JPH03224774A - printing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a printing device such as a dot printer.

(Prior Art) For example, a wire dot impact type printer is configured with a carriage that slides on a guide bar provided along a platen, and is equipped with a print head, an ink ribbon, etc. that makes a printing wire appear and retract from its tip. . Then, printing is performed by hitting the printing wire via an ink ribbon onto the printing paper set on the platen.

Therefore, in such a printer, in order to perform proper printing, it is necessary that a gap of an appropriate distance exists between the surface of the printing paper and the tip of the print head (print wire). In recent years, devices incorporating an adjustment mechanism that automatically adjusts the gear have been developed. This adjustment mechanism includes, for example, a contact/separation mechanism that rotates the guide bar around an axis eccentric from its axis to move the carriage in a direction toward and away from the platen, before starting the printing operation. The ribbon mask located at the tip of the print head is pressed against the print paper on the platen with a predetermined pressure, and then the carriage is pulled away from the paper surface by an appropriate distance. In this case, a control device such as a microcomputer stores in advance the position of the carriage when the ribbon mask is pressed against the platen at a pressure equivalent to the predetermined pressure, for example at the time of shipment. Then, from the difference between this memorized carriage position and the carriage position when the ribbon mask is pressed against the printing paper,
The thickness of the printing paper is detected, and the carriage is separated by an appropriate distance that is preset according to the thickness of the printing paper. Thereby, printing operations can be performed on printing paper of various thicknesses while the print head is always separated by a distance suitable for printing.

(Problem to be Solved by the Invention) By the way, the contact/separation mechanism transmits the rotational force of a drive gear provided on the step motor side, for example, to the driven gear on the guide bar side via a torsion coil spring. When the load torque of the driven gear exceeds a predetermined value, the torsion coil spring deforms and no rotational force is transmitted. Thereby, the ribbon mask can be pressed against the printing paper with a predetermined pressure corresponding to the spring force of the torsion coil spring.

However, when used for a long period of time, for example, the spring force of this torsion coil spring changes, and as a result, the force with which the ribbon mask is pressed against the paper surface changes from that at the beginning of use. Further, after long-term use, the frictional force of each part of the contact/separation mechanism changes, and this also causes the force with which the ribbon mask is pressed against the paper surface to change from that at the beginning of use.

On the other hand, platens are generally made of rubber, but as they are used for long periods of time, they deteriorate and the amount of deflection changes even when the same pressing force is applied. Sometimes.

In this way, if the force of pressing the ribbon mask onto the paper surface changes, and the amount of deflection of the platen changes from the initial one,
The conventional adjustment mechanism described above causes the following problems. In other words, the position of the carriage, which is the reference for detecting the thickness of the printing paper, is set at the time of shipment before use and is fixed at that value, so when the ribbon mask is pressed against the printing paper, If the amount of deflection of the platen is greater than the original value, the thickness of the printing paper will be detected to be thinner than it actually is.

As a result, if the gap is adjusted as is, the distance between the print head and the print paper will be inappropriate, leading to deterioration in print quality such as poor print density.

The present invention has been made in view of the above circumstances, and its purpose is to prevent the pressing of the leading end of the carriage from occurring between the printing paper and the print head even if there is a change in force or a change in the amount of deflection of the platen. An object of the present invention is to provide a printing device capable of appropriately adjusting a gap.

[Structure of the Invention (Means for Solving the Problems) The printing device of the present invention is provided with a mechanism for moving the carriage toward and away from the platen, and when printing paper is not set on the platen. means is provided for detecting the position of the carriage at this time by pressing the front end of the carriage against the platen using a contact/separation mechanism, and a storage means is provided for storing the position of the carriage detected by the detection means, and the printing paper is placed on the platen. A means is provided for detecting the position of the carriage at this time by pressing the leading end of the carriage against the printing paper on the platen using a contact/separation mechanism when it is set, and the position of the carriage detected by the detection means and the storage means are The present invention is characterized by a configuration in which a means is provided for determining the position of the carriage during printing based on a difference from the stored position of the carriage, and a means is provided for driving the approaching/separating mechanism to move the carriage to the determined position. have

(Operation) According to the above means, by pressing the front end of the carriage against the platen when there is no printing paper, the position of the carriage, which serves as a so-called reference for detecting the thickness of printing paper, is detected and this is stored. . By performing such detection and memorization appropriately, it is possible to obtain a reference position that corresponds to the state of the approach/separation mechanism and platen at that time. The thickness can be detected. Therefore, even if the pressing force changes or the amount of deflection of the platen changes due to long-term use, for example, an appropriate gap can always be formed between the print paper and the print head.

