JPH0431073A - Automatic printer head gap adjustment mechanism - Google Patents

Abstract

PURPOSE:To set an appropriate head gap over an entire area and thereby perform satisfactory printing be correcting the head gap in an area where an eccentric angle and the head gap are deviated from a linear relationship. CONSTITUTION:A non-linear area is corrected so that an eccentric angle is proportional to a had gap and each sheet thickness is set to the corrected eccen tric curve. Then a gap between a printing head 6 and a recording sheet 10 with each set sheet thickness, that is, a correction value (a) is calculated and the number of corrected motor steps corresponding to the correction value (a) is stored in memory at a control part 51. After that, the number of corrected motor steps corresponding to the correction value (a) is added to a reference motor step count by a command entered from UCE 53 based on a potential value detected during automatic head gap adjustment. Further, a pulse signal of the added step count is connected to a drive circuit 52 to drive a step motor 24 under control. Thus automatic gap adjustment is actuated to set a specified head gap (G).

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application] The present invention provides an automatic head gap adjustment mechanism for a printer that automatically adjusts the gap between a print head and recording paper.

[Prior art 1] In various printers, in order to maintain the print density at a predetermined level, it is necessary to increase the gap between the printing paper and the recording paper (hereinafter referred to as the gap) by Hg. Adjustment of the head gap is particularly important for printers that use γ-dots for wire dot type impact printing.

In other words, if the head gap 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 paper will be stained by the ink ribbon.
The glint wire not only causes problems such as the ink ribbon getting caught and causing paper jams, but also causes the wire itself to wear out significantly, resulting in a lack of durability.

Therefore, recently, various mechanisms and devices have been developed to automatically adjust the head gap.
1-187063, a printer head gap self-adjustment mechanism has been disclosed. This head problem
The 1lJ adjustment mechanism uses an eccentric shaft, which is rotated by the drive of a step motor, which lowers the print head and presses it against the recording paper to detect the zero position, and then moves the step motor in the opposite direction. The print head is rotated to move the print head back from the zero position by a predetermined amount.

[Intelligence to be Solved by the Invention] However, in such a conventional automatic head gap adjustment mechanism, the eccentric angle of the eccentric shaft and the head gap form a substantially sine curve, so that It is not possible to obtain a directly proportional relationship, and therefore, when the print head deviates from the linear curve, even if the step motor is driven with a pulse signal of a predetermined number of steps and the print head is moved backward, the head gap cannot be set to an appropriate value. First, there is a problem in that the eccentric angle becomes large, especially in the case of thick copy paper.

Therefore, the present invention has been made in view of the conventional problems as described above, and its purpose is to ensure that the head gap is at an appropriate value when adjusting the head gap using an eccentric shaft. An object of the present invention is to provide an automatic gap adjustment mechanism for a printer that can be set.

[Means for Solving the Problem] In order to achieve the above object, the present invention provides an automatic head gap adjustment mechanism for a printer that automatically adjusts the gap between the print head of an impact printer and a paper surface using an eccentric shaft. Correct the area that deviates from the linear curve in the eccentricity curve of the shaft so that the eccentricity angle and head clearance are directly proportional,
By setting the paper thickness, the gap between the head and the paper is calculated from the corrected eccentric curve, and a 1iIII gap adjustment operation is provided so that the head gap is always kept at a constant value.

[Function] In the eccentricity curve of the eccentric shaft, the area that deviates from the linear curve is corrected so that the eccentricity angle and the head gap maintain a direct proportional relationship, and when the paper thickness is set, the head and paper distance according to the corrected eccentricity curve are corrected. The number of steps corresponding to this gap is added to the reference number of motor steps in the control section, and when automatic gap adjustment is performed, a head gap that compensates for the shortfall in the number of steps is set. .

[Example 1] The present invention is illustrated in the drawings! ! A detailed explanation will be given based on an example.

