JPH06115195A - Ink jet printer - Google Patents

Abstract

PURPOSE:To effectively convey a sheet without contaminating a print surface. CONSTITUTION:A sheet printed by a printing unit having an ink jet head is discharged by using a sheet delivery roller 81 and a plurality of star wheels 82 rotating while interposing the sheet under pressure between the delivery roller and the wheels. The wheels 82 are aligned with two as one set, supported to both ends of a shaft 86, and a center of the shaft 85 is energized toward the roller 81 by a spring 87.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of a paper discharge structure in an ink jet printer.

More specifically, the present invention relates to a technique capable of ejecting a printed sheet without contaminating it.

[0003]

2. Description of the Related Art In general, an ink jet printer is designed to eject ink onto a sheet for printing.
If the printed paper is discharged using, for example, a pair of rubber rollers, there is a problem in that the undried ink adheres to the rubber roller on the printing surface side and the printing surface becomes dirty.

Therefore, conventionally, as shown in FIG. 15, a sheet discharge roller 1 made of an elastic material such as rubber and a plurality of star wheels 2 which rotate while sandwiching a sheet between the sheet discharge rollers 1 are used. An inkjet printer has been proposed in which the paper P1 printed by the inkjet head H is discharged (JP-A-2-41277).

Each of the star wheels 2 is biased toward the paper discharge roller 1 by a shaft 3 having a spring property.

[0006]

The conventional printer described above has the following problems.

That is, since the star wheel 2 is biased toward the paper discharge roller 1 by the shafts 3 each having one spring property, the star wheel 2 has the spring property (that is, the biasing force) of the shaft 3 which is the biasing member. If there is variation, there is a problem that this variation directly appears as variation of the pressing force of the star wheel 2 on the paper discharge roller 1.

If the pressing force of the star wheel 2 against the paper discharge roller 1 is small, the conveying force for the paper cannot be obtained. On the other hand, if the pressing force is too large, holes are easily formed in the paper and the printing surface is easily soiled. Cause

The present invention solves the above problems, and an object of the present invention is to provide an ink jet printer which can reliably convey a paper without contaminating the printing surface.

[0010]

In order to achieve the above object, the present invention presses a sheet printed by a printing section having an ink jet head between a sheet discharge roller and the sheet discharge roller. An inkjet printer that ejects using a plurality of rotating star wheels while rotating,
The present invention is characterized in that a shaft body supporting two ends of the star wheel as a set is supported at both ends thereof, and a biasing member for biasing the central portion of the shaft body toward the paper discharge roller.

[0011]

Since the present invention has the above-mentioned structure, it operates as follows.

That is, the star wheels are supported as a set of two on both ends of the shaft body, and the central portion of the shaft body is urged toward the paper discharge roller by the urging member. Even if there is a variation in the biasing force, this variation is distributed to the two star wheels via the shaft, and the variation in the pressing force of the star wheel with respect to the paper discharge roller is halved.

Therefore, according to the ink jet printer of the present invention, even if the biasing force of the biasing member varies, the pressing force of the star wheel against the paper discharge roller is stable, and as a result, the printing surface is not contaminated. The paper can be reliably transported.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view showing an embodiment of an ink jet printer according to the present invention, FIG. 2 is a plan view, and FIG. 3 is a left sectional view.

In FIG. 3, 10 is an automatic paper feeder, 20
Is an automatic paper feed path, 30 is a paper feed roller, 40 is a gate roller that is in pressure contact with and follows the paper feed roller 30, 50 is a pinch roller that is in pressure contact with and follows the paper feed roller 30, 60 is a printing unit, and 70 is a discharge unit. A paper path, 80 is a transport unit provided in the paper discharge path 70, 90 is a discharge unit, and 100 is a paper discharge tray.

The automatic paper feeding device 10 directly feeds the paper P by the bottom portion 11a of the lower case 11 (see FIG. 1) of the printer.
Stacker is formed.

The paper P is fed to the automatic paper feed path 20 one by one by the operation of the paper feed roller 12 (see FIGS. 1 and 4) provided only at the center. Paper feed roller 12
As shown in FIG. 4, the paper feed motor 200 connects the gear train 210 to the gear 3 fixed to one end of the paper feed shaft 31.
2, gear 33 fixed to the other end, sun gear 13, planetary gear 14, gear 1 fixed to paper feed roller shaft 16
5, and is driven to rotate via the paper feed roller shaft 16.
The planetary gear 14 is disengaged from the gear 15 and only when the carriage, which will be described later, comes to the paper feed position.
It is supposed to mesh with.

