JPH0576914B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a platen gap adjustment device for adjusting the platen gap between the platen of a printer and the tip of a print head.

[Conventional technology]

There are known printers that perform printing by interposing an ink ribbon and paper between the print head and the platen, and in this type of printer, a platen gap necessary for printing is formed between the print head and the platen. However, this gap needs to be changed depending on the thickness of the paper.

Therefore, many of these printers are equipped with a device for adjusting the platen gap.

Various types of platen gap adjustment devices have been put into practical use, including one shown in FIG. 8, for example.

FIG. 8 is a perspective view of a printer equipped with a conventional platen gap adjustment device.

In the figure, reference numeral 1 denotes a carriage shaft arranged parallel to the platen 2. A carriage 4 with a print head 3 mounted thereon is slidably attached to the carriage shaft 1, and a space is moved along the platen 2 by means of a traveling means (not shown). It is now possible to move.

Both ends of the carriage shaft 1 are movably supported in elongated holes provided in a pair of left and right frames 6 so as to be able to approach and move away from the platen 2, and are supported on the platen 2 side by a sling 7 as a biasing means. is energized by

Additionally, cams 8 are installed at both ends of the carriage shaft 1.
is attached, and this cam 8 is in contact with a stopper provided near the front end of the elongated hole of the frame 6.

Furthermore, at one end of the carriage shaft 1,
A driven gear 9 for applying rotational force to the carriage shaft 1 is provided, and a driving gear 11 of a pulse motor 10 is meshed with the driven gear 9.

A slit disk 12 is provided at the other end of the carriage shaft 1, and the position of the print head 3 can be optically detected by the slit disk 12 and a photo sensor 13. Elements 7 to 13 constitute a platen gap adjustment device.

Reference numeral 14 denotes a sheet of paper on which printing is performed by the print head 3, and 15 an ink ribbon. It is set to run between the ribbon protector (not shown) and a ribbon protector (not shown).

The operation of the platen gap adjusting device having such a structure is as follows.

First, after the paper 14 is wrapped around the platen 2 and set, when the pulse motor 10 rotates a certain amount in the forward direction, the carriage shaft 1 rotates together with the cam 8 via the drive gear 11 and the driven gear 9. Due to the action of the cam 8, the carriage shaft 1 rotates and moves in a direction away from the platen 2 against the spring 7.

At this time, the carriage 4 and the print head 3 mounted thereon simultaneously move away from the platen 2 and stop at a predetermined position.

Next, when the pulse motor 10 rotates in the opposite direction, the carriage shaft 1 also rotates in the opposite direction together with the cam 8 via the driving gear 11 and the driven gear 9.
Due to the restoring force of the spring 7, the carriage shaft 1 rotates and moves in the direction approaching the platen 2, so the print head 3 also moves in the direction approaching the platen 2 together with the carriage 4.

As a result, when the ribbon protector (not shown) comes into contact with the platen 2 through the paper 14 on the platen 2, the print head 3 is no longer attached to the platen 2.
It becomes impossible to move in the direction of , and the pulse motor 10 loses synchronization.

At this time, the slit disk 12 also stops, so
The photo sensor 13 no longer outputs pulses, and it is detected that the pulse motor 10 is electrically out of step.

Thereafter, the pulse motor 10 rotates in the forward direction again by a preset amount of rotation, and as a result, the print head 3 is separated from the platen 4 by a certain amount along with the carriage 4, so that the surface of the paper 14 and the tip of the print head 3 are separated from each other by a certain amount. A constant platen gap is set in between.

This setting of the platen gap can be similarly performed for sheets 14 of different thicknesses.

[Problem that the invention seeks to solve]

However, in the conventional platen gap adjustment device described above, the reference position of the print head is detected indirectly by the slit disk and the photo sensor via the carriage shaft, so it is not only difficult to accurately detect the position. Since it has the characteristics shown in FIG. 9, there are the following problems.

That is, according to the conventional platen gap adjustment device, even after the ribbon protector located in front of the print head contacts the platen through the paper, the pulse motor continues to compress the paper and further bends the ribbon protector, etc. while rotating. When the reaction force against the pulse motor matches the torque of the pulse motor, the pulse motor steps out and stops rotating, so the pulse motor always overruns by ΔN from the zero gap state and the pulse motor stops rotating. It will be suspended.

