JPH0435180Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a printer that prints using a print head that moves in space in opposition to a platen, and in particular, a printer that adjusts the distance of the print head to the platen according to the set paper thickness. The present invention relates to a ribbon protector for preventing ribbon contamination by being interposed between a sheet of paper set between the platen and print head of a printer having a platen gap adjustment function and an ink ribbon.

[Conventional technology]

The technical background of this invention is described below.

In printers that print with a print head that moves in space in opposition to the platen, it is necessary to print on paper of different thickness in order to eliminate deterioration in print quality, bent head pins, ink ribbon contamination, and poor carriage spacing. , it is necessary to always maintain a constant distance from the surface of the paper to the tip of the print head.

FIG. 11 is a perspective view showing a conventional example of a printer having a paper thickness detection function and a platen gap adjustment function.

In the figure, 1 is a platen, and 2 is a print head facing the platen 1. The print head 2 is mounted on a carriage 4 that moves along a carriage shaft 3 and performs printing operations.

Both ends of the carriage shaft 3 are fixed to cams 5. 6 is a pulse motor that rotates the cam 5 via gears 7a and 7b, and 8 is a spring. Reference numeral 9 denotes a slit disk, and 10 a photo sensor for detecting pulses by the rotation of the slit disk. The slit disk 9 and the photo sensor 10 electrically detect step-out of the pulse motor 6.

11 is a sheet of paper set between the platen 1 and print head 2, and 12 is an ink ribbon.

Ribbon protector to prevent ribbon contamination
The platen gap adjustment function of this conventional example is not shown because it is not involved in any way.

With the above configuration, the following operations are performed to always keep the distance from the surface of the paper to the tip of the print head constant for sheets of different thickness.

First, when the paper 11 is wound around the platen 1, the pulse motor 6 rotates forward, and the gears 7a, 7b
The cam 5 fixed to the carriage shaft 3 rotates to move the carriage shaft 3 to the platen 1.
Move while rotating in the direction away from the object.

At this time, the carriage 4 and the print head 2 mounted on the carriage 4 simultaneously move in a direction away from the platen 1 and stop at a predetermined position.

Subsequently, the pulse motor 6 rotates in the reverse direction, and the print head 2 moves toward the platen 1 and hits the platen 1 with the paper 11 and the ink ribbon 12 sandwiched therebetween.

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 no pulse is output to the photo sensor 10, which detects that the motor is out of step. At this point, the pulse motor 9 is again corrected in advance. It rotates forward by a prescribed amount of rotation, and a constant gap is formed between the surface of the paper 11 and the tip of the print head.

Since the prescribed amount of rotation is always the same, a constant gap can be maintained between the surface of the paper 11 and the tip of the print head 2 even if the paper thickness is different.

[Problem that the invention attempts to solve]

However, in the conventional technology with the above-mentioned configuration,
Due to the characteristics shown in FIG. 12, the following problems arise.

In other words, according to the prior art, the print head compresses the paper and ink ribbon, and the pulse motor rotates while deflecting the carriage shaft, and when this reaction force matches the torque of the pulse motor, the pulse motor rotates. Because it goes out of step and stops,
The pulse motor always stops when the pulse motor overruns by ΔN from the gap zero state.

This 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.
As a result, there was a problem that the return amount X of the print head became unstable.

Another problem is that the device is expensive because it uses a slit disk and a photo sensor.

In view of the above problems, the present invention detects the paper thickness of the paper without applying any physical reaction force that would interfere with the adjustment of the print head's platen gap adjustment mechanism, and adjusts the paper thickness for paper of different paper thickness. The purpose is to always keep the distance from the surface of the paper to the tip of the print head accurately and constant.

The present invention further allows for paper with different thicknesses.
By always keeping the distance from the surface of the paper to the tip of the print head accurately, you can prevent deterioration of printer print quality, bending of the head pin, contamination of the ink ribbon, etc.
The purpose is to eliminate carriage space malfunctions.

[Means for solving problems]

In order to achieve the above object, the present invention provides a pressure sensing function to the ribbon protector conventionally placed in front of the print head to prevent ribbon contamination. The state, that is, the reference position for platen gap adjustment is detected.

