JPH05104744A - Dot matrix printer - Google Patents

Abstract

PURPOSE:To carry out a stable printing without the influence from a previous printing action on a next printing action even if head gaps are different for every printing action. CONSTITUTION:A head gap is determined in accordance with the maximum thickness of supplied paper (envelopes or the like). After a printing action is conducted by the output of one drive pulse, a controller 32 outputs a brake pulse, which makes a return speed of a printing wire substantially zero in the path of returning, and continues printing. This brake pulse is generated at the same timing for all parts of paper of various thickness, thus having no need to be adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dot matrix printer, and more particularly to a technique for achieving stable printing operation.

[0002]

2. Description of the Related Art Conventionally, a dot matrix printer has a print head having a plurality of print wires and records each dot by a printing operation in which each print wire collides with a print sheet. Is a printer that expresses characters and the like. This dot matrix printer will be described with reference to the drawings. FIG. 1 shows the configuration of a print head 1 of a dot matrix printer. When a drive pulse is applied to the print magnet 2, the armature 3
Are attracted to the print magnet 2. The armature 3 pushes the print wire 4, and the print wire 4 collides with the print paper 6 via the print ribbon 5. At this time, dots are printed by the print wire 4. When the drive pulse disappears, the return spring 7 pulls the print wire 4 and the armature 3 back, hits the back stopper 8, and hits the back stopper 8.
The return spring 7 stops the print wire 4 and the armature 3 with several vibrations. The relationship between the displacement X of the print wire 4 and the drive pulse at this time is shown by the solid line in FIG.

[0003]

However, the above-mentioned dot matrix printer has the following problems. The problem will be described below. FIG. 8 shows an example of a dot pattern to be printed. The dot row in the second row has a dot interval of 1, the dot row in the 6th row has an interval of 2, and the dot row in the 10th row has an interval of 3 dots. The dot columns of each row in FIG. 8 are printed by the same print wire 4 while moving in the horizontal direction at different times. Therefore, as shown in FIG. 8, the driving cycle of the print wire 4 varies depending on the dot pattern. The dotted lines in FIGS. 7 and 9 show the second dot printing operation with different cycles. FIG. 7 shows a state in which the next drive pulse is applied in a phase in which the print wire 4 has a printing direction, that is, a positive speed, and the dotted line in FIG. The driving pulse is applied in a phase having a speed of.

In the case of the second printing operation of FIG. 7, since the initial speed has a positive speed, the kinetic energy of the printing wire 4 at the time of the collision with the paper becomes larger than that at the time of the first collision. However, in the case of the second printing operation in FIG. 9, since the initial speed has a negative velocity, the kinetic energy of the printing wire 4 at the time of the collision with the paper becomes smaller than that of the first collision. As in the case of FIG. 9, when a drive pulse is applied in a state of having a negative velocity component, the collision energy of the second time becomes smaller than the collision energy of the first time, falls below a predetermined printing energy, and normal dot printing is performed. Can not be.

In order to solve the problems described above, a means as disclosed in Japanese Patent Publication No. 60-2197 has been proposed. According to this method, a dot matrix printer is provided with a pattern generating means for generating a dot pattern, a means for detecting an interval of dots to be printed for each printing element by a dot pattern output from the pattern generating means, and the detected means. By providing means for generating a pulse having a waveform corresponding to the dot interval for each printing element, the printing operation of the printing element is ensured and a predetermined printing energy is secured.

According to this method, as shown in FIG. 10, after the time τ2 when the print wire 4 (FIG. 1) returns, another drive pulse is applied to the print magnet 2 for the time τ3, and the back stopper 8 collides. Change the timing.
When such a drive pulse is applied to the print magnet 2, it collides with the back stopper 8 immediately before the second regular drive pulse enters and the speed changes in the positive direction, and the waveform W1 becomes a waveform W2. The residual force of the first drive indicated by the dotted line can be used for the second drive.

However, according to this method, the following two
A new issue of points arises. First, as a first point, in Japanese Examined Patent Publication No. Sho 60-2197, means for detecting the interval of dots to be printed for each printing element by the dot pattern output from the above-mentioned pattern generating means, and the detected dot The means for generating a pulse having a waveform corresponding to the interval for each printing element is a considerably complicated circuit. For example, in a 24-pin printer, this circuit has 24 circuits, which hinders the price reduction of the printer. If these means are realized by software, in a 24-pin printer, this process is repeated 24 times every time one column is printed, which impedes the speedup of the printer. Moreover, even if this means is realized by hardware, a large number of circuits are required.

