JP3023417B2 - Inkjet printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to an ink jet printer, and more particularly to a device for preventing clogging of a head nozzle.

(Prior Art) An inkjet printer is provided with a device for preventing or recovering from clogging of a head nozzle. Here, an example of this type of conventional apparatus will be described with reference to FIG.

Reference numeral 1 denotes a suction pump. The pump 1 has a piston 3 slidably fitted in a cylinder 2, and a negative pressure and a positive pressure are applied to a suction chamber 2A on the right side of the piston 3 in the cylinder 2 in the drawing. Pressure. An inflow port 4 and an outflow port 5 are formed on the right end face of the cylinder 2 in the drawing so as to face the suction chamber 2A. The inflow port 4 communicates with the cap member 7 that covers the head nozzle via the first tube 6. On the other hand, the outlet 5 communicates with the outside of the pump 1 via the second tube 8. In addition, inflow port 4
Inside, a first check valve (one-way valve) 9 that allows fluid to pass only in the direction from the cap member 4 to the inside of the pump 1 is provided. On the other hand, the outlet 5 is provided with a second check valve 10 that allows fluid to pass only from the inside of the pump 1 to the outside.

A motor gear 11 is fixed to an output shaft of a motor (not shown) as a drive source.
An eccentric cam 13 whose center is integral with a gear 12 that meshes with the gear 12 is provided. One end of a crankshaft 14 is rotatably mounted at a position offset from the center of the cam 13, and the other end of the crankshaft 14 is rotatably mounted on the piston 3. . Therefore, while the cam 13 makes one rotation, the piston 3 makes one reciprocation between the position shown by c and the position shown by b.

Then, the rotation of the motor causes the motor gear 11 to rotate in one direction and the eccentric cam 13 to rotate. Accordingly, the piston 3 is driven to reciprocate via the crankshaft 14. The piston 3 first moves to the left from the position indicated by c, and the suction chamber 2A in the pump 1 is in a negative pressure state, and the inside of the cap member 7 fitted to the head nozzle surface is also in a negative pressure state. Become. As a result, ink and bubbles in the head nozzle are sucked out, sucked into the suction chamber 2A via the first tube 6 and the first check valve 9, and are temporarily stored therein. The motor is continuously rotating, so that the piston 3 starts moving rightward in the drawing after moving to the position indicated by b. As a result, the pressure in the suction chamber 2A increases, and the ink accumulated in the suction chamber 2A is discharged to the outside through the second tube 8.

Such a series of operations is performed for one cycle or two to three cycles to prevent and recover clogging of the head nozzle.

(Problem to be Solved by the Invention) In the conventional device, the piston 3 is reciprocally driven by continuously rotating the eccentric cam 13 in one direction. Is fixed in advance. At the same time, since the volume at the initial position in the pump 1, the tube 6, and the cap member 7 communicating with the pump 1 is also constant, the maximum negative pressure applied to the head nozzle surface during the clogging prevention and recovery operation is constant. .

Incidentally, clogging prevention and recovery operations include (1) automatic operation when a head is replaced with a new head,
(2) An operation automatically performed to prevent clogging even if clogging does not actually occur after printing several sheets, and (3) user's operation when clogging occurs. There is a recovery operation performed in response to a manual operation (for example, an operation of pressing a button). The operations (1) and (2) are both supported by software on a computer that controls the inkjet printer.

The case (3) originally requires the highest negative pressure,
In the conventional device, in the cases of (1) and (2), (3)
As in the above case, clogging is prevented and the recovery operation is performed at the maximum negative pressure, and there is a problem that excess ink that does not need to be sucked is absorbed and removed in order to prevent clogging.

The present invention is intended to solve such a problem, and it is possible to variably set the ink suction force in response to clogging prevention and recovery operations in various cases, respectively. An object of the present invention is to provide an ink jet printer having a clogging prevention device capable of absorbing an appropriate amount of ink in some cases and reducing waste of ink.

[Configuration of the invention]

(Means for Solving the Problems) In order to achieve the above object of the apparatus for preventing clogging of a head nozzle, an ink jet printer of the present invention has a piston shaft that reciprocates and has a pressure corresponding to the position of the piston shaft. Inside the pump, a first fluid passage communicating the head nozzle with the inside of the pump, and passage of fluid only in a direction from the head nozzle to the inside of the pump provided in the first fluid passage. A first check valve, a second fluid passage connecting the inside of the pump to the outside, and a fluid provided only in the direction from the inside of the pump to the outside provided in the second fluid passage. A second check valve that allows the passage of a stepper motor, a stepping motor, a cam driven by the stepping motor through normal and reverse rotation through a reduction gear train, and a support base. A pump lever having one end rotatably supported and the other end connected to a piston shaft of the pump; and a cam and a pump lever respectively provided on the cam and the pump lever and slidably engaged with each other to correspond to the rotation angle of the cam. A first cam portion and a cam receiving portion for rotating the pump lever by an angle and a second cam portion provided on the cam actuate the cam to rotate in a direction to increase the pressure in the pump. And a switch for stopping the stepping motor.

