JPH10291344A - Platen unit and serial printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the print quality from lowering at a part of a recording medium supported by a central platen. SOLUTION: Side platens 2, 3 arranged on the opposite sides of a central platen 1 are provided, respectively, with a part 11 for pressing the central platen 1 in the direction retracting from the scanning face of a print head 4 when the side platens 2, 3 are applied with a pressure from the print head 4 and retracted. Consequently, under a state where a recording medium 8 on the side platen 2 or 3 is stopped at the forward end of the print head 4, the central platen 1 is retracted simultaneously by the pressing part 11 when the side platen 2 or 3 is retracted from the scanning face of the print head 4 so that the side platen 2 or 3 facing the print head 4 will be substantially flush with the surface of the central platen 1. Since printing is performed without vibrating the print head 4 in a region of recording medium 8 supported flatly in the range between one side platen 2 or 3 and the central platen 1, a uniform and clear print state is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a platen device and a serial printer.

[0002]

2. Description of the Related Art First, FIGS. 4 and 5 show a conventional example of a serial printer having a platen device of a three-division system. The platen device A has a central platen 1 and side platens 2 and 3 arranged on both sides of the central platen 1.
These platens 1, 2, 3 are arranged in a line along the scanning direction of the print head (dot printer head) 4, and are guided by a guide shaft 6 erected on a base 5 with respect to the scan surface of the print head 4. It is supported to move forward and backward. Also, these platens 1, 2, 3 are provided with springs 7
The platens 1, 2, and 3 are urged in the direction in which they advance with respect to the scanning surface of the print head 4, so that the advance positions of the printing head 4 with respect to the scanning surface are restricted by stoppers (not shown). It is configured. In this case, since the platens 1, 2, and 3 are slidably fitted to the plurality of guide shafts 6, they are displaced in parallel to the base 5.

The print head 4 is mounted on a carriage (not shown), and is configured to reciprocate with the carriage along the arrangement direction of the platens 1, 2, and 3. Ink ribbon (not shown) at the tip of print head 4
A guide 9 for partitioning the recording medium 8 and pressing the recording medium 8 is provided fixedly, and a window (not shown) facing the print wire (not shown) of the print head 4 is provided at the center of the guide 9. Are open.

In such a serial printer, the print head 4 is moved together with the carriage in the direction in which the platens 1, 2, and 3 are arranged, and the print head 4 is driven in the course of this movement to perform printing on the recording medium 8.

[0005] In this case, the recording medium 8 such as a booklet is supported by the central platen 1 to support the binding margin 8a at the center in an open state, and the both sides of the recording medium 8 are supported by the side platens 2 and 3. As shown in FIGS. 4 and 5, the surface of the recording medium 8 such as a booklet does not become flat depending on how the pages are opened. Therefore, a three-part platen device A is used to support the recording medium 8 as flat as possible. .

FIG. 4 shows a state in which the number of pages on the left side of the recording medium 8 is small and the number of pages on the right side is large, and the left side platen 2 holds the recording medium 8 against the guide 9 of the print head 4. Therefore, the print head 4 is retracted from the print head 4 against the urging force of the spring 7, and the central platen 1 and the right side platen 2 do not receive the pressure from the guide 9 of the print head 4. The printing head 4 advances to the scanning surface by the urging force. The advance position is regulated by the aforementioned stopper.

FIG. 5 shows a state in which the number of pages on the left side of the recording medium 8 is large and the number of pages on the right side is small, and the left side platen 2 holds the recording medium 8 against the guide 9 of the print head 4. In addition, since the number of pages is large, the print head 4 retreats greatly against the urging force of the spring 7, and the central platen 1 and the right side platen 2 do not receive pressure from the guide 9 of the print head 4. Therefore, the recording medium 8 advances to the scanning surface of the print head 4 by the urging force of the spring 7 until the recording medium 8 comes into contact with a stopper (not shown). The amount of advance at this time is increased by the smaller number of pages of the recording medium 8.

When the print head 4 reaches the central platen 1, the recording medium 8 is pressed by the guide 9 of the print head 4, and the central platen 1 scans the print head 4 against the urging force of the spring 7. Retreat from the face. When the print head 4 reaches the right side platen 3, the side platen 3 is pressed against the guide 9 of the print head 4 by the recording medium 8. Retreat from the scan plane. That is, since the distance between the distal end surface of the guide 9 of the print head 4 and the base 5 is constant, the scanning surface of the print head 4 (extended surface of the distal end surface of the guide 9) is constant.

[0009]

Here, as shown by arrows in FIGS. 4 and 5, when printing on the left side page of the recording medium 8 opened in the process of moving the print head 4 from left to right, The center platen 1 supporting the periphery of the binding portion 8a of the recording medium 8 has its surface advanced to the scanning surface side of the print head 4 beyond the surface of the left side platen 2, so that the side platen 2 and the center platen 1 Is formed at the boundary between the recording medium 8 and the recording medium 8. That is, since the recording medium 8 is bent so that the vicinity of the binding portion 8a protrudes toward the scanning surface of the print head 4, the guide 9 of the print head 4 moving from left to right is bent at the bent portion of the recording medium 8. When the print head 4 moves further to the right, the print head 4 receives a large resistance from the recording medium 8 and the central platen 1 supporting the recording medium 8 and vibrates. Since the print wire also vibrates due to this vibration, the print dot becomes large. This allows
For example, when printing characters, when compared by the thickness of the printed characters, thin and delicate characters are printed in a portion far from the binding margin 8a, but thick and outlines are blurred near the binding margin 8a. Characters are printed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to prevent a decrease in print quality in a portion of a recording medium supported by a center platen.

[0011]

According to the first aspect of the present invention,
A central platen supporting a central portion of the recording medium, and side platens arranged on both sides of the central platen and supporting both sides of the recording medium, are arranged in a line along a scanning direction of a reciprocally driven print head. In a platen device provided to be supported in a manner to advance and retreat urged in a direction to advance to the scanning surface of the print head, the side platen,
When the side platen retreats from the print head under the pressure of the print head, a pressing portion is provided for pressing the center platen in a direction to retreat from the scanning surface of the print head. Therefore, when the recording medium on the side platen is pressed against the tip of the print head, the side platen retreats by receiving pressure from the print head via the recording medium. The platen is pressed in a direction to retract from the scan surface of the print head. This makes it possible to make the surfaces of the side platen and the center platen facing the print head substantially coincide with each other.

According to a second aspect of the present invention, there is provided a print head which is driven reciprocally, a center platen which supports a binding portion of an open booklet in a state orthogonal to a scanning direction of the print head,
Side platens supporting both sides of the open booklet arranged on both sides of the central platen are arranged in a line along the scan direction of the print head, and in a direction in which the print plate advances with respect to the scan surface of the print head. In a serial printer provided so as to be urged to move forward and backward, the side platen moves the center platen when the side platen retreats from the print head under the pressure of the print head. And a pressing unit that presses in a direction to retreat from the scanning surface. Therefore, when the recording medium on the side platen is pressed against the tip of the print head, the side platen retreats by receiving pressure from the print head via the recording medium. The platen is pressed in a direction to retract from the scan surface of the print head. This makes it possible to make the surfaces of the side platen and the center platen facing the print head substantially coincide with each other.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a serial printer and a platen device according to the present invention will be described with reference to FIGS. 4 and 5 are denoted by the same reference numerals and description thereof is omitted.

The platen device B in the present embodiment is
It has a central platen 1 and side platens 2 and 3 arranged on both sides of the central platen 1.
A pressing portion 11 for pressing a protruding piece 10 protruding from both ends of the central platen 2 is formed at an end on the side of the central platen 2.

In this configuration, the print head 4 is moved together with the carriage in the direction in which the platens 1, 2, 3 are arranged, and the print head 4 is driven in the course of this movement to print on the recording medium 8. In this case, in the recording medium 8 such as a booklet, the binding margin 8a which becomes the center in the open state is supported by the central platen 1 in a state orthogonal to the scanning direction of the print head 4, and both sides of the binding margin 8a Platen 2, 3
Supported by

The state shown in FIG. 1 is a state where the number of pages on the left side of the recording medium 8 is small and the number of pages on the right side is large, and the state shown in FIG. Is small, but in any state, the left side platen 2
Since the recording medium 8 is pressed by the guide 9 of the print head 4, it retreats from the print head 4 against the urging force of the spring 7, and the projecting piece 10 of the central platen 1 is pushed by the pressing portion 11 of the side platen 2. The left side platen 2 and the center platen 1 are depressed and retracted from the scan surface of the print head 4.
And the right side platen 3 does not receive the pressure from the guide 9 of the print head 4, and advances to the scan surface of the print head 4 by the urging force of the spring 7. The advance position is regulated by the aforementioned stopper.

Here, as shown by arrows in FIGS. 1 and 2, when printing is performed on the left page of the recording medium (booklet) 8 opened in the process of moving the print head 4 from left to right, the recording medium 8 The central platen 1 supporting the periphery of the binding margin 8a
Since the surface of the recording medium 8 is maintained in a state in which it coincides with the surface of the left side platen 2, the entire left side page of the recording medium 8 serving as a print area can be maintained flat. Here, the printing area is a portion where the booklet 8 is placed on the platens 1 and 2. Therefore, the print head 4 is located on the left side platen 2.
In the process of reaching the binding margin 8a beyond the boundary between the print head 4 and the central platen 1, the resistance that the print head 4 receives from the recording medium 8 is small and does not change. Accordingly, the vibration of the print head 4 is suppressed, and the entire left page can be printed uniformly and with high resolution.

The right side platen 3 advances to the scanning surface side of the print head 4 beyond the center platen 1 until the movement of the print head 4 advances and receives the pressure of the guide 9.
A step occurs at the boundary between the center platen 1 and the side platen 3, and the recording medium 8 is bent by the step, and the guide 9 of the print head 4 moving from left to right hits the bent part of the recording medium 8. It vibrates when touched, but there is no problem if it is not printed on the right page in this process.