(Embodiment) An embodiment in which the present invention is applied to a dot printer will be described below with reference to the drawings.

First, in FIG. 2, which shows a schematic configuration of the main parts of a dot printer, which is a printing device, a carriage 1 is connected to a platen 2.
It is attached to the side bar 3 in a slidable manner. Further, a fixed bar 4 provided parallel to the guide bar 3 is loosely inserted into a slide hole 1a provided on the front side of the carriage 1 in the figure. The carriage 1 is moved along a guide bar 3 by a well-known carriage drive mechanism including a pair of pulleys, a belt, a drive motor 5 (see FIG. 3), etc. (not shown). Note that these platens 2. Guide bar 3. Both ends of the fixing bar 4 are supported by side plates (not shown) provided on the main body of the printer. Also, Figures 4 to 7
As shown in the figure, near the platen 2, there is a
A paper detection sensor 7 for detecting whether printing paper 6 is set on top is disposed.

The carriage 1 is provided with, for example, a dot-impact print head 8 facing the platen 2, and an ink ribbon cassette (not shown) is replaceably attached thereto.

Further, a ribbon mask 9 is attached to the tip of the carriage 1 to prevent the printing paper 6 from being stained by an ink ribbon (not shown). As is well known, the print head 8 has a plurality of printing wires arranged vertically at its tip, and projects the printing wires toward the platen 2 to move the ink ribbon forward through the through hole 9a of the ribbon mask 9. It's meant to be pushed. As a result, the print head 8 moves in the horizontal direction with respect to the print paper 6 set on the platen 2 as the carriage 1 moves, and hits the ink of the ink ribbon onto the paper surface of the print paper 6. It is designed to print. Further, the printing paper 6 is transported by a paper feeding mechanism 1 that rotates the platen 2 and the like.
0 (see Figure 3).

Therefore, in order to perform proper printing by the print head 8, a gap G (see FIG. 7) of an appropriate distance must be formed between the paper surface of the print paper 6 and the tip of the print head 8. Is required. Here, a mechanism for adjusting this gear knob G will be explained.

That is, as shown in FIG. 2, eccentric shaft portions 3a (only one side is shown) are integrally provided at both ends of the guide bar 3 at positions eccentric from the axis thereof. This eccentric shaft portion 3a
is rotatably supported by the side plate, so that the guide bar 3 is rotatable in the directions of arrows X and Y about an axis eccentric from its axis, so that as the guide bar 3 rotates, The carriage 1 moves in a direction toward and away from the platen 2. and,
The eccentric shaft portion 3a is connected to a contact/separation mechanism 11, and the guide bar 3 is moved in the direction of the arrow X by this contact/separation mechanism 11.

It is designed to rotate in the Y direction. This contact/separation mechanism 11
In this case, the rotational force of the step motor 12 is reduced in speed and transmitted to a drive gear 14 rotatably provided on the shaft 13, and the rotational force of the drive gear 14 is transmitted to the drive gear 14 rotatably provided on the shaft 13. is transmitted to the driven gear 15 via the pin 16,
Further, the rotational force of the driven gear 15 is transmitted to a swing gear 17 fixed to an end of the eccentric shaft portion 3a.

At this time, one end of the bin 16 is fixed to the driven gear 15, and the other end is inserted into a long hole 18 formed in the drive gear 14 so as to extend in the circumferential direction. The spring force of a torsion coil spring 19 provided in the slot 14 pushes the slot 18 toward one end 18a.

With this, the rotation of the drive gear 14 in the direction of arrow Y' due to the forward rotation of the step motor 12 is directly transmitted to the driven gear 15, and the guide bar 3 is rotated in the direction of arrow Y.
The carriage 1 is configured to retreat in a direction away from the platen 2.