(Operation) In the ink jet printer of the present invention, when preventing or recovering from clogging of the head nozzle, first, a cam is driven by a stepping motor via a reduction gear train, and this cam rotates in one direction (forward direction). . And
A pump lever interlocks with the cam via a first cam portion and a cam receiving portion slidably engaged with each other, and the pump lever rotates by an angle corresponding to the rotation angle of the cam. Accompanying this, the piston shaft of the pump connected to the pump lever moves in one direction, and the pressure in the pump decreases. This allows the ink to flow from the head nozzle to the first
Is drawn into the pump through the fluid passage. At this time,
The second check valve prevents air from flowing into the pump from the outside via the second fluid passage. Next,
The cam is driven by the stepping motor, the cam rotates in the opposite direction, and the pump lever rotates in the opposite direction. Along with that, the piston axis moves in the opposite direction,
The pressure inside the pump increases. Thereby, the ink is discharged from the inside of the pump to the outside of the pump via the second fluid passage.
At this time, the first check valve prevents ink or air from flowing backward from the inside of the pump to the head nozzle via the first fluid passage. As the cam rotates in the direction in which the pressure in the pump increases, the switch is operated by the second cam receiving portion of the cam, and the stepping motor stops.

Then, by changing the number of steps of the stepping motor when the cam rotates in the forward direction, the rotation angle of the cam changes and the rotation angle of the pump lever also changes. The amount of movement has changed,
The pressure generated in the pump also changes according to the position of the piston shaft, and the force for sucking ink changes.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2 showing a configuration of a head nozzle clogging prevention device of an ink jet printer. In the following description, the vertical direction in FIG. 2 will be referred to as the vertical direction.

Reference numeral 21 denotes a first support base, and reference numeral 22 denotes a second support base disposed below and parallel to the first support base 21.

Then, on the lower right side of the first support base 21 in the figure,
A suction pump 23 is attached. The pump 23 comprises a pump body 2 and a bellows 26 which can be extended and contracted and whose one end is fixed to the pump body 24 by a fixture 25. One end of the bellows 26 on the side of the main body 24 is open, and a piston shaft 27 protrudes from the closed other end. Then, the piston shaft 27 reciprocates linearly and the bellows 26
Expands and contracts, so that a pressure corresponding to the position of the piston shaft 27 is generated inside the pump 24, that is, inside the bellows 26.

The pump body 24 has an inlet 28 and an outlet 29 arranged side by side. One end of a flexible tube 30 is connected to the inflow port 28 from the outside, and the other end of the tube 30 is connected to a cap member 31 that covers a head nozzle (not shown). Thus, the inside of the inflow port 28 and the tube 30 form the first fluid passage 32 that connects the head nozzle to the inside of the pump 23. On the other hand, from the outlet 29
33 is formed so as to protrude, and the inside of the outlet 29 and the inside of the tube 33 are connected to the second to connect the inside of the pump 23 to the outside.
Fluid passage 34 is formed. Further, a first check valve 35 is mounted in the inflow port 28, and a second check valve 36 is mounted in the outflow port 29 by a fixture 37. The first check valve 36 allows fluid to pass in the direction from the head nozzle to the inside of the pump 23, and does not allow passage in the direction from the inside of the pump 23 to the head nozzle. on the other hand,
The second check valve 36 allows the fluid to pass in the direction from the inside to the outside of the pump 23 and does not allow the fluid to pass in the direction from the outside to the inside of the pump 23.

A vertical support shaft 41 is provided on the left side of the second support base 22 in the figure.
Thus, the idler gear 42 is supported rotatably forward and backward. The idler gear 42 meshes with a reduction gear train (not shown) that meshes with a gear attached to an output shaft of a stepping motor (not shown) serving as a drive source of the suction pump 23, and transmits power transmitted from the stepping motor. It is for communication.

A cam shaft 43 is vertically supported between the support bases 21 and 22 between the idler gear 42 and the piston shaft 27. That is, both ends of the cam shaft 43 are
Fixed to 1,22 respectively. A cam 44 is mounted on the cam shaft 43 so as to be freely rotatable in the forward and reverse directions. A gear portion integrally formed below the cam 44 with the cam shaft 43 as a central axis.
The idler gear 42 meshes with 45. As a result, the cam 44 receives the power from the stepping motor and is driven to rotate forward and backward.

