JPS6042033B2 - dot printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dot-type printer in which a recording paper is inserted between a printing stand and a pressing body, and the pressing body is pressed against the printing stand to perform dot matrix printing on the recording paper. In particular, the present invention relates to a printer in which the pressing body is mounted on a carrier, and the carrier is constrained to move parallel to the printing surface.

There are two types of dot printers: drum type and wire dot type.

A drum-type dot printer has a plurality of printing dots protruding from the outer periphery of the printing stand drum with the phases shifted in the axial and circumferential directions, and by rotating the printing stand drum, a desired dot is positioned at the printing position, and the dot is The drum is in charge of a printing hammer as a pressing body, and is configured to perform dot matrix printing on recording paper inserted between the drum and the hammer. In this type of printer, the hammer hits different positions for each printing dot with respect to one printing hammer, so the hammer must be large, and this makes it difficult to operate the hammer at high speed, making it difficult to print. The drawback was that the speed could not be increased. Therefore, the present inventors installed the hammer on a carrier and moved the carrier in the direction of the drum axis in synchronization with the rotation of the printing drum, thereby ensuring that the center position of the hammer was always in charge of each printing dot. We have developed a printer that can. On the other hand, wire dot type printers insert a recording paper between the printing stand and a dot wire as a pressing body, and feed the recording paper intermittently one dot at a time. The wire is moved in a direction parallel to the printing stand and perpendicular to the paper feeding direction, and the wire is pressed against the surface of the recording paper at a predetermined timing to perform dot matrix printing on the recording paper. In this way, in the case of dot-type printers in which a carrier equipped with a printing hammer as a pressing body and a dot wire is moved back and forth in a straight line, the timing of the carrier's operation is determined by the rotation of the printing base drum in both the drum type and wire dot type. Alternatively, it is necessary to synchronize with the paper feeding operation, and one possible means for this purpose is the one shown in FIG.

That is, 101 in the figure is a rotating cam whose distance from the center of rotation to a cam surface 101a gradually changes in the direction of rotation, and a cam roller 103 supported on one end of a carrier 102 is elastically attached to the cam surface 101a by a spring 104. to press. Therefore, by appropriately setting the shape of the cam surface 101a of the rotary cam 101 and rotating it in synchronization with the rotation operation of the printing stand drum or paper feeding operation, the operation timing of the carrier and the operation timing of the printing stand drum or paper feeding can be adjusted. Can be synchronized. By the way, if a rotating cam as shown in Fig. 1 is used, it is possible to move the carrier in a reciprocating straight line with a simple configuration, but in this case, the cam allows the carrier to move at a constant level with respect to a constant angle change. Since the cam surface is formed in such a manner that the amount of movement can be obtained, a concave curved portion 101b as shown in FIG. 2 is formed on the cam surface.

Therefore, if the cam 101 is rotated at too high a speed, the cam roller 103 will jump over the portion 101b, making the operation of the carrier 102 unstable and causing poor printing quality. This could also result in misplacement. For these reasons, there has been a problem in that it is difficult to perform high-speed printing in dot printers that use rotary cams to move carriers back and forth in a straight line. The present invention has been developed based on these circumstances, and the object thereof is to mount a pressing body on a carrier, and cause the carrier to move in a reciprocating straight line parallel to the marking base using a rotary cam, so that the center of the pressing body is always aligned with the marking base. In addition to making the pressing body smaller and lighter, the cam surface of the rotary cam is formed into a convex curved shape around the entire circumference to stabilize the movement of the carrier and enable high-speed printing. It's about making it possible.

Hereinafter, the present invention will be explained based on detailed illustrative examples.

First, FIGS. 3 to 7 show an embodiment in which the present invention is applied to a drum type dot printer, and FIG. 3 is a plan view thereof.

A U-shaped drum support fitting 2 is fixed to the inside of the base 1, and both ends of the stamping drum 3 are rotatably supported on both sides of the metal fitting 2. A pulse motor 5 is fixed to the left outer side of the base 1. The shaft 6 of this motor 5 extends inside the base 1 so that its center line coincides with the shaft of the stamp stand drum 3, and both ends 4 and 6 are connected by a joint 7. Further, a bevel gear 8 is fixed to the shaft 6 of the motor 5. This bevel gear 8 meshes with another bevel gear 9, and the shaft 10 of this gear 9 is connected to the base 1.
It is supported by a support stand 11 fixed above. Both bevel gears 8 and 9 have the same number of teeth and are adapted to rotate the shaft 4 of the printing drum 3 and the shaft 10 of the bevel gear 9 at the same speed. The shaft 10 of the bevel gear 9 is orthogonal to the shaft 4 of the marking drum 3, and a rotary cam 12 is fixed to the shaft 10.
A carrier 13 is mounted on the base 1 so as to be movable forward and backward in a direction parallel to the axis 4 of the drum 3. A cam roller 14 is supported at one end of the carrier 13 on the cam 12 side, and a compression coil spring 15 is interposed between the other end of the carrier 13 and the right edge of the base 1. The axis of the cam roller 14 is parallel to the axis 10 of the cam 12, the cam roller 14 is parallel to the axis 10 of the cam 12, and the cam roller 14 is elastically abutted on the outer peripheral cam surface 12a of the cam 12 by the spring 15. . The pulse motor 5 serves as a driving source for the printing stand drum 3, and at the same time functions as a carrier driving means together with the bevel gears 8, 9 and the cam 12. Note that the spring 15 is supported by a cylindrical spring guide 17 fixed to the base 1. A large number of printing dots 18 are formed on the outer periphery of the printing stand drum 3.
are arranged in a so-called spiral shape with equal axial and circumferential intervals.

