JPH0577520A - Printing gap controlling device in wire printing head apparatus - Google Patents

Abstract

PURPOSE:To hold printing quality to a proper state by correcting the expanse of the gap between the tip of a printing wire and the surface of the paper on a platen due to the abrasion of the printing wire of a printing head. CONSTITUTION:A contact and separation mechanism moving a carriage in directions separated from and coming into contact with a platen counter 31 counting the total striking number of times of a printing wire, a memory means 29 storing the total striking number of times, and a drive motor 15 driving the contact and separating on mechanism in order to correct the stop position of the carriage in contact and separation directions on the basis of the stored total striking number of times are provided and the movement of the carriage in the platen direction is controlled corresponding to abrasion quantity of the printing wire by a control unit 26 so as to make a printing gap proper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for adjusting a gap between a tip of a printing wire and a platen in a printing wire printing head device in consideration of a consumption amount of the printing wire for printing on a printing sheet. Is.

[0002]

2. Description of the Related Art In a wire dot impact type printer, a carriage is slidably and reciprocally reciprocally provided on a pair of front and rear guide bars and an auxiliary shaft provided along a platen. It is configured to have a print head, ink ribbon, etc. that allows the print wire to project and retract. Then, printing is performed by printing a printing wire on the printing paper set on the platen surface via an ink ribbon.

In order to perform proper printing with this type of printer (printing device), it is necessary that the gap between the surface of the printing paper and the tip of the printing wire is appropriate. Therefore, in recent years, printers incorporating a mechanism for automatically adjusting the gap have been developed. This type of adjusting mechanism rotates a guide bar, such as a round bar, into which the carriage is slidably moved in the left-right direction so as to be eccentric with respect to the axis of the guide bar so as to rotate the operation shaft, and thus the carriage and thus the print head. It is configured so that it can be moved and adjusted in the contact and separation direction with respect to the platen, and the ribbon mask plate located at the front end of the print head is pressed against the surface of the printing paper on the platen with a predetermined pressure before starting the printing operation, and then, The carriage is configured to be appropriately separated from the surface of the printing paper.

A controller such as a microcomputer in the printer is provided with a front and rear position (contact) of the carriage when the ribbon mask plate is pressed against the platen with no printing paper at the predetermined pressing force at the time of shipping, for example. (Separation position) is stored in advance, and the printing paper thickness is detected by the difference in carriage movement when the paper is set on the platen and the ribbon mask plate is pressed during printing work, and the printing paper thickness is determined according to this printing paper thickness. The carriage is controlled to be separated by a preset distance.

[0005]

However, even with the adjusting mechanism described above, the amount of wear of the printing wire cannot be corrected. That is, when the printer is used for a long period of time, the tip portion of the print wire is worn and the total length of the print wire becomes short. Then, even if the gap is appropriate at first, the gap will be widened due to the abrasion, and the print density will be thinned or the gap will be too large. There is a problem that the distance traveled becomes large and an accident such as the tip of the printing wire being caught by the ink ribbon is likely to occur.

The present invention aims to solve the above problems.

[0007]

In order to achieve the above-mentioned object, according to the present invention, a carriage is moved along a platen, and a print wire is printed on a print head provided on the carriage to print on the platen. In a wire print head device including a printing mechanism for printing,
A contacting / separating mechanism for moving the carriage in the contacting / separating direction with respect to the platen, a counter means for counting the total number of markings of the print wire, and a position for correcting the contacting / separating direction stop position of the carriage based on the total number of markings. And a correction means for driving the contact / separation mechanism.

[0008]

[Embodiments] Next, embodiments embodying the present invention will be described. FIG. 1 shows a schematic configuration of a printing mechanism of a printer,
The carriage 1 is slidably fitted on a guide bar 3 arranged along the longitudinal direction of the platen 2. In the guide groove 5 formed in the rearward U-shape at the rear end of the carriage 1,
It is loosely fitted to an auxiliary bar 4 arranged in parallel behind the guide bar 3. The left and right ends of the platen 2, the guide bar 3, and the auxiliary bar 4 are supported by side plates of a chassis (not shown). A timing belt 6 attached to the carriage 1 is wound around a pair of left and right pulleys (not shown), and the timing belt 6 is moved left and right along the guide bar 3 by a carriage driving motor 7 (see FIG. 3) and the like. Is configured.

The print head 8 mounted on the carriage 1 has a plurality of print wires 9 which are projected and retracted from the nose portion 8a toward the platen 2 by a driving means such as a piezoelectric element or an electromagnetic coil. A ribbon mask 11 for preventing the printing paper 10 from being soiled by an ink ribbon (not shown) is provided upright at the tip of the carriage 1. The tip of the printing wire 9 and the through hole 11a in the ribbon mask 11 are provided.
An ink ribbon cassette (not shown) is replaceably arranged so that the ink ribbon may pass between the two. Further, a sensor 12 such as an optical sensor for detecting whether or not the printing paper 10 is set on the platen 2 is provided near the platen 2.

