JPH0576915B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a platen gap adjustment device for a printer that performs printing by a print head that moves in space in opposition to a platen.

[Conventional technology]

In printers that print using a print head that moves in space in opposition to the platen, paper thickness is It is necessary to always keep the distance from the paper surface to the print head tip, that is, the platen gap, constant for different types of paper.

If such a platen gap is adjusted manually by an operator,
Differences may occur between individual operators, or adjustment errors may occur, making it impossible to achieve the objective.

Therefore, printers have been proposed that are equipped with a device that automatically adjusts the platen gap.

FIG. 9 is a perspective view of a printer equipped with a conventional platen gap adjustment device.

In the figure, 1 is a platen, 2 is a print head facing the platen 1, and the print head 2 is
is mounted on the carriage 4 so that its tip faces the platen 1.

This carriage 4 is movably attached to a carriage shaft 3 provided parallel to the platen 1, so that the print head 2 moves together with the carriage 4 along the platen 1 to perform a printing operation.

5 is a cam fixed to both ends of the carriage shaft 3; 6 is a pulse motor that rotates the cam 5 via gears 7a and 7b; and 8 is a spring.

9 is a slit disk; 10 is a photo sensor that outputs a signal according to the slit as the slit disk 9 rotates; these slit disk 9 and the photo sensor 10 electrically detect the rotation and step-out of the pulse motor 6. can do.

11 is a sheet of paper set on the platen 1 so as to pass between the platen 1 and the print head 2, and 12 is a sheet of paper set so as to travel between the tip of the print head 2 and a ribbon protector located in front of it. It is an ink ribbon.

In a printer equipped with the above-mentioned elements, the conventional platen gap adjusting device also includes the elements 5 to 10 mentioned above.

This platen gap adjustment device always sets the platen gap, which is the distance from the surface of the paper 11 to the tip of the print head, using the following operation for sheets 11 of different thicknesses.

First, when the paper 11 is wound around the platen 1 and set, the pulse motor 6 rotates in the forward direction, and this rotation is transmitted to the carriage shaft 3 via the gears 7a and 7b.

Therefore, the carriage shaft 3 and the cam 5 fixed to the carriage shaft 3 rotate together to move the carriage shaft 3 away from the platen 1 against the spring 8.
The print head 2 moves back with respect to the platen 1 together with the carriage 4 and stops at a predetermined position.

Subsequently, when the pulse motor 6 rotates in the reverse direction, the print head 2 moves forward with the carriage 4 relative to the platen 1 due to the restoring force of the spring 8, and the ribbon protector (not shown) abuts against the platen 1 through the paper 11.

Here, print head 2 is no more than platen 1.
direction, and the pulse motor 6 loses synchronization.

At this time, the rotation of the slit disk 9 also stops and the photo sensor 10 no longer outputs a pulse signal.
As a result, it is detected that the motor is out of step.

At this point, the pulse motor 9 rotates forward again by a predetermined amount of rotation, thereby creating a constant gap between the surface of the paper 11 and the tip of the print head 2.

[Problem that the invention seeks to solve]

However, in the above-mentioned conventional platen gear adjustment device, the adjustment of the platen gear is performed indirectly by adjusting the position of the carriage shaft, so even if there is distortion in the carriage shaft, it is not taken into consideration. ± to specified amount
There is a problem in that distortion occurs and it is difficult to obtain an appropriate platen gap.

Furthermore, since the conventional apparatus described above has the characteristics shown in FIG. 10, it is difficult to obtain an appropriate platen gap in this respect as well.

In other words, according to the conventional device, after the ribbon protector located in front of the print head compresses the paper, the pulse motor rotates while further bending the ribbon protector, and the reaction force from them is applied to the pulse motor. Since the pulse motor steps out and stops when the torque matches the torque of

The amount of overrun ΔN depends on the torque difference between the pulse motors, so if there are variations in the initial torque of the pulse motor, a decrease in torque due to temperature rise, or fluctuations in voltage, the amount of overrun will change, resulting in a printout. There is a problem in that the return amount X of the head becomes unstable and it becomes difficult to obtain an appropriate platen gap.

In addition, in the conventional device, since the platen gap is adjusted by rotating the carriage shaft, a rotating means such as a gear and a driving means such as a motor for driving the rotating means must be provided at one end of the carriage shaft. Therefore, there is a problem that the device becomes large in size, and there is also a problem that the device becomes expensive due to the use of a slit disk and a photo sensor.