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, and as a result, the print There is a problem in that the return amount X of the head becomes unstable, making it difficult to accurately detect the position described above, and also making it difficult to set an appropriate platen gap for printing.

Furthermore, since it is essential to install an expensive pulse motor, slit disk, and photo sensor, and a circuit for controlling the pulse motor is also required, there is a problem that the cost of the device increases.

The present invention has been made to solve these problems, and provides a platen gap adjustment device that can reliably set an appropriate platen gap depending on the thickness of paper and can reduce the cost of the device. The purpose is to

[Means for solving problems]

In order to achieve this object, the present invention includes a carriage shaft supported by a pair of left and right frames so as to be able to approach and move away from a platen, and a carriage shaft that is mounted so as to move along the platen. a printhead mounted on the carriage for printing on paper set on the platen via an ink ribbon; and a ribbon mounted on the carriage so as to be located in front of the tip of the printhead. In the platen gap adjustment device for a printer, the ribbon protector is provided with two conductive films facing each other;
In addition, spacers are provided on the facing surface of one of the films, and a plurality of spacers are provided on the frame at the same intervals as the platen gap suitable for printing.
and a second engaging part that engages with one of the first engaging parts, and is provided on the carriage shaft so that the carriage shaft can be moved relative to the platen by manual operation. A lever for moving the print head toward and away from the print head, and a lever for moving the carriage shaft close to the platen to bring the tip of the print head into contact with the platen through the two films constituting the ribbon protector. and a notification means for notifying that the reference position of the print head has been detected when the two films come into contact and become electrically conductive.

[Effect]

According to the present invention having such a configuration, when adjusting the platen gap, first, when the operator operates a lever to bring the carriage shaft closer to the platen, the tip of the print head moves between the two sheets forming the ribbon protector. When the two films come into contact with the platen through the film and become electrically conductive, the notifying means notifies the operator that the reference position of the print head has been detected. When the lever is operated so that the second engaging part engages the first engaging part one position before the position where the second engaging part is engaged with the first engaging part, and the position between the first engaging parts is The carriage shaft is moved away from the platen by an amount corresponding to the distance.

The distance between the first engaging portions is the same as the platen gap suitable for printing, so that a platen gap suitable for printing is set between the tip of the print head and the paper.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a perspective view of a printer equipped with a platen gap adjustment device according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes a carriage shaft arranged parallel to the platen 2. A carriage 4 with a print head 3 mounted thereon is slidably attached to the carriage shaft 1, and a space is moved along the platen 2 by means of a traveling means (not shown). It is now possible to move.

Both ends of the carriage shaft 1 are movably supported in elongated holes provided in a pair of left and right frames 6 so as to be able to approach and move away from the platen 2, and are supported on the platen 2 side by a spring 7 as a biasing means. is energized by

Additionally, cams 8 are installed at both ends of the carriage shaft 1.
is attached, and this cam 8 is in contact with a stopper provided near the front end of the elongated hole of the frame 6.

Further, a lever 17 is fixed to one end of the carriage shaft 1, and a second lever 17 is fixed to one end of the carriage shaft 1.
A plurality of square holes 19 as first engaging parts corresponding to the projections 18 are arranged in an arc shape at equal intervals on one frame 6. There is.

Here, the interval between each square hole 19 is a platen gap that is an appropriate interval between the paper 11 set on the platen 2 and the tip of the print head 3 that prints on this paper via the ink ribbon 15. are set at the same interval.

In addition, one square hole 19 is provided in the lever 17,
A plurality of protrusions 18 may be formed on the frame 6.

Reference numeral 20 denotes a ribbon protector, and the platen gap adjusting device according to this embodiment is composed of the ribbon protector 20, the cam 8, the lever 17, the square hole 19, and a notification means to be described later.

2 shows details of the ribbon protector 20, FIG. 2A is a side view, FIG. B is a front view, and FIG. 3 is an exploded perspective view of the ribbon protector.

This ribbon protector 20 is the ink ribbon 15
In addition to preventing the paper 11 from being soiled by the paper 11, it also has a function of detecting a reference position for adjusting the platen gap of the print head 3.

Specifically, the ribbon protector 20 is constructed by joining a first film 21 and a second film 23 with a frame-shaped double-sided adhesive sheet 22.