As a result, the print head 8 is moved to the carriage 1
Printing paper 10 set on the platen 2 as the paper moves.
In contrast to this, while laterally moving, ink is ejected onto the surface of the printing paper 10 to print. The print paper 10 is vertically fed by a paper feed mechanism 13 such as a tractor unit that rotates the platen 2 or vertically feeds the paper. In order to properly maintain the print quality, a print gap (gap) G having an appropriate distance is required between the tip of the wire, and by extension, the tip of the print head 8 and the surface of the print paper 10. Next, a print gap adjusting mechanism for adjusting the size of the gap G will be described.

Eccentric shafts 3a, which are eccentric with respect to the axis of the guide bar 3, are provided at both left and right ends of the guide bar 3 so as to project therefrom.
Both the left and right eccentric shafts 3a are rotatably supported by the left and right side plates of the chassis, and the carriage 1 is brought into contact with the platen 2 by rotating the guide bar 3 forward and backward around the shaft center of the eccentric shaft 3a. It is possible to move away. A contact / separation mechanism 14 is connected to the one eccentric shaft 3a. The rotational force of a drive motor 15 such as a step motor in the contact / separation mechanism 14 is transmitted to a drive gear 17 rotatably supported by a support shaft 16, and this drive force is also rotatably provided on the support shaft 16. The driven power 18 is transmitted to the driven gear 18 via a pin 19, and the rotational power is transmitted from the driven gear 18 to a swing gear 20 such as a fan fixed to the eccentric shaft 3a.

A pin 19 protruding from the driven gear 17
Is loosely fitted in an arc-shaped play hole 21 formed in the drive gear 17, one end of which is locked to the drive gear 17, and the other end of which is the pin 1
The pin 19 is biased to one end of the play hole 21 by the torsion spring 22 locked to the pin 9. With this, the drive motor 1
By the normal rotation of 5, the rotation of the drive gear 17 in the A direction is transmitted to the driven gear 18 as it is, the guide bar 3 is rotated in the X ′ direction, and the carriage 1 retracts in the direction away from the platen 2. On the contrary, when the drive motor 15 is rotated in the reverse direction to rotate the drive gear 17 in the B direction, the rotational force is transmitted to the driven gear 18 via the pin 19 against the force of the torsion spring 22, and the guide bar 3 is moved in the X direction. And the carriage 1 is moved forward so as to approach the platen 2. At this time, when the ribbon mask 11 comes into contact with the surface of the platen 2 or the printing paper 10 on the surface and the pressure becomes equal to or higher than a predetermined pressure,
The load torque of the driven gear 18 also becomes a predetermined value or more, the elastic force of the torsion spring 22 prevents the rotational force from being transmitted to the pin 19, and the driven gear 18 stops. The stop means (slip means) for stopping the driven gear 18 due to this overload may have a well-known configuration including a pressing spring and a friction plate.

The driven gear 18 is provided with an encoder 25 composed of a rotary plate 23 having a large number of slits formed at regular intervals in the circumferential direction, and a photo interrupter 24 for detecting light blocking / passing by the slits. It is provided.
The encoder 25 detects a position where the driven gear 18 is stopped (hereinafter referred to as an origin O) and realizes the gap G when the ribbon mask 1 on the front surface of the print head 8 is pressed against the platen 2 or the print paper 10. The output is provided to the control device 26. As shown in FIG. 3, the control device 26 includes a central processing unit (CPU) 27, a read-only memory (ROM) 28 for storing a control program described later, and a storage means 29 for storing various data. (Non-volatile random access memory, NVRAM) and a bus 30 for connecting these to each other. This central processing unit 27 is a dynamic RAM (DRA) of several kilobytes.
M) is used, and this DRAM is used as a work area. This control device 26, based on the output of the total number of printings stored in the storage means 29 by the output from the sensor 12 for detecting the paper, the encoder 25, and the counter 31 for counting the number of times the printing wire is used, Forward / reverse rotation control of the drive motor 14 is executed in accordance with a program to be described later, and a print gap adjusting unit and a correcting unit thereof are configured.

The counter 31 prints on the print head 8 from a buffer memory (not shown) that stores print data for one or two lines of the print paper 10 based on a print command to the printer. At the time of command, the number of times the printed wire is used is counted. In addition, this counter 31
May be configured by a program stored in the DRAM in the central processing unit 27 and the read-only memory 28.

The storage means 29 adds and accumulates the total number of times of printing, which includes the trial printing work from the time of production of the printing device and the wire used for the printing work, and stores it. The storage means 2
Reference numeral 9 is for holding the stored data even when the power supply to the printing device is turned off. Next, the print gap adjustment control and its correction control will be described with reference to the flowchart shown in FIG.

