respect to the platen, and a rotatable head holding member to which the thermal head is attached. A cam member having a cam groove with which a part of the head holding member engages, and a rotatable drive source for driving the cam member, and the cam line has an inclined cam diagram. It was formed as represented in a straight line shape, by controlling the rotation amount of the drive source, has a structure which is adapted to control the pressure contact pressure against the platen of the thermal head.
[0011]
Further, as a second solving means for solving the problem, the cam member can be rotated, the driving source is configured by a pulse motor, and the rotation amount of the driving source is controlled by the number of driving steps, The rotation angle of the cam member is controlled.
[0012]
Further, as a third solving means for solving the above problem, a reference marker indicating a rotation reference position of the cam member is provided on the cam member, and a detection member capable of detecting the reference marker is arranged in the vicinity of the cam member. And after the detection member detects the reference marker, the drive source is rotated by a predetermined number of drive steps to rotate the cam member by a predetermined rotation angle.
[0013]
Further, as a fourth means for solving the above problem, after the drive source is rotated by a predetermined number of steps, the rotation of the drive source is locked so that the drive source does not forward / reverse, The cam member is prevented from rotating.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the thermal transfer printer of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a carriage according to the present invention, FIG. 2 is a plan view of the main part of the carriage, FIG. 3 is a side view of the main part of the carriage, and FIG. 4 is a plan view of the cam member according to the present invention. 5 is an explanatory diagram for explaining a cam diagram according to the present invention, and FIG. 6 is a graph for explaining a change curve of the pressure contact pressure of the thermal head according to the present invention.
[0015]
First, the main part of the thermal transfer printer of the present invention will be described with reference to FIG. 1. A flat platen 1 is disposed at a predetermined position of a frame (not shown), and a flat printing surface 1a made of rubber or the like is provided on this surface. Is formed.
A carriage 2 that is pivotally supported by a carriage shaft (not shown) and is movable along the platen 1 is disposed on the side facing the platen 1.
The carriage 2 is configured such that an appropriate drive belt 3 wound around a pair of pulleys (not shown) is reciprocated by carriage drive means such as a motor (not shown). An FPC 4 that transmits electric power, a control command, and the like to a desired mechanism in the carriage 2 (not shown) is disposed.
[0016]
The carriage 2 is provided with a thermal head 6 attached to a head mounting base 5, and a plurality of heating elements (not shown) are provided on the surface facing the platen 3. It is formed in a line.
An ink ribbon (not shown) is accommodated on the upper surface of the carriage 2, and a ribbon cassette (not shown) for guiding the ink ribbon between the thermal head 6 can be mounted.
[0017]
A winding bobbin 7, a supply bobbin 8, a winding roller drive shaft 9, and a supply roller drive shaft 10 protrude from the upper surface of the carriage 2.
On the opposite side of the thermal head 6 from the side facing the platen 1, an FPC cover 11 for storing and protecting FPCs (not shown) corresponding to the FPCs 4 individually routed is provided at an appropriate interval. Yes.
A cassette mounting table 12 on which the ribbon cassette can be positioned and mounted is attached to the upper surface of the carriage 2 so that a head driving means and the like, which will be described later, inside the carriage 2 are closed from above.
[0018]
As shown in FIGS. 2 and 3, the head driving means for raising / lowering the thermal head 6 with respect to the platen 1 can freely rotate a cam member 13 having a gear on its outer peripheral portion at a desired position of the carriage 2. It is arranged. A cam groove 14 is formed on the rear surface of the cam member 3 as shown by a broken line.
As shown in FIG. 3, the thermal head 6 is fixed to a head mounting base 5 via a heat radiating plate 6a made of aluminum or the like. The head mounting base 5 is a head made of a metal plate having a substantially L-shape in plan view. The holding member 15 is attached to one end side 15a via an elastic member 16 such as a coil spring.
When the head holding member 15 is rotated by rotation of a driving source 20 described later and the thermal head 6 is lowered to the platen 1 side, the elastic member 16 acts on the printing surface 1a of the platen 1 with a predetermined pressure. It comes to come in pressure contact.