Next, the second problem will be described.
In Japanese Examined Patent Publication No. 60-2197, the distance between the position where the tip of the printing wire 4 is present when printing is not driven and the position of the printing paper (hereinafter referred to as the head gap).
Is not taken into consideration. I will explain this issue a little more. Now, a case will be described in which the printing wire 4 is not driven again during the returning time τ2. The solid and dotted waveforms in FIG. 11 are the loci of the tips of the print wires 4 when the head gaps are different. Therefore, like Japanese Patent Publication No. 60-2197,
When printing is performed continuously, the timing at which the print wire 4 returns is different, so depending on the head gap, in the case of the second printing operation as in FIG. 9, it has a negative speed in the initial state, The kinetic energy applied to the print wire 4 at the time of the collision with the paper becomes smaller than that at the first collision, falls below a predetermined printing energy, and normal dot printing cannot be performed.

In order to solve the second problem, it is possible to keep the print gap constant or to suppress the variation within a minute range. However, this method has already been filed and published by the applicant.
This cannot be done by printing an envelope or a slip as shown in No. 83181. That is, FIG.
Printing between the line a and the line b in the envelope 31 of FIG.
The shaded part is the part where two sheets of paper overlap.
The part where dots are drawn is the part where three sheets of paper overlap, and the part where diagonal lines are drawn on the grid is the part where four sheets are overlapped. Therefore, the printing gap is constant in order to perform the above-mentioned normal dot printing. Even if you try to keep the
When printing the overlapped part, the part where three pieces of paper with adjacent points are overlapped or the grid is shaded 4
Since there are overlapping portions, the print head cannot be brought close to the print paper so as to have an appropriate head gap. In such a case, the amount of movement of the printing wire varies, and thus the speed at which the printing wire returns to the back stopper varies, and as a result, stable printing operation is difficult to obtain. The present invention solves the above-mentioned problems, and provides a dot matrix printer capable of performing stable printing operation regardless of the head gap, without requiring a complicated circuit or software for complicated processing. With the goal.

[0010]

In order to achieve the above object, the present invention is directed to a print head having a plurality of print wires which are operated according to predetermined print data and which moves along a surface of a print sheet. In a dot matrix printer that colors or develops color on a print sheet by pressing the print wire against an ink ribbon existing between the print head and the print sheet, application of power for driving the print wire once The control means outputs a braking pulse for making the return speed of the print wire which is being returned later to a speed that does not affect the next drive immediately before the contact with the back stopper. In the dot matrix printer described above,
A braking pulse is generated at the same timing for driving all print wires.

[0011]

According to the above construction, when the control means and the print wire are driven, the print wire is pressed against the ink ribbon to cause the printing paper to be colored or colored with dots, and when the print wire returns to a predetermined position. Immediately before the collision with the back stopper, a braking pulse that outputs the returning speed of the printing wire that is in the process of returning to a speed that does not affect the next driving is output. Since the range of the timing of the return of the print wire in the head gap that is normally set is known in advance, the output of the braking pulse may be set at a predetermined timing according to it, and is changed according to the head gap, paper thickness, etc. No need. By the above operation, if the head gap is set to the normal value, the drive of the print wire is not affected by the previous operation, and stable head drive is performed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a plan view of the dot matrix printer, in which the side plates 10 form a pair to form a frame body. A platen 12 having a flat paper support surface 11 is attached to the side plates 10, and a plurality of pairs of paper feed rollers (not shown) rotated by a paper feed motor 41 (see FIG. 3) are provided. Platen 1
The print head 1 is arranged so as to face the paper support surface 11 of the second sheet. This print head may have the same structure as that shown in FIG.

A guide shaft 13 and a guide rail 14 are attached to the side plate 10 in parallel with the platen 12,
The print head 1 is mounted on a carriage 15 slidably supported by a guide shaft 13. A part of an endless timing belt 16 is fixed to the lower surface of the carriage 15, and the timing belt 16 is moved by a pair of pulleys 17 and a carriage moving motor 42 (see FIG. 3), so that the carriage 15 moves to the platen. 1
Moved along 2. The print head 1 is of a wire dot type, and a solenoid 43 (see FIG. 3) is an appropriate one of a plurality of print wires housed in the nose portion 18 facing the print paper at a constant interval. excitation·
The carriage 15 is moved back and forth according to the demagnetization, and the carriage 15
Is moved along the guide shaft 13 to perform printing. The solenoid 43 corresponds to the print magnet 2 shown in FIG.

