JPH0431074A - Automatic head gap adjustment device of printer - Google Patents

Abstract

PURPOSE:To set an appropriate head gap by detecting optically and action until a printing head is allowed to come in contact with the surface of a sheet and driving a motor by the number of steps corresponding to the detection signal to move the printing head backward. CONSTITUTION:When a head gap is adjusted, a printing head 6 descends from a position which is previously set as a reference and detects a distance upto a position where the head 6 comes in contact with a sheet 10, that is, a distance upto a zero position as a pulse count. This pulse count is entered in an auxiliary control part 52. Then this auxiliary control part 52 counts a detected pulse entered from a rotation detection part 55. The auxiliary control part 52 drives a motor 24 by the number of steps corresponding to the count at the time of a zero position detection, and moves the printing head 6 backward over a specified distance. Thus a specified gap G is set between the sheet surface 10 and the tip 6a of the printing head 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic head gap adjustment device for automatically adjusting the gap between a print head and a recording paper surface in an impact printer.

[Conventional technology]

In each type of printer, it is necessary to adjust the gap between the print head and the recording head (hereinafter referred to as the head gap) in order to achieve a predetermined print density. In a printer using an impact type print head, this head gap adjustment Jl is one point. In other words, if the head function [1] is too large, the printing pressure will be weak and the print will be thin, while if it is too small, the printing pressure will be strong and the recording material may smudge the ink ribbon or the print wire. This is because the ink ribbon gets caught and causes problems such as clogging, and the wire itself suffers significant wear and lacks durability.

Therefore, recently, a mechanism that automatically adjusts the head gap,
The device was developed by a woodcutter, for example in 1986.
- Printer head gap movement vI according to No. 187063
Four adjustment devices have now been disclosed. This head Kakuhara self-adjusting device uses an eccentric shaft, which is rotated by the drive of a step motor, thereby lowering the print head and pushing it away from the recording hole to the zero position. is detected, and then the step motor is rotated in the opposite direction by a predetermined number of steps to move the print head back from the zero position by a predetermined amount.

[Problems to be Solved by the Invention] In such a conventional head-to-head retaining S-adjustment cover,
Mechanically, the number of steps of the step motor and the eccentric angle of the eccentric shaft that moves the print head up and down (the rotation angle of the guide shaft that is connected to the eccentric shaft) are proportional to each other, but the eccentric angle and the head The gap is approximately a sine curve, and controlling only the specified number of steps when the print head rises does not correspond to the paper thickness for recording purposes and does not result in a t-head gap.
As shown in figure (a), eccentricity [f8. III is 45°
(In the case of an approximately sine curve pointing upwards rather than in direct proportion, I
A predetermined head gap G can be set by driving the step motor with a specified number of motor steps P in the J near area, but a predetermined head gap G can be set by driving the step motor with the same specified number of motor steps P in the non-IJ near area. Also, the head gap g1 (G<'gt) is too large. Also,
As shown in Figure 7), if gA center curve ■ is a substantially sine curve pointing downwards from 45 degrees, if the step motor is similarly driven at the specified number of motor steps P in the linear region, the predetermined result will be reached. Although the head gap G can be set,
In the non-linear region, even if IKlvl with the same specified motor step number P, the head distance II g 2 (G >
g z , ), which is too small.

For this reason, it is not possible to set the head gap to an appropriate value according to the paper thickness of the book, and if the plate is a thick copy book used as a side dish, the eccentric angle will become large. I've run into a lot of problems.

Therefore, in view of the above-mentioned conventional problems, the present invention is a quaternary one, and its purpose is to
? lBl! When using gold to fill the head gap,
An object of the present invention is to provide an automatic head gap adjustment device for a printer, which allows the head gap N to be set to an appropriate value.

[Ninth way to solve section @]

To achieve the above object, the present invention provides an automatic head gap adjustment device for a printer that holds a print head movably forward and backward relative to a paper surface and automatically adjusts the gap between the print head and the paper surface. a motor for advancing and retracting the print head; a means for optically comparing the position of the print head from its set position to the point where it contacts #J; It is equipped with a control section that drives the motor to retract the print head.
Effect J In the present invention, when adjusting the head gap between the print head and the paper surface, it is possible to reliably set the head gap of 7 to an appropriate value in relation to the paper thickness of the entire paper. .

〔Example〕

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings.

Fig. 1 is a block diagram of the circuit configuration of an automatic head gap adjustment device for a printer according to the present invention, Fig. 2 is a perspective view of the print head section of a horizontal impact printer, Fig. 3 is a rim axis type head 1 dark loss. ＠Second view of the IIh construction site, No. 41]
and (b) are a sectional view and a partial plan view of the synchronization supervisory mechanism.