[0019]
The head holding member 15 is disposed on the lower side of the cam member 13, and a rotatable roller 15 c is erected at the end of the other side 15 b that is a part of the cam member 13. The cam groove 14 is engaged.
The head holding member 15 is pivotally supported on a support shaft 17, and a torsion coil spring 18 is wound around the support shaft 16, and one side 15a of the head holding member 15 is arranged in the direction of arrow A shown in FIG. It is elastically biased toward the platen 1 side.
[0020]
As shown in FIG. 2, an idle gear 19 comprising a two-stage gear meshes with the gear on the outer peripheral portion of the cam member 13, and this idle gear 19 is connected to the rotating shaft of a drive source 20 such as a pulse motor. The attached motor pinion 21 is engaged.
By controlling the number of drive steps of the drive source 20, the amount of rotation (rotation angle) of the drive source 20 can be controlled.
The cam member 13 is viewed from the back side where the cam groove 14 as shown in FIG. 4 is formed. The back surface 13a of the cam member 13 is composed of an outer wall 14a and an inner wall 14b. The cam groove 14 is formed with a depth and a width.
A roller 14c indicated by a two-dot chain line that is movable when the cam member 13 rotates is engaged in the cam groove 14.
[0021]
The cam groove 14 is formed with first and second cam positions 14d and 14e in a range of a predetermined rotation angle, and the first cam position 14d is camped from one side closer to the rotation center of the cam member 13. The member 13 is formed in a curved shape up to the other side on the outer peripheral side on the side far from the rotation center.
The shape of the cam groove 14 of the first cam position 14d, as shown in FIG. 5, the cam diagrams are formed as represented in inclined straight line shape at a predetermined angle. Therefore, when the cam member 13 is rotated when the roller 15c is located at the first cam position 14d, the dimension from the rotation center of the cam member 13 to the roller 15c moving in the cam groove 14 is the same as the cam member 13. The angle changes linearly in proportion to the rotation angle.
[0022]
The cam groove 14 of the second cam position 14e is connected to the other side of the first cam position 14d, and has a predetermined rotation angle with the same radius from the rotation center of the cam member 13 near the outer periphery of the cam member 13. It is formed within the range. Therefore, as shown in FIG. 5, the cam groove 14 at the second position 14e becomes a horizontal cam diagram that does not incline, and the cam member 13 rotates when the roller 15c is positioned at the second position 14e. Even so, the distance from the roller 15c to the rotation center of the cam member 13 does not change.
[0023]
In addition, a reference marker (not shown) indicating the rotation reference position of the cam member 13 is provided at a predetermined position on the back surface 13a on the side where the cam groove 14 is formed, and a detection member that can detect this reference marker ( (Not shown) is disposed in the vicinity of the cam member 13, and after the detection member detects the reference marker, the drive source 20 is rotated by a predetermined number of drive steps to rotate the cam member 13 by a predetermined rotation angle. It has become.
[0024]
The relationship between the rotation of the cam member 14 as described above and the up / down operation of the thermal head 6 will be described. First, in the up state in which the thermal head 6 is separated from the platen 1, the roller 15c moves to the second cam position 14e. It is located in the cam groove 14 and is in contact with the inner wall 14 b by the elastic force of the torsion coil spring 18.
While the roller 15c is in the second cam position 14e, even if the cam member 13 is rotated, the thermal head 6 remains up and does not move toward the platen 1 side.
[0025]
Next, when the cam member 13 is rotated in the direction of arrow C and the roller 15c is moved from the second cam position 14e into the cam groove 14 of the first cam position 14d, the head holding member 15 shown in FIG. The thermal head 6 moves to the platen 1 side by rotating clockwise about the shaft 17.
When the cam member 13 is further rotated in the direction of arrow C by a predetermined rotation angle, the thermal head 6 is lowered with respect to the platen 1, and a heating element (not shown) of the thermal head 6 is moved to an ink ribbon (not shown). The ink ribbon and the recording member are pressed and sandwiched between the thermal head 6 and the platen 1.
