JPH08267787A - Ink jet printer - Google Patents

Abstract

PURPOSE: To provide a simple valve mechanism for setting the pressure inside a protective cap at the atmospheric pressure which is not required to be disposed in the periphery of the protective cap. CONSTITUTION: In an ink jet printer, a suction tube 15 and a pressure tube 16 are mounted on a protective cap 11. The suction tube 15 is connected with a negative pressure section, while the pressure release tube 16 is opened to atmosphere. A valve function cam 21 for shutting off the communication of the tube by squeezing the tube and recovering the communication by restoring the shape of the tube is disposed on the middle section of the pressure release tube 16. The cam 21 is rotated at the timing set by a driving source other than the driving source for driving a printing head, and stopped in the state that the tube is crushed at the position which is the dead point regarding the reaction from the tube side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printer having an ink jet type print head and a protective cap for protecting its nozzle array.

[0002]

2. Description of the Related Art Ink jet printers are equipped with a protective cap in order to maintain a good condition of a nozzle row exposed on the front surface of a print head. The protective cap is a container type that covers the nozzle row on the front of the print head at the home position and adheres closely to the print head to prevent the ink at the nozzle tip from drying out and sucking air, and a series of printing operations starts. Before the ink is discharged, the inner space of the container is set to a negative pressure part so that the high density ink at each nozzle tip is removed all at once.

Further, if the container portion is always in a hermetically sealed state, the inside is pressurized when capping the nozzle row with the protective cap, and air is pushed from the tip of the nozzle to form bubbles. When bubbles occur, normal dots can no longer be formed. On the other hand, even when the cap is removed, the inside of the protective cap has an unnecessary negative pressure, and therefore bubbles may be caught in the tip of the nozzle. For this reason, the protective cap is usually provided with a valve mechanism for communicating the inside of the container to the atmospheric pressure at a timing. In many cases, the valve mechanism is arranged directly or close to the protective cap and has a structure interlocking with the traveling movement of the carriage that moves the print head.

However, if a valve mechanism for communicating with the atmospheric pressure is provided in the protective cap or in the vicinity of the protective cap, the unit of the protective cap and the valve mechanism becomes large, and the mechanical structure of the entire printer is rational and efficient. Difficult to do. Further, since the drive of the valve mechanism is driven by the traveling of the carriage, the traveling distance of the carriage must be increased, which makes it difficult to make the printer compact. Moreover, the conventional valve mechanism has a complicated structure, which increases the cost of the printer.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a valve mechanism for making the inside of a protective cap at atmospheric pressure has a simple and reliable structure and does not need to be arranged around the protective cap. The challenge is to provide an inkjet printer that has

[0006]

The present invention relates to an inkjet printer. A suction tube and a pressure release tube are attached to the protective cap in communication with the inner space thereof. The end of the suction tube is connected to the negative pressure section. The end of the pressure release tube is open to the atmosphere. A valve function cam is arranged in the middle portion of the pressure release tube to block the tube communication by crushing the tube and restore the communication by restoring the shape of the tube.

The valve function cam is rotated at a timing by a drive source separate from the drive source for driving the print head,
The tube is stopped in a state of being crushed at a position that is a dead center for the reaction from the tube side. It is preferable to adopt the following configuration.

A configuration in which the valve function cam is arranged in a marginal space position inside the printer away from the periphery of the protective cap. The drive mechanism for the negative pressure part and the drive mechanism for the valve function cam are used as one drive source that is switched and used, and when the negative pressure part is driven, the valve function cam is at the dead point position in the state where the tube is collapsed.

[0009]

The suction tube communicates the internal space of the protective cap with negative pressure, and the pressure release tube communicates the internal space of the protective cap with atmospheric pressure. The valve function cam opens and closes the internal space with respect to atmospheric pressure. The valve function cam that squeezes the tube to block the communication of the tube and restore the communication by restoring the shape of the tube simplifies the structure around the protective cap and also ensures the opening and closing of the internal space against atmospheric pressure. To do.