The present invention provides a ribbon protector that is set between the platen and the print head of a printer that moves the print head in space to face the platen, and is interposed between the paper and the ink ribbon to prevent ribbon contamination. The main body has a structure in which two plate-like members are stacked together, each having a window portion through which the pins of the print head can pop out, and the inner wall of the two plate-like members is at least in the press-contact area of the tip of the print head. The ribbon protector is provided with a function as a paper thickness detection means by disposing conductive members facing each other and interposing a spacer made of an elastic member between the two plate-like members. It is characterized by

[Effect]

With the above configuration, in the present invention, when pressure is applied from the horizontal direction, the spacer is compressed, and the conductive parts provided facing the inner walls of the two plate-like members come into contact with each other, and are electrically conductive.

In addition, since the present invention is actually a ribbon protector installed between the platen and the print head, the horizontal pressure is generated when the print head approaches the platen and comes into contact with the ribbon protector. Yes, if the present invention is set in advance to a position where the print head contacts the paper with a certain pressure, the spacer is compressed and the conductive parts of the two plate members come into contact, the print head is brought closer to the platen and the platen gap is pressed. When the spacer is set to zero, the moment the platen gap reaches zero, the spacer is compressed and the conductive part becomes conductive.This conduction allows the paperboard to be detected and the reference position for adjusting the print head's platen gap to be set, that is, the platen. The gap zero position can be detected.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view showing an embodiment of the present invention;
FIG. 2 is a front view of the same embodiment, and FIG. 3 is a side view of the same.

In the figure, 13 and 14 are films made of a base material such as polyester, which constitute the main body of the ribbon protector. The film 13 has an electrode 13a and a diamond-shaped window 13b through which the pins of the print head can pass, and a plurality of elastic rubber protrusions 15 are formed protruding from the surface facing the film 14. At the same time, 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 13, the film 14 has a diamond-shaped window 14b through which the electrode 14a and the pin of the print head can pass. A metal film is coated as a conductive part except for the part. The reason why this opposing point 16 is a portion not coated with a metal film is that the rubber projections 15 of the film 13 are coated with a metal film by vacuum deposition.

Reference numeral 17 denotes a double-sided adhesive tape for bonding the films 13 and 14 having the above structure, and this double-sided adhesive tape 17 is an insulator.

In this embodiment, a rubber protrusion 15 is provided on the film 13 as a spacer that provides a certain distance between the conductive parts of the films 13 and 14 and eliminates this distance by compressing it by external pressing force. The present invention is not limited to this, and for example, an elastic insulating net or the like may be interposed between the films 13 and 14 to serve as a spacer.

According to the present embodiment having the above configuration, when pressure is applied from the horizontal direction, the rubber protrusion 15 is compressed, and the conductive parts of the films 13 and 14 come into contact with each other and become electrically conductive.

In other words, since this embodiment deals with the ribbon protector provided between the platen and the print head, the horizontal pressure is generated when the print head approaches the platen and comes into contact with the ribbon protector. If this embodiment is set in advance at a specified position, the position of the print head can be detected by the conduction of the conductive portion.

FIG. 4 is a perspective view showing a first usage example of the present invention;
FIG. 5 is a side view of the same.

In the figure, 1 is a platen, 2 is the platen 1
The print head 2 is mounted on a carriage 4 that moves along a carriage shaft 3 and performs printing operations.

12 is an ink ribbon set between the platen 1 and the print head 2; 11 is a sheet of paper wound around the platen 1 as a printing medium.

18 is the ribbon protector of the present invention shown in FIG.
The ink ribbon 12 is fixed on the carriage 4 so as to be interposed between the ink ribbon 12 and the ink ribbon 12. In this usage example, this fixing is performed by fixing the connector 19 connected to the electric circuit on the carriage 4, and inserting the lower end of the ribbon protector 18 into this.

20 rotates the pinion 22 along the rack 21 to move the carriage 4 to the carriage shaft 3.
This space motor 20 is mounted on the carriage 4.

23 is a pulse motor for adjusting the platen gap, and the details of the mechanism for automatically adjusting the platen gap of the print head 2 will be explained below with reference to the drawings.