The present invention has been made to solve these problems, and provides an inexpensive platen gap adjustment device that can obtain an appropriate platen gap depending on the thickness of the paper, does not increase the size of the device, and is inexpensive. The purpose is to

[Means for solving problems]

In order to achieve this object, the present invention includes a print head that prints, via an ink ribbon, on paper set on the platen on a carriage mounted on a carriage shaft so as to move along the platen; In this platen gap adjustment device for a printer equipped with a ribbon protector located in front of the front end of the print head, the ribbon protector has a configuration in which two conductive films are opposed to each other and a spacer is provided on the opposing surface of one of the films. and is provided at the rear end of the carriage, and by moving the rear end up and down, the carriage is rotated around the carriage shaft, and the tip of the print head approaches and moves away from the platen. a carriage vertical movement means, a pulse motor provided at the rear end of the carriage for operating the carriage vertical movement means, and a platen gap adjustment mechanism;
rotating the pulse motor so that the carriage up-and-down movement means raises the rear end of the carriage and brings the leading end of the print head closer to the platen;
When the tip of the print head contacts the platen through the two films forming the ribbon protector and the two films come into contact and become electrically conductive, the pulse motor stops rotating, and then the print head stops rotating. and motor control means for rotating the pulse motor in the opposite direction by a certain amount so that the carriage vertical movement means lowers the rear end of the carriage by a certain amount so that a certain platen gap is created between the leading end of the head and the paper. Features.

[Effect]

In the present invention having such a configuration, when adjusting the platen gap, the motor control means causes the pulse motor to rotate, and the carriage vertical movement means raises the rear end of the carriage to bring the front end of the print head closer to the platen. When the tip of the print head contacts the platen through two films forming a ribbon protector and the two films come into contact and become electrically conductive, the motor control means stops the rotation of the pulse motor.
Thereafter, the motor control means reversely rotates the pulse motor by a certain amount, thereby lowering the rear end of the carriage by a certain amount via the carriage up-and-down movement means, whereby the print head contacts the platen as a reference position. As the leading edge moves away from the platen, a constant platen gap is obtained between the leading edge of the printhead and the paper.

〔Example〕

Examples will be described below with reference to the drawings.

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a side view of the same, FIG. 3 is an exploded perspective view of a main part of the same embodiment, and FIG. 4 is a partially cutaway front view of the same.

In the figure, 1 is a platen, 2 is a print head facing the platen 1, and the print head 2 is
is mounted on the carriage 4 so that its tip faces the platen 1.

This carriage 4 is movably attached to a carriage shaft 3 provided parallel to the platen 1, and the print head 2 moves along the platen 1 together with the carriage 4 to perform a printing operation.

Reference numeral 11 indicates a sheet of paper wound around and set on the platen 1, and 12 indicates an ink ribbon.

Reference numeral 13 denotes a space motor fixed to the lower surface of the carriage 4. A pinion 15 meshed with a rack 14 is attached to the rotating shaft of this space motor 13 as shown in FIG. This causes the carriage 4 to move along the carriage shaft 3.

A pulse motor 16 is used as a power source for adjusting the platen gap, and is controlled by a motor control circuit (motor control means) not shown.

Reference numeral 17 denotes a parallel link member, and as shown in FIG. 3, this parallel link member 17 has a slider portion 17a having an engagement slit and a fixing portion 17b having a screw hole, which are connected by two parallel flexible plates. shaped portion 17c,
It has a structure in which it is integrally connected by 17d.

The parallel link member 17 is fixed to the lower surface of the carriage 4 by passing a fixing screw 18 through a corner of the rear end of the carriage 4 and screwing it into a screw hole in the fixing part 17b. The rear end of the carriage 4 is slidably held by engaging the engagement slit of the slider portion 17a.

On the other hand, the pulse motor 16 is connected to the fixing screw 18 on the rear end side of the carriage 4, as shown in FIG.
It is fixed near the corner on the opposite side.

The pulse motor 16 has a shaft portion 21 having an adjustment screw 20 cut therein.
A nut 22 is screwed on.

This nut 22, together with the shaft portion 21 and the parallel link member 17, constitutes a carriage vertical movement means for vertically moving the rear end of the carriage 4, and the nut 22 has a pair of parallel parts in its outer shape.
It fits into an oval hole 23 provided in the slider portion 17a of the parallel link member 17, and its tip abuts the bottom of the oval hole 23 as shown in FIG.

Here, the relationship between the rotation of the pulse motor 16, the operation of the parallel link member 17, and the platen gap will be explained.

