An ink jet head capping device

Abstract: An ink jet head capping device has a member (8) arranged so that, when an ink jet head (1) is covered by a cap (2), it is located in a position to avoid interference with the cap. The member (8) is operable in response to a release operation of the cap to pass between the ink jet head and the cap. A cleaning mechanism (10) is provided on the member (8) and has a shape effective to wipe ink from at least a part of the ink jet head (1).

Description: This invention relates to an ink jet head for use in an ink jet printing apparatus. In a conventional ink jet capping device, as shown in Figure 5, a cleaning belt 15 having a scraping function is arranged in parallel to a cap 14 and is rotated by a driving belt 19. An arm 16 supports the cleaning belt 15 and the cap 14, and is integral with or connected to a support shaft 20 to undergo pivotal movement to move between a capped position and a released position with respect to an ink jet head (not shown) disposed above the cap 14. Further, in a colour ink jet printing apparatus, a plurality of heads, one for each of four colour tones (yellow, magenta, cyan and black) are aligned so that three additional caps are disposed adjacent the cap 14 in parallel with the support shaft 20. Therefore, the dimensions of the ink jet head capping device is enlarged in the axial direction of the support shaft 20 in the case of a colour ink jet printing apparatus. In this case, so as to save space, a single cleaning belt is commonly used sequentially to effect cleaning of the four colour inks rather than providing an additional three cleaning belts. In the above noted construction, additional space is needed in the axial direction of the support shaft 20. The ink jet head capping device must be disposed within the ink jet head printing apparatus but outside a printing region, thereby causing the drawback that the overall dimension of the printing apparatus is enlarged especially in the widthwise direction of a sheet of printing paper. This drawback is significant in view of the recent demand for reduction in size of printing apparatus. Further, in the case of colour ink jet printing apparatus, a single cleaning belt 15 is commonly used to effect sequential cleaning of respective colour inks, since four cleaning belts could not be provided for the four colour inks for the above same reason. Therefore, previously, cleaning ink of one colour tone may be deposited on a head of the next colour tone to be cleaned thereby causing mixture of the inks and serious degradation of image quality. In DE-A-3,528,926 there is disclosed an ink jet head which is provided with a capping device comprising a first movable member which carries a cap, the first movable member being movable into and out of an operative position in which the ink jet head is covered by the cap; and a cleaning mechanism having a shape effective to wipe ink from at least a part of the ink jet head, the cleaning mechanism being movable into and out of an operative position in which it effects such wiping. A similar disclosure is made in US-A-4,371,881. According to the present invention there is provided an ink jet head which is provided with a capping device comprising a first movable member which carries a cap, the first movable member being movable into and out of an operative position in which the ink jet head is covered by the cap; and a cleaning mechanism having a shape effective to wipe ink from at least a part of the ink jet head, the cleaning mechanism being movable into and out of an operative position in which it effects such wiping characterised in that the cleaning mechanism is carried by a second movable member which is separate from the first movable member, there being a movement effecting means for moving each movable member into its operative position at a time when the other member is out of its operative position, the arrangement being such that when the movement effecting means are operated and thereby the cap is out of its operative position, the cleaning mechanism is caused to pass between the ink jet head and the cap, and when the cap moves out of its operative position, the cleaning mechanism is located in a position to avoid interference with the cap. The movement effecting means may comprise a cam mechanism. Each of the movable members is preferably a pivotally mounted member. The ink jet head in one embodiment, includes means for maintaining the distance between the cleaning mechanism and the ink jet head when the former is moved into its operative position. The cleaning mechanism may be carried by a resilient portion of the second movable member to urge the cleaning mechanism towards the ink jet head. The cleaning mechanism may comprise a plurality of wiper blades. The invention is illustrated, merely by way of example, in the accompanying drawings, in which:- Figure 1 is a side view of one embodiment of an ink jet head according to the present invention; Figure 2 is a perspective view of the ink jet head of Figure 1; Figure 3 is a view showing a cap releasing position of the ink jet head of Figure 1; Figure 4 is a view showing a cleaning operation of the ink jet head; and Figure 5 is a schematic view of a prior art ink jet head. Figures 1 and 2 illustrate an ink jet head according to the present invention having a capping device comprising a wiper member 10 with three rows of four transverse protruding blades effective to scrape ink jet nozzles 1a and ink jet faces 1b (Figure 2) of ink jet heads 1 for four different colour tones. For each ink jet head there are a plurality (three shown) of blades arranged in succession effective to improve scraping or wiping performance. The wiper member 10 is supported by a cleaning arm 8 which is mounted for rotation about a cleaning arm support shaft 11. The cleaning arm 8 is biased by a spring 13 in the direction of a rest position when the ink jet heads are capped. The cleaning arm 8 has a branch supporting a roller 7 which is in contact with a drive cam 6b such that the cleaning arm 8 undergoes pivotal movement upon rotation of the drive cam 6b so that the cleaning arm 8, and thus the wiper member 10, can be moved into and out of an operative position. A drive cam 6a is co-axially supported with the drive cam 6b in contact with a roller 5 which is attached to a branch of a cap arm 3. The cap arm 3 is mounted for rotation about an arm support shaft 4 so that the cap arm 3 can undergo pivotal movement around the shaft 4 upon rotation of the drive cam 6a. As shown in Figure 2, the drive cams 6a, 6b are off-set from each other in the thickness or axial direction thereof to enable concurrent operation. The cap arm 3 supports four caps 2 such that each cap 2 can cover and seal a corresponding ink jet nozzle 1a in a capped position. The cap arm 3 is biased in a capping direction as shown in Figure 1 by a spring 12 shown in Figure 2. The cap arm 3 is pivoted by the rotation of the drive cam 6a to effect closing and opening of the caps so that the cap arm 3 is movable into and out of an operative position in which the ink jet heads 1 are covered by the caps 2. Next, the operation of the ink jet head capping device will be described. As shown in Figure 1, in the operative or capped position, the wiper member 10 is in a rest position between the arm support shaft 4 and the caps 2 so as to avoid interference with the caps 2. When moving the caps to a released position, the drive cams 6a, 6b start to rotate in a clockwise direction such that firstly, the cap arm roller 5 moves along a cam face of the drive cam 6a to start pivoting the cap arm 3 in the clockwise direction about the arm support shaft 4 to shift to a cap releasing position. Then, the caps 2 move to a position where they do not interfere with travel of the wiper member 10 positioned at the top of the cleaning arm which can be pivoted around the cleaning arm support shaft 11. Concurrently, the drive cam 6b is rotated to act on the cleaning arm roller 7 to start pivoting of the cleaning arm 8 in the clockwise direction. The pivoting of the cleaning arm 8, causes the wiper member 10 to move between ink jet heads 1 and the caps 2 to effect and complete cleaning of the ink jet nozzles 1a and the ink jet faces 1b. This sequence is shown in Figure 3. Further, as shown in Figure 4,a roller 9 is attached to the top end of the cleaning arm 8. When the wiper member 10 is displaced between the ink jet heads 1 and the caps 2 during the pivotal movement of the cleaning arm 8, the roller 9 comes into sliding contact with one of the ink jet faces 1b to maintain the height of the wiper member 10 relative to the ink jet faces 1b when the wiper member 10 is moved into its operative position. Further, as shown in Figure 4, the cleaning arm 8 has a U-shaped resilient portion just under the wiper member 10, this portion easily bending thereby to facilitate height adjustment of the wiper member 10. In this embodiment, the wiper member 10 is composed of rubber material; however it can be composed advantageously of brush hair of a finely slit blade in brush form. The ink jet head capping device described in relation to Figures 1 to 4 avoids the increase in size referred to in connection with Figure 5 and so prevents increase in size of the ink jet printing apparatus as a whole. Further, in the case of colour ink jet printing apparatus, a plurality of wiper blades can be provided for four different colour tones of ink thereby to avoid mixing of the different inks which is caused in the prior art ink jet head capping device where a single cleaning belt is commonly applied to four different ink jet heads. Thus high quality printing is maintained. In order to solve the problems of the conventional ink jet head capping device where a cleaning belt is arranged in parallel and adjacent to the cap, the ink jet head capping device shown in Figure 2 is such that a wiper member 10 is disposed in the widthwise direction in parallel to a row of caps 2 which can come into contact with respective ink jet heads 1 as shown in Figure 1. In the capped position where extra or leaked ink is absorbed or the ink jet heads are non-operative, the wiper member 10 held at one end of the cleaning arm 8 is in a rest position to avoid interference with the caps 2 and the cap arm 3 which supports the caps 2. On the other hand, in the cap releasing position as shown in Figure 3, the caps 2 and the cap arm 3 are displaced to a rest position by rotating the cap arm 3 in the clockwise direction around the arm support shaft 4. The cleaning arm 8 is operated to rotate clockwise around the cleaning arm support shaft 11 to a position between the ink jet heads 1 and the caps 2. The wiper member 10 is attached to the cleaning arm 8 and is effective to remove deposits on the ink jet heads. The wiper member 10 is displaced to avoid interference with the caps 2 and the cap arm 3, and thereafter starts cleaning of the ink jet heads. Thus, in co-operation with movement of the cap arm which carries the caps for capping ink jet heads, the cleaning arm 8, carrying the wiper member, operates to act on respective ink jet heads to remove excess ink and deposits.