FIG. 6 is an exploded perspective view showing the platen gap adjustment mechanism of this usage example, and FIG. 7 is a partially cutaway front view of the same.

Reference numeral 24 denotes a parallel link member, and as shown in FIG. Part 24c,
24d.

The parallel link member 24 is fixed to the carriage 4 by passing a fixing screw 32 near the corner of the rear end of the carriage 4 and screwing it into the screw hole of the fixing part 24b. By engaging the engagement slit of the slider portion 24a, the rear end of the carriage 4 is slidably held.

The pulse motor 23 has a shaft portion 26 having a right-hand screw 27 for adjustment, as shown in FIG. It is screwed into place near the corner of the side via a nut 28. This nut 28 has a pair of parallel parts in its outer shape, and is fitted into an oval hole 29 of the slider part 24a to prevent rotation.

The nut 28 is fitted into an oval hole 29 provided in the slider portion 24a of the parallel link member 24, and its tip is brought into contact with the slider portion 24a of the parallel link member 24 as shown in FIG. It's summery.

With the above configuration, when the pulse motor 23 rotates in the CW direction, since the shaft 26 of the pulse motor 23 has a right-handed thread 27, the nut 28 is drawn toward the pulse motor 23, and as a result, the tip of the shaft 26 moves back to the carriage 4 side.

Then, the flexible plate-like portions 24c and 24d recover to their original flat state due to their own restoring force, and at the same time the rear end of the carriage 4 is pulled down, causing the carriage 4 to move in the direction of arrow B around the carriage shaft 3. At the same time, the print head 2 also rotates, and its leading end surface separates from the surface of the platen 1. Therefore, the platen gap becomes larger.

Conversely, when the pulse motor 23 rotates in the CCW direction, the nut 28 separates from the pulse motor 23, and as a result, the tip of the shaft 26 advances toward the slider portion 24a.

Then, the slider portion 24a receives the pressing force of the nut 28, but the slider portion 24a is engaged with the base plate 25 by the engagement slit.
Since this base plate 25 is fixed,
As the tip of the nut 28 advances, the flexible plate-like parts 24c and 24d between the slider part 24a and the fixed part 24b fixed to the carriage 4 are bent, and the fixed part is bent with respect to the slider part 24a. 24b becomes a raised shape.

The flexible plate-like portions 24c and 24d are parallel to each other,
Moreover, the effect is that the slider portion 24a can be bent so as not to be inclined with respect to the base plate 19.

As a result, the rear end of the carriage 4 is pushed up, causing the carriage 4 to rotate in the direction of arrow A around the carriage shaft 3. At the same time, the print head 2 also rotates so that its tip surface touches the surface of the platen 1. approach. Therefore, the platen gap becomes smaller.

The operation of this usage example with the above configuration will be explained with reference to the drawings.

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

First, by rotating the pulse motor 23 by a certain amount in the CW direction, the nut 28 is drawn toward the pulse motor 23, the parallel link member 24 is restored to its original flat state, and the rear end of the carriage 4 is lowered to connect the platen gear. The operator spreads out paper 1 and
1 around the platen 1 and set the paper.

The pulse motor 23 is rotated in the CCW direction, using the completion of paper setting as a trigger, or the input of a switch (not shown), etc., to rotate the nut 28.
is advanced toward the parallel link member 24 side, the fixed part 24b is lifted up from the slider part 24a, the rear end of the carriage 4 is raised, the platen gap is closed, and the print head 2 is moved as shown in FIG. 8a.
Move closer to platen 1. When the print head 2 hits the platen 1, it crushes the rubber protrusion 15 of the film 13, as shown in FIG. 8b. As a result, the conductive portions of the films 13 and 14 come into contact, and the films 13 and 14 are electrically connected.

This conduction detects that the print head 2 has contacted the paper with a constant pressure, and the device detects the paper thickness and obtains the reference position for platen gap adjustment of the print head 2, that is, the zero point of the platen gap. to stop the pulse motor 23,
Next, by rotating the pulse motor 23 by a predetermined amount in the CW direction, the nut 28 is drawn toward the pulse motor 23, and the parallel link member 24
is restored to its original flat state, and the rear end of the carriage 4 is lowered to obtain a platen gap α that has been set appropriately for printing in advance.

In the first usage example above, a configuration was shown in which the platen gap adjustment mechanism was fully automatically controlled.
The invention can also be used with manual platen gap adjustment mechanisms.

For example, FIG. 9 shows a perspective view of a configuration in which the platen gap adjustment mechanism is manual as a second usage example.

It has a manual lever 30, this lever 30
The platen gap is adjusted by the angle of the platen gap.

In the second usage example, the ribbon protector 18
As shown in the wiring diagram in Figure 10, the film 13,
The wiring is such that when the conductive portion 14 becomes conductive, the lamp 31 lights up.

With the above configuration, the operator wraps the paper 11 around the platen 1 and sets it, tilts the lever 30 in the direction of the arrow and brings the print head 2 close to the platen 1 until the lamp 31 lights up, and then moves the printer to the position of the lever where the lamp 31 lights up. By returning the lever one step further and fixing it, a constant platen gap can be easily obtained.

Similarly, a configuration may be adopted in which a buzzer sounds instead of lighting the lamp 31.

[Effect of idea]

According to the present invention described in detail above, the ribbon protector placed in front of the print head to prevent ribbon contamination is provided with a pressure detection function. In other words, if used as a paper thickness detection means for detecting the reference position for platen gap adjustment, it will be possible to detect the paper thickness of the set paper and adjust the print head's platen gap without applying any physical reaction force to the print head's platen gap adjustment mechanism. The reference position can be obtained. This eliminates the instability of the print head platen gap adjustment amount caused by physical reaction force as in the past, and allows the distance from the paper surface to the print head tip to remain accurately constant for paper of different paper thickness. This has the effect that it can be maintained.

In addition, by providing a detection means for detecting the reference position for platen gap adjustment on the front of the print head, detection can be performed directly.
This has the effect that detection is more accurate than conventional indirect detection, and accurate platen gap adjustment can be performed.

Furthermore, as mentioned above, the distance from the surface of the paper to the tip of the print head can always be kept accurately constant for paper of different thicknesses, resulting in good print quality and no problems such as head pin bending, ink ribbon contamination, etc. This has the effect of providing a printer free of carriage space malfunctions.

Furthermore, since there is no need to provide a slit disk or a photo sensor to detect the zero platen gap, it is expected that the cost of the device will be reduced.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention;
Fig. 2 is a front view of the same embodiment, Fig. 3 is a side view of the same embodiment, Fig. 4 is a perspective view showing the first usage example of the present invention, and Fig. 5 is a side sectional view of the same usage example. , Fig. 6 is an exploded perspective view of the platen gap adjustment mechanism of the same usage example, Fig. 7 is a partially cutaway front view of the same, Fig. 8 a, b,
c is a side view of essential parts showing the operation of the same usage example, Figure 9 is a perspective view showing the second usage example of the present invention, Figure 10 is a circuit diagram of the same usage example, and Figure 11 is a perspective view of the conventional example. figure,
FIG. 12 is a graph showing the characteristics of the conventional example. 1...Platen, 2...Print head, 11
... Paper, 12 ... Ink ribbon, 13, 14 ...
...Film, 13b, 14b...Window part, 15...
rubber protrusion.

Claims (1)

[Claims for Utility Model Registration] 1. In a printer that prints by moving the print head in space opposite the platen, the ink ribbon is interposed between the paper set between the platen and the print head to prevent ribbon contamination. The ribbon protector is for preventing and detecting a platen gap, and has a structure in which two plate-like members are stacked together, each having a window portion through which the pins of the print head can pop out, and the two plate-like members are overlapped. At least conductive members are disposed facing each other on the inner walls of the press-contact range at the tip of the print head, each of the conductive members is connected to an individual electrode, and there is a space between the two plate-like members. A ribbon protector, characterized in that a spacer made of an elastic member is interposed to form a ribbon protector, so that the conductive member is electrically connected when the two plate-like members are pressed. 2. Utility model registration claim 1, characterized in that, as a spacer for forming a space, rubber protrusions of a certain height are dotted on the inner wall of one or both of two plate-like members. ribbon protector.