On the front edge of the carrier 13, which is close to the drum 3, a large number of printing hammers 19, which serve as pressing bodies and which take charge of the same number of printing dots 18, are arranged at equal intervals.
As shown in FIG. 4, each printing hammer 19 is attached to a portion of the carrier 13 facing the stamping drum 3 so as to be able to move forward and backward in a direction toward and away from the marking drum 3 (that is, in a direction perpendicular to the operating direction of the carrier 13). has been done. Printing hammer 1
A nut 20 is screwed onto the rear end of the printing hammer 9, and the nut 20 is pushed from the front by a spring 21, so that the printing hammer 19 is always held at a position away from the printing base drum 3. Further, electromagnetic plungers 22 corresponding to each printing hammer 19 are mounted on the carrier 13 in a staggered manner. The movable body 23 of the plunger 22 and the nut 20 are connected by a thin wire-shaped connecting rod 24, and by energizing the coil 25 of the plunger 22 and moving the movable body 23 in the direction of the printing stand drum 3, The hammer 19 is designed to hit the printing dots 18 on the printing stand drum 3. Note that the movable body 23 is always urged in the direction opposite to the drum by the leaf spring 26. The printing dots 18 provided on the printing stand drum 3 are arranged at intervals of angle θ in the rotational direction and at intervals of a in the axial direction, as shown in FIG. Furthermore, each row of print dots 18 is arranged with the inclination changing by half a circle as shown in FIG. The line of printed dots is discontinuous at that part. On the other hand, as shown in FIG. 7, the cam 12 is symmetrical with respect to a straight line connecting the maximum radius position and the center of rotation,
Unused cam surface area 12 of the cam surface drawn by the shaded area
The cam surface area other than b appears as a linear function of the angle from the maximum radius position, and the radius decreases by a each time the cam surface rotates by 0 from the maximum radius position. In other words, in the range other than the unused cam surface area 12b, if the maximum radius of the cam 12 is r, then the maximum radius position is n
The radius of the position rotated by θ is r−Na. The unused cam surface area 12b extends over an angle φ on the opposite side of the maximum radius position. This unused cam surface area 12
b is formed from a curved convex surface with a substantially constant radius, which has the effect of preventing the formation of a dent in a portion of the cam surface 12a and making the entire cam surface 12a a convex curved surface. When the maximum radius position of the cam 12 contacts the cam roller 14,
The carrier 13 will be located at the far right side as shown in FIG.
8, the rightmost dot is positioned on the movement line of the printing hammer 19, that is, at a predetermined printing position. Both ends of a shaft 28 of an ink roller 27 are rotatably supported on both sides of the drum support fitting 2.
The outer periphery of the dot 18 of the stamp stand drum 3 is always in contact with the dot 18 of the stamp stand drum 3.

Next, the operation of this dot type printer will be explained.

When the recording paper 29 to be printed is inserted between the printing base drum 3 and the printing hammer 19 and a printing command is given, the pulse motor 5 rotates in a fixed direction by an angle θ in response to this printing command, and at the same time each electromagnetic plunger 22 coils 25 are excited at a predetermined timing and each printing hammer 19 hits a printing dot 18 on the printing stand drum 3. And stamp stand drum 3
Every half rotation, a paper feeding device (not shown) is activated to feed the recording paper 29 one dot at a time, so that dot matrix printing is performed on the recording paper 29. In addition,
During the period when the cam roller 14 is in contact with the unused area 12b of the rotary cam 13, the carrier 13 remains on the leftmost side, and the part of the printing stand drum 3 where no printing dots 18 are provided is positioned at the printing position. During that period, the printing hammer 19 does not operate. According to the above dot printer, the printing stand drum 3 and the cam 12 are rotated at the same speed by the common motor 5.

Then, each time the drum 3 rotates by an angle θ, the next dot 18 appears at the print position shifted by a in the axial direction, but as the drum 3 rotates by O, the carrier 13 also Since the hammer 19 is moved by a increments of a in the positional shift direction, the center of the hammer 19 always matches the print dot 18 located at the print position, and the center position of the print hammer 19 can always hit the print dot 18. Therefore, the hammer 19 always receives a load at the central position, resulting in a long life and a stable supporting state of the hammer 19. Also hammer 1
No. 9 can be made smaller because the off-center portion j is unnecessary, and if the hammer is made lighter, high-speed operation becomes easier and printing speed can be increased. According to this printer, the means for operating the carrier 13 can be easily constituted by the rotary cam 12, and moreover, since the cam surface 12a of the rotary cam 121 is formed in a convex curved shape over the entire circumference, , Disadvantages of using a rotary cam (the cam roller separates from the cam surface due to the recess formed in a part of the cam surface, making the operation of the carrier unstable).

