JPH082059A - Automatic paper thickness adjusting mechanism - Google Patents

Abstract

PURPOSE:To shorten the operation time and adjust automatically the printing distance with good accuracy without forming impressions on a printing paper in an automatic paper thickness adjusting mechanism of a serial dot impact printer. CONSTITUTION:A differential transformer constituted of a differential coil 23 and a highly permeable material core 24 such as iron is placed on a carriage 3. One end of the highly permeable material core is connected with a push solenoid 26, and the other end is connected with the same through a coil spring. When a printing head 2 is moved to the side of a platen 1 in the state of opening the push solenoid and pressing a contact arm 6 to the plate side, the contact arm is pushed back. The proper printing distance is judged by the output voltage value from the differential transformer and control is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial dot impact printer having an automatic paper thickness adjusting mechanism for automatically adjusting a gap between a print head and a printing paper mounted on a platen, and more particularly to a differential transformer. The present invention relates to an automatic paper thickness adjusting mechanism that adjusts a gap using a container.

[0002]

2. Description of the Related Art As shown in FIG. 5, a conventional automatic paper thickness adjusting mechanism disclosed in Japanese Patent Application Laid-Open No. 03-097578 is mounted on a platen 1 on which printing paper is mounted and mounted on the platen 1. The print head 2 that prints on the print paper, the carriage 3 that mounts the print head 2 and moves parallel to the platen 1 along the guide shaft 5, and the gap between the print head 2 and the print paper change. And a displacement mechanism for moving the print head 2 so as to operate. A contact arm 6 is placed on the carriage 3 on the front side of the platen 1 from the print head 2.

The above-mentioned displacement mechanism is a mechanism for moving the carriage 3 forward and backward with respect to the platen 1 by the rotation of the eccentric shaft 4. A separate gear train is used for forward and backward movement. The forward gear train includes gears 7 to 15. Further, the power of the motor 22 is transmitted to the eccentric shaft 4 via the small gear 11, the large pulley 12, and the rubber belt 13 which are interposed between the motor gear 21 and the forward gear train. The reverse gear train is composed of gears 14 to 20, and the power of the motor 22 is transmitted to the eccentric shaft 4 via the motor gear 21 and the one-way clutch 19 interposed in the reverse gear train.
Here, the one-way clutch 19 is incorporated so as to idle with respect to the rotation direction when the carriage 3 moves forward. Further, the forward gear train and the reverse gear train have a large gear ratio of the reverse gear train.

Next, the actual movement will be described. The carriage 3 is moved forward with respect to the platen 1 by a certain motor pulse using the forward gear train. When the contact arm 6 mounted on the carriage 3 comes into contact with the printing paper on the platen 1, the carriage 3 starts to slide and the rubber belt 13 in the forward gear train stops moving any more, and eventually stops.
At this time, the reverse gear train does not affect the forward movement because the one-way clutch 19 idles. After stopping the motor 22,
The reverse rotation of the motor causes the carriage 3 to move backward by a predetermined motor pulse using the reverse gear train to set the gap. At this time, since the power is transmitted to the forward gear train by the rubber belt and the gear ratio is smaller than that of the reverse gear train, the rubber belt 13 slides between the small pulley 11 and the large pulley 12, and the backward movement is not affected. It had a mechanism called.

[0005]

In this conventional automatic paper thickness adjusting mechanism, since the contact between the contact arm on the carriage and the printing paper on the platen is not sensed, by design, the amount of contacting motor pulses + α pulses. However, since it is necessary to rotate the motor without fail, it is difficult to shorten the operation time.

Further, the tension and frictional force of the rubber belt transmit the power of the motor to move the carriage forward, and when the printing paper on the platen comes into contact with the contact arm, the rubber belt starts to slide and the carriage stops, but in reality, to some extent. He began to slip after applying deformation to the platen and contact arm. Here, the rubber belt is affected by the tension and the frictional force depending on the atmosphere, the above-mentioned deformation amount is different, and as a result, the gap is affected, it is difficult to always keep the printing distance constant.