In FIG. 2, reference numeral 1 denotes a printing mechanism, which is arranged vertically in parallel and is slidably held by a pair of guide shafts 2.3, and includes a carriage 4 and a motor (not shown). The shirt l-2 runs by the drive of the carriage 4 and guides the carriage 4.
, 3, a conventional WA-known wire dot type mortar head 6 mounted on the carriage 4, a card holder 7, and the # of the carriage 4.
It is composed of an ink ribbon 8, a platen 9, etc., which are fed in the printing direction.

The print head 6 is supported by a carriage 4 so as to be able to move forward and backward in the vertical direction with respect to the recording disk 10, and the gap between the print head 6 and the paper surface, that is, the head gap (G), is adjusted to the paper thickness by a head gap alignment adjustment mechanism, which will be described later. Regardless, the timing belt 5 is set to a constant value regardless of the purpose, and when printing starts, the timing belt 5 starts running, printing 2 is performed while moving in the left and right direction with the carriage 4, and when printing for one line is finished, the timing belt 5 starts running. The motor rotates to perform a line feed, and the print head 6 prints while moving in the opposite direction to the arrow.The above operation is repeated, and as printing progresses, the recording paper 10 moves in the direction of the arrow in Figure 2. K so that it is gradually transferred in the direction.

3 and 4 show an automatic head gap adjustment machine 1l120 for the print head 6, which is rotatably disposed on a side plate (left side frame) 21a and a guide shaft 2.
One end is connected to the eccentric shaft 22, and another fresh water 2 is connected to the above.
3, and a rotation transmission mechanism 2 that transmits the rotation of the step motor 24 to the eccentricity @22.
5 and the rotational force in the direction in which the print head 6 descends is applied to the eccentric shaft 2.
The spring 26 etc. attached to 2 provides a low yakuza structure. The fitting hole of the 41 core sheath 22, where the axial load of the guide shaft 2 is indicated, is eccentric to the center of the outer shape of the broken shaft 22, and this outer shape is the same as the bearing hole. It has been translated into Japanese and can be rotated freely. However, when the single-core shaft 22 rotates, the guide shaft 2 moves up and down in accordance with the amount of eccentricity of the fitting hole, thereby changing the head position.

The rotation transmission mechanism 25 is press-fitted and fixed to the output shaft 30 of the step motor 24 and includes a drive gear 31, and a first intermediate gear 32 is meshed with the drive gear 31. The first intermediate gear 32 integrally has a sleeve 34, is rotatably disposed on a shaft 33 protruding from the side plate 23, and has a one-way clutch 36 integrally equipped with a slip gear 35. is installed. The slip gear 35 is rotatably disposed on a support shaft 37 protruding from the side plate 23.
It meshes with the intermediate gear 38. A third intermediate gear 39, which also has a rotational index, is provided at the leakage part of the support 31, and this third intermediate gear 39 has an eccentric angle L? It is provided integrally with s22 and is mated with the subordinate gear 4G. A stopper pin 41 is attached to this driven gear 40, and when the n1 print head 6 rises to the maximum height position, that is, the head lifting position, the retraction microswitch 42 is energized by the pin 41, and the retraction microswitch 42 is activated. The operation is now completely stopped.

The -1 clutch 36 is free with respect to the first intermediate gear 32 during the zero position detection operation of the print head 6 (when the lower surface of the head is pressed against the recording paper), and is free from the first intermediate gear 32 when the print head 6 is detected after the zero position is detected. During the head gap setting operation (returning operation) for retracting the head upward by a certain distance, the sleeve 34
The first intermediate gear 32 is configured to rotate integrally with the first intermediate gear 32 and transmit the rotation of the first intermediate gear 32 to the slip gear 35.

The spring 26ζ9Sll of the graben of the guide shaft 2
2111 is fixed to the other side plate (stone side frame) 21b with screws, and lttlim is fixed to the guide shaft 2 with screws.

In this case, by screwing the print head 6 into the guide shaft 2 for a long time, a rotational force is normally applied to the eccentric shaft 22 in the direction in which the print head 6 descends.
Zero rank ′j! When the eccentric shaft 22 is rotated when the L is released, it is released and the spring force is weakened.

Since the step motor 24 is supplied with a holding current sufficient to generate a driving force balanced with the spring force of the normal spring 26, the rotation transmitter 1125 is locked. This stops the step motor 24 and output shaft 3Of:
When left free, the spring 26 prevents the eccentric shaft 22 from rotating. However, it is also possible to lock the eccentric shaft 22 by engaging a pawl operated by a solenoid or the like with the driven gear 40 without supplying the holding current to the step motor 24. The step motor 24 is used during the head gap setting operation and when the print head 6
It is driven when pushing up to the highest position.