When the paper feed roller 12 is rotating, the fed paper is fed by pressing the leading end between the paper feed roller 30 and the gate roller 40 which rotate in the direction opposite to the paper feed direction. Skew is removed by rotating around the roller 12 portion (in the direction of arrow X in FIG. 4), and then wound around the paper feed roller 30 that rotates in the paper feed direction.
It reaches the printing unit 60 via the pinch roller 50.

The printing section 60 is formed between an ink jet head 62 attached to a carriage 61 that reciprocates in a direction orthogonal to the paper surface in FIG. 3 and the upper surface of the intermediate frame 110. Reference numeral 63 is a guide shaft that guides one end of the carriage 61, and 120 is an upper frame that guides the other end of the carriage 61.

The paper printed by the printing unit 60 is discharged onto the paper discharge tray 100 via the conveying unit 80 and the discharging unit 90.

As shown in FIG. 1, the transport section 80 includes six discharge rollers 81 (specifically, eight discharge rollers 81) made of an elastic material such as rubber.
1a to 81f) and six star wheels 82 provided to face the paper discharge rollers 81a to 81f, respectively.
(Specifically, 82a to 82f).

Three paper discharge rollers 81 are fixed to two rotary shafts 83 and 84 supported by the intermediate frame 110, and three paper transfer rollers 30 are provided as shown in FIG.
Gears 83a, 84 fixed to the rotary shafts 83, 84 from the left and right paper feed rollers via transmission gears 85, 85
When a is rotationally driven, it is rotated. Since FIG. 4 shows the drive system of the rollers and the like in a developed state, the positional relationship of the rollers and the like does not necessarily match the other figures.

The transmission gear 85 includes a gear portion 85a meshing with the gear (83a or 84a) fixed to the rotating shaft (83 or 84), a roller portion 85b in rolling contact with the paper feed roller 30, and a common shaft 85c. Are integrally configured, and both ends of the common shaft 85c are rectangular holes 111 formed in the intermediate frame 110 as shown in FIGS.
It is movably supported by. With such a structure, the transmission gear 85 operates as a one-way clutch. That is, as shown in FIG.
When 0 rotates in the paper feeding direction, the transmission gear 85 moves to the rectangular hole 1
It moves downward along 11 (meshing direction) and transmits the power of the paper feed roller 30 to the paper discharge roller 81. As shown in FIG. 6, when the paper feed roller 30 rotates in the direction opposite to the paper feed direction, the transmission gear 85 moves upward (toward the escape direction) along the rectangular hole 111, and the power of the paper feed roller 30 is discharged. Do not tell the roller 81. Therefore, the discharge roller 81 is
It rotates only when the paper feed roller 30 rotates in the paper feed direction, and does not rotate when the paper feed roller 30 reversely rotates.

As shown in FIGS. 1 and 4, the star wheels 82 are fixed to each of the two ends of the three shaft bodies 86 in sets of two. Both ends 86a of the shaft 86 are shown in FIG.
As shown in FIG. 8, it is supported by the upper frame 120.
Reference numeral 121 denotes a support portion formed by bending a part of the upper frame 120 downward, and both ends 86a of the shaft body 86 are supported by a long hole 122 formed in the support portion 121 so as to be vertically movable. Reference numeral 87 is a spring that forms a biasing member, and is inserted into and attached to the tongue piece 123 of the upper frame 120.
One end 87a of the spring 87 is engaged with the frame 120, and the other end 87b is engaged with the central portion 86b (see FIG. 4) of the shaft body 86 and pushed down to make a set of two star wheels 82. Is urged toward the paper discharge roller 81. In this way, since the central portion of the shaft body 86 is biased toward the paper discharge roller 81 by the spring 87, the spring 8
Even if there is a variation in the biasing force of No. 7, this variation is distributed to the two star wheels 82 via the shaft body 86, and the variation in the pressing force of the star wheel 82 against the paper discharge roller 81 is halved. In this embodiment, the pressing force of the shaft body 86 by the spring 87 is set to 40 g, and the pressing force of the one star wheel against the paper discharge roller 81 is set to 20 g.