Here, the first film 21 has a diamond-shaped hole 24 in the center of a base material such as polyester having a predetermined shape, through which the printing pin of the print head 3 passes, and on the surface facing the second film 23. A plurality of rubber protrusions 25 as elastic spacers are formed in a vertically and horizontally aligned state, and a conductive metal coating 26 is formed.
is coated by a manufacturing method such as vacuum evaporation and connected to the electrode 27.

On the other hand, the second film 23 has a diamond-shaped hole 28 in the center of a base material such as polyester formed in the same shape as the first film 21, through which the pins of the print head 3 pass, and On the surface facing the film 21, a portion 2 facing the rubber protrusion 25 is provided.
All but 9 are coated with a conductive metal film 30 and connected to an electrode 31.

The double-sided adhesive sheet 22 is formed into a frame shape with a rectangular hole 32, and the first and second films 21,
23 is bonded so that the metal coatings 26 and 30 face each other, and also serves as insulation between the metal coatings 26 and 30 during non-gap adjustment.

FIG. 4 is a circuit diagram showing the electric circuit of the platen gap adjusting device.

As seen in this figure, a power source 33 and a GAP lamp 34 as a notification means are connected in series between the electrode 27 of the first film 21 and the electrode 31 of the second film 23 of the ribbon protector 20. Here, a light emitting diode is used for the GAP lamp 34.

Further, in this embodiment, the electrodes 27 and 31 of the first and second films 21 and 23 are connected to a power source 33 and
A connector is used to connect to the GAP lamp 34, and this connector is fixed on the carriage 4, and by inserting the electrodes 27, 31 of the first and second films 21, 23 into this connector, the ribbon The protector 20 is attached to the carriage 4 so that it is located in front of the tip of the print head 20.
It is installed on.

FIG. 5 is a front view showing an example of the operation section of the printer.

In the figure, reference numeral 35 denotes an operation panel, on which various operation switches 36 are arranged, various display lamps are provided next to the operation switches 36, and at the right end of this display lamp row are the
A GAP lamp 34 is arranged.

Next, the operation of the above-mentioned configuration will be explained with reference to FIG. 6.

FIG. 6 is an explanatory diagram showing the operation of this device, in which FIG. 6A shows the conductive state, and FIG. 6B shows the state with a proper platen gap set.

First, after inserting the paper 14 between the platen 2 and the ribbon protector 20, wrapping it around the platen 2, and setting it, when the operator rotates the lever 17 in the direction of the arrow shown in FIG. The carriage shaft 1 moves toward the platen 2, and along with this, the ribbon protector 20 also approaches the platen 2 together with the carriage 4 and print head 3.

With this approach, the first film 21 of the ribbon protector 20 comes into contact with the paper 14 on the platen 2, and furthermore, the tip of the print head 3 pushes the second film 23 of the ribbon protector 20. The leading end of the print head 3 contacts the platen 2 via the second films 21 and 23.

As a result, the rubber projections 25 of the first film 21
is crushed and the first and second films 21, 2
The metal films 26 and 30 of No. 3 come into contact with each other and are electrically conductive.

This electrical continuity closes an electrical circuit,
The GAP lamp 34 lights up.

The lighting of this GAP lamp 34 means that the reference position of the print head 3 has been detected, so the operator can determine the position where the protrusion 18 of the lever 17 engages with the square hole 19 of the frame 6 when the GAP lamp 34 is lit. Then, the lever 17 is returned until the protrusion 18 engages with the square hole 19 one stage before the square hole 19.

As a result, the print head 3, together with the carriage 4 and the ribbon protector 20, is separated from the platen 2 by an amount corresponding to the distance between the square holes 19, and the print head 3 is printed between the paper 11 on the platen 2 and the leading edge of the print head 3. The appropriate platen gap is set.

FIG. 7 is a front view showing other embodiments of A and B.

This embodiment has almost the same configuration as the previous embodiment, but the notification means is different.

That is, what is shown in FIG. A is the operation panel 3.
5 are provided with red and blue GAP lamps 34a and 34b,
The red GAP lamp 34a is used to display the reference value of the platen gap, and the blue GAP lamp 34b is used to display the appropriate value of the platen gap.

The operation of this embodiment is almost the same as that of the previous embodiment, but when the red GAP lamp 34a lights up, the first-stage lever 17 is moved back one stage, thereby the blue GAP lamp 34b lights up, and the red GAP lamp 34a lights up. of
By turning off the GAP lamp 34a, it can be confirmed that an appropriate value for the platen gap has been obtained.