To explain the operation of such head space automatic adjustment gl iso structure 20, first, the step motor 24 is controlled to IA by biased force from the control section, and the print head 6 is raised to the maximum height position. At this time, due to the rotation of the step motor 24, the drive gear 31 - the first intermediate gear 32 - the one-way clutch 3
6-Slip gear 35-Second intermediate gear 3! I- is transmitted to the driven gear 40 via the third intermediate gear 39, and the bias IL? Axis 2
2 is rotated in a direction in which the print head 6 retreats from the recording paper 10. As a result, the spring force is accumulated in the spring 26. When the print head 6 reaches a predetermined height, the pin 41 provided on the driven gear 40 comes into contact with the retraction microswitch 42 and is energized to stop the print head 6. When the print head 6 reaches the highest position and a certain period of time has elapsed, the holding 1cfL' is supplied to the step heater 24 and the rotation transmission mechanism 25 is locked.

Next, the recording paper 10'' is fed to the lower part of the print head 6,
The zero position of the print head 6 is detected. At this time, the supply of the holding current is stopped, and the step motor 24 is stopped. Then, rotation transmission -1!11125r! step motor 24
One core I with the spring force of the rounded spring 26 which becomes free against
Rotate It122. After this time, the guide shaft 2/:II: presses the print head II against the recording paper 10 via the card holder 7 and the ink ribbon 8 in order to rotate together with the eccentric shaft 22 and gradually descend.

Next, when the pressing operation is completed, pulses of the number of steps corresponding to the predetermined head gap (G) K are applied to the step motor 24 to drive the motor 24, and the output J
I3t) is transmitted to the driven gear 4 by the rotation transmission mechanism 25.
0, the eccentric shaft 22 along with the driven gear 40
rotates and tightens the spring 26, at the same time the guide shaft 2t' is pushed up at a height of about 1-1 according to its rotation angle,
Thus, a predetermined head gap <c,> is set. Then, after the step motor 24 is maintained in a driven state with a holding current and the rotation transmission mechanism 25 is locked, the above-described printing operation by the print head 6 is performed.

Figure ig1 is a block diagram of the circuit configuration for controlling the head gap according to this embodiment, and includes a main control section 51 consisting of a microprocessor (hereinafter referred to as CPU) and memory, and a sub-control section similar to this but slightly less complex. The main control section 51 is provided with a head gap setting device 53 using a dip switch or the like, and the output of the setting device 53 is provided to the main control section 51. It is used to exchange data with a device (hereinafter referred to as UCE).

However, the sub-side # section 52 is given a command from the main control section 51 and a detection signal from a rotation detection section 55, which will be described later. 1 to drive the motor (hereinafter referred to as motor) 24? , main control unit 51, A system a-N52U, each *
The CPU executes all the instructions in the memo+)cp and performs predetermined control operations while accessing reliable data to the memory.

Here, the rotation detection section 55μ, the above-mentioned 3442, and the one-way latte 36 constituting the rotation transmission mechanism 25 of FIG.
The outer periphery of the VC layer f′L is a nine-slit plate 56, and the slit plate 56 is provided with four layers n arranged at equal intervals (12
When adjusting the head gap, the print head (F'! ( D) 6 is the preset position -"
R<Head retraction position is used as a reference, and the number of pulses is detected as the number of pulses that the head descends from that position and presses against the surface of the paper 1a, that is, the zero position, and the pulses are input to the sub-control unit 52. You're lying, this vice'! II Gobe 5
2, the detection pulses input from the rotation detector 4555 are counted, and when the zero position is detected, the motor 24 is driven by the number of steps corresponding to the counted number, and the print head 6 is moved a certain distance ad. By retracting the print head 60 by a certain amount, a predetermined gap G is set between the paper surface 10 and the print head 60 base 216a.

At this time, after the zero position "f" is calculated, the number of steps n for driving the motor 24 to move the print head 6 backward is ?1], for example, the first
As shown in the table, an integer number corresponding to the number of steps corresponding to the pulse count up to zero violet sunrise is stored in the CPU as data, and control is performed based on that count number. ing. As a reminder, in Table 1, the pulse count number C is an integer between θ and 36, and C
≦121 Table C≦12 or CaB6 = 200 215 = 17 = 18 = 20; 21 2≦C≦24 5≦C≦27 8≦C≦30 1≦C≦35 Figure 5 shows the above example Head storage automatic base (＾Gλ
,) v5117, and as a king a.
Main part of the control i11 status by the CPU of the control unit 52 a-
It is a chart.