Fig. 1 is a block diagram of the circuit configuration of the automatic head gap adjustment mechanism of a printer according to the present invention, Fig. 2 is a perspective view of the print head section of a horizontal impact printer, and Fig. 3 is an eccentric shaft type automatic head gap adjustment mechanism. A perspective view of the mechanism, Figure 4 is a sectional view of the adjustment mechanism, and Figure 5 shows the eccentric angle of the eccentric shaft and the motor steering angle.
FIG. 6 is a diagram showing the relationship between the number of protrusions and the head gap, and FIG. 6 is a side view showing the state of adjustment of the head gap.

In FIG. 2, l is a printing mechanism, which is driven by a carriage 4 that is slidably held by a pair of guide shafts 2.3 that are arranged vertically and in parallel, and a motor (not shown). A timing belt 5 is moved by a timing belt 5 to reciprocate the carriage 4 along the guide shaft 2.3; It is composed of an ink ribbon 8, a platen 9, etc., which are fed in the direction.

The print head is supported along with the carriage 4 so as to be able to move forward and backward in the vertical direction with respect to the recording paper 10, and the gap with the paper surface, that is, the gap between the print head and the paper surface is adjusted by an automatic head gap adjustment mechanism, which will be described later.
・! The timing belt 5 is automatically set to a constant value regardless of the paper thickness, and the timing belt 5 is automatically set to a constant value regardless of the paper thickness.
As it runs, it prints while moving in the left and right direction with the carry-soji 1, and when the printing of the ] portion is completed, the motor rotates to perform a line feed, and then the print head 6 moves in the opposite direction. The configuration is such that the above operation is repeated, and as the printing progresses, the recording paper 10 is gradually transported in the direction of the arrow in FIG. 2.

3 and 4 show an automatic gap adjustment mechanism 20 for the print head 6, in which an eccentric shaft 22 rotatably disposed on a side plate 21 and connected to one end of the guide shaft 2. , a step motor 24 disposed on a side plate 23 different from the above, a rotation transmission mechanism 25 that transmits the rotation of the step motor 24 to the eccentric shaft 22, and a rotational force in the direction in which the print head 6 descends. It is generally composed of a spring 26 and the like that applies the force to the eccentric shaft 22. The fitting hole of the eccentric shaft 22 into which the shaft end of the guide shaft 2 is fitted is,
It is eccentric by Δd with respect to the center of the outer shape of the eccentric shaft 22, and this outer shape is rotatably supported by a bearing hole provided in the side plate 21.

Therefore, when the eccentric shaft 22 rotates, the guide shaft 2 moves up and down according to the eccentricity Δd of the fitting hole, thereby changing the head gap (G).

The rotation transmission mechanism 25 includes a drive gear 31 that is fixed to the output shaft 30 of the step motor 24 in a positive direction, 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 slip gear 35 integrally formed in the sleeve 34. Direction Kula Sochi 36 is located. The slip gear 35 meshes with a second intermediate gear 38 rotatably disposed on a support shaft 37 protruding from the side plate 23 . A third intermediate gear 39, which is also rotatable, is provided at the tip of the support shaft 37, and this third intermediate gear 39 meshes with a driven gear 40 provided integrally with the eccentric shaft 22. A friction transmission plate 41 is inserted between the second intermediate gear 38 and the second intermediate gear 38 .

The one-way clutch 36 is free with respect to the first intermediate gear 32 when the zero position of the print head 6 is detected (when the lower surface of the head is pressed against the recording paper), and after the zero position is detected, the one-way clutch 36 is free from the first intermediate gear 32. During a head gap setting operation (returning operation) in which the head is retracted upward by a certain amount, the sleeve 34 rotates integrally with the sleeve 34, and the rotation of the first intermediate gear 32 is transmitted to the slip gear 35.

The spring 26 is a torsion coil spring fitted to the outer layer of the eccentric shaft 22, and its end 26a is locked to the side plate 21, and its other end 26b is fixed to the eccentric shaft 22 with a screw.