Small-diameter shafts 19 and 20 are provided at both ends of the guide shaft 13, and eccentric bodies 21 and 2 are provided on the shafts 19 and 20, respectively.
2 are fitted and fixed to the respective eccentric bodies 21, 2
2 is rotatably fitted into the through holes 23 and 24 formed in the side plate 10. Side plate 10 of one eccentric body 21
A driven gear 25 is concentrically fixed to a projecting end of the step motor 26, and is meshed with a drive gear 28 fixed to an output shaft 27 of the step motor 26.
Is rotated, the eccentric bodies 21 and 22 and the guide shaft 13 are rotated, the carriage 15 is moved in the front-rear direction, and the print head 1 approaches the platen 12.
Be separated. Therefore, by controlling the rotation amount of the step motor 26 and appropriately selecting the position of the carriage 15, the head gap, which is the gap between the print head 1 and the platen 12, can be set to a desired size. In addition, the eccentric bodies 21, 22, and
The head gap is set to a desired size by the structure of the driven gear 25, the step motor 26, the drive gear 28, and the like.

A reference position detecting piece 29 is fixed to the projecting end of the other eccentric body 22 from the side plate 10 in a direction to extend in the radial direction from the eccentric body 22, and the side plate to which the eccentric body 22 is fitted. A reference position detection sensor 30 including a photosensor (not shown) having a light emitting element and a light receiving element is attached to the outer surface of the device 10. When the reference position detection piece 29 enters between the light emitting element and the light receiving element of the reference position detection sensor 30 due to the rotation of the eccentric body 22 and the light is blocked, the reference position detection sensor 30 outputs a detection signal. The rotation of the step motor 26 is stopped based on the output signal, and the movement of the carriage 15 in the front-rear direction is stopped. In this embodiment, the reference position detection piece 29 is provided so that the print head 1 stops at the retracted end position farthest from the platen 12.

In this embodiment, an envelope 31 as shown in FIG. 5 is taken as a recording medium on which printing is performed. In the unfolded state, the envelope 31 has a shape in which four triangular ear pieces each having four sides of the main body are added around the rectangular main body. The three ears of the four ears are overlapped with each other and the edges are pasted together to form a bag, and the remaining one functions as a lid, and the ears that overlap when the lid is closed. Depending on the number of pieces, there are three types of thickness. Further, as shown in FIG. 6 with different hatching, the portion of the envelope 31 delimited by the lines a and b is 3
Includes different thicknesses. The shaded area is the area where two sheets of paper overlap, and the dotted area is 3 pieces of paper.
The overlapped portion is a portion in which a grid-like slanted line is an overlapped portion of four sheets.

Next, the control device 32 for controlling the present dot matrix printer will be described with reference to FIG. CP
The computer is mainly provided with a U33, a ROM 34, a RAM 35, and a bus 36 connecting them. An input interface 37 is connected to the bus 36, and the reference position detection sensor 30 and the host computer 38 are connected to the input interface 37, and a ROM card 39 is also connected to the input interface 37. The ROM card 39 is composed of an integrated circuit, and the thickness of the envelope 31 is stored for each portion (hereinafter, referred to as a pixel) having a size corresponding to one print dot of the print head 1. The bus 36 also has a paper feed motor 41, a carriage movement motor 42, a solenoid 43, and a step motor 2 via an output interface 40.
6 etc. are connected.

The RAM 35 is provided with a reception buffer 44, an image buffer 45, a thickness memory 46, a print position designation data memory 47 and the like. The reception buffer 44 is
The print data supplied from the host computer 38 is stored. This print data is supplied as code data with 1 bit consisting of 8 bytes.
When read from the reception buffer 44 at the time of printing, it is expanded into image data. In the matrix of pixels for one character set according to the number of print wires 4 provided in the nose portion 18 of the print head 1, each print wire 4
Is converted into pattern data for instructing the hitting point position (the position of the pixel in which the print wire 4 is driven to form a dot), and the data is stored in the image buffer 45. The thickness memory 46 stores the thickest thickness contained in one print line. Furthermore, R
The OM 34 stores position data of the print head 1 corresponding to a plurality of types of thickness set for each fixed range. This position data is data set based on the retracted position. The ROM 34 also stores programs necessary for printing, including a program for printing one line shown in the flowchart shown in FIG. 4 described later.