When the pulse motor 16 rotates in the CCW direction shown in FIG.
is separated from the pulse motor 16, and its tip moves toward the slider portion 17a, pressing the slider portion 17a.

This slider portion 17a engages with a base plate 19 through an engagement slit, and since this base plate 19 is fixed, the nut 2
As the tip of the slider 17a moves, the slider portion 17a
and a fixed part 17b fixed to the carriage 4.
The flexible plate portions 17c and 17d between the slider portion 17a are bent, and the fixed portion 17b is lifted up from the slider portion 17a.

The flexible plate-like portions 17c and 17d are parallel to each other,
Since the slider portion 17a can be bent without tilting with respect to the base plate 19, the rear end of the carriage 4 is pushed up horizontally.
Therefore, the carriage 4 rotates around the carriage shaft 3 in the direction of arrow A shown in FIG. The platen gap becomes smaller.

On the other hand, when the pulse motor 16 rotates in the CW direction, the nut 22 is drawn toward the pulse motor 16 by the action of the screw 20, and the tip of the nut 22 moves toward the carriage 4, so that the flexible plate portion 17c , 17d recovers to its original flat state due to its own restoring force.

Along with this, the rear end of the carriage 4 is pulled down, and the carriage 4 rotates in the direction of arrow B around the carriage shaft 3, so that the print head 2 also rotates together with this, so that its tip surface touches the surface of the platen 1. Since the platen gap is separated from the platen gap, the platen gap becomes larger.

Returning to the explanation of FIG.

A ribbon protector 24 has a pressure-sensitive function that becomes electrically conductive when subjected to a certain pressure, and this ribbon protector 24 and the pulse motor 16
and the parallel link member 17 constitute the platen gap adjustment device of this embodiment.

This ribbon protector 24 is located in front of the print head 2 and is fixed on the carriage 4 so as to be interposed between the paper 11 and the ink ribbon 12. This fixation is performed by connecting a connector 25 connected to a detection circuit (not shown) to the carriage 4. 4.
This is done by inserting an electrode, which will be described later, formed at the lower end of the ribbon protector 24 into the connector 25.

FIG. 5 is a front view showing an example of the configuration of the ribbon protector 24, FIG. 6 is a side view of the same, and FIG. 7 is an exploded perspective view of the same.

In the figure, 26 and 27 are films made of polyester or the like, and the film 26 has an electrode 26a and a diamond-shaped window 26b through which the pins of the print head 2 can pass, and a surface facing the film 27. A plurality of elastic rubber protrusions 28 are formed in the protrusion, and a metal film serving as a conductive portion is coated by a manufacturing method such as vacuum deposition.

On the other hand, like the film 26, the film 27 has a diamond-shaped window 27b through which the electrode 27a and the pins of the print head 2 can pass. All parts except for are coated with a metal film as a conductive part.

The reason why the facing point 29 is a non-coated portion is because the rubber protrusion 28 of the film 26 is coated with a metal film by vacuum deposition.

Reference numeral 30 denotes a double-sided adhesive tape formed in the shape of an insulating frame, and the films 26 and 27 are bonded together using this double-sided adhesive tape 30.

In addition to the rubber protrusion 28, a spacer that provides a certain distance between the conductive parts of the films 26 and 27 and eliminates this distance by external pressing force may be, for example, an elastic insulating material. A sexual web etc. can be considered.

Next, the operation of the above-mentioned configuration will be explained using FIG. 8 together with the above-mentioned figures.

8a, b, and c are side views of essential parts showing the operation of this embodiment, in which a is a state in which the print head 2 approaches the platen, b is a state in which it abuts against the platen 1, and c is a state in which the print head 2 is in contact with the platen 1. This shows a state of further separation.

First, when adjusting the platen gap, a motor control circuit (not shown) rotates the pulse motor 16 in the CW direction to draw the nut 22 toward the pulse motor 16, restores the parallel link member 17 to a flat state, and lowers the rear end of the carriage 4. Expand the platen gap by

In this state, the operator wraps the paper 11 and sets the paper 11.

After the paper 11 has been set, the motor control circuit rotates the pulse motor 16 in the CCW direction, moves the nut 22 toward the parallel link member 17, lifts the fixed part 17b relative to the slider part 17a, and removes the carriage 4. Raise the rear end.

As a result, the print head 2 moves in the direction of the arrow and approaches the platen 1, as shown in FIG. 8a.