In this case, the spring 26 is a twisted layer and the eccentric shaft 22
By being attached to the eccentric shaft 22, a rotational force in the H direction in which the print head 6 descends is usually applied to the eccentric shaft 22, and when the eccentric shaft 22 is rotated when detecting the zero position, the b force is weakened when the eccentric shaft 22 is released.

The step motor 24 normally locks the rotation transmission mechanism 25 by being supplied with a holding current sufficient to generate a driving force that balances the spring force of the spring 26. This is to prevent the spring 26 from rotating the eccentric shaft 22 when the step motor 24 is stopped and the output shaft 30 is left free. However, without supplying a holding current to the step motor 24, a pawl operated by a solenoid or the like is engaged with the driven gear 40, and the eccentric shaft 2
It is also possible to lock 2.

The step motor 24 is driven when setting the head gap and when pushing the print head 6 to the highest position.

To explain the operation of the automatic gap adjustment mechanism 20, first, the step motor 24 is driven by a signal from the control section, and the print head 0 is moved to the highest position. At the second time, the rotation of the step motor 24 is as follows: drive gear 31 - first intermediate gear 32 - one-sided clutch 3
It is transmitted to the driven gear 40 via the 6-slip gear 35-2nd intermediate gear 38-9 friction transmission plate 41-3rd gear 39, and rotates the eccentric shaft 22 in the direction in which the print head 6 moves backward from the recording paper 1o. . Therefore, the spring 26 is squeezed and accumulates spring force. When the print head 6 retreats to a predetermined height, the pin 42 provided on the driven gear 4o comes into contact with a stopper (not shown) and stops, and thereafter the friction transmission plate 4
The rotation of the second intermediate gear 38 is caused by the slip of the first gear and the third
This prevents damage to the motor 24 and the rotation transmission mechanism 25 by not transmitting it to the three intermediate gears. When the print head 6 reaches the highest position and a certain period of time has elapsed, a holding current is supplied to the step motor 24 to transmit rotation! Lock horizontal 25.

Next, the recording paper 1o is fed to the end portion of the print head 6, and 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, since the rotation transmission mechanism 25 becomes free with respect to the step motor 24, the eccentric shaft 22 is rotated by the spring force of the spring 26. As a result, the guide shaft 2 rotates together with the eccentric shaft 22 and gradually descends, so that the print head 6 is pressed against the recording paper 10 via the card holder 7 and the ink ribbon 8.

Next, when the pressing operation is completed, a pulse voltage of the number of steps corresponding to a predetermined head gap (G) is applied to the step motor 24 to drive the motor 24. Then, the rotation of the output shaft 30 is transferred to the driven gear 40 by the rotation transmission mechanism 25.
As a result, the eccentric shaft 22 rotates together with the driven gear 40, tightening the spring 26, and at the same time pushing up the guide shaft 2 to a height position corresponding to the rotation angle, thereby achieving a predetermined head gap (G). is set. After the step motor 24 is held in the driving stratification state by a holding current and the rotation transmission mechanism 25 is locked, the above-described printing operation by the print head 6 is performed.

FIG. 5 is a diagram showing the relationship between the eccentric angle of the eccentric shaft 22, the number of motor steps, and the throat gap (G). As is clear from this figure, since the eccentric angle and the head gap change drawing a substantially sine curve as described above, there is a linear region A and a non-linear region t4B. therefore,
In linear region A, the standard motor step number P (@
For example, a predetermined head gap (G) can be set by driving the step motor 24 at a speed of 40 steps (for example, 40 steps). g, making it impossible to obtain a predetermined head gap (G), and it is necessary to correct this.

FIG. 6 is a diagram showing the adjustment status of the head gap in the non-linear region, where g is the head gap when driven with the standard motor step number P, and a is the correction value for obtaining a predetermined head gap (G). It is.