Further, the first gear is located above the idler gear 42,
A pin 46 is vertically fixed below the support 21. A bearing 48 formed at one end of the pump lever 47 is rotatably fitted into the pin 46. Thus,
The pump lever 47 is supported so as to be capable of rotating around the center axis of the pin 46 and along the lower surface of the first support 21. A connecting shaft 49 hanging down from the other end of the pump lever 47 is rotatably penetrated by the piston shaft 27. Accordingly, the piston shaft 27 operates in conjunction with the rotation of the pump lever 47, and at this time, the pump lever
The larger the rotation angle of 47, the larger the amount of movement of the piston shaft 27. The cam shaft 43 is
In order not to hinder the rotation of the pump lever 47, the pump lever 47 passes through an arc-shaped long hole 50 formed at the center of the pump lever 47 and centered on the center of rotation.

The pump lever 47 has a bearing 48 and a connecting shaft 49.
A support shaft 51 is formed hanging from an intermediate position between the support shaft 51 and a lever roller 52 serving as a cam receiving portion. On the other hand, a groove cam 53 as a first cam is formed on the upper surface of the cam 44.
The groove cam portion 53 is spirally formed with respect to the cam shaft 43, and has a shape gradually separated from the cam shaft 43 in the counterclockwise direction in FIG. An arc-shaped groove 54 centered on the cam shaft 43 is formed so as to be connected to an end of the groove cam 53 near the cam shaft 43. The lever roller 52 enters the groove cam portion 53 and is slidably engaged therewith. Thus, the cam 44 and the pump lever 48
And the rotation angle of the pump lever 47 increases as the rotation angle of the cam 44 increases.

Further, below the first support 21, the cam 44
A switch 61 for detecting the position in the rotating direction of the switch 61 is mounted. In this switch 61, a rotatable switch lever 62 slides along a cam surface 63 as a second cam portion formed on the outer peripheral surface of the cam 44, and is operated by the cam surface 63. Things. More specifically, the cam surface 63 has a different distance from the cam shaft 43 via the step portion 64 on one side and the other side of the cam 44, and is more displaced from the cam shaft 43 on the cam surface 63. Switch lever 62 in remote position
When there is a switch 61, the switch 61 is turned on, and when the switch lever 62 is located closer to the cam shaft 43 on the cam surface 63, the switch 61 is turned off. And step 64
Is located at a position where the switch lever 62 contacts when the lever roller 52 is located at the end of the groove cam portion 53 on the cam shaft 43 side. Further, the switch 61 is connected to a control circuit of the stepping motor by a lead wire 65, and when the switch 61 is turned off, the stepping motor stops.

 Next, the operation of the above embodiment will be described.

When preventing or recovering from clogging of the head nozzle, first, the cap member 31 is actuated by driving means (not shown) to cover the head nozzle.

Next, the stepping motor rotates forward by a predetermined number of steps, and the rotational power of the stepping motor is transmitted to the cam 44 via the reduction gear train and the idler gear 42, and the cam 44 rotates in the forward direction (44F direction in the drawing). I do. With the rotation of the cam 44, the pump lever is set in the groove cam portion 53 of the cam 44.
When the 47 lever roller 52 rotates and slides relatively away from the camshaft 43, the pump lever 47 rotates in the forward direction (47F direction in the drawing) around the pin 46. Pulled by this pump lever 47, the pump 23
Moves in the illustrated 27F direction. As a result, the bellows 26 expands and the volume in the pump 23 increases, and at the same time, the pressure in the pump 23 decreases. Thus pump 23
Due to the negative pressure generated inside, ink is sucked from the head nozzle together with air into the pump 23 through the cap member 31, the tube 30, and the opened first check valve 35. At this time,
The closed second check valve 36 prevents air from flowing into the pump 23 from outside via the tube 33. This also enables suction of ink from the head nozzle.

Thereafter, the stepping motor rotates in the reverse direction, and the cam 44 is driven by the stepping motor, and the cam 44 rotates in the opposite direction (the 44R direction in the drawing). Therefore, the pump lever 47 also rotates in the opposite direction (the 47R direction shown), and the piston shaft 27 of the pump 23 also moves in the opposite direction (the 27R direction shown). Accordingly, the bellows 26 shrinks, the volume in the pump 23 decreases, and the pressure in the pump 23 increases. as a result,
The ink and the air temporarily stored in the pump 23 are discharged to the outside of the pump 23 through the opened second check valve 36 and the tube 33. At this time, the closed first check valve 35 prevents backflow of ink and air from inside the pump 23 toward the cap member 31.