The star wheel 82 is rotated by being driven by the paper discharge roller 81, and is pinched between the paper and the paper discharge roller 81 when the paper is conveyed.

The diameter and the number of teeth of the paper feed roller 30, the transmission gear 85, and the paper discharge roller 81 are the same as those of the paper discharge roller 81.
The peripheral speed is about 12% of the peripheral speed of the paper feed roller 30. Therefore, the paper P
As shown in FIG. 9, in the printing section 60, the printing is performed by being pulled by the paper discharge roller 81 and the star wheel 82 and floating in the air.

As shown in FIGS. 1 and 3, the discharging section 90 includes both side supporting sections 91 and 91 for supporting both side portions of the sheet printed on the upper surface by the printing section 60 and discharged from below, and a central section of the sheet. And a push-down portion 92 that pushes downward.

The both-sides support portion 91 is composed of a fixed rib integrally formed with the intermediate frame 110. As shown in FIG. 1, the both-sides supporting portions 91 are arranged at positions of the star wheels 82 on both sides of the star wheel 82, as viewed from the sheet conveying direction. As shown in FIG. 9, the upper surface 91a of the both-sides support portion 91 is inclined upward in the paper discharge direction.

The push-down section 92 is composed of a serrated roller, and is rotatably supported by an arm 93 rotatably attached to the upper frame 120. Arm 9
As shown in FIG. 10, 3 has a bifurcated shape 93a, 93a, and a first stopper 93b, 93b is provided at the tip thereof.
Are formed so as to project laterally. In addition, the second stoppers 93c, 9c are spaced apart from the first stopper by a slight distance.
3c is formed so as to project laterally. Upper frame 120
Has a square hole 123 (see FIG. 9) in its bent portion. In the square hole 123, the forked part 93a of the arm,
The first stopper 93 in a state in which the distance between the 93a is reduced.
The arm 93 is attached to the upper frame 120 by passing b and 93b and releasing the forked portions 93a and 93a.
After being attached, the upper frame 120 is sandwiched by the first stopper 93b and the second stopper 93c with a distance that does not hinder the rotation of the arm. It does not come off from 123.

Next, the paper discharge operation in the above printer will be described.

(I) As shown in FIG. 9, the paper P printed by the printing unit 60 is conveyed by being pinched by the paper discharge roller 81 and the star wheel 82 and pulled.

At this time, as described above, since the central portion of the shaft 86 of the star wheel is biased toward the paper discharge roller 81 by the spring 87, the biasing force of the spring 87 varies. However, this variation is distributed to the two star wheels 82 via the shaft 86, and the variation in the pressing force of the star wheel 82 on the paper discharge roller 81 is halved.

Therefore, the pressing force of the star wheel 82 against the paper discharge roller 81 (that is, the paper P) becomes stable,
As a result, the printing surface is not contaminated and the paper is reliably transported.

(Ii) When the leading edge Pa of the sheet enters the sheet discharge section 90, both side portions of the leading edge Pa are gradually guided upward by the upper surfaces 91a of the both side supporting sections 91. At the same time, the central portion Pa1 of the tip edge Pa gradually pushes up the push-down portion 92 while rotating the arm 93 in the counterclockwise direction. On the contrary, the central portion Pa1 of the tip edge Pa gradually falls below the push-down portion 92. Due to the weight of the entering and pushing-down portion 92 and the arm 93, the pushing-down portion 92 and the arm 93 are pushed down as compared with the side portions.

In this way, the paper P is gradually discharged from the leading end thereof while being forcibly biased into a concave shape in which the printing surface is depressed when viewed from the discharge direction.

At this time, since the push-down section 92 is supported by the rotatable arm 93, the sheet P is pushed down by the turning operation of the arm 93 when the leading edge of the sheet P hits the push-down section 92. The operation of entering below is smoothly performed.

(Iii) FIG. 11 shows a state in which the paper P is discharged halfway.

As shown in this figure, when the paper P is forcibly biased in a concave shape when viewed from the discharge direction, the paper P becomes stiff and is conveyed in a floating state. For this reason, as shown in FIG. 12, the ejected paper P is printed on the printing surface P1 of the paper P1 which is first printed, ejected, and stacked.
The time until sliding contact with f is delayed, and the printed paper P1
The time for the ink to dry is secured.

