JPH0858184A - Dot impact printer - Google Patents

Abstract

PURPOSE: To provide a dot impact printer constituted so that a printing distance is set corresponding to the thickness of paper and accurate and sharp printing is performed corresponding to the thickness of the paper. CONSTITUTION: A gap adjusting mechanism 4 adjusting the gap between the printing head 2 on a carriage 3 and printing paper P to set the same to the optimum value is provided. A paper detection arm mechanism 6 outputting specific paper data upon the contact with the paper P on a platen 1 is provided on the carriage 3 and a carriage advance position detection mechanism 7 outputting the positional shift data of the carriage 3 toward the platen 1 on the basis of preliminarily specified reference position data is provided. A gap setting control circuit 10 operating the thickness of the paper P is operated on the basis of the data from both of the carriage advance position detection mechanism 7 and the paper detection arm mechanism 6 to calculate the retreat position data of the carriage 3 and controlling the operation of the gap adjusting mechanism 4 on the basis of the calculated data is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot impact printer, and more particularly to a dot impact printer having an automatic paper thickness adjusting mechanism for automatically adjusting a gap between a print head and a platen or print paper.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional example of an automatic paper thickness adjusting mechanism provided in a dot impact printer. In the conventional example shown in FIG. 2, the platen 5 on which the print paper P is mounted is used.
1, a print head 52 that prints on the print paper P mounted on the platen 51, and a carriage 53 that mounts the print head 52 and moves in parallel to the platen 51.

Further, there is provided a position displacement mechanism for moving the print head 52 so that the gap between the platen 51 and the print head 52 changes depending on the thickness of the print paper P. The same mechanism is disclosed in, for example, Japanese Patent Laid-Open No. 3-97578.

A contact arm 56 is mounted on the carriage 53 on the front side of the platen 51 from the print head 52. The position displacement mechanism described above uses the eccentric shaft 54.
Is a mechanism for moving the carriage 53 forward and backward with respect to the platen 51.

Further, when the carriage 53 moves forward and backward, an independent gear train is used. Here, when the carriage 53 moves forward, the gears 57a in FIG.
57b, 57c, 57d, belt mechanism 58, gear 57
The forward gear train composed of e and 57f functions to transmit the driving force of the motor 60 to the eccentric shaft 54. Reference numeral 60a
Indicates a drive gear, and reference numeral 55 indicates another guide shaft for the carriage 53.

When the carriage 53 moves backward,
Gear 59a, one-way clutch 59b, gear 59c,
The reverse gear train composed of 59d, 59e, 57e, and 57f functions to transmit the driving force of the motor 60 to the eccentric shaft 54.

Here, the one-way clutch 59b is incorporated so as to idle in the direction of rotation 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.

Therefore, the carriage 53 is attached to the platen 51.
On the other hand, when the carriage 53 is moved forward by a predetermined motor pulse by using the forward gear train described above, first, the carriage 53 contacts the platen 51 or the printing paper P by the contact arm 56 mounted on the carriage 53 and moves forward. The belt mechanism 58 in the gear train starts to slip and cannot move any further, and eventually stops. At this time, the reverse gear train does not affect the forward movement because the one-way clutch 59b idles.

After the motor 60 is stopped, the reverse rotation of the motor 60 causes the carriage 53 to move backward by a predetermined motor pulse using the reverse gear train to set the gap. This time,
Since power is transmitted to the forward gear train by the belt mechanism 58 and the gear ratio is set smaller than that of the reverse gear train, the rubber belt 58c slides between the small pulley 58a and the large pulley 58b, and does not affect the backward movement. It is like this.

[0010]

However, in the above-mentioned conventional example, since the timing of contact between the contact arm 56 on the carriage 53 and the platen 51 is not clear, the number of motor pulses to be contacted is not clear. In reality, it is necessary to rotate the above-mentioned motor by "+ α pulses". Therefore, in actual operation, there is a disadvantage that the operation time is relatively long.

Further, in the above conventional example, the motor power is transmitted by the tension and frictional force of the rubber belt 58c, the carriage 53 moves forward, and when the platen 51 and the contact arm come into contact with each other, the rubber belt starts to slide and the carriage stops. However, in practice, it began to slip after applying some deformation to the platen and contact arm 56.

Here, the rubber belt 58c is affected by the tension and the frictional force due to the atmosphere, and 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. It was Rubber belt 5
When the tension of 8c is strong, the force of the contact arm 56 pushing the platen 51 becomes strong, which causes an indentation on the pressure sensitive paper. On the contrary, when it is weak, the rotational load of the gear train exceeds the power transmission force of the rubber belt 58c and the carriage 53 does not move. , It was difficult to balance it.

