JPH07117290A - Serial dot printer device - Google Patents

Abstract

PURPOSE:To prevent occurrence of an unnecessary shade while giving a clear copy print to a printing medium composed of a number of sheets in a set, by contriving the shape of projecting parts provided on a platen. CONSTITUTION:A platen so opposed to a printing head as to hold, together with the printing head, the surface and the rear of the large-width side of a printing medium is constructed so that it runs in the same direction as the printing head synchronously with this head. On the surface of the platen, projecting parts 31 are provided at positions being opposite to dot pins 30 in the printing head. The shape of the fore end faces of these projecting parts is so formed as to be long along the direction of the adjacent projecting parts 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print head which runs along the surface of a print medium, and is arranged opposite to the print head with the print medium sandwiched therebetween, and in the same direction in synchronization with the print head. The present invention relates to a serial impact printer having a platen configured to move.

[0002]

2. Description of the Related Art Conventionally, an impact printer has placed a set of a plurality of print media on which pressure-sensitive paper such as carbon paper is stacked on the surface of a cylindrical platen, and dot pins are applied from the front side of the print media. It is used when printing all at once with the impact force of. As such a printer,
Recently, a multi-leaf set (so-called multi-part paper) in which a large number of sheets (for example, 10 sheets) are piled up to create a double slip.
There has been a demand for a material that can be printed on the target print medium.

However, when printing on a large number of sheets, there are the following two problems. First, since printing is performed with a sufficient density on the lowermost printing paper, there is a problem that when the printing is performed with a strong printing pressure, the uppermost paper is pierced by dot pin holes. Another problem is that the impact force of the dot pins is dispersed and the printed characters are more likely to be blurred as the lower layer of paper near the platen surface is approached.

As a conventional technique for solving this problem, Japanese Patent Application Laid-Open No. 54-163108 discloses a configuration in which a vibration generator such as an ultrasonic vibration oscillator is connected to the platen to print while vibrating the platen at a high frequency. . That is,
When the dot pins are in a state of protruding to the platen with the print medium sandwiched between them, by causing the platen to face the direction in which the dot pins project and vibrating back and forth at high frequency, the pressing energy is also applied from the back side of the print medium. It is added to make the print clear.

However, in this technique, since the platen having a width larger than the paper width is used, it is necessary to forcibly vibrate the entire platen having this large mass at a high frequency, and a vibration generator having a large generated vibration energy is required. There is a problem that the size of the printer becomes large and the vibration generator continues to operate during the printing operation, which increases the running cost.

[0006] Therefore, the present applicant has previously filed Japanese Utility Model Application No. 4-16.
No. 4196, a platen having a small area is arranged so as to face a print head with a print sheet as a print medium sandwiched therebetween, the platen is moved in the same direction in synchronization with the print head, and We have proposed an impact printer that is configured to have a protrusion so as to face the dot pin in the print head.

According to this structure, when the dot pin applies a striking force to the printing paper, the printing paper is sandwiched between the surfaces of the protrusions having a small cross-sectional area, so that the striking force is not dispersed but concentrated on a small area. To do. As a result, it was possible to clearly print on all the leaves of the printing paper of the multi-sheet set.

[0008]

However, this structure has the following problems. That is, FIG.
As shown in 0, when the dot pin 100a hits the print-receiving medium 101 of the multi-leaf set toward the surface of the opposing projection 102a, the print-receiving medium 101 is moved in the direction of arrow A, and the projection 102a also reacts. Pressure is applied to a large number of sheets of paper and the dot pin 1 at the specified printing point
The printing of the portion 00a is performed.

In this case, since the protruding portions 102b and 102c having the same protruding length are also located at the portions adjacent to the protruding portion 102a, the back surface of the print-receiving medium 101 is the tip of these protruding portions 102b and 102c. When the dot pin 100a protrudes in the striking direction, the print target medium 10
When 1 is pushed in the direction of the protruding portion (direction A), pressure as a reaction is also applied to the back surface side of the print-receiving medium 101 from the tips of the adjacent protruding portions 102b and 102c. As a result,
Unnecessary shadows were generated on the lower layer side of the stacked sheets.