When the cam member 13 is further rotated in the direction of arrow C from this state, the roller 15c that is in contact with the inner wall 14b of the cam groove 14 is in contact with the outer wall 14a side, and the center of rotation of the first cam position 14d is along the outer wall 14a. Is moved to the end 14f on the side close to, and the rotation of the cam member 13 is stopped.
At this time, the roller 15c can be moved substantially linearly from the outer peripheral portion of the cam member 13 to the terminal end 14f on the side close to the rotation center, and by the movement of the roller 15, the pressure contact pressure of the thermal head 6 against the platen 1 is As shown in FIG. 6, it can be varied steplessly inclined substantially linearly.
[0026]
That is, in the thermal transfer printer of the present invention, the shape of the cam groove 14 is formed so as to be a cam line diagram having a substantially linear inclined curve, so that the number of drive steps of the drive source 20 can be arbitrarily changed. Thus, the rotation angle of the cam member 13 can be arbitrarily changed.
Therefore, the pressure contact pressure of the thermal head 6 against the platen 1 can be varied steplessly by merely controlling the number of drive steps of the drive source 20 according to the type of ink ribbon.
Further, the shape of the cam groove 14, since the cam diagrams are formed as represented in a straight line shape inclined, without increasing the shape of the cam member 13, the inclination angle of the cam diagram Therefore, the rotational load of the drive source 20 can be reduced.
[0027]
In addition, the pressure contact pressure of the thermal head 6 with respect to a predetermined number of drive steps from the reference marker (not shown) of the drive source 20 and the optimum pressure contact pressure for each type of ink ribbon are obtained in advance, for example, monochrome When the ink ribbon is changed to a metallic color ink ribbon, the amount of rotation of the drive source 20 is controlled by the number of drive pulses, and the rotation angle of the cam member 13 is controlled, so that the optimum thermal for the metallic color ink ribbon is achieved. The pressure of the head 6 against the platen can be controlled.
Then, after rotating the drive source 20 by a predetermined number of steps, the rotation of the drive source is locked so that the drive source 20 does not forward / reverse, and the cam member 13 resists the pressure contact pressure of the thermal head 6. Therefore, the rotation of the cam member 13 is prevented so as not to reverse.
The method of locking the rotation of the drive source 20 is to keep one or two phases energized without changing the motor phase of the drive source 20 such as a pulse motor by control from a control unit (not shown). This is possible.
[0028]
Thermal transfer printer of the present invention, the thermal head 6 by making up / down cam grooves 14 to which the cam diagrams represented in a straight line shape inclined, the pressing pressure with respect to the platen 1 of the thermal head 6, is set The maximum pressure contact pressure can be arbitrarily changed in a stepless manner.
Therefore, even if there are many types of recording media or ink ribbons, the pressure contact pressure of the thermal head against the platen can be controlled to an optimum state for printing, and a high-quality image can be printed.
[0029]
In the present invention, the cam member 13 is described as a rotatable disk-shaped member, but the cam member 13 is configured to be slidable (not shown), and the cam groove 14 is formed in an inclined linear shape. But it ’s okay. In this case, the shape of the cam groove can be a straight line having the same inclination angle as that of the cam diagram, and the cam groove can be easily manufactured.
[0030]
【The invention's effect】
Thermal transfer printer of the present invention, the shape of the cam groove of the cam member, by its cam diagram is formed as represented in a straight line shape inclined to control the amount of rotation of the drive source, the thermal head Since the pressure contact pressure on the platen is controlled, the pressure contact pressure on the platen can be selected in a stepless manner without increasing the cam member, and with the optimum pressure contact pressure for each type of ink ribbon, Printing can be performed by pressing the recording member against the platen. Therefore, even if there are many types of ink ribbons, it is possible to provide a thermal transfer printer that can print high-quality images.