[0013]

An object of the present invention is to improve the inconvenience of the conventional example, and particularly to set a printing distance according to the paper thickness of the paper, thereby performing accurate and clear printing according to the paper thickness.
At the same time, it is an object of the present invention to provide a dot impact printer with improved durability of the head.

[0014]

According to the present invention, 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 are arranged parallel to the platen. It is equipped with a carriage that moves, a gap adjusting mechanism that is provided alongside this carriage to adjust the gap between the print head and print paper on the carriage to set an optimum value, and a printer case that houses and holds these parts. ing.

The print head on the carriage is provided with a paper detection arm mechanism which outputs predetermined paper information when it comes into contact with the paper on the platen.

Further, a carriage forward position detecting mechanism that engages with the carriage and outputs positional deviation information of the carriage to the platen side based on previously specified reference position information is fixedly installed at a predetermined position of the printer case. There is.

Then, the thickness of the sheet on the platen is calculated based on the information from the carriage forward position detecting mechanism and the sheet detecting arm mechanism to calculate the backward position information of the carriage, and based on this, the gap adjustment described above is performed. Providing a gap setting control circuit for controlling the operation of the mechanism,
The configuration is adopted. This aims to achieve the above-mentioned object.

[0018]

[Operation] First, when the entire apparatus is set to the operating state, first, the gap adjusting mechanism 4 is operated to retract the carriage 3 until the rear end of the carriage 3 engages with the carriage advancing position detecting mechanism 7.

Next, the gap adjusting mechanism 4 is actuated again to move the carriage 3 forward with respect to the platen 1. The platen 1 includes the arm member 6A mounted on the carriage 3.
When it contacts with, the strain gauge 6B mounted on the arm member 6A is distorted, so that the strain gauge 6B outputs a predetermined signal corresponding to the strain amount, and the strain information is sent to the gap setting control circuit 10.

In this case, the gap setting control circuit 10 stops the rotation of the motor 14 and then reversely rotates the motor 14 to move the carriage 3 backward to the carriage advance position detecting mechanism 7 as described above. During this period, the gap setting control circuit 10 counts the number of pulses of the motor 14 and thereby specifies the distance from the reference position of the carriage 3 to the platen 1. After that, the carriage 3 is advanced to the printing paper P. At that time, the gap setting control circuit 10 also counts the number of pulses of the motor 14.
Here, the gap setting control circuit 10 recognizes the paper thickness based on the pulse numbers of both of them, and retracts the carriage 3 to a predetermined printing distance according to the paper thickness.

[0021]

An embodiment of the present invention will be described below with reference to FIG.

In the embodiment shown in FIG. 1, a platen 1 on which a printing paper P is mounted, a printing head 2 for printing on the printing paper P mounted on the platen 1, and a printing head 2 are mounted. A carriage 3 that moves in parallel to the platen 1, and a gap adjusting mechanism 4 that is provided in parallel with the carriage 3 and that adjusts a gap between the print head 2 on the carriage 3 and the print paper P to set an optimum value. A printer case (not shown) that stores and holds these units is provided.

The carriage 3 is provided with a paper detection arm mechanism 6 which is provided adjacent to the print head 2 on the carriage 3 and outputs predetermined paper information when the paper P on the platen 1 is abutted. .

Further, a carriage forward position detecting mechanism 7 that engages with the carriage 3 and outputs positional deviation information of the carriage 3 to the platen 1 side based on previously specified reference position information is provided at a predetermined position of the printer case 5. It is fixedly installed on the back side of the print head 2 in FIG.

Based on the information from the carriage advance position detecting mechanism 7 and the paper detecting arm mechanism 6, the platen 1
The thickness of the upper paper P is calculated to calculate the retracted position information of the carriage 3, and based on this, the gap adjustment mechanism 4
There is provided a gap setting control circuit 10 for controlling the above operation (by controlling the rotation pulse amount of the stepping motor 14 described later).

Here, the paper detection arm mechanism 6 comprises an arm member 6A provided upright on the carriage 3 and a strain gauge 6B mounted on the back surface of the arm member 6A. Reference numeral 8 indicates a strain gauge output conversion circuit for converting the output of the strain gauge 6B into a predetermined electric signal. Further, the contact surface with the platen 1 provided at the tip of the arm member 6A is arranged so as to be located in front of the platen 1 with respect to the print head 2.

The gap adjusting mechanism 4 described above includes a shaft eccentric support shaft 13 that eccentrically supports a guide shaft 12 that guides the movement of the carriage 3, and a stepping motor 14 that rotationally drives the shaft eccentric support shaft 13.
The gear trains 14A and 14B transmit the rotational force of the stepping motor 14 to the shaft eccentric support shaft 13. Specifically, the gap adjusting mechanism 4 is constructed by rotating the eccentrically rotating guide shaft 12 to rotate the platen 1.
It is a mechanism for moving the carriage 3 forward or backward with respect to.