) can be easily resolved and high-speed printing becomes possible. Next, the embodiment shown in FIG. 8 will be described.

This is an application of the present invention to a wire dot type printer, and the figure is a plan view of the same printer. One piece of recording paper 29 is placed between the stamp stand 31 and the dot wire 32 as a pressing body.
While feeding the paper intermittently by dots, the carrier 33 with the dot wire 32 attached is moved in a direction parallel to the printing stand 31 and perpendicular to the paper feeding direction (left and right in the figure).
The wire 32 is pressed against the recording paper 29 at a predetermined timing while moving the recording paper 29 to perform dot matrix printing on the paper surface. In addition, 34 in the figure
is the base, 35 is the drive shaft for paper feeding, and 36 is the carrier 3.
3 is an electromagnetic plunger for driving dot wires arranged in a staggered manner, 37 is an ink ribbon inserted between the recording paper 29 and the dot wire 32, and 38 is a guide roller for guiding the ink ribbon. The ink ribbon 37 is wound between a pair of left and right ribbon spools 39, 39.
A pulley 40 is attached to each spool 39, and both pulleys 40, 40 are connected by an endless belt 41 and rotate integrally. A gear 42 is attached to one of the spools 39, and this gear 42 meshes with a small gear 43 fixed to the drive shaft 35 to rotate at a low speed. The drive shaft 35 includes:
Furthermore, a large gear 44 is fixed, and this gear 44 meshes with a small gear 46 fixed to the camshaft 45 to drive the camshaft 45 to rotate at high speed. A rotating cam 47 similar to that of the embodiment described above is fixed to the cam shaft 45, and a cam roller 48 attached to one end of the carrier 33 is brought into contact with a cam surface 47a of the cam 47. Note that the cam roller 48 is constantly pressed against the cam surface 47a by a compression coil spring 49. In the above wire dot type printer as well, the cam surface 47a of the rotary cam 47 is formed on a convex curved surface over its entire circumference, enabling the rotary cam 47 to rotate at high speed and performing high-speed printing. There is.

Also in this example, as in the previous example,
An unused cam surface 47b of the cam surface 47a of the rotating cam 47 that does not follow a certain rule is considered an unused portion, and the dot wire 32 is not driven while the cam roller 48 is in contact with this unused cam surface area 47b. It is becoming more and more difficult to do so.
As described in detail above, according to the present invention, the pressing body is mounted on a carrier, and the carrier is configured to reciprocate in parallel with the stamp stand by a rotating cam, thereby reducing the size and weight of the pressing body. I can do it.

In addition, the minimum radius of the cam surface of the rotating cam and the vicinity thereof are curved convex surfaces as unused cam surface areas, and by forming the cam surface in a convex shape over the entire circumference, even when the cam is rotated at high speed, it can be easily mounted on the carrier. The cam roller can follow the cam surface smoothly and reliably, making the carrier operation stable. Therefore, the pressing body is made smaller and lighter, and high-speed printing becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a plan view schematically showing a carrier driving device in a dot printer, FIG. 2 is a plan view of a rotary cam used in the device, and FIGS. 3 to 7 show an embodiment of the present invention. FIG. 3 is a plan view showing a portion of FIG. 3 in cross section, FIG. 4 is a sectional view showing a portion of FIG. 3 on an enlarged scale, and FIG. 5 is a perspective view showing a portion of FIG. 3 on an enlarged scale. 6 is an exploded view showing a part of the marking stand driver l, FIG. 7 is a plan view of the rotary cam, and FIG. 8 is a plan view showing another embodiment of the present invention. 3...Marker drum, 12...Rotating cam, 12a...Cam surface, 13...Carrier,
19... Printing hammer (pressing body), 29...
・Recording paper, 31...Marking stand, 32...Dot wire (pressing body), 33...Carrier, 4
7... Rotating cam, 47a... Cam surface,
12b, 47b...Irregular cam surface area.

Claims (1)

[Claims] 1. A rotatably driven printing stand, a pressing body that presses against this printing stand and prints a dot matrix on the recording paper inserted between it and the printing stand, a carrier to which this pressing body is mounted, and a dot matrix formed on the outer periphery. a rotary cam that moves the carrier in a reciprocating straight line on a cam surface parallel to the marking stand and perpendicular to the feeding direction of the recording paper in synchronization with the rotation of the printing stand, and one end of the carrier attached to the rotating cam; a compression coil spring that elastically presses a cam roller provided at A certain area on the opposite side is an unused cam surface area consisting of a curved convex surface with a substantially constant radius, and the radius at a position other than the unused cam surface area is expressed as a linear function of the angle from the maximum radius position, The marking stand is characterized in that a plurality of printing dots are formed at equal intervals in the axial direction and in the circumferential direction in an area other than an area corresponding to an unused cam surface area of the rotary cam. Dot printer.