On the other hand, the rotation of the drive gear 14 in the direction of arrow X'' due to the reverse rotation of the step motor 12 is transmitted to the driven gear 15 via the torsion coil spring 19 and the guide bar 3
is rotated in the direction of arrow X, so that the carriage 1 moves forward in a direction approaching the platen 2. At this time, the movement of the carriage 1 in the forward direction is regulated by the ribbon mask 9 at the tip of the carriage 1 coming into contact with the platen 2 or the printing paper 6 set on the platen 2. Driven gear 1
When the load torque 5 exceeds a predetermined value, the torsion coil spring 19 is deformed and the rotational force is no longer transmitted to the pin 17, so that the driven gear 15 stops. In other words, the pressing force when the carriage 1 is pressed against the platen 2 or the printing paper 6 is a pressure corresponding to the spring force of the torsion coil spring 19.

In addition, this approaching/separating mechanism 11 includes an encoder 22 which includes a rotating disk 20 that is attached to the driven gear 15 and has a large number of slits 20a, and a photointerrupter 21 that detects transmission/blocking of light through the rotating disk 20. is provided.

This encoder 22 is used to detect that the driven gear 15 has stopped when the carriage 1 is pressed against the platen 2 or the printing paper 6, and to move the carriage 1 to the platen 2 or the printing paper 6.
This is for stopping at a predetermined position (hereinafter referred to as origin 0) that is sufficiently far away from the origin, and its output is given to a control device 23 (see FIG. 3), which will be described in detail later.

As shown in FIG. 3, this control device 23 includes a CPU (Central Processing Unit) 24, a ROM (Read Only Memory) 25 that stores programs, etc. to be described later, and a RAM (Random Access Memory) that temporarily stores various data. ) 26 and a bus 27 interconnecting them.

This control device 23 executes energization/disconnection control of the step motor 12 based on the outputs of the paper detection sensor 7 and the encoder 22 according to a program to be described later, and constitutes each means referred to in the present invention. It has become.

In this case, the control device 23 determines the position of the carriage 1, that is, the origin O
The distance traveled from the step motor 12 is detected as the number of drive pulses of the step motor 12. And control device 2
The ROM 25 of No. 3 stores in advance data on the number of driving pulses NB from the position of the carriage 1, that is, from the origin O, which forms the optimum gap G for printing. In this embodiment, the thickness A of the printing paper 6 (the number of drive pulses NA described later)
), the optimum gap G interval is set differently depending on the print head 8.
is increasing its impact. Therefore, the data on the number of driving pulses NB has different values corresponding to the number of driving pulses N^.

Note that the control device 23 also controls the carriage drive mechanism and paper feeding mechanism 10.

The printer also includes a paper type detection means 28 such as a limit switch for detecting whether the printing paper 6 is a single sheet or a continuous sheet.
is provided, and this output is given to the control device 23.

Next, the operation of the above configuration will be explained. When the power switch (not shown) of the printer is turned on and the power is turned on, the control device 23 controls the surface of the print paper 6 and prints according to the procedure (program) shown in the flowchart of FIG. 1 stored in the ROM 25. The gap G between the head 8 and the tip is adjusted.

First, in steps 81 to S4, as a preparation stage for a printing operation, an operation is performed to move the carriage 1 located at an arbitrary position to a printing start position. In step S1, the carriage 1 is moved backward (in the direction of arrow Y) from the platen 2 by the contact/separation mechanism 11 and stopped at the origin O (fourth
(see figure). This stopping, that is, stopping the driving of the step motor 12 is done based on the output of the encoder 22. In other words, while the carriage 1 is moving, the signal waveform from the encoder 22 changes alternately between high and low levels at short time intervals, but when the carriage 1 reaches the origin O, the signal waveform changes. The low level (or high level) continues for a certain period of time, and upon detection of this, the driving of the step motor 12 is stopped. Then, the carriage 1 is moved by the carriage drive mechanism until the home position is detected (steps S2 and S3), and then moved by a predetermined distance and stopped at the print start position (step 84).