The structure in which the valve function cam is rotated at a timing by a drive source separate from the drive source for driving the print head makes it possible to dispose the valve mechanism at a position away from the periphery of the protective cap, and Depending on the position of the cam, the valve function cam that can be rotated independently from the movement of the carriage is stopped by crushing the tube at the position where it becomes a dead point for the reaction from the tube side. Since the cam itself is locked with respect to rotation, when the drive source of the valve function cam is disconnected from the valve mechanism, it does not move unexpectedly even without a special lock mechanism, and the operation of the valve function cam is reliable. Becomes

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an ink jet type print head 1 in a home position and a maintenance device 2 located opposite thereto. Reference numeral 3 is a frame to which the carriage shaft 4 and the guide plate 5 are fixed. Reference numeral 6 is a timing belt, which is driven by a head reciprocating motor 7 fixed to the bottom of the frame 3. The print head 1 is inserted into the carriage shaft 4 at the front part (platen side), and the rear part is slidably mounted on the upper surface of the guide plate 5, and is connected to the timing belt 6 at the lower part.

The print head 1 is an ink jet type having a well-known structure and has a nozzle row 8 for ejecting ink in dot units on the front surface. Further, the head reciprocating motor 7 is under the control of a control device 9 containing a system program. The maintenance device 2 includes a protection cap 11 and a wiper 12 mounted on a maintenance base 10, a mechanism for advancing and retracting the print head 1 toward and from the print head 1 at the same timing as the movement of the print head 1, and the inside of the protection cap 11 with timing. It is provided with a negative pressure section 13 for making a negative pressure and a valve mechanism 14 for communicating with the atmosphere (FIG. 2). The movement of the protective cap 11 and the wiper 12 to the print head side is performed by the spring 28, but there is a stopper (not shown) so as not to slip out of the maintenance base 10.

The protective cap 11 is in the shape of a container having a recess, and a fluorosilicone rubber cover 11a is provided inside the recess.
Is installed. The cover 11a is intended to facilitate the removal of ink stains and improve the adhesion to the print head 1. The tip of the suction tube 15 and the tip of the pressure release tube 16 are connected to and communicate with the internal space of the protective cap 11 formed by the recess. The end of the suction tube 15 is connected to the pump 17 of the negative pressure section 13. The negative pressure portion 13 is incorporated in the maintenance base 10 and includes a switching gear 18 and an idle gear 19.
It is driven by the motor 29 via (a, b). The pump 17 is a so-called tube pump, and when the rollers 20 arranged at predetermined intervals are rotated, the suction tube 15 is sequentially crushed to perform pump operation.

The end of the pressure release tube 16 is open to the atmosphere via a valve function cam 21 in the middle. The valve function cam 21 sandwiches the pressure release tube 16 between itself and the frame and crushes it. The valve function cam 21 is driven by the valve mechanism 14. The valve mechanism 14 is driven by a motor 29 via the switching gear 18, the idle gear 22 (a, b), and the cam gear 23, which are incorporated in the maintenance base 10. The valve function cam 21 is attached to the cam drive shaft 24 of the cam gear 23. In this example,
First and second cams 25, 26 for alternately advancing and retracting the protective cap 11 and the wiper 12 are also attached to the cam drive shaft 24. Reference numeral 27 (a, b) is a cam follower, which is provided integrally with the protective cap 11 and the wiper 12, and is always provided with the cam 2 by the spring 28 (a, b).
It is pressed to the 5 and 26 side.

The first and second cams 25 and 26 are formed by cutting a part of a disk along a predetermined chord to form facing portions 25a and 26a. The initial phase difference is set. Regarding the first cam 25, the state in which the facing portion 25a faces the cam follower 27a and is vertical (FIG. 4) is the initial state. In this state, the protective cap 11 is pushed out toward the print head 1 by the spring 28 to cover the nozzle row 8 of the print head 1, but the cam follower 27a and the facing portion 2 of the first cam 25 are covered.
There is a distance d2 smaller than the radius d1 cut out by the chord from 5a. The relationship between the second cam 26 and the cam follower 27b is almost the same, except that there is a difference in rotation angle of 180 °.

Reference numeral 29 is a motor, and the switching gear 18
The negative pressure part 13 and the valve mechanism 14 serve as a common drive source via the switching gear 18. The motor 29 is under the control of the control device 9, but is a drive source separate from the head reciprocating motor 7.