Claims: An ink jet head (1) which is provided with a capping device comprising a first movable member (3) which carries a cap (2), the first movable member (3) being movable into and out of an operative position in which the ink jet head (1) is covered by the cap (2); and a cleaning mechanism (10) having a shape effective to wipe ink from at least a part of the ink jet head (1), the cleaning mechanism (10) being movable into and out of an operative position in which it effects such wiping characterised in that the cleaning mechanism (10) is carried by a second movable member (8) which is separate from the first movable member (3), there being a movement effecting means (6a,6b) for moving each movable member (3,8) into its operative position at a time when the other member is out of its operative position, the arrangement being such that when the movement effecting means (6a,6b) are operated and thereby the cap (2) is out of its operative position, the cleaning mechanism (10) is caused to pass between the ink jet head (1) and the cap (2), and when the cap (2) moves out of its operative position, the cleaning mechanism (10) is located in a position to avoid interference with the cap (2). An ink jet head as claimed in claim 1 characterised in that the movement effecting means comprises a cam mechanism (6a,6b). An ink jet head as claimed in claim 1 or 2 characterised in that each of the movable members (3,8) is a pivotally mounted member. An ink jet head as claimed in any preceding claim characterised by means (9) for maintaining the distance between the cleaning mechanism (10) and the ink jet head (1) when the former is moved into its operative position. An ink jet head as claimed in any preceding claim characterised in that the cleaning mechanism (10) is carried by a resilient portion of the second movable member (8) to urge the cleaning mechanism (10) towards the ink jet head (1). An ink jet head as claimed in any preceding claim characterised in that the cleaning mechanism (10) comprises a plurality of wiper blades.

Inventors: MIDORIKAWA MASARU C O SEIKO IN, MIDORIKAWA, MASARU, C/O SEIKO INSTRUMENTS INC.
Applicants: SEIKO INSTR INC, SEIKO INSTRUMENTS INC.
Application year: 1990
Main classification: B41J2
IPC codes: A01M23, B41J2