The one shown in FIG. B is different in that a display section 37 is provided on the operation panel 35 as a notification means so that a message can be displayed, and an SEL (selection) switch 38 is provided.

In the above configuration, first, the SEL switch 38 is pressed to set the offline state.

Next, the lever 17 is rotated in the direction in which the platen gap decreases to remove the metal coatings 26 and 26 of the first and second films 21 and 23 of the ribbon protector 20, respectively.
When 30 is made conductive, a message as shown is displayed on the display section 37.

When the lever 17 is returned one step in accordance with this message, a proper platen gap is set and the message display disappears at the same time.

It should be noted that the present invention is not limited to the embodiments described above, and it goes without saying that various modifications can be made.

For example, in the embodiment described above, the rubber protrusion 25 was used as a spacer between the first and second films 21 and 23 of the ribbon protector 20, but it may be replaced with an elastic resin protrusion.

Moreover, it can also be used as a buzzer notification means in place of the GAP lamp 34 or the like.

〔Effect of the invention〕

As explained above, in the present invention, when adjusting the platen gap, when the lever is manually operated to bring the cartridge shaft closer to the platen, the tip of the print head passes through the two films constituting the ribbon protector and moves toward the platen. When the two films come into contact and become electrically conductive, the notifying means notifies the operator that the reference position of the print head has been detected. Manually operate the lever so that it engages the first engaging part one position before the position where it is engaged with the first engaging part, and the distance corresponds to the distance between the first engaging parts. The carriage shaft is moved away from the platen.

Therefore, according to this, the reference position of the print head can be directly detected using the ribbon protector, and the carriage shaft can be moved by an amount corresponding to the distance between the first engaging parts by manually operating the lever. Since the platen gap is set by moving away from the platen, the return amount does not become unstable unlike in the past, and the distance between the first engaging parts is the same as the platen gap that is appropriate for printing. , it is possible to reliably set an appropriate platen gap according to the thickness of the paper.

In addition, since the reference position of the print head is detected using a ribbon protector made of an inexpensive conductive flexible plate instead of an expensive pulse motor, slit disk, and photo sensor, the structure is simple and the pulse motor can be controlled. The circuit can also be omitted, and the cost of the device can be reduced.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a printer equipped with a platen gap adjustment device according to an embodiment, Fig. 2 is a configuration diagram showing a ribbon protector, Fig. 3 is an exploded perspective view showing the ribbon protector, and Fig. 4 shows an electric circuit. 5 is a plan view showing the operating section of the printer, FIG. 6 is an explanatory diagram showing the operation of the device, FIG. 7 is a front view showing another embodiment, and FIG. 8 is a conventional example. The perspective view and FIG. 9 are graphs showing the characteristics of the conventional example. 1... Carriage shaft, 2... Platen,
3...print head, 4...carriage, 8...
...Cam, 14...Paper, 17...Lever, 18...
... Protrusion, 19 ... Square hole, 20 ... Ribbon protector, 21 ... First film, 22 ... Double-sided adhesive sheet, 23 ... Second film, 25 ... Rubber protrusion, 26 ... Metal film, 30...metal film, 3
3...Power supply, 34, 34a, 34b...GAP lamp, 37...Display section, 38...SEL switch.

Claims (1)

[Scope of Claims] 1. A carriage shaft supported by a pair of left and right frames so as to be able to approach and move away from the platen, and a carriage attached to the carriage shaft so as to move along the platen;
A printhead is mounted on the carriage and prints on the paper set on the platen via an ink ribbon, and a ribbon protector is mounted on the carriage so as to be located in front of the tip of the printhead. In the platen gap adjustment device for a printer, 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 the ribbon protector is arranged at the same distance as the platen gap that is appropriate for printing. and a plurality of first engaging parts provided on the frame, and a second engaging part that engages with one of the first engaging parts, and provided on the carriage shaft, and a manual a lever that moves the carriage shaft toward or away from the platen when operated; and a lever that moves the carriage shaft toward or away from the platen to move the tip of the print head between the two sheets forming the ribbon protector. By bringing the film into contact with the platen, the above 2.
1. A platen gap adjustment device comprising: a notification means for notifying that the reference position of the print head has been detected when two sheets of film come into contact and are electrically conductive.