To solve this problem, for example, an elastic body such as rubber is embedded in the recesses around the protrusions 102a, 102b, 102c, and the back side of the print medium 101 is supported by the surface of this elastic body. It is conceivable that since the print medium 101 is supported by the wide surface of the elastic body, the concentration of impact force on the print medium 101 is alleviated as in the conventional technique, and the sharpness of printed characters is poor. That problem could not be solved.

An object of the present invention is to solve these problems by devising the surface shape of the tip of the protrusion.

[0012]

To achieve the above object, according to the present invention, a print head which runs along a surface of a print medium and a print head which is arranged to face the print head with the print medium interposed therebetween are provided. In a serial dot printer including a platen that runs in the same direction in synchronization with the print head and a protrusion provided on the platen facing the dot pin of the print head, the tip surface shapes of the protrusions are adjacent to each other. It is formed so as to be elongated in the direction of the protruding portion.

[0013]

EXAMPLES Next, examples embodying the present invention will be described. FIG. 1 is a perspective view of a main part of a serial dot printer, FIG. 2 is a side view of a main part of the serial dot printer, and FIG. 3 is a front view of a first embodiment showing an arrangement state of dot pins. As shown, the first carriage 11 that supports the print head 10 of the printer is slidably supported by the main guide shaft 12. An auxiliary guide shaft 14 is loosely fitted in a rearward U-shaped guide groove 13 of the first carriage 11 so as to be movable back and forth toward a platen 16 described later. The platen 16 is fixed on a second carriage 15 slidably supported by guide shafts 17 and 18 extending in parallel with the main guide shaft 12.

Pulleys 20, 21 of the same diameter provided on a drive shaft 19 extending in a direction orthogonal to the main guide shaft 12 in the front-rear direction.
The timing belts 22 and 23 wound around are locked to the first carriage 11 and the second carriage 15, respectively, and the drive shaft 19 is driven by a drive motor (not shown) such as a step motor capable of rotating in the forward and reverse directions. The first carriage 11 and the second carriage 15 are configured to reciprocate in synchronization with each other in the same direction.

The first carriage 11 is rotated in the forward and reverse directions about the eccentric shaft center provided at the end portion of the main guide shaft 12 so that the first carriage 11 is moved to the second carriage 1.
The front and back surfaces of No. 5 are adjusted for perspective movement so that the printing gap can be adjusted. Print information is transmitted from a control device (not shown) via a flexible printed wiring cable 24 connected to the print head 10, and via a drive mechanism (not shown) including an electromagnetic solenoid or a piezoelectric element built in the print head 10. , Nose portion 10a of print head 10
The dot pins 30 are driven to project toward the protrusions 31 provided on the surface of the platen 16, and the printing operation is performed toward the print-receiving medium 32 that is pressure-sensitive paper such as printing paper. As shown in FIG. 2, an ink ribbon 33 is inserted between the print-receiving medium 32 and the tip surface of the nose portion 10a, and the uppermost sheet of the print-receiving medium 32 is printed by the ink ribbon 33. However, after the second sheet, a copy can be obtained by striking force (impact force) with respect to the pressure-sensitive ink layer applied on the surface of each sheet (the layer coated with microcapsules containing ink particles). ing.

Further, as described above, by moving the carriage 11 and the platen 16 in the same direction in synchronization with the printing operation, the tip end of the dot pin 30 which projects is always opposed to the front surface of the protrusion 31. You will be in the position you did. As shown in FIG. 2, the print-receiving medium 32 includes a pair of paper feed rollers 25 arranged on the upstream side and the downstream side of the conveyance.
The paper is fed by being sandwiched by a, 25b and 26a, 26b in a direction intersecting with the moving direction of the carriages 11, 15 (direction orthogonal to each other, arrow B direction).

Next, the shape of the surface (tip surface) of the protrusion 31 in the present invention will be described. Figure 3 shows the print head 1
When viewed from the front at the tip of the nose portion 10a of No. 0, 24 dot pins 30 are arranged in a rhombus shape. In FIG. 3, the arrow C direction is the direction in which the first and second carriages 11 and 15 move. 1 for each dot pin 30
Independent projections 31 are provided on the surface of the platen 16 in correspondence with the pair 1. The tip surface shape of each protrusion 31 is formed so as to be elongated in the direction of the adjacent protrusion 31.

The shape of the tip surface of the protrusion 31 shown in FIG. 4A is a rhombus and is long toward the adjacent protrusion 31.
FIG. 5 is a perspective view of the protrusion 31 shown in FIG. The tip surface shape of the protrusion 31 in FIG. 4 (b) is one in which thin ribs 31b, 31b are integrally projected from both sides of the main protrusion 31a which is substantially equal to the cross-sectional (circular) shape of the dot pin 30. 6 shows a perspective view thereof. The embodiment of FIG. 4 (c) is a modification of the embodiment of FIG. 4 (b), in which the tip (free end side) of each rib 31b is connected to a circular portion 31c having a slightly larger tip surface shape. .

For example, as shown in FIG. 7, when the dot pins 30 are arranged in a zigzag pattern in two rows in a direction orthogonal to the carriage movement direction, the tip surface shape of each protrusion 31 is shown. May be formed in an elliptical shape having a major axis with respect to the direction of the adjacent protrusions (the orthogonal direction). The dot pins 30 and the protrusions 31 corresponding thereto may be arranged in an annular shape in a front view, in a zigzag arrangement in two diagonal rows, or the like.

To explain the printing operation by such a configuration, at the time of printing operation, the ink ribbon 33 and the print medium 32, which is a pressure sensitive paper, are inserted between the surface of the platen 16 and the print head 10 to print. When the dot pin 30 projects toward the protrusion 31 in response to the command, the area of the tip of the protrusion 31 is substantially the same as the cross-sectional area of the dot pin 30, so the pressing force due to the impact force of the dot pin 30 is It will only cover a range approximately equal to the cross-sectional area of 30. In other words, unlike the case where the platen has a large area, the impact force of the dot pin 30 does not disperse. From the paper nearer to the paper nearer to the paper nearer to the protrusion 31, approximately the same pressing force is applied, and clear copy printing can be performed on all the papers.

In this case, when one dot pin 30 is projected and hits the print medium 32 toward the corresponding protrusion 31, the pressing force of the dot pin 3 causes the surface side of the print medium 32 to be pressed. The layers of are depressed. At this time, if the shape of the tip surface of each protrusion 31 is formed to be longer than that of the adjacent protrusion 31, the interval between the recesses between the adjacent protrusions 31 is reduced, and the print medium 32 is The back surface is less likely to be dented by being supported by the front surface of the tip end of the adjacent projection 31 (see FIG. 8). On the other hand, at the central portion of the tip surface of the protrusion 31 at the corresponding position, the back surface of the print-receiving medium 32 sinks into (the smaller diameter side of the tip surface) so as to be depressed, and the reaction force from the protrusion 31 side The printing spot is strongly pressed onto the print-receiving medium 32. As a result, the striking force of the dot pin is concentrated on the protrusion 31 corresponding to the portion where the dot pin 30 projects, and clear printing can be obtained, and the printing target corresponding to the adjacent protrusion 31 is printed. Unnecessary shading does not occur on the lower layer paper of the medium 32.

As shown in FIG. 9, a concave portion opening toward the print head 10 is formed on the front surface of a support body 40 supported by a second carriage 15 (see FIG. 1) that moves laterally in synchronization with the print head 10. A piezoelectric element 42 formed by laminating a large number of piezoelectric ceramics is formed in the recess 41, and the base end of the piezoelectric element 42 is fixed to the support body 40. The left and right ends of the spring plate 43 adhered to are fixed to the support body 40, and the platen 16 provided with the projection 31 in each of the embodiments is fixed to the front surface of the spring plate 43.