Next, the printing on the envelope 31 will be described. The dot matrix printer is provided with a paper guide (not shown) that comes in contact with two sides parallel to the feeding direction of the recording medium and guides the movement thereof. Are set symmetrically and are automatically fed to the print start position by the paper feed roller. Further, when the power is turned on, the carriage 15 is moved to the left end position in the horizontal movement range of the carriage 15, and the host computer 38 receives the reception buffer 44.
The print data is transferred to. This print data is for envelope 31
Is set with reference to the left and top edges of
It contains data representing the size of the envelope 31. And
Printing is started by pressing the print start switch. However, the carriage 15 detects the reference position corresponding to the left end of the envelope 31 and the right end of the envelope 31 based on the data indicating the size of the envelope 31. Is driven to move to and from the position corresponding to.

Next, the printing of one line will be described with reference to FIG. Here, a case will be described in which printing is performed on a portion delimited by lines a and b in the envelope 31 of FIG. In step S1 (hereinafter abbreviated as S1; the same applies to other steps), the host computer 38.
1 of the print data transferred from the receive buffer 44 to the receive buffer 44
The print data for the line is read, and the print data is expanded into image data and stored in the image buffer 45 in S2. Then, in S3, the paper thickness data of the portion to be printed based on the print data stored in the image buffer 45 is read from the ROM card 34, and in S4, the thickest thickness of the read paper thickness data. Are stored in the thickness memory 46. At this time, if the difference between the thickest thickness and the thinnest thickness exceeds an assumed predetermined value, an error may be generated.

Subsequently, the head gap is changed in S5. The print head 1 is positioned at a position corresponding to the thickness stored in the thickness memory 46, and position data corresponding to the thickness stored in the thickness memory 46,
The amount of movement and the direction of movement of the print head 1 are calculated from the position data corresponding to the thickness of the portion to be printed next, and the step motor 26 is driven based on the calculation result, so that the print head 1 becomes thicker. Is moved to the position corresponding to Then, printing is performed in S6. Here, the print magnet 2 is used to drive the head for τ1 hour.
A drive pulse is applied to the print wire 4 to cause the print wire 4 to project, and printing is performed. After that, it waits for the printing wire 4 to recover for τ2 hours, and τ3 immediately before contacting the back stopper 8 on the way.
The head is driven for a time, and a braking pulse is applied to the print wire 4. As a result, the return speed of contact with the back stopper 8 is set to zero. As is clear from the above description, in this embodiment, the ROM card 39 constitutes the paper thickness data storage means, and the portion of the ROM 34 that stores S3 to S5,
The part that executes S3 to S6 of the CPU 33 constitutes the control means 4.

FIG. 11 shows the relationship between the head gap of the print head 1 and the displacement of the print wire 4. Three types are taken up, including the upper and lower limits of the head gap in normal use. The timing to apply the braking pulse is after the print wire 4 when the head gap is large and after the print wire 4 starts to recover, and before the time when the print wire 4 when the head gap is small is retracted to the back stopper 8 side most. Is desirable. This corresponds to the range of the illustrated period d. The above control can be realized by applying the braking brake in this range.

Although the paper thickness data is supplied from the ROM card 39 in the above embodiment, the paper thickness data memory is provided in the RAM 35 without using the ROM card 39 and the paper thickness data is stored in the RAM 35. The storage means may be used to supply the paper thickness data. In this case, the paper thickness data is stored in the host computer 38 and is transferred to the paper thickness data memory at the time of printing. On this occasion,
First, the code data representing the supply of the paper thickness data is supplied to the paper thickness data memory 48, then the parameter of the number of the paper thickness data is supplied, and then the paper thickness data is supplied. The supplied paper thickness data is stored in the paper thickness data memory,
In printing, the required paper thickness data is read out as in the ROM card 39. In addition, in the paper thickness data memory,
It may be volatile or non-volatile.

Further, the ROM card 39 may be used to supply the paper thickness data from the ROM card 39 to the paper thickness data memory. In this case, ROM card 39
May be removed after the data transfer. Further, the ROM card 39 may or may not be rewritable of data, and may be volatile or non-volatile.
critical Erasable Program
If the data is rewritable and non-volatile like a ble ROM) card, the paper thickness data transferred from the host computer 38 to the memory may be stored in the ROM card 39. Good. This eliminates the need to transfer data from the host computer 38 to the paper thickness data memory each time the power is turned on when the paper thickness data memory is volatile. Furthermore, when a plurality of printing devices are used, the ROM card 39 is made to store the data of the host computer 38 only for one printing device, and for the other printing devices, the ROM card 39 is used for paper printing. Data may be supplied to the thickness data memory.