The valve function cam 21 has a substantially wedge shape with a wide tip and a thin thickness, and contacts the pressure release tube 16 with a smooth surface of the tip portion. The cam 21 has a function of crushing the pressure release tube 16 between the horizontal portion of the frame 3 (FIG. 5), but when the tube 16 is in the most crushed state, the tip end and the shaft of the cam drive shaft 24 are crushed. Line connecting cores (P0
-P2) coincides with the direction of the reaction force from the side of the tube 16 and becomes the dead center position for the reaction. Further, the dead center position coincides with that when the first cam 25 is at the initial position.

In operation, when the print head 1 reaches the home position by the print end command, the motor 29 of the maintenance device 2 is driven according to the position detection result regarding the movement of the sensor or the print head. At this time, the first cam 25 is rotated by 180 °, and the protective cap 11 is separated from the print head 1 by the circumference of the cam 25 and moved forward (platen side) by a distance d1-d2. It is in. Further, the switching gear 18 is the valve mechanism 1
It has been switched to the 4 side. Therefore, the cam gear 23 is driven and the protective cap 11 is pushed by the spring 28 and projects toward the print head 1. The protective cap 11 eventually covers the nozzle row 8 of the print head 1 and collides with the print head 1 to stop further movement. Cam gear 2
3 further rotates and is stopped when the first cam 25 reaches the initial position. The rotation of the first cam 25 during this period is
After the rear end T of the cam acting surface is separated from the cam follower 27a, the distance between the facing portions 25 becomes the distance d2, which is θ in angle.

Looking at the rotation of the valve function cam 21, the rotation starts from the position P2 in FIG. 5, reaches P3, and then rotates the angle θ to reach the position P0. P
The position 3 is a position where the point T of the first cam 25 is separated from the cam follower 27a, and at this position, the valve function cam 2
The tip of 1 does not completely crush the tube 16, and the pressure release tube 16 is in communication. P0 is the dead center position of the valve function cam 21.

Therefore, before the protective cap 11 completely covers the nozzle array 8 of the print head 1, the tip of the valve function cam 21 is between P2 and P3, and the pressure release tube 16 is in communication with the protective cap 11. The internal space communicates with atmospheric pressure. As a result, even if the protective cap 11 is rapidly moved toward the print head 1 and brought into contact with the print head 1, the internal space of the protective cap 11 is not pressurized. After the protective cap 11 completely covers the nozzle row 8, the valve function cam 21
Moves from P3 to P0 and completely crushes the pressure release tube 16 to cut off communication. As a result, the inside of the protective cap 11 is sealed, and the valve function cam 11 is stopped at the dead center position.

When a print command is issued again, the switching gear 18
Is switched to the negative pressure portion 13 side, and the pump 17 is driven. The internal space of the protective cap 11 is set to a negative pressure, the ink at the tip portion is sucked out from each nozzle of the nozzle row 8 of the print head 1, and the nozzle row 8 is maintained. The pump 17 is stopped after a predetermined rotation (several rotations), the switching gear 18 is switched to the valve mechanism 14 side, the cam shaft 24 is rotated, and the first and second cams 25 and 26 are rotated. First cam 25
Initially, after rotating by an angle θ until the start end S of the cam acting surface contacts the cam follower 27a, the cam follower 27a is pushed forward against the spring 28 and rotated by 180 °. As a result, the protective cap 11 is separated from the print head 1 and the nozzle row 8 is released.

At this time, the valve function cam 21 is completely crushed by the rotation of the angle θ from the position P0 to the position P1 where the starting end S of the first cam 25 is in contact with the cam follower 27a and the communication is cut off. The tube 16 is brought into communication with the atmosphere by slightly separating it from the pressure release tube 16 in the state. After the tip of the valve function cam 21 has passed the position P1, the pressure release tube 16 is completely released and the communication state is maintained.

Therefore, at the beginning of the printing operation, the pressure inside the sealed inner space of the protective cap 11 is once made negative and the nozzle row 8 is maintained, and then the protective cap 11 is moved to the print head 1.
Immediately before the protective cap 11 is separated from the internal space, the internal space is communicated with the atmospheric pressure. This prevents the internal space from becoming negative pressure when the protective cap 11 is separated from the print head 1. Further, while the pump 17 is operating, the switching gear 18 is switched to the negative pressure portion 13 side, and the valve mechanism 14 side of the valve function cam 21 is disconnected from the drive source, so that looseness is likely to occur. Since the valve function cam 21 is stopped at the dead point position related to the reaction, it does not rotate unexpectedly.