In Fig. 5, first, “Pulse period 200 pps
4) j 101, Kuronokutsukurusu? Determine the frequency division ratio of the divider that divides the signal and sends it to the drive circuit 54,
Motor rotation direction/advance sensor) J102 gives a command to the drive circuit 54 to set the motor 24, for example, in a normal rotation state, and also configures the CPU and sends a counter for driving the motor to the forward step by I n = 360 J103. Set the number. Same RK, 1 pulse counting reset J
After resetting the pulse counting counter in the CPU with 121, drive pulses are sent out from the drive circuit 54 with motor 1 step drive 104, and I n=n-I.
J 105 subtracts the said counter and in-〇↑''
1θ6 is checked, and all iterations from step 104 are performed while this is N (No). At this time, the pulse counting counter is set to the print head 6 which is not # in the step drive of the motor 24.
The pulses from the nine rotation detection section 55 are sequentially counted in accordance with the fall of the rotation detecting section 55 (step 122).

If step 106 becomes Y (YES), the print head 6 has finished advancing (zero position detection), and steps 101 and I
1 pulse period 230 p ps set for W1” 10
7, and set 1 motor, 1 direction, and the amount of retreat 110
8, this time a command to set the reverse state is sent to the drive circuit 54, and in response to the count number C of pulses up to the zero position transition, in response to step aK of the friend motor 24, for example, rii
1=36−+−A J 10! Step 10 by i
3. Set the motor drive counter to P and turn to L step 10.
Same as 4-106, 1 motor 1 step work" 110,
Execute I n-=n-I J 111n=ofu 1112, repeat step 110 and subsequent steps until step 112 is N, and step 112 becomes Y! 'i After the print head 6-A ends, and a series of automatic head gap adjustment (AGAJ) is completed.

According to this embodiment, when adjusting the head gap, pulses are counted according to the advance distance stK until the print head 6 pushes from its reference position to the surface of the paper 10, and
The print head 6 corresponds to the count number C, and the number of steps is 9.
How to drive and retract K, how to move one of the front sheets
4, the head spacing can also be set to an appropriate value. For example, the sixth
Figure (as shown in a): In the case of 1 piece of 10dE, 2
If the number of pulse counts C for the forward distance t is 31≦C≦35 and the pulse count is 31≦C≦35 with a pulse of 00pps/Q period, the distance, %d total 48
It is driven by steps (see Table 1, 8).
If the number of membranes 10 is 8 as shown in Figure 6b, and the count number C is 17 when moving forward, the distance d is 40 when retreating.
By driving by steps, it is possible to create an optimal head M" which corresponds to Gijun. You get punished by what you get.

By the way, is the number of steps of the motor and the head clearance of the conventional model A relatively comparable? In other words, if the paper is thin, it will not be effective, and if the paper is thick, it will require the use of a higher-ranking detective or commando manpower each time.
The head gap automatic adjustment 'jfe't of the present invention has the advantage of being able to accommodate any paper thickness.

〔Effect of the invention〕

As mentioned above, in the present invention, the print head is held movably forward and backward relative to the paper surface all around the circumference, and the relationship between the plate print head and the paper surface is improved.
Printer head auto adjustment that automatically adjusts l'thg
! 4. Detect the movement fil' from the time when the print head comes into contact with the paper surface from the alignment lid to the time when the print head comes into contact with the paper surface.
! The motor is driven by the number of steps corresponding to I to move the print head backward. So, overpressure can be set throughout the head gap. Therefore, it is possible to perform good printing, prevent the ink ribbon from staining the recording paper, and prevent paper jams. This can bring about great effects, such as improving the durability of the same as above.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the circuit configuration of the head gap adjustment device for a printer according to the present invention, FIG. 2 is a perspective view of the print head of a horizontal impact printer, and FIG. Figure 4 (- and -7) are a sectional view and a partial plan view of the adjustment mechanism; Flowchart of the control status of the head WIill D4 adjustment in the embodiment fIIK shown in FIG.
+ and - are diagrams showing the relationship between the eccentric angle of one core shaft, the number of motor stelleruffs, and the head gap for explaining the drawbacks of the conventional example. 2.3...Fist guide shaft, 4.e.Carriage, 6..Print head, 8..ink ribbon, 1
0...Recording paper, 2G...-°Head 1-1 gap @
-Adjustment mechanism, 22...Eccentric shaft, 24.ee.Step motor, 51..Enjoyment, 1tIIl@ section, 52..Sub-control section, 53..Setting device, 54.. - Drive MJ convex road, 55... Rotation detection section. License applicant: Tamura Denshin Seisakusho Co., Ltd. NEC Co., Ltd.

Claims (1)

[Claims] An automatic head gap adjustment device for a printer that holds a print head movably forward and backward with respect to a paper surface and automatically adjusts a gap between the print head and the paper surface, comprising: a motor that moves the print head forward and backward; means for optically detecting the position from the set position to the point where the print head comes into contact with the paper surface, and a control unit that drives the motor in a step number corresponding to the detection signal to retract the print head. An automatic printer head gap adjustment device characterized by: