JPS5938914B2 - Print guard for printers - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a print guard for a printer in which the shape of the print guard for preventing staining of printing paper covering a type drum has been improved.

FIG. 1 shows a part related to a conventional print guard for a line printer.

That is, in Figure 1, A is a type drum, the opening is a semicircular print guard that covers the type drum, and C is a print hammer of the same number as the number of digits on the type drum, which is controlled by an electromagnetic solenoid and illuminates the type on the type drum. , 2 is the outer surface of the print guard (the surface corresponding to the print hammer)
With the printing paper laid on top, the blind guard drawer has a large number of hammer passage opening holes which are shaped so that the hammer can pass through the printing paper 2 and are adjacent to each other in the direction of the printing hammer. With this configuration, when the print hammer illuminates the type on the type drum through the printing paper 2, the printing paper contacts only the illuminated type and other It is designed to prevent contact with the type to prevent it from becoming soiled. . By the way, according to such a conventional configuration, the print guard drawer has a semicircular shape, and the printing paper 2 also curves in a semicircular shape and follows the entire outer surface of this, and as a result, as shown in FIG. As shown, the entire circumference of the printing paper 2 to the type area is in contact with the entire periphery of the hammer passing opening lobe of the print guard drawer and receives a reinforcing action, so that when the printing paper 2 is illuminated by the print hammer, the printing paper 2 The action of deforming in the direction of the type drum while being pulled in the direction of the arrow in Figure 2 is obstructed by the print guard drawer.
There is a drawback that uneven shading occurs in one print, so it was necessary to increase the impact force of the blind hammer. The present invention has been made to eliminate the above-mentioned drawbacks, and its purpose is to provide a guard portion that is sandwiched between openings extending in the rotational direction of the type drum and located approximately at the center of the guard portion located between the type characters of adjacent columns of the type drum. By providing a protrusion that protrudes from the circumferential surface of the type on the type drum, and by making the circumferential length of the protrusion cut by the circumferential surface of the type shorter than the circumferential length of the type, the print hammer has the best impact. To provide a print guard for a printer, which can smoothly move printing paper toward a type drum with action, and can provide a good printing condition without uneven shading even with a relatively weak impact force.

Hereinafter, an embodiment in which the present invention is applied to a line printer in which two electromagnetic solenoids drive and control two print hammers will be explained with reference to FIGS. 3 to 7.

Reference numeral 1 denotes a machine frame, on which a type drum 2 made of an elastic material such as hard rubber is rotatably installed horizontally, and a plurality of digits are arranged on the circumference of the type drum 2. M digits of type 3 are engraved on the top, and each digit has a plurality of the type 3, and as can be seen from Figure 4, the type 3 of adjacent digits are staggered. It is arranged like a monkey.

Reference numeral 4 denotes an ink roller, which is installed on the machine frame 1 and normally comes into pressure contact with the type drum 2, and is rotated by the friction thereof to apply ink to the type characters 3.

Reference numeral 5 designates leaf springs that are formed by cutting a single spring material board to have the same number of digits as the above-mentioned number of digits, and these common sides 5a are integrated by insert molding a base 63 made of synthetic resin,
It is supported by the machine frame 1 via the base 6.

At the free end of each of these leaf springs 5 facing the type drum 2, there are print hammers 8 made of synthetic resin that face each digit of the type drum 2 with a printing paper 7 interposed therebetween and are arranged in the digit direction. These printing hammers 8 are integrally supported by insert molding, so that the biasing force for moving them to the printing position can be applied independently. Reference numeral 9 indicates the same number of first leaf springs as the number of digits, and reference numeral 10 indicates a second leaf spring that faces each of the first leaf springs 9. These are each formed by cutting a single spring material board. The common side portion, which is the base end thereof, is connected to a support column 11 made of synthetic resin by insert molding, and the support column 11 is installed horizontally on the machine frame 1.

As a result of this configuration, the first spring 9 and the second spring 10 form a set of leaf springs, and the same number of leaf springs as the print hammers 8 are provided.
The free ends of the first leaf spring 9 and the second leaf spring 10 are placed in a vertical position to sandwich one print hammer 8 from above and below, and are bent into a semicircular shape for the purpose of increasing strength. The tip portions 9a, 10a are adapted to engage with the engaging step portions 8a, 8b of the print hammer 8, and the print hammer 8 is held at the rest position when at least one of them is in the engaged state. It's getting old. Reference numeral 12 denotes a first cam group, which consists of a plurality of eccentric cams 12a that are placed vertically between the first and second leaf springs 9 and 10 and correspond to the girder, and each of these eccentric cams 12a rotates as it rotates. The first and second leaf springs 9 and 10 are alternately elastically moved in the vertical direction to engage their tip portions 9a and 10a with the engagement stepped portion 8a of the print hammer 8.
The eccentric cams 12a are designed to alternately release the engagement between the eccentric cams 12a and 8b, and in particular, each eccentric cam 12a is designed to release the engagement between the adjacent eccentric cams 12a so that the release operation is in opposite phase between each set corresponding to the adjacent girder. Their eccentric directions are set to be opposite to each other so as to have a vertical phase difference of 180 degrees.

Reference numeral 13 denotes a second cam group consisting of 14 eccentric cams 13a that can come into contact with the intermediate portions of the leaf springs 5 corresponding to each digit,
With the rotation of these eccentric cams 13a, the print hammer 8 is forcibly returned from the printing position to the rest position against the spring force of the leaf spring 5. In particular, the return action is effective against the spring force of the leaf spring 5. In order to perform the rotation in an inverted phase relationship, the eccentric cams 13a are set such that their eccentric directions are opposite to each other so that adjacent eccentric cams 13a have a vertical phase difference of 180 degrees. It is being

14 is one set of leaf springs 9, 10 forming the pair.
and the other set of leaf springs 9 and 10 adjacent to each other in a digit-corresponding manner. Two solenoid cores 1
6, and each of the 14 solenoid cores 16 is a synthetic resin-made solenoid core 16 installed upright on a printed circuit board 17 disposed on the machine frame 1 at a position facing each of the second leaf springs 10 below. The engagement pieces 18 are held by engagement means so as to be arranged in the digit direction.

Reference numeral 19 denotes a print card disposed in the machine frame 1 so as to substantially surround the type drum 2 and the ink roller 4, and 20 indicates the print card to form a paper guide path 21 for guiding the print paper 7. A paper guide provided in opposing relation to the guard 19 for each type drum 2.
Hammer passage openings 22 and 23 are formed in the portion facing the print hammer 8.

24 is a paper feed roller, and 25 is a drive motor, which serves as a drive source for the type drum 2, the first cam group 12, the second cam group 13, and the paper feed roller 24.

Now, in the print guard 19, the guard portion 19 is located between the printed characters of adjacent digits near the printing position.
As shown in FIGS. 5A and 5B, a is curved so that it has two reversely curved W-shaped cross-sectional shapes that are continuous with respect to the curved surface of the type drum 2, and the protrusion 19b at the center of the type drum 2
It protrudes from the upper surface of the type. Further, this print guard 19 has a large number of openings 22 formed in the direction of the beam for passing the hammer through. Each type 3 on type drum 2 is the sixth
As shown in FIG. A, the hammers can be exposed through the openings 22 for passing each hammer under conditions that do not inhibit the rotation of the type drum 2. Further, as shown in detail in FIG. 6B, the protruding portion of the guard portion 19a protrudes from the circumferential surface of the type as described above, but the circumference cut by the circumferential surface of the type of the protruding portion 19b The direction length a is shorter than the circumferential length b of the type 3, and the tip of the protrusion 19b is positioned approximately at the center of the circumferential length of the type 3. In the above configuration, the type drum 2, the first and second cam groups 12 and 13 are constantly rotated, and the first cam group 12 and the second cam group 13 have the same rotational speed,
In addition, the time required for one rotation of the first cam group 12 is set to be the same as the time required to move one character among the plurality of characters 3 provided at each digit on the type drum 2. .

Next, the printing operation of the line printer configured as described above will be explained using one digit as an example. That is, as the eccentric cam 12a of the first cam group 12 rotates, the first leaf spring 9 and the second leaf spring 10, which is in a pair of relationship opposite to the first leaf spring 9, rotate their tip portions 9a and 10a. The engagement of the print hammer 8, the state of simultaneously engaging the connecting steps 8a and 8b, and the operation of alternately releasing the engaged state are repeated. As long as these three states are repeated,
The print hammer 8 is held in a rest position. The print signal is synchronized with the eccentric cam 12a, and is delivered to the tortoise solenoid 14 when the second leaf spring 10 is pressed downward by the eccentric cam 12a, that is, to the disengaged upright position, and the electromagnetic solenoid 14 is thereby activated. The solenoid core 16 attracts the pressed second leaf spring 10 and holds it in the disengaged position. In this holding state, the eccentric cam 12
The continued rotation of a causes the first leaf spring 9 to move upwardly and disengage its tip 9a from the engagement step 8a of the print hammer 8. Then, the print hammer 8 is rapidly moved onto the type drum 2 by the spring force of the leaf spring 5, and strikes a predetermined type 3 through the printing paper 7.
Perform printing. In addition, immediately before the above-described hitting action of the print hammer 18, the eccentric cam 13a of the second cam group 13
is sufficiently far away from the leaf spring 5. After the above-mentioned striking action is completed, the eccentric cam 13a presses the print hammer 8 against the spring force of the leaf spring 5, and the two leaf springs 9, 10 whose opposing distance has already been restored to the minimum due to the rotation of the eccentric cam 12a. Forcibly move it from the printing upright position to the printing body stop position so as to insert it between the tips 9a and 10a of the
Thus, the print hammer 8 has its own engagement steps 8a, 8b.
and each tip portion 9a, 10 of both leaf springs 9, 10.
The engagement with a is restored and preparations are made for the next printing operation. The printing operation is performed in the same manner as above for multiple digits, but in that case, the printing operation is performed for the preceding digit in the phase relationship,
Thereafter, a printing operation for digits having an opposite phase relationship is performed, and after printing for one line is performed in this way, the printing paper 7 is fed by one line. Next, the function of the print guard 19 related to the above-described printing operation will be described.

That is, as described above, the guard portion 19a of the print guard 19 in the vicinity of the printing position has two continuous W-shaped cross-sections that are reversely curved with respect to the curved surface of the type drum 2, and the center portion thereof is located around the type periphery. Since it protrudes from the surface, the printing paper 7 guided along the outer surface of the print guard 19 contacts only the protruding part 19b of the guard part 19a, faces the other guard parts 19a with a space, and the printing paper 7 is guided along the outer surface of the print guard 19. 7, the printing paper 7 does not touch the arrows 26 and 2 in FIG. 5B when it is hit by the printing hammer 8.
As shown by 6, 27a, 27a and 27b, 27b, the printed characters are drawn from six directions toward the center of the printing area 7a and moved smoothly in the three directions while wrapping around them, only being hindered by the protrusion 19b of the guard portion 19a. Since the entire surface of the type 3 is contacted with uniform pressure, good print quality without unevenness in density can be obtained. In particular, as shown in FIG. 7, this print guard 19 can be used even when the adjacent print hammers 8a and 8b hit the type 3 at the same time, or when the print hammers 8c and 8d hit the type 3 one after another. It is also possible to print with good quality. That is, in the case of simultaneous printing of adjacent digits, the printing paper 7 can be wrapped around the paper without difficulty, and in the case of printing one digit, the portion of the printing paper 7 located in the digit sandwiched between can be placed on both sides of the printing paper 7. The protruding portion 19b of the guard portion 19a prevents contact between the printing surface and unnecessary printing. Moreover, the protrusion 1 of the guide portion 19a
The circumferential length a cut by the peripheral surface of the type 9b is the type 3
is shorter than the circumferential length b of the type 3, and the tip of the protrusion 19b is located approximately at the center of the circumferential length b of the type 3, so when pressing the printing paper 7 against the type 3 surface during printing with the print hammer 8, , the resistance that the print hammer 8 receives from the print guard 19 is due to the protrusion 19b of the guard portion 19a.
This is far less than the resistance received from the entire periphery of the open roof as seen in the conventional example, and sufficient printing results can be obtained even if the impact force of the print hammer 8 is relatively weak. Further, in the above embodiment, a print guard formed by pressing a thin plate was disclosed, but for example, as shown in FIG. 8, a print guard 1 of the present invention
It is also possible to form a guard portion 19a by providing an opening 22 common to all the girders and allowing the print hammer to pass through, and by stretching one continuous wire 28 between each girder in the opening 22.