In the next step S5, based on the detection by the paper type detection means 28, it is determined whether the set printing paper 6 is a single sheet or a continuous sheet. Here, in the case of a single sheet, in the next step S6, the paper detection sensor 7 determines whether or not the printing paper 6 is set on the platen 2 (Paper E
nd is not detected), and if the printing paper 6 is set here, the printing paper 6 is ejected by the paper feed mechanism 10 (Step S7), the platen 2
After binding with no printing paper 6 on top, proceed to the next step S.
Proceed to step 9. On the other hand, in the case of continuous ledger, in step S8,
If the printing paper 6 is not set on the platen 2 (
If Yes), the process proceeds to step S9 as in the case of the ticket, and only if it is set (No), the process proceeds to step S14, which will be described later.

Now, when the printing paper 6 is not set on the platen 2 as described above, steps 89 to S are performed.
At step 11, the position of the carriage 1 when the ribbon mask 9 at the tip of the carriage 1 is pressed against the platen 2 is detected and stored in the RAM 26. That is, in step S9,
Applying a drive pulse to the step motor 12, the approaching/separating mechanism 11
The carriage 1, which was at the origin O, is moved forward (in the X direction). As the carriage 1 moves forward, the ribbon mask 9
comes into contact with the platen 2 (see FIG. 5). At this time, as described above, the carriage 1 is pressed against the platen 2 due to the pressing force corresponding to the spring force of the torsion coil spring 19, and the rotating disk 2
When the encoder 22 detects the stop of 0 (step 510), the power supply to the step motor 12 is stopped.

Then, the number of drive pulses NL given to the step motor 12 up to the time of this stop is stored in the RAM 26 as the moving distance L (position) of the carriage 1 from the origin O (step 511). Thereafter, the step motor 12 is energized and the carriage 1 is retreated to the origin O (step 51
2) Next, the paper feeding mechanism 10 sucks the printing paper 6 and sets it on the platen 2 (step 81).
3).

Then, in steps 314 to S18, the gap G is adjusted at the time of starting printing. First, in step S14, a drive pulse is applied to the step motor 12, and the carriage 1, which was at the origin O, is moved forward (in the X direction) by the contact/separation mechanism 11. As the carriage 1 moves forward, the carriage 1 now comes into contact with the paper surface of the printing paper 6 (see FIG. 6). Similarly, at this time,
The carriage 1 is pressed against the printing paper 6 by force according to the spring force of the torsion coil spring 19, and the encoder 22 detects the stop of the rotating disk 2o due to the stop of the driven gear 15 at this time. (Step 515) Power supply to the step motor 12 is stopped. The number of driving pulses N given to the step motor 12 until this stop is the moving distance M (position) of the carriage 1 from the origin O.
(Step 516), and the difference between the distance distance and the distance M, that is, the difference between the number N of drive pulses stored in the RAM 26 and the number NM of drive pulses is calculated (Step 517).

At this time, the difference between the number of driving pulses NL and the number of driving pulses N is the number of driving pulses NA corresponding to the thickness A, since the difference between the distance and the distance M corresponds to the thickness A of the printing paper 6. . In step S18, the position of the carriage 1 (the number of drive pulses NB of the step motor 12) corresponding to the calculated number of drive pulses NA is read from the data stored in the ROM 25, and in the next step s19, the position of the carriage 1 corresponding to the number of drive pulses NA calculated is read out. The step motor 12 is energized by the number of drive pulses (NMNB) that should cause the carriage 1 to retreat from the position to the position of the number of drive pulses NB, and the carriage 1 retreats from the surface of the printing paper 6 by that amount (FIG. 7). reference). Incidentally, in the step 817, if the result in step S8 is "No" and the number of drive pulses NL is not detected at that time, the value of the number of drive pulses NL detected last time and stored in the RAM 26 is used as is. It has become so.

As a result, the adjustment of the gap G between the surface of the printing paper 6 and the print head 8 is completed, and it becomes possible to start the printing operation. At this time, the carriage 1 performs the printing operation at an optimal position according to the thickness A of the printing paper 6. In this case, since both the distance M and the distance are detected, the so-called absolute thickness A of the printing paper 6 can be detected, and the gap G with an appropriate interval can be reliably formed. As a result, printing is performed with high print quality without defective print density.