The above is an embodiment, and the present invention is not limited to the illustrated configuration. The mechanism for driving the valve function cam 21 can be performed independently of the driving of the first and second cams 25, 26. Further, since the pressure release tube 16 is highly flexible, the end portion of the pressure release tube 16 is arranged in a space position inside the printer away from the periphery of the protective cap 11, and the valve function cam 2 is provided.
1 may also be placed in that position. The pump of the negative pressure portion 13 is not limited to the tube pump.

[0025]

According to the structure of claim 1, the valve mechanism for crushing and releasing the pressure release tube by the valve function cam serves as a valve mechanism for communicating the inside of the protective cap with the atmospheric pressure at a timing. The valve mechanism for releasing the pressure has a very simple structure. In addition, the communication with the atmospheric pressure and the interruption are surely performed. As a result, the maintenance device of the printer can be made compact, and the cost can be reduced.

Since the valve function cam is rotated by a drive source separate from the drive source for driving the print head, the drive of the valve function cam can be set up prior to the movement of the print head. There is less time lag in operation.

Since the valve function cam is stopped in a state in which the tube is crushed at a position which becomes a dead point in the reaction from the tube side, it is self-locked and does not move.
Therefore, even if the drive source is switched to the negative pressure side during this period, no particular trouble occurs on the valve mechanism side.

According to the second aspect of the invention, the spare space inside the printer can be effectively used, and the maintenance device and the mechanism around it can be simplified, and the mechanical structure of the entire printer is rational and efficient. Can be one.

According to the third aspect of the invention, since the drive mechanism of the negative pressure portion and the drive mechanism of the valve function cam are used by switching one drive source, the number of drive sources in the printer can be suppressed. It is possible to reduce the cost, and when the negative pressure portion is driven, the valve function cam is prevented from swaying by setting the dead position of the tube in a collapsed state. No special stopper is required, and it can be made compact.

[Brief description of drawings]

FIG. 1 is a plan view showing a part of a printer.

FIG. 2 is a perspective view showing a drive mechanism.

FIG. 3 is a perspective view showing an outline of a mechanism regarding a protective cap.

FIG. 4 is a side view for explaining the operation of the first cam.

FIG. 5 is a side view for explaining the operation of the valve function cam.

[Explanation of symbols]

 1 Print Head 2 Maintenance Device 3 Frame 4 Carriage Shaft 5 Guide Plate 6 Timing Belt 7 Head Reciprocating Motor 8 Nozzle Row 9 Controller 10 Maintenance Base 11 Protective Cap 11a Cover 12 Wiper 13 Negative Pressure Part 14 Valve Mechanism 15 Suction Tube 16 Pressure release tube 17 Pump 18 Switching gear 19 Idle gear 20 Roller 21 Valve function cam 22 Idle gear 23 Cam gear 24 Cam drive shaft 25 First cam 25a Face facing portion 26 Second cam 26a Face facing portion 27 (a, b) Cam follower 28 Spring 29 motor

Claims (3)

[Claims] 1. A suction tube and a pressure release tube are attached to the protective cap so as to communicate with the inner space thereof,
The end of the suction tube is connected to the negative pressure part, the end of the pressure release tube is opened to the atmosphere, and the tube is crushed in the middle part of the pressure release tube to cut off the tube communication and restore the shape of the tube. A valve function cam for recovery is arranged, and this cam is rotated at a timing by a drive source that is separate from the drive source that drives the print head, and crushes the tube at a position that is a dead point for reaction from the tube side. Inkjet printer characterized by being stopped in a closed state. 2. The ink jet printer according to claim 1, wherein the valve function cam is arranged at a spare space position inside the printer away from the periphery of the protective cap. 3. The drive mechanism for the negative pressure portion and the drive mechanism for the valve function cam have one drive source that is switched and used, and when the negative pressure portion is driven, the valve function cam causes a dead tube collapsed state. Claim 1 or claim 2 characterized in that it is at a point position
The inkjet printer described in 1.