With this structure, the piezoelectric element 42 is synchronized with the impact operation of the dot pin 30 of the print head 10.
When a voltage is applied to the piezoelectric element 42,
The platen 16 and, by extension, the projection 31 apply an impact force from the back surface side of the print medium 32 toward the dot pins 30. Therefore, in combination with the impact force of the dot pins 30, the print medium It is possible to perform clearer printing on 32. The piezoelectric element 4
The voltage is applied to 2 for the number of print media 32 (the number of sheets)
It may be controlled so that it is turned off when the number is small and is turned on only when the number is large. In this way, the platen 16 is mounted via the piezoelectric element 42 mounted on the second carriage 15.
When driven back and forth, the driven parts (platen 16 and spring plate 4
Since the mass of 2) is small, the required energy can be reduced, which can contribute to energy saving and each component can be made compact.

Further, in order to reduce the abrasion of the protrusion 31 due to the repeated impact with the dot pin 30, it is preferable to form the protrusion 31 in each of the above-mentioned embodiments by a member having abrasion resistance. For example, in a case where the base portion 34 and the protrusion portion 31 are integrally formed as shown in FIG.
It is made of wear resistant material such as cemented carbide, high speed steel, alumina ceramics, zirconia ceramics, silicon carbide ceramics, silicon nitride ceramics and artificial ruby.

The surface of the projection 31 in each of the above-described embodiments made of ordinary carbon steel or the like is coated with hard chrome having a layer thickness of 5 microns or more and titanium nitride coating or nitriding treatment having a layer thickness of 3 microns or more. Apply or iron alloy (steel, etc.)
The wear resistant layer may be formed by performing induction hardening or carburizing on the above. In each of the above-mentioned embodiments, as shown in FIG. 10, a block-like one formed by integrally or implanting the protrusions 31 in the form of ridges or independent parts on the base 34 is used as the surface of the platen 16 or If it is configured to be attached to the second carriage 15, there is an effect that material cost, processing cost, etc. can be significantly reduced. By reducing the height of the protrusion 31, the breakage accident of the protrusion 31 can be reduced.

[0026]

As described above, according to the present invention, the print head which runs along the surface of the print medium and the print head which is disposed so as to face the print head with the print medium sandwiched therebetween. In a serial dot printer having a platen that runs in the same direction in synchronism with the above, and a protrusion provided on the platen so as to face the dot pin of the print head, the protrusions on the tip surface of each protrusion are adjacent to each other. Since it is formed so as to be elongated in the direction of the portion, the print medium is projected in the direction in which the tip surface of the protrusion facing the hit dot pin location intersects with the longer one. Since the print medium is supported in a flat shape without being greatly depressed along the direction of the adjoining protrusion, a portion facing the dot pin that is projecting is curved. Collision An effect that the back surface of the print medium to the tip of the protrusion printing for the back side of the sheet of the print medium is adjacent with the sharp is unable unwanted shadow is pressed by the outer peripheral parts.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part of a printer.

FIG. 2 is a side view of a main part of the printer.

FIG. 3 is a front view array diagram of dot pins.

4 (a), (b) and (c) are front views of an example of a protrusion.

5 is a perspective view of a protrusion corresponding to the embodiment of FIG. 4 (a).

6 is a perspective view of a protrusion corresponding to the embodiment of FIG. 4 (b).

FIG. 7 is a front view showing another arrangement state of dot pins.

FIG. 8 is an explanatory view of the operation of the present invention.

FIG. 9 is a perspective view of an example using a piezoelectric element.

FIG. 10 is a diagram illustrating the operation of the prior art.

[Explanation of symbols]

 10 Print Head 11 First Carriage 15 Second Carriage 16 Platen 19 Drive Shaft 20,21 Pulley 22,23 Timing Belt 30 Dot Pin 31 Protrusion 32 Printed Medium 33 Ink Ribbon 34 Stand 41 Piezoelectric Element 42 Spring Plate

Claims (1)

[Claims] 1. A print head which runs along the surface of a print medium, a platen which is arranged so as to face the print head with the print medium sandwiched therebetween, and which runs in the same direction in synchronization with the print head, In a serial dot printer device including a dot pin of a print head and a protrusion provided on a platen facing the dot pin, the tip surface shape of each protrusion is formed to be elongated in the direction of the adjacent protrusion. Serial dot printer device.