Next, the operation of the above embodiment will be described.

First, when the entire apparatus is set to the operating state,
First, the gap adjusting mechanism 4 is operated to retract the carriage 3 until the rear end of the carriage 3 engages with the carriage advancing position detecting mechanism 7.

Next, the gap adjusting mechanism 4 is operated again, and the carriage 3 is moved forward with respect to the platen 1. The platen 1 includes the arm member 6A mounted on the carriage 3.
Upon contact with, the strain gauge 6B mounted on the arm member 6A is distorted, so that a predetermined signal corresponding to the strain amount is output from the strain gauge 6B. This strain gauge 6B
Is converted into, for example, a digital signal by the strain gauge output conversion circuit 8 and sent to the gap setting control circuit 10.

In this case, the gap setting control circuit 10 stops the rotation of the motor 14 and then reversely rotates the motor 14 to move the carriage 3 backward to the carriage advance position detecting mechanism 7 as described above. At this time, the gap setting control circuit 10 counts the number of pulses of the motor 14 from the time when the signal of the strain gauge output conversion circuit 8 is output to the time when the signal of the carriage forward position detection mechanism 7 is output, With this, the distance from the reference position of the carriage 3 to the platen 1 is specified.

After that, the carriage 3 is advanced to the printing paper P. At that time, the gap setting control circuit 10 keeps the motor 1 until the output from the strain gauge output conversion circuit 8 is output.
Count 4 pulses. Here, the gap setting control circuit 10 recognizes the paper thickness based on the pulse numbers of both of them, and retracts the carriage 3 to a predetermined printing distance according to the paper thickness.

As described above, in this embodiment, the strain gauge 6B, the strain gauge output conversion circuit 8, the carriage forward position detecting mechanism 7, the gap setting control circuit 10 and the like are constructed and equipped as described above. It is possible to obtain the effect like.

Since it is possible to reliably detect the presence or absence of contact between the platen 1 and the arm member 6A, it is not necessary to rotate the stepping motor 14 more than in the conventional case, and the operating time can be shortened at this point. Became.

.. Since the guide shaft 12 is eccentrically rotated only by the gears and the carriage is moved forward, at the same time, the sheet detection arm mechanism 6 also detects the amount of distortion.
It became possible to set a more accurate printing distance.

.. It is also possible to limit the amount of strain and thus the pressure with which the arm member 6A pushes the platen 1, and thus it is possible to operate with a weak force without making an impression on the pressure sensitive paper or the like.

.. It is possible to recognize the paper thickness of the print paper P, and it is possible to set the print distance according to the paper thickness.

[0038]

Since the present invention is constructed and functions as described above, according to the present invention, the printing distance can be set according to the paper thickness of the paper by the action of the gap adjusting mechanism and the gap setting control circuit for controlling the operation thereof. This enables accurate and clear printing according to the paper thickness.
It is possible to provide an unprecedented excellent dot impact printer capable of improving the durability and reliability of the entire apparatus.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing a conventional example.

[Explanation of symbols]

 1 Platen 2 Print Head 3 Carriage 4 Gap Adjustment Mechanism 6 Paper Detection Arm Mechanism 6A Arm Member 6B Strain Gauge 7 Carriage Advance Position Detection Mechanism 10 Gap Setting Control Circuit 12 Guide Shaft 13 Shaft Eccentric Spindle 14 Stepping Motor P Printing Paper

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, a carriage for mounting the printing head and moving in parallel to the platen, and this carriage. In a serial dot impact printer having a gap adjusting mechanism that is attached to the carriage and adjusts a gap between the print head on the carriage and the print sheet to set an optimum value, and a printer case that houses and holds these units, The carriage is equipped with a paper detection arm mechanism that is provided in parallel with the print head on the carriage and outputs predetermined paper information when it comes into contact with the paper on the platen. The front of the carriage that outputs the positional deviation information of the carriage to the platen side based on the reference position information A position detection mechanism is fixedly installed at a predetermined position of the printer case, the thickness of the paper on the platen is calculated based on information from the carriage advance position detection mechanism and the paper detection arm mechanism, and the carriage retreat position information is calculated. And a gap setting control circuit for controlling the operation of the gap adjusting mechanism based on the calculated value. 2. The paper detection arm mechanism comprises: an arm member provided upright on the carriage; and a strain gauge mounted on a back surface portion of the arm member. Dot impact printer. 3. The gap adjusting mechanism includes a shaft eccentric support shaft that eccentrically supports a guide shaft that guides the movement of the carriage, and a stepping motor that rotationally drives the shaft eccentric support shaft. The dot impact printer according to claim 1, wherein the dot impact printer is a printer.