First, the printer is turned on to initialize the printer. At this time, the contents of the counter 31 (undefined when the power is turned on) are cleared to zero. Next, at step 401, it is judged by the sensor 12 whether or not the printing paper 10 is set on the platen 2, and when it is not set,
The paper feeding operation step is repeatedly executed until the sensor 12 is turned on (step 402).

After confirming that the printing paper 10 is set, the carriage 1 is moved to the platen 2 at step 403.
To a position where the carriage 25 presses the platen 2 with a predetermined pressing force to stop the forward movement by the encoder 25 to detect the origin O (step 40).
4). Then, in step 405, the storage means 29 is used until then.
The total number of printing times N stored in is read.

On the other hand, the wear amount of the print wire is experimentally determined according to the total number N of printings of the print wire, and the drive pulse M (the amount of advance of the carriage) of the drive motor 15 corresponding to the wear amount and the total mark. The relationship with the number of hits N is tabulated in advance and stored in the read-only memory (ROM) 28.
Before starting the printing operation, the driving pulse number M of the driving motor 15 is read from the total printing number N stored in the storage means 29 (step 406), and the carriage 1 is retracted by a predetermined distance (step 407). As a result, the gap G from the surface of the print sheet 10 to the tip of the print wire is appropriately maintained.

The printing operation is executed in this state, and the number of times the printing wire is printed is counted by the counter 31 accordingly (steps 408 and 409). Then, for example, the end of the printing operation is judged depending on whether the next data is input within a fixed time (step 410), and if not, the process returns to step 408 to continue the printing. If the processing is completed, the data stored in the counter 31 (printing frequency) is added to the stored content of the storage means 29 and stored (step 411). After this, the counter 31 is cleared to 0.

In the embodiment, the count value of the counter 31 may be transferred to the storage means 29 every time one line is printed, that is, every time the carriage return / line feed signal is input. Further, in the printing work for a single slip, the paper feeding operation may be performed before the printing is completed. Also in this case, the count number of the counter 31 is added to the stored value of the storage unit 29, and the added value is stored. After that, the operations from step 401 to step 407 are performed, the counter is cleared to 0, and then the printing of the next page is started.

Normally, the operation of adjusting the gap G is not executed midway from the time the power is supplied to the printer to the time it is turned off, or the series of printing operations is completed, but the printing operation on continuous paper is continued for a long time. In such a case, the printing operation is temporarily interrupted at appropriate time intervals or at every knot of a large number of continuous forms sheets, and the drive motor 15 is set to a predetermined value according to the total number N of printings stored in the storage unit 29. It is also possible to drive the number of drive pulses M to adjust the gap G and then control to restart the printing operation.

EEPRO is used as the storage means 29.
When M is used, the number of rewritable times is generally about tens of thousands. Therefore, for example, each time a specific address (2 bytes) of the EEPROM is counted 10,000 times, the address is rewritten to another address and the counting is continued so that the number of rewriting of the specific address does not exceed 10,000.

[0023]

As described above, according to the present invention, the amount of wear of the printing wire is known according to the number of times the printing wire is printed. Therefore, according to the corresponding relationship,
That is, the carriage is moved according to the total number of printings to adjust the gap between the carriage and the platen. Accordingly, even if the printing wire is worn and the gap is widened due to long-term use of the printing apparatus, the gap can be automatically adjusted to an appropriate value. Therefore, it is possible to perform printing with a constant print density at all times, the print quality is stabilized, and troubles due to inappropriate gaps can be eliminated.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a printing apparatus.

FIG. 2 is a side view showing a relationship between a carriage and a platen.

FIG. 3 is a functional block diagram of control means.

FIG. 4 is a flowchart of gap control.

[Explanation of symbols]

 1 Carriage 2 Platen 3 Guide Bar 3a Eccentric Shaft 4 Auxiliary Bar 7 Carriage Drive Motor 8 Print Head 9 Print Wire 10 Print Paper 11 Ribbon Mask 12 Sensor 13 Paper Feed Mechanism 14 Contact / Separation Mechanism 15 Drive Motor 16 Spindle 17 Drive Gear 18 Driven Gear 19 pin 20 Oscillating gear 21 Play hole 22 Torsion spring 25 Encoder 26 Controller 27 Central processing unit 28 Read only memory (ROM) 29 Storage means (NVRAM) 31 Counter

Claims (1)

[Claims] 1. A wire print head device comprising a print mechanism for printing on a print sheet on a platen by printing a print wire on a print head provided on the carriage while moving the carriage along the platen.
A contacting / separating mechanism for moving the carriage in the contacting / separating direction with respect to the platen, a counter means for counting the total number of markings of the print wire, and a position for correcting the contacting / separating direction stop position of the carriage based on the total number of markings. A print gap adjusting device in a print wire print head device, comprising: a correction means for driving the contact / separation mechanism.