Further, by forming such that the cam diagram of the shape of the cam groove is represented in a straight line shape inclined at a small cam member, and also a drive source for small, low torque, the pressure contact pressure of the thermal head The thermal transfer printer can be reduced in size.
[0031]
In addition, the cam member can be rotated, the drive source is configured by a pulse motor, the rotation amount of the drive source is controlled by the number of drive steps, and the rotation angle of the cam member is controlled. By controlling the number of driving steps, the rotation angle of the cam member can be changed, and the optimum pressure of the thermal head can be obtained corresponding to many types of ink ribbons.
[0032]
In addition, a reference marker indicating a rotation reference position of the cam member is provided on the cam member, a detection member capable of detecting the reference marker is disposed in the vicinity of the cam member, and the detection member detects the reference marker, Since the drive source is rotated by a predetermined number of drive steps and the cam member is rotated by a predetermined rotation angle, the cam member can be reliably rotated by a predetermined rotation angle, and the thermal head can be rotated by a platen. Can be welded at an optimum pressure.
[0033]
Further, after the drive source is rotated by a predetermined number of steps, the drive source is locked so as not to be forward / reverse so that the cam member is prevented from rotating. After the pressure contact with the platen, the cam member is prevented from rotating by the lock of the drive source, and the pressure contact pressure of the thermal head does not change. For this reason, the thermal head during printing can always be brought into pressure contact with the platen with an optimum pressure, and a high-quality image can be printed.
[Brief description of the drawings]
FIG. 1 is a perspective view of a carriage according to the present invention.
FIG. 2 is a plan view of an essential part of a carriage according to the present invention.
FIG. 3 is a side view of an essential part of a carriage according to the present invention.
FIG. 4 is a plan view of a cam member according to the present invention.
FIG. 5 is an explanatory diagram of a cam diagram according to the present invention.
FIG. 6 is a graph for explaining a change curve of pressure contact pressure of a thermal head according to the present invention.
FIG. 7 is a plan view of a cam member of a conventional thermal transfer printer.
FIG. 8 is an explanatory diagram of a cam diagram of a conventional thermal transfer printer.
[Explanation of symbols]
1 Platen 1a Printing surface 2 Carriage 3 Drive belt 4 FPC
5 Head mounting table 6 Thermal head 7 Winding bobbin 8 Supply bobbin 9 Pinch roller 10 Pinch roller 11 FPC cover 12 Cassette mounting table 13 Cam member 13a Back surface 14 Cam groove 14a Outer wall 14b Inner wall 14d First cam position 14e Second cam position 14f End 15 Head holding member 15a One side 15b The other side 15c Roller 16 Elastic member 17 Support shaft 18 Torsion coil spring 19 Idle gear 20 Drive source 21 Motor pinion 22 Winding gear

Claims (4)

A platen, a thermal head that can be moved up / down with respect to the platen, a rotatable head holding member to which the thermal head is attached, and a cam member having a cam groove with which a part of the head holding member is engaged. , and a rotatable drive source for driving the cam member, the shape of the cam groove, formed such that the cam diagram is represented in a straight line shape inclined, the rotation amount of the drive source A thermal transfer printer characterized by controlling the pressure contact pressure of the thermal head against the platen.   The cam member is rotatable, the drive source is constituted by a pulse motor, the rotation amount of the drive source is controlled by the number of drive steps, and the rotation angle of the cam member is controlled. The thermal transfer printer according to claim 1.   A reference marker indicating the rotation reference position of the cam member is provided on the cam member, a detection member capable of detecting the reference marker is provided in the vicinity of the cam member, and after the detection member detects the reference marker, a predetermined marker is provided. 3. The thermal transfer printer according to claim 2, wherein the cam source is rotated by a predetermined rotation angle by rotating the driving source by the number of driving steps.   After the drive source is rotated by a predetermined number of steps, the rotation of the drive source is locked so that the drive source does not rotate forward / reversely to prevent the cam member from rotating. The thermal transfer printer according to claim 2 or 3.

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