Further, when the tension of the rubber belt is high, the force of the contact arm pushing the platen is increased to cause an indentation on the printing paper such as pressure sensitive paper. The carriage was stuck and it was difficult to balance it.

An object of the present invention is to solve the above-mentioned conventional problems, shorten the operation time, and automatically adjust the printing distance with high accuracy without causing an impression on the printing paper. It is to provide an automatic paper thickness adjusting mechanism.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a platen on which a print sheet is mounted, a print head for printing on the print sheet mounted on the platen, and a print head mounted on the platen and moved in parallel with the platen. An automatic paper thickness adjusting mechanism of a serial dot impact printer having a carriage for carrying out the above and a displacement mechanism for moving the print head so that the gap between the print head and the printing paper is changed. -Shaped differential coil, a differential transformer composed of a high-permeability material core inserted into the differential coil, and a carriage connected to one end surface of the high-permeability material core through a coil spring. The output of the differential transformer is converted into an electric signal by the push solenoid mounted on the, the contact arm that is connected to the other end surface of the high-permeability material core and can contact the printing paper on the platen. That is a differential transformer circuit, characterized in that it has a differential transformer output control circuit for setting the printing distance based on the electrical signal from the differential transformer circuit.

[0010]

When the push solenoid is opened, the contact arm comes into contact with the printing paper on the platen by the force of the coil spring, and when the push solenoid is closed, the contact arm is pulled by the coil spring and separated to the rear of the print head. Further, when the push solenoid is opened by the displacement mechanism and the carriage is advanced to the platen side when the push solenoid is opened, the contact arm that was in contact with the printing paper is pushed back while changing the output from the differential transformer. The differential transformation output control circuit stops the forward movement of the carriage when an electric signal corresponding to the set printing distance is input from the differential transformation circuit.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of an embodiment of the present invention.
The automatic paper thickness adjusting mechanism of this embodiment includes a platen 1 on which a printing paper is mounted, a print head 2 for printing on the printing paper mounted on the platen 1, and a print head 2 placed on the platen 1. And a displacement mechanism for moving the print head 2 so that the gap between the print head 2 and the print sheet changes. In addition, a cylindrical differential coil 23 on the carriage 3 and a high magnetic permeability material core 24 such as iron inserted in the differential coil 23.
A differential transformer composed of and is mounted.

FIG. 2 shows an exploded view of the differential transformer portion.
One end surface of the high-permeability material core 24 is connected to a push solenoid 26 via a coil spring 25, and the other end surface is connected to a contact arm 6 capable of contacting the platen 1. Here, the differential coil 23 and the push solenoid 26
Is fixed to the carriage 3, and the high-permeability material core 2 is
The coil spring 4 and the coil spring 25 are housed inside the cylindrical differential coil 23 and can slide inside the cylinder.

The differential coil of the differential transformer comprises a primary coil and a secondary coil, and the primary coil is excited by a constant AC voltage. By moving the high-permeability material core 24,
An output is obtained on the secondary coil.

The secondary coil is connected to a differential transformer circuit 27 which converts its output into an electric signal.

The displacement mechanism is a mechanism for moving the carriage 3 forward and backward with respect to the platen 1 by the rotation of the eccentric shaft 4, and the eccentric shaft 4 is rotated by the motor 22, the motor gear 21, and the gear 15. The motor 22 is connected to the differential transformation output control circuit 28. Further, the differential transformer output control circuit 28 is connected to the differential transformer circuit 27, and controls the stop of the motor 22 based on the electric signal from the differential transformer circuit 27.

Next, the operation of the differential transformer will be described.
3 and 4 are diagrams showing the states of the differential transformer when the push solenoid is open and when the push solenoid is closed.

First, as shown in FIG. 3, when the push solenoid 26 is opened, the push solenoid 26 presses the coil spring 25, so that the contact arm 6 contacts the printing paper on the platen 1 by the force of the coil spring 25. . When the push solenoid 26 is closed, as shown in FIG. 4, the push solenoid 26 pulls the coil spring 25, so that the contact arm 6 is pulled by the coil spring 25 and moves away to the rear of the print head 2.

