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EP-4737128-A1 - IMAGE FORMING APPARATUS

EP4737128A1EP 4737128 A1EP4737128 A1EP 4737128A1EP-4737128-A1

Abstract

An image forming apparatus includes a belt (24) configured to convey a sheet, a recording head (2301), a movable member (26) configured to be movable in a first direction such that the belt (24) is moved closer to and farther from the recording head (2301), a first adjusting member (29) configured to adjust a distance in the first direction between the ejection plane (S2) and the conveyance plane (S1), and a second adjusting member (28) disposed on the movable member (26). The first adjusting member (29) is configured to move such that an abutment position at which the first adjusting member (29) and the second adjusting member (28) abut against each other. The second adjusting member (28) is configured to change a position of the movable member (26) with respect to the abutment position so that the distance in the first direction is changed.

Inventors

  • Mori, Eikou

Assignees

  • Canon Kabushiki Kaisha

Dates

Publication Date
20260506
Application Date
20251027

Claims (16)

  1. An image forming apparatus comprising: a belt (24) configured to convey a sheet along a conveyance plane (S1) formed by a portion of an outer circumferential surface (24a) of the belt (24); a recording head (2301) disposed to face the belt (24), the recording head (2301) having an ejection plane (S2) at which ink is ejected from the recording head (2301) toward the sheet being conveyed by the belt (24); a movable member (26) configured to be movable in a first direction such that the belt (24) is moved closer to and farther from the recording head (2301); a first adjusting member (29) configured to adjust a distance in the first direction between the ejection plane (S2) and the conveyance plane (S1) at a position where the belt (24) faces the ejection plane (S2) by moving the movable member in the first direction; and a second adjusting member (28; 51) disposed on the movable member (26), arranged to abut against the first adjusting member (29), wherein the first adjusting member (29) is configured to move such that the first adjusting member (29) and the second adjusting member (28; 51) abut against each other at an abutment position, and wherein the second adjusting member (28; 51) is configured to adjust the distance in the first direction by changing a position of the movable member (26) in the first direction with respect to the abutment position.
  2. The image forming apparatus according to claim 1, further comprising: a fixing member (290) configured to fix the second adjusting member (28; 51) with respect to the movable member (26) such that the second adjusting member (28; 51) is immovable after the movable member (26) is assembled to the image forming apparatus, wherein the first adjusting member (29) is configured to move the movable member (26) in a state where the second adjusting member (28; 51) is fixed by the fixing member (290).
  3. The image forming apparatus according to claim 1 or 2, further comprising: a plurality of rollers (20, 21, 22, 23) around which the belt (24) are stretched; and a frame (2201) configured to support the plurality of rollers (20, 21, 22, 23), wherein the recording head (2301) is fixed to the frame (2201), and wherein the movable member (26) is disposed movably in the frame (2201).
  4. The image forming apparatus according to claim 3, wherein the frame (2201) includes an opening portion (43) into which at least a portion of the second adjusting member (28; 51) is inserted, and wherein the first adjusting member (29) is configured to contact the at least the portion of the second adjusting member (28; 51) exposed from the opening portion (43).
  5. The image forming apparatus according to any one of claims 1 to 4, wherein the movable member (26) is a sucking unit configured to cause the sheet to be sucked on the belt (24).
  6. The image forming apparatus according to any one of claims 1 to 5, wherein the first adjusting member (29) is a first cam (29) configured to rotate around a first axis and including a first outer circumferential surface (29a) formed such that a distance from the first axis to the first outer circumferential surface (29a) varies in accordance with a rotational angle around the first axis.
  7. The image forming apparatus according to claim 6, further comprising: a driving portion (M, 30, 31, 32) configured to drive and rotate the first cam (29), wherein the second adjusting member (28;51) is configured to be operated manually by a user.
  8. The image forming apparatus according to claim 7, wherein a rotation direction of the first cam (29) by the driving portion (M, 30, 31, 32) is limited to one direction.
  9. The image forming apparatus according to claim 8, wherein the driving portion (M, 30, 31, 32) includes: a driving source (M) configured to generate driving force; a driving shaft (31) configured to transmit the driving force from the driving source (M) to the first cam (29); and a one-way clutch (32) disposed on the driving shaft (31) and configured to limit the rotation direction of the first cam (29) to the one direction.
  10. The image forming apparatus according to claim 8 or 9, further comprising: a control portion (600) configured to control the driving portion (M, 30, 31, 32), wherein the control portion (600) is configured to adjust the distance by causing the driving portion (M, 30, 31, 32) to rotate the first cam (29) by an amount of rotation based on a thickness of the sheet.
  11. The image forming apparatus according to any one of claims 6 to 10, wherein the second adjusting member (28; 51) is a second cam (28) configured to rotate around a second axis and including a second outer circumferential surface (28a) formed such that a distance from the second axis to the second outer circumferential surface (28a) varies in accordance with a rotational angle around the second axis, and wherein the first outer circumferential surface (29a) and the second outer circumferential surface (28a) are configured to abut against each other at the abutment position.
  12. The image forming apparatus according to claim 11, wherein an adjustable range of the distance in a case where the second cam (28) is rotated while a rotation phase of the first cam (29) is fixed is larger than an adjustable range of the distance in a case where the first cam (29) is rotated while a rotation phase of the second cam (28) is fixed.
  13. The image forming apparatus according to claim 12, wherein at least a portion of the second outer circumferential surface (28a) has a polygonal shape that includes a plurality of sides having different distances from the second axis when viewed in a direction along the second axis.
  14. The image forming apparatus according to claim 13, wherein the second cam (28) is configured to be fixed to the movable member (26) so as not to rotate, in a state where any one of the plurality of sides is in contact with the first outer circumferential surface (29a).
  15. The image forming apparatus according to any one of claims 1 to 10, wherein the second adjusting member (28; 51) is a slide member (51) configured to slide in a direction in which the belt (24) is moved closer to and farther from the recording head (2301).
  16. The image forming apparatus according to claim 15, wherein the slide member (51) is (i) provided with a long hole (51a) elongated in a direction in which the belt (24) is moved closer to and farther from the recording head (2301), (ii) fixed to the movable member (26) by a fixing member (290) inserted in the long hole (51a), and (iii) configured such that a position of the slide member (51) with respect to the movable member (26) is changed in accordance with a position of the fixing member (290) with respect to the long hole (51a).