In the above embodiment, the thickness of the recording medium is measured in advance, and the paper thickness data is stored in the paper thickness data memory. May be measured and stored in the paper thickness data memory. That is, the carriage 1 of the printing apparatus
5, a paper thickness detector (not shown) is provided side by side with the print head 1 in the left-right direction. The paper thickness detector irradiates the recording medium with light and determines the paper thickness based on the amount of received reflected light. It should be detected.

Further, in the above-described embodiment, the printing is performed based on the print position designation data for designating the print position for each thickness of the paper and the print data. Print data may be created. Further, although the case where the envelope 31 is printed has been described in the above embodiment, the present invention can be applied to an apparatus for printing a copy slip, a vinyl sheet, a magnetic sheet or the like, for example.

In the method described above, the carriage 15 is moved in the vertical direction with respect to the paper according to the value of the thickness memory 46, and the head gap is changed for printing. However, the thickness memory 46 is eliminated. Without moving the carriage 15, set the head gap to a normal value,
It may be possible to properly print even on a plurality of sheets of paper that are always overlapped. In that case, a structure for moving the thickness memory 46 and the carriage 15 in the vertical direction with respect to the paper is not necessary, and thus the cost is reduced. In this case, the maximum value of the return time of the print wire 4 changes depending on the size of the head gap.
If the thickness memory 46 is provided, the printing cycle may be controlled according to the data. In addition to the print cycle, the drive pulse width, the braking pulse output timing, the second drive pulse output timing, and the second pulse width may be changed.

As described above, according to the printing apparatus of the present embodiment, the control means 32 detects the predetermined data, drives the printing wire 4 based on the detected data, and performs the printing wire 4 once. With respect to the reciprocating motion of the above, a braking pulse is output to set the return speed of the printing wire 4 which is in the process of returning to 0 immediately before the contact with the back stopper 8. As a result, even if the thickness of the paper is slightly different for one print sheet or the type of print sheet is frequently changed, the drive of the previous print wire 4 is performed regardless of the paper thickness. 4 is not affected, and printing can be performed uniformly and efficiently.

[0029]

As described above, according to the present invention, by applying the braking pulse at an appropriate timing, the driving of the print wire after the second time is not affected by the energy of the previous operation, and the print wire is always operated. Operates from a predetermined position. Therefore, a complicated circuit or software for complicated processing is not required for recording media having different thicknesses, and stable printing operation can be performed regardless of the head gap.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a head section of a conventional dot matrix printer and a dot matrix printer of this embodiment.

FIG. 2 is a partial cross-sectional plan view showing a main part of the dot matrix printer according to the present embodiment.

FIG. 3 is a block diagram of a control device that controls the present dot matrix printer.

FIG. 4 is a flow chart showing a part of a program stored in a ROM of the control device, which is deeply related to the present invention, and extracted.

FIG. 5 is a rear view showing an envelope on which printing is performed by the present dot matrix printer.

FIG. 6 is a diagram showing each row of the same envelope and showing each region having a different thickness.

FIG. 7 is a diagram showing a relationship between a print wire of a printer and a drive pulse.

FIG. 8 is a diagram showing a printed dot pattern.

FIG. 9 is a diagram showing a relationship between a printing wire and a driving pulse when printing is performed a second time.

FIG. 10 is a diagram showing a relationship between a print wire and a drive pulse when the second printing is performed.

FIG. 11 is a time chart showing the relationship between the head gap of the print head and the displacement of the print wire.

[Explanation of symbols]

 1 print head 4 print wire 8 back stop 30 reference position detection sensor 32 control device

Claims (2)

[Claims] 1. An ink ribbon in which a print head having a plurality of print wires, which is operated according to predetermined print data, moves along a surface of a print sheet and is present between the print head and the print sheet. In a dot-matrix printer that colors or develops color on the printing paper by pressing the printing wire on the back side of the printing wire, the speed of the printing wire that is returning after applying power for one-time driving of the printing wire A dot matrix printer characterized in that it has a control means for outputting a braking pulse for a speed that does not affect the next driving immediately before contact. 2. The dot matrix printer according to claim 1, wherein braking pulses are generated at the same timing for driving all print wires.