With this approach, the film 26 of the ribbon protector 24 comes into contact with the paper 11 on the platen 1,
Furthermore, the print head 2 pushes the film 27 of the ribbon protector 24, and eventually this film 27
The ribbon protector 24 abuts against the platen 1 via the film 26 and paper 11.

At this time, as shown in FIG. 8b, the film 26
The rubber protrusion 28 of the film 26 is crushed, and the conductive parts of the films 26 and 27 come into contact with each other.
and 27 are electrically connected.

When continuity at this time is detected by a detection circuit (not shown), the motor control circuit controls the pulse motor 1.
6 is stopped, and this state is set as the reference position of the print head 2, that is, the platen gap zero position.

After that, the motor control circuit controls the pulse motor 1.
6 in the CW direction by a predetermined amount to draw the nut 22 toward the pulse motor 16, and by lowering the rear end of the carriage 4 by a certain amount using the restoring force of the parallel link member 17, the tip of the print head 2 is moved. The paper 11 on the platen 1 is separated from the paper 11 by a certain amount, thereby setting the platen gap α appropriate for printing.
get.

〔Effect of the invention〕

As explained above, in the present invention, when adjusting the platen gap, the motor control means causes the pulse motor to rotate, so that the carriage up-and-down movement means raises the rear end of the carriage to bring the tip of the print head closer to the platen. When the tip of the head comes into contact with the platen through two films constituting a ribbon protector, and when these two films come into contact and become electrically conductive, the motor control means stops the rotation of the pulse motor, and then the motor control means stops the rotation of the pulse motor. The control means reversely rotates the pulse motor by a certain amount, so that the rear end of the carriage is lowered by a certain amount via the carriage vertical movement means, whereby the print head is moved from the position where it abuts the platen to the reference position. is moved away from the platen, thereby providing a constant platen gap between the printhead tip and the paper.

Accordingly, since it is possible to directly detect the reference position of the print head and adjust the platen gap, it is possible to reliably set an appropriate platen gap depending on the thickness of the site.

In addition, in the present invention, since all the components related to the drive for adjustment are mounted on the carriage, it is not necessary to provide a rotating means such as a gear and a driving means such as a motor for driving this rotating means at one end of the carriage shaft as in the conventional case. This eliminates the problem of increasing the size of the device, and also reduces the cost of the device by detecting the reference position of the print head using an inexpensive conductive film ribbon protector instead of an expensive slit disk or photo sensor. It also has the effect of being able to reduce the price.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a sectional view of the same side, FIG. 3 is an exploded perspective view of a main part of the same embodiment, FIG. 4 is a partially cutaway front view of the same, and FIG. 5 is a front view showing an example of the configuration of the pressure sensitive mechanism of the same embodiment. , 6th
7 is an exploded perspective view of the same, FIG. 8 is a side view showing the operation of the same embodiment, FIG. 9 is a perspective view of the conventional example, and FIG. 10 is a characteristic of the conventional example. This is a graph showing. 1...platen, 2...print head, 3...
...carriage shaft, 4...carriage, 16
...Pulse motor, 17...Parallel link member, 1
9... Base plate, 24... Ribbon protector, 25... Connector, 26, 27... Film.

Claims (1)

[Scope of Claims] 1. A print head that prints on paper set on the platen via an ink ribbon, on a carriage attached to a carriage shaft so as to move along the platen; In a platen gap adjustment device for a printer equipped with a ribbon protector located in front of a leading end, the ribbon protector has a configuration in which two conductive films are opposed to each other, and a spacer is provided on the opposing surface of one of the films, Carriage up and down movement means provided at the rear end of the carriage, by moving the rear end up and down, the carriage is rotated around the carriage shaft, and the tip of the print head approaches and moves away from the platen. a pulse motor provided at the rear end of the carriage to operate the carriage vertical movement means; and a pulse motor provided at the rear end of the carriage to operate the carriage vertical movement means; and when adjusting the platen gear, the carriage vertical movement means raises the rear end of the carriage to move the front end of the print head to the platen. The pulse motor is rotated so that the print head approaches the ribbon protector, and the tip of the print head contacts the platen through the two films forming the ribbon protector.
When two sheets of film come into contact and become electrically conductive, the pulse motor stops rotating, and then the carriage vertical movement means moves the carriage up and down so that a constant platen gap is created between the print head tip and the paper sheet. A platen gap adjusting device comprising: motor control means for rotating the pulse motor in the opposite direction by a certain amount so that the end of the platen gap is lowered by a certain amount.