In this way, according to this embodiment, when the power is turned on, the platen 2
Since the position of the carriage 1 is detected by pressing the carriage 1 against the platen 2 without the printing paper 6 set on top, it can be used as a standard for detecting the thickness of the printing paper 6. The position of carriage 1 is
It will be detected accordingly. Therefore, as in the past, the position of the carriage, which is the standard for detecting the thickness of printing paper, is fixed to the position at the time of shipment. Unlike those in which the thickness of the printing paper may be detected as a value different from the actual value due to changes, it is possible to obtain a reference position that corresponds to the state of the approaching/separating mechanism 11 and the platen 2.
When the leading end of the carriage 1 is pressed against the printing paper 6, the thickness A of the printing paper 6 can be accurately detected. As a result, even if the pressing force changes or the amount of deflection of the platen 2 changes due to long-term use, the printing paper 6
An appropriate gap G can always be formed between the print head 8 and the print head 8.

In the above embodiment, the distance between the gaps G is varied depending on the thickness A of the printing paper 6, but the gaps G may be formed at the same distance regardless of the thickness of the printing paper. Further, the operation of pressing the front end of the carriage 1 against the platen 2, detecting and storing the position of the carriage 1 at this time does not have to be performed every time the printer is powered on, but may be performed as appropriate.

In addition, the present invention can be implemented with appropriate modifications within the scope of the invention.

[Effects of the Invention] As is clear from the above description, according to the printing device of the present invention, a mechanism for moving the carriage toward and away from the platen is provided, and the printing paper is set on the platen. A means is provided for detecting the position of the carriage at this time by pressing the front end of the carriage against the platen using a contact/separation mechanism at a time when the printing paper is not in use. A means is provided for detecting the position of the carriage by pressing the leading end of the carriage against the printing paper on the platen using a contact/separation mechanism when it is set on the platen, and detecting the position of the carriage detected by this detection means and the above-mentioned position of the carriage. Means for determining the position of the carriage during printing based on the difference from the position of the carriage stored in the storage means is provided, and means for driving the approaching/separating mechanism to move the carriage to the determined position is provided. , Pressing the tip of the carriage during use has an excellent effect in that the gap between the printing paper and the print head can be adjusted appropriately even if the force changes or the amount of deflection of the platen changes. It is something.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a flowchart of gap adjustment, FIG. 2 is a perspective view showing the main parts of the printer, FIG. 3 is an overall block diagram, and FIGS. Figure 7 is a longitudinal side view showing the carriage part. Figure 4 shows the carriage at the origin O, Figure 5 shows the carriage pressed against the platen, and Figure 6 shows the carriage pressed against the printing paper on the platen. FIG. 7 shows the pressed state and the state in which gap adjustment has been completed. In the drawings, 1 is a carriage, 2 is a platen, 3 is a guide bar, 3a is an eccentric shaft portion, 6 is a print paper, 7 is a paper detection sensor, 8 is a print head, 9 is a ribbon mask, 11 is a contact/separation mechanism, and 12 is a paper detection sensor. A step motor, 22 an encoder, and 23 a control device (each means).

Claims (1)

[Claims] 1. In a device that prints on printing paper on the platen using a print head provided at the tip of the carriage while moving the carriage along the platen, the carriage is moved toward and away from the platen. a contact/separation mechanism; a means for detecting the position of the carriage at this time by pressing the front end of the carriage against the platen by the contact/separation mechanism when the printing paper is not set on the platen; a storage means for storing the position of the carriage; and when the printing paper is set on the platen, the contact/separation mechanism presses the leading end of the carriage against the printing paper on the platen to detect the position of the carriage at this time. means for determining the position of the carriage during printing based on the difference between the position of the carriage detected by the detection means and the position of the carriage stored in the storage means; and means for moving the carriage to the determined position. A printing device characterized by comprising: means for driving the contact/separation mechanism so as to cause the contact/separation mechanism to move.