Description

TECHNICAL FIELD The present disclosure relates to an image forming apparatus that forms images on sheets. BACKGROUND Japanese Patent Application Publication No. 2009-285952 describes an ink-jet image forming apparatus in which a gap adjusting mechanism operates in a case where a platen that supports a conveyance belt is moved back and forth with respect to a recording head in the thickness direction of sheets, so that the gap between the recording head and the conveyance belt changes. In addition, Japanese Patent Application Publication No. 2020-157574 describes another ink-jet image forming apparatus in which a plurality of recording heads is moved individually with respect to a platen that supports a conveyance belt, so that the gap between an individual recording head and the platen is adjusted. SUMMARY The present disclosure provides a new technique related to adjustment of a gap between recording head and a belt. The present disclosure in its first aspect provides an image forming apparatus as specified in claim 1. Optional features are specified in claim 2 to 16. Features of the present disclosure will become apparent from the following description of embodiments with reference to the attached drawings. The following description of embodiments is described by way of example. In the present disclosure, since the first adjusting member and the second adjusting member are included, the distance from the ejection plane of the recording heads to the conveyance plane of the conveyance belt that conveys the sheet can be adjusted more properly. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating an image forming system that includes an image forming apparatus of the present embodiment.FIG. 2 is a schematic diagram illustrating a print belt unit.FIG. 3 is a perspective view illustrating a pressure chamber and a negative-pressure generating unit.FIG. 4 is a schematic diagram illustrating the pressure chamber and a print-belt-unit frame.FIG. 5 is a perspective view illustrating a state where a single recording head is fixed to the pressure chamber.FIG. 6 is a perspective view illustrating a print-gap adjusting mechanism.FIG. 7 is a block diagram illustrating a control system of the print-gap adjusting mechanism.FIG. 8A is a side view illustrating a manual adjusting cam that is in contact with an automatic adjusting cam at a scale mark of 5.FIG. 8B is a side view illustrating the manual adjusting cam that is in contact with the automatic adjusting cam at a scale mark of 8.FIG. 9A is a side view illustrating a state where the pressure chamber is most distant from the recording head by the automatic adjusting cam.FIG. 9B is a side view illustrating a state where the pressure chamber is moved closest to the recording head by the automatic adjusting cam.FIG. 10A is a side view illustrating another embodiment of the manual adjusting cam in a state where the pressure chamber is most distant from the recording head by the automatic adjusting cam.FIG. 10B is a side view illustrating the other embodiment of the manual adjusting cam in a state where the pressure chamber is moved closest to the recording head by the automatic adjusting cam. DESCRIPTION OF THE EMBODIMENTS Hereinafter, embodiment(s) of the present disclosure will be described with reference to the accompanying drawings. First, an image forming system that includes an image forming apparatus of the present embodiment will be described with reference to FIG. 1. An image forming system 100 illustrated in FIG. 1 is a so-called sheet-fed printing machine that forms an image on a sheet S by using ink and reaction liquid. For example, the image forming system 100 is used in the commercial/industrial printing field. The sheet S may be any sheet as long as the sheet can accept the ink. For example, the sheet S may be a paper sheet, such as a regular paper sheet or a thick paper sheet, a plastic film such as an overhead projector sheet, or a cloth sheet. As illustrated in FIG. 1, the image forming system 100 includes a feeding module 1000, a print module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, a reversing module 6000, and a stacking module 7000. The sheet S on which an image is to be formed is fed from the feeding module 1000, subjected to various processes when conveyed along the conveyance path in the above-described modules, and finally discharged to the stacking module 7000. The feeding module 1000 includes a plurality of (three in the present embodiment) cassettes 1100a, 1100b, and 1100c. Each of the cassettes 1100a to 1100c can store the sheet S. Each of the cassettes 1100a to 1100c can be drawn toward the front side of the apparatus for storing the sheet S. The feeding module 1000 conveys the sheet S, one by one, from any one of the cassettes 1100a to 1100c to the print module 2000. Thus, each of the cassettes 1100a to 1100c includes a separation belt and a conveyance roller. Note that since the above-des