Further, the cam 44 rotates in the direction of 44R, and the lever roller 5
When 2 reaches the end of the grooved cam portion 53 on the cam shaft 43 side, that is, when the bellows 26 is maximally contracted, the switch lever 62 reaches the step portion 64 on the cam surface 63 of the cam 44 and the cam shaft 43 And the switch 61 is turned off. At the same time,
The stepping motor stops. During driving of the stepping motor, the switch lever 62 is in a state of being turned in the opposite direction, and the switch 61 is on.

At the time of preventing such head nozzle clogging and recovery operation, if the number of steps of the stepping motor when the cam 44 rotates in the 44F direction is changed, the rotation angle of the cam 44 changes, and the pump lever 47 The rotation angle also changes, but if this rotation angle changes, the piston shaft 27 of the pump 23
The amount of movement of the bellows 26 (the length of expansion and contraction of the bellows 26) also changes, the pressure generated in the pump 23 changes in accordance with the position of the piston shaft 27, and ink is sucked to change the force. That is, as the number of steps of the stepping motor increases, the rotation angle of the cam 44 and the pump lever 47 increases, and the amount of movement of the piston shaft 27 increases, so that a larger negative pressure is generated inside the pump 23, More ink will be drawn into the pump 23.

In the prevention and recovery of head nozzle clogging,
Compared to the case where (1) the head is replaced or (2) the clogging does not occur after printing several sheets, but is performed to prevent the clogging beforehand,
(3) When clogging actually occurs, a particularly large negative pressure is required when the clogging is performed in response to a manual operation by a user. Therefore, in this case, by increasing the number of steps of the stepping motor, a larger negative pressure is generated in the pump 23 as described above, and ink is sufficiently sucked. On the other hand, in the cases (1) and (2), the amount of movement of the piston shaft 27 is reduced by reducing the number of steps of the stepping motor, and the suction force of the pump 23 is reduced.

Note that such divided control can be handled by software on a computer that controls the stepping motor.

In this way, it is possible to variably set the ink suction force corresponding to the clogging prevention and recovery operations in various cases, and thus it is possible to suction an appropriate amount of ink in each case. In addition, ink is not removed by suction, and waste of ink is reduced.

In the above-described embodiment, the stepping motor only performs one reciprocation in the forward and reverse rotations during one clogging prevention and rotation operation. However, the present invention is not limited to this. For example, 1
Prevents clogging, performs two reciprocations of forward and reverse rotation during recovery operation, or pumps one reciprocation and two reciprocations
Subtle settings such as changing the negative pressure generated in 23 are also possible.

〔The invention's effect〕

According to the present invention, in a device for preventing clogging of a head nozzle of an ink jet printer, a negative pressure generated in a pump can be variably set only by changing the number of steps of a stepping motor which is a driving source of a pump for sucking ink. Therefore, since the ink suction force can be changed, an appropriate amount of ink can be suctioned in each case corresponding to the clogging prevention and recovery operations in various cases, and extra ink is used in each case. Can be prevented from being removed by suction, and waste of ink can be reduced.

[Brief description of the drawings]

FIG. 1 is a horizontal sectional view of an apparatus for preventing clogging of a head nozzle showing an embodiment of an ink jet printer of the present invention, FIG. 2 is a vertical sectional view of the same, FIG. 3 is clogging of a head nozzle of a conventional ink jet printer. It is sectional drawing which shows an example of a prevention device. 21 ... Support, 23 ... Pump, 27 ... Piston shaft, 32 ...
... first fluid passage, 34 ... second fluid passage, 35 ... first
Check valve, 36 ... second check valve, 44 ... cam, 47 ... pump lever, 52 ... lever roller as cam receiving portion,
53... A groove cam portion as a first cam portion, 62... A switch, 63... A cam surface as a second cam portion.

Claims (1)

(57) [Claims] A pump having a reciprocating piston shaft for generating a pressure corresponding to the position of the piston shaft therein; a first fluid passage for communicating a head nozzle with the inside of the pump; A first check valve that is provided in the fluid passage of the head and allows passage of fluid only in a direction from the head nozzle to the inside of the pump; and a second fluid passage that communicates the inside of the pump to the outside. A second check valve provided in the second fluid passage and allowing passage of the fluid only in a direction from the inside to the outside of the pump; a stepping motor; and the stepping motor through a reduction gear train. A cam driven in forward and reverse rotation; a pump lever having one end rotatably supported by a support base and the other end connected to the piston shaft of the pump; A first cam portion and a cam receiving portion that are slidably engaged with each other and rotate the pump lever by an angle corresponding to the rotation angle of the cam; and a second cam portion provided on the cam. And a switch for stopping the stepping motor as the cam rotates in a direction to increase the pressure in the pump.