Here, as shown in FIG. 11, the paper P is
Since the sheet is conveyed in a flat state when viewed from the discharge direction in the conveying section 80 in the previous stage of being discharged while being forcibly biased into the concave shape, the influence of the concave shape of the sheet P is It is blocked by the transport unit and does not reach the printing unit 60. Therefore, good print quality is ensured.

(Iv) The paper P is further conveyed, and as shown in FIG.
As shown in FIG. 5, when the trailing edge Pb passes the transport unit 80, the transport force is lost, and the trailing edge Pc of the sheet is retained by the discharge unit 90 in a concave shape.

(V) The succeeding paper P2 is printed, and as shown in FIG.
As shown in FIG. 3, the leading edge P2a passes through the transport unit 80 and hits the trailing edge Pb of the preceding sheet P, whereby the holding of the preceding sheet P by the discharge section 90 is released (released). The state is shown in FIG. 14). Preceding paper P
When the sheet is pushed to the succeeding sheet P2, the holding is released and the sheet is stacked on the previously printed sheet (P1 in FIG. 12). Therefore, the time until sliding contact with the printed sheet is further increased. Be delayed.

(Vi) As shown in FIG. 14, after the leading edge P2a of the succeeding sheet P2 is applied to the trailing edge Pb of the preceding sheet P to release the holding of the preceding sheet P1, the succeeding sheet P2 Stop the transport once. This stopping operation can be performed by counting the number of pulses of the paper feed motor 200 and stopping the driving of the motor 200 when the number of pulses reaches a predetermined number.

As described above, when the method of pushing out the preceding sheet P by applying the leading edge P2a of the succeeding sheet P2 to the trailing edge Pb of the preceding sheet P, the leading edge P2a of the succeeding sheet P2 and the leading edge P2a of the succeeding sheet P2 are adopted. The trailing edge Pb of the preceding paper P engages with the printed paper P ahead of the preceding paper P.
1 (see FIG. 12) may become uncertain, but once the conveyance of the succeeding sheet P2 is temporarily stopped, the inertia of the preceding sheet P2 is utilized to make the succeeding sheet P2. Leading edge P2a of the sheet and trailing edge Pb of the preceding sheet
It is possible to reliably release the engagement with and to ensure the stacking operation of the preceding paper P on the previous printed paper P1.

As described above, according to the ink jet printer of this embodiment, two star wheels 82 are provided.
Since the central portion of the shaft body 86 supported at both ends as a set is biased by the spring 87 toward the paper discharge roller 81, even if the biasing force of the spring 87 varies, this variation causes the variation. It is distributed to the two star wheels 82 via 86, and the variation in the pressing force of the star wheels 82 on the paper discharge roller 81 is halved.

Therefore, the pressing force of the star wheel 82 against the paper discharge roller 81 (that is, the paper P) becomes stable,
As a result, it is possible to reliably convey the paper without contaminating the printing surface.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be appropriately made within the scope of the present invention.

[0048]

According to the present invention, the pressing force of the star wheel with respect to the paper discharge roller is stabilized, and as a result, the paper can be reliably conveyed without staining the printing surface.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of an inkjet printer according to the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a left side sectional view of the same.

FIG. 4 is a development view of the drive system.

FIG. 5 is a partially enlarged side sectional view of the same.

FIG. 6 is a partially enlarged side sectional view of the same.

FIG. 7 is a partially enlarged side sectional view of the same.

FIG. 8 is a partially enlarged plan view of the same.

FIG. 9 is a partially enlarged side sectional view of the same.

FIG. 10 is a perspective view of the pressing section.

FIG. 11 is a perspective view for explaining the operation.

FIG. 12 is a perspective view for explaining the operation.

FIG. 13 is an operation explanatory perspective view.

FIG. 14 is a perspective view for explaining the operation.

FIG. 15 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 60 printing unit 62 inkjet head P paper 81 discharge roller 82 star wheel 86 shaft 87 spring

Claims (1)

[Claims] 1. An inkjet printer that discharges a sheet printed by a printing unit having an inkjet head using a sheet discharge roller and a plurality of star wheels that rotate while pinching the sheet between the sheet discharge rollers. And
An inkjet printer comprising: a shaft body that supports two sets of the star wheels at both ends thereof; and a biasing member that biases the central portion of the shaft body toward the paper discharge roller.