In that case as well, it goes without saying that the shape of the guard portion 19a of the wire 28 needs to be W-shaped with the central portion protruding. It goes without saying that the print guard for a printer according to the present invention is not limited to the line printer of the above-described embodiment type.

As described above, the present invention provides a print guard for preventing contamination of printing paper that covers a type drum and has a plurality of openings extending in the rotational direction of the type drum. A protrusion that protrudes from the circumferential surface of the type on the type drum is provided approximately at the center of the guard section that stands between the type on the girder, and the length in the circumferential direction cut by the circumferential surface of the type of the protrusion is determined by the circumferential length of the type. By making it shorter than the length in the circumferential direction, the print paper can be moved smoothly toward the type drum without getting dirty. Also, the resistance that the print hammer receives from the print guard is only from the protruding part of the guard, so the impact force is relatively weak. However, its effects are extremely large, such as being able to obtain good printing without unevenness in density.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view showing the main parts of a conventional printer, Fig. 2 is a perspective view illustrating the deformation effect of printing paper in the conventional printer, and Figs. 3 and 4 are each an embodiment of the present invention. Figure 5A is a perspective view of the main parts of the print guard;
Figure B is an enlarged perspective view of the main parts of the print guard with printing paper laid down, Figure 6A is a vertical sectional view showing the print guard along with other parts, and Figure 6B is the guard part of the print guard. An enlarged explanatory view, Fig. 7 is a plan view of the main part showing the print guard in a folded cross-sectional state together with other parts, and Fig. 8 is an enlarged explanatory view.
The figure is a perspective view showing another embodiment of the print guard. In the figure, 2 is a type drum, 3 is a type, 7 is a printing paper, 8 is a print hammer, 1 is a print guard, 19a is a guard portion, 19b is a protrusion, and 22 is an opening for passing the hammer through.

Claims (1)

[Claims] 1. A rotatable type drum 2 is covered with a rotatable type drum 2 having a plurality of type characters 3 for a plurality of digits on the circumferential surface, and type 3 for at least one character for each digit.
In the print guard 19 for preventing dirt on the printing paper 7, which has a plurality of openings 22 extending in the rotational direction of the type drum 2 so that the characters are independently exposed, A protruding portion 19b that protrudes from the circumferential surface of the type 3 of the type drum 2 is provided approximately at the center of the guard portion 19a located between the type 3 of adjacent columns,
A print guard for a printer characterized in that a circumferential length a cut by the circumferential surface of the type 3 of the protrusion 19b is shorter than a circumferential length b of the type 3. 2. The print guard for a printer according to claim 1, wherein the cross-sectional shape of the card portion 19a is formed into two reversely curved W-shapes that are continuous with respect to the curved surface of the type drum 2.