When printing on the right side page, the print head 4 is moved to the right end of the right side page without printing, and printing is performed in the process of moving the print head 4 from the right side to the left side. In this process, the right side platen 3 retreats from the scanning surface of the print head 4 against the urging force of the spring 7 because the recording medium 8 on the right side platen 3 is pressed by the guide 9 of the print head 4. Sometimes, the center platen 1 supporting the periphery of the binding portion 8a of the recording medium 8 has its protruding piece 10 pressed by the pressing portion 11 of the side platen 3, so that the surface of the center platen 1 has the right side platen 3 Is maintained in a state coinciding with the surface. Therefore, the recording medium 8 serving as a print area
The entire page to the right of can be kept flat. Accordingly, in the process in which the print head 4 reaches the binding margin 8a over the boundary between the right side platen 3 and the center platen 1, the resistance that the print head 4 receives from the recording medium 8 is small and does not change. Therefore, the vibration of the print head 4 can be suppressed, and the entire right page can be printed with a uniform resolution. When printing the portion placed on the side platen 3 side, printing is performed from the right end of the booklet 8 to the left side. Therefore, printing over the step at the boundary between the side platen 3 and the center platen 1 is not possible. Absent. Therefore, a clear printing state can be obtained.

Although the binding margin 8a is supported substantially at the center of the central platen 1, the number of pages of the recording medium 8 on the downstream side in the moving direction of the print head 4 is smaller than the number of pages on the upstream side in the moving direction of the print head 4. When the number of pages is larger than the number of pages, the guide 9 comes into contact with the stepped portion due to the difference in the number of pages until the center of the print head 4 reaches the binding margin 8a. When printing near the binding margin 8a, the shorter the guide 9, the better. Desirably, it is about one-third of the length of the central platen 1, but there is little effect up to the same magnification.

[0021]

According to the first aspect of the present invention, the side platens arranged on both sides of the center platen are arranged such that when the side platens are retracted from the print head under the pressure of the print head, the center platen is moved downward. Is provided in the direction in which the recording medium on the side platen is pressed against the tip of the print head, the side platen is moved through the recording medium. When the print head is retracted by receiving pressure, the pressing portion can press the central platen in a direction in which the central platen is retracted from the scanning surface of the print head. This makes it possible to make the surfaces of the side platen and the center platen facing the print head substantially coincide with each other. Therefore, printing is performed without vibrating the print head in the area of the recording medium that is supported flat in the range between the one side platen and the center platen,
A uniform and clear printing state can be obtained.

According to the second aspect of the present invention, the central platen supports the binding portion of the open booklet orthogonally to the moving direction of the print head, and the central platen is disposed and opened on both sides of the central platen. A side platen for supporting both sides of the booklet, wherein the side platen retreats from the scanning surface of the print head when the side platen retreats from the print head under the pressure of the print head. In the state where the booklet on the side platen is pressed against the front end of the print head, the side platen retreats by receiving pressure from the print head via the booklet. At the time of retreat, the pressing portion can press the central platen in a direction to retreat from the scan surface of the print head. This makes it possible to make the surfaces of the side platen and the center platen facing the print head substantially coincide with each other. Therefore, even if the print head is moved in the direction orthogonal to the binding portion of the booklet, a uniform and clear printing state can be obtained up to the vicinity of the binding portion.

[Brief description of the drawings]

FIG. 1 is a front view showing a serial printer and a platen device according to an embodiment of the present invention.

FIG. 2 is a front view showing a serial printer and a platen device.

FIG. 3 is a perspective view of a platen device.

FIG. 4 is a front view showing a conventional serial printer and a platen device.

FIG. 5 is a front view showing a serial printer and a platen device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Central platen 2, 3 Side platen 4 Print head 8 Recording medium, booklet 8a Binding margin 11 Pressing part

Claims (2)

[Claims] 1. A central platen supporting a central portion of a recording medium, and side platens arranged on both sides of the central platen and supporting both sides of the recording medium, along a scanning direction of a reciprocally driven print head. In a platen device arranged in a line and urged in a direction to advance with respect to the scanning surface of the print head and supported so as to be able to move forward and backward, the side platen is configured such that the side platen has a pressure of the print head. A platen device, comprising: a pressing portion that presses the central platen in a direction to retreat from the scanning surface of the print head when receiving the print head from the print head. 2. A reciprocating print head is provided, a central platen for supporting a binding portion of an open booklet in a state orthogonal to a scanning direction of the print head, and a central platen disposed on both sides of the central platen and opened. Side platens that support both sides of the booklet are arranged in a line along the scanning direction of the print head, and are urged in a direction to advance with respect to the scanning surface of the print head to be supported so as to be able to advance and retreat. In the above serial printer, the side platen is pressed in a direction to retreat the center platen from the scanning surface of the print head when the side platen retreats from the print head under the pressure of the print head. And a serial printer.