Next, the actual operation will be described. The push solenoid 26 is opened to bring the contact arm 6 into contact with the printing paper on the platen 1. In this state, when the carriage 3 is moved forward with respect to the platen 1 by the displacement mechanism, the contact arm 6 that has been in contact with the printing paper is pushed back.
As a result, the high-permeability material core 24 becomes the differential coil 23.
It moves inside and an output is generated in the secondary coil of the differential coil 23. The output is converted into an electric signal (analog signal, digital signal) by the differential transformer circuit 27 and sent to the differential transformer output control circuit 28.

The differential transformer output control circuit 28 monitors the electric signal from the differential transformer circuit 27, and outputs the electric signal when the print head 2 reaches a predetermined printing distance with respect to the printing paper (threshold value). Value) is exceeded, the differential transformer output control circuit 28
Stops the motor 22. After that, the push solenoid 26 is closed and the contact arm 6 is separated from the platen 1.

[0021]

As described above, the present invention has a configuration including a differential transformer, a differential transformer circuit, and a differential transformer output control circuit. Since it can be detected by the position of the arm, it is not necessary to rotate the motor more than before, and the operating time can be shortened. Secondly, the eccentric shaft is rotated only by the gear to move the carriage, and the contact arm is pressed against the platen side only by the force of the coil spring, so that the platen and the contact arm are hardly deformed and the printing distance is more accurate. It has become possible to set. Third, the pressure that the contact arm pushes against the platen can be limited by the coil spring,
It became possible to operate with a weak force without making impressions on printing paper such as pressure-sensitive paper.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is an exploded view of the differential transformer portion of the embodiment of the present invention.

FIG. 3 is a diagram for explaining the operation of the differential transformer portion.

FIG. 4 is a diagram for explaining the operation of the differential transformer portion.

FIG. 5 is a perspective view showing an example of a conventional technique.

[Explanation of symbols]

 1 Platen 2 Printing Head 3 Carriage 4 Eccentric Shaft 5 Guide Shaft 6 Contact Arm 7-10 Gear 11 Small Pulley 12 Large Pulley 13 Rubber Belt 14-18 Gear 19 One-way Clutch 20 Gear 21 Motor Gear 22 Motor 23 Differential Coil 24 High Permeability Material core 25 Coil spring 26 Push solenoid 27 Differential transformer circuit 28 Differential transformer output control circuit

Claims (3)

[Claims] 1. A platen on which printing paper is mounted, a print head for printing on the printing paper mounted on the platen,
Automatic paper thickness for a serial dot impact printer that has a carriage on which the print head is placed and moves in parallel with the platen, and a displacement mechanism that moves the print head so that the gap between the print head and the print paper changes In the adjusting mechanism, a differential transformer that is mounted on the carriage and has a cylindrical differential coil and a high-permeability material core that is inserted into the differential coil, and a high-permeability material core A push solenoid connected to one end surface via a coil spring and mounted on the carriage, a contact arm connected to the other end surface of the high-permeability material core and capable of contacting the printing paper on the platen, and a differential transformer. Automatic paper thickness control, which has a differential transformer circuit that converts the output of the printer to an electrical signal and a differential transformer output control circuit that sets the printing distance based on the electrical signal of the differential transformer circuit. Mechanism. 2. When the push solenoid is opened, the contact arm comes into contact with the printing paper on the platen by the force of the coil spring, and when the push solenoid is closed, the contact arm is pulled by the coil spring to the rear of the print head. When the carriage is advanced to the platen side when the push solenoid is separated and the push solenoid is opened by the displacement mechanism, the contact arm that is in contact with the printing paper is pushed back while changing the output from the differential transformer. The automatic paper thickness adjusting mechanism according to claim 1. 3. The differential transformation output control circuit stops the carriage forward movement when an electric signal corresponding to a set printing distance is input from the differential transformation circuit. Automatic paper thickness adjustment mechanism.