Note that D is the initial gap.

FIG. 1 is a professional diagram of the circuit configuration for performing the gap correction described above, in which 51 is a control unit (CPU) consisting of a microprocessor, memory, etc., 52 is a drive circuit, and 53 is an electronic meter I! Top I of W etc! Seed ([JCE) CPU 5
1 is used to exchange data with the UCE53.

The way to correct the gap is to correct the non-linear area KB (Figure 5) so that the eccentric angle is directly proportional to the gutter gap, and then set each paper thickness in a ratio of 1 to the corrected eccentric curve. , to print on each paper thickness...l drawer and recording paper 10
The gear knob, that is, the correction value a is calculated, and the correction motor step number P1 corresponding to the correction value a is stored in the memory of the control unit 51. The corrected motor step number PI corresponding to the correction value a is added to the reference motor step number P based on the command human power from the UCE 53 based on the detection. and,
The pulse number 1 of the added number of steps (P2P+) is sent to the drive circuit 52, and the drive circuit 52 drives and controls the steno motor 24, thereby performing automatic gap jil adjustment according to the paper thickness. , a predetermined head gap (G) is set.

In other words, the eccentricity curve 61 (FIG. 5) in the non-linear region B is corrected to a corrected eccentricity curve 61 that matches the eccentricity curve 60 in the linear region A, and the corrected eccentricity curve 61A at each eccentricity angle is set. Store the upper head gap in memory. If the eccentric angle O1 at the time of automatic gutter adjustment is known, the gutter gap at the second time is G1 on the notation correction eccentricity curve 61 and g on the actual eccentricity curve G1,
Mode correction corresponding to that J (Gg) or step force P1
What is necessary is to calculate this and add it to the reference motor step number P.

2 Effects of the Invention Song 1 As described above, the automatic head gap adjustment mechanism of the printer according to the present invention is a printer in which the print head is moved forward and backward relative to the recording paper using the -6 axis to set the gutter gap. In the above, since the gap is corrected in the J range where the eccentric angle lead gap deviates from the linear relationship, it is possible to set four appropriate heddle gaps in the entire area. Therefore, it is possible to perform good printing, prevent blurred printing, stains on the recording paper by the ink ribbon, paper jams, etc., and also enables the use of various types of paper with different paper thicknesses, and also improves the durability of the print wire. This can bring about great effects, such as improving performance.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of the circuit configuration of the automatic head gap adjustment mechanism of the printer according to the present invention, Fig. 2 is a perspective view of the print head section of a horizontal impact printer, and Fig. 3 is an eccentric shaft type printer. Fig. 4 is a lateral sectional view of the automatic gap adjustment mechanism, Fig. 5 is a diagram showing the relationship between the eccentric angle of the eccentric shaft, the number of motor steps, and the head gap, and Fig. 6 is a diagram showing the relationship between the head gap and the eccentric angle of the eccentric shaft. FIG. 3 is a side view showing how the gap is adjusted. 2.3--Guide shaft, 4--Carriage, 6
1--Print head, 8--ink ribbon, 10--recording paper, 20--1-head gap automatic adjustment F! 1 structure, 22
- Eccentric shaft, 24... Step motor, 51-1
Control unit, 53-m-higher model. Patent applicant: Tamura Electric Manufacturing Co., Ltd.

Claims (1)

[Claims] In an automatic head gap adjustment mechanism of a printer that automatically adjusts the gap between the print head of an impact printer and the paper surface using an eccentric shaft, an eccentric curve of an eccentric shaft that deviates from a linear curve is defined as eccentricity. The angle and head gap are corrected so that they are directly proportional, and by setting the paper thickness, the gap between the head and paper is calculated from the corrected eccentric curve, and automatic gap adjustment is performed so that the head gap always remains at a constant value. 1. An automatic head gap adjustment mechanism for a printer, characterized in that it is provided with a control section that performs the adjustment.