JP4763873B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet image forming apparatus, and more particularly to a type of image forming apparatus that performs printing on a recording material (paper, cloth, etc.) wound around a rotating drum while fixing a print head and rotating the rotating drum. About.
[0002]
[Prior art]
Inkjet image forming apparatuses include a type that performs printing by moving a print head, and a recording material that is wound around a rotary drum while the print head is fixed and the rotary drum is rotated as described above. There are some types that print. In the latter image forming apparatus, since the axial direction of the rotary drum is the main scanning direction, a print head having a length equal to or larger than the print width (axial length) of the recording material wound around the rotary drum (wide width). Print head).
[0003]
[Problems to be solved by the invention]
As described above, in a type of image forming apparatus that performs printing on a recording material wound around a rotary drum while fixing the print head and rotating the rotary drum, a wide print head is required. The print head becomes large.
[0004]
Also, the resolution of printing is determined by the nozzle arrangement (pitch), and it is necessary to manufacture a print head according to the resolution. Finer nozzle arrangements require positional accuracy and are difficult to manufacture. When the head is enlarged, there is a problem that the cost is further increased.
[0005]
The present invention presupposes a type in which printing is performed on a recording material wound around a rotary drum while fixing the print head and rotating the rotary drum, and can be printed at high speed without increasing the size of the print head. An object is to provide an image forming apparatus.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 is an inkjet image forming apparatus in which a plurality of print heads are fixed and printing is performed on a recording material that is wound around a rotating drum and moves. In the printing head, during the printing operation, each nozzle is arranged in the axial direction of the rotating drum and corresponding to the printing width in the printing width direction of the recording material, and the movement of the recording material with each other The holding body is held by the holding body so as to be displaced in the direction, and is movable in the nozzle arrangement direction of the print head together with the plurality of print heads at a time other than the printing operation. Oh it is, and wherein the retracting said print head by said moving to a position away from the rotary drum.
[0008]
The invention of claim 2, wherein, in the image forming apparatus according to claim 1, wherein the plurality of print head is characterized by being arranged helically around the rotary drum.
Since the print head is spirally arranged around the rotating drum and printing is performed while rotating the rotating drum, wide printing is efficiently performed by a non-wide print head.
[0009]
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect , the holding body is formed in a cylindrical shape, and the plurality of print heads are fixed to an inner peripheral portion thereof. To do.
Since the print head is attached to the inner periphery of the holding body movable in the axial direction of the rotary drum, when the recording material is wound around the rotary drum, the print head is located away from the rotary drum (for example, above) The recording material can be quickly attached.
[0010]
In the image forming apparatus according to the first aspect, the rotation of the rotary drum and the printing by the print head may be synchronized.
At this time, it is preferable that the signal of the rotary encoder provided on the rotary drum is input to the print head control unit via the synchronization detection unit.
Since the rotation of the rotating drum and the printing by the print head are synchronized, high-definition printing is performed without being affected by the rotation unevenness of the rotating drum.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention, and FIG. 2 is a front view of a print head.
The ink jet type image forming apparatus shown in FIG. 1 performs printing on a recording material 3 wound around a rotary drum 2 by a print head 1. The recording material 3 is usually coated paper, but may be a cloth if dedicated ink is used. The rotating drum 2 is rotated by an AC motor 4. A rotary encoder 5 is attached to the shaft of the rotary drum 2.
[0015]
The print head 1 of the present invention is characterized in that a large number of spirals are arranged around the rotary drum 2. Specifically, the print head 1 is helically fixed to the inner peripheral portion of the cylindrical holder 6. The curve indicated by the symbol A schematically shows how the print head 1 is arranged in a spiral. The size of the rotary drum 2 varies depending on the size of the print size, but in the present invention, one having a wide width is suitable.
[0016]
The holding body 6 is movable in the axial direction of the rotary drum 2, that is, in the vertical direction in the figure. Accordingly, the print head 1 fixed to the inner peripheral portion of the holding body 6 can also move in the axial direction of the rotary drum 2.
[0017]
A rotary encoder 5 attached to the shaft of the rotary drum 2 is connected to the synchronization detection unit 7. The synchronization detection unit 7 is connected to the print head control unit 8. Therefore, the rotation speed of the rotary drum 2 is detected by the rotary encoder 5, the signal is taken into the print head control unit 8 via the synchronization detection unit 7, and the rotation of the rotary drum 2 and the print head 1 are controlled by controlling the print timing. Since the printing can be synchronized with each other, high-definition printing can always be performed even if the rotating drum 2 has uneven rotation.
[0018]
As shown in FIG. 2, the print head 1 is provided with nozzle holes 11 arranged at a reference resolution. The image forming apparatus of the present embodiment is assumed to be monochrome, but it is of course possible to provide a color image forming apparatus by providing Y, M, C, and K print heads.
[0019]
Prior to the printing operation, first, the print head 1 is retracted from the rotary drum 2 by moving the holding body 6 upward in FIG. In this state, the recording material 3 is wound around the rotary drum 2. Thereafter, the holding body 6 is lowered, and the print head 1 is moved to a predetermined position of the rotary drum 2.
[0020]
Then, printing is performed on the recording material 3 on the rotating rotary drum 2 by the print head 1. Here, since the print head 1 is arranged in a spiral shape, printing is sequentially performed in the main scanning direction of the recording material 3 by the rotation of the rotary drum 2. That is, printing can be performed on the recording material 3 by using the print head 1 that is much shorter than the width (length in the axial direction) of the recording material 3, that is, not wide.
[0021]
As described above, the rotational speed of the rotary drum 2 is detected by the rotary encoder 5, and the signal is input to the print head control unit 8 via the synchronization detection unit 7. The rotation is synchronized, and accurate printing is performed.
[0022]
【The invention's effect】
According to the present invention, for a plurality of print heads, during the printing operation, the respective nozzles are arranged corresponding to the print width in the print width direction of the recording material, and are displaced from each other in the moving direction of the recording material. Since they are arranged in a state, wide printing can be efficiently performed by a non-wide print head, and the apparatus can be downsized and the print head manufacturing cost can be reduced.
Further, since the holding body that holds the plurality of print heads can move in the nozzle arrangement direction of the print head together with the plurality of print heads during a time other than the printing operation, the print head can be moved from the print area of the recording material. It can be retreated to a distant position, and the recording material can be quickly attached.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention.
FIG. 2 is a front view of a print head.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Print head 2 Rotating drum 3 Recording material 4 AC motor 5 Rotary encoder 6 Holder 7 Synchronization detection unit 8 Print head control unit 11 Nozzle hole

Claims (3)

In an inkjet image forming apparatus that fixes a plurality of print heads and performs printing on a recording material that is wound around a rotating drum and moves,
The plurality of print heads are arranged so that the nozzles of the plurality of print heads are arranged in correspondence with the print width in the print width direction of the recording material in the axial direction of the rotary drum, and Is held by the holding body so as to be displaced in the moving direction of
The holding member, when the non-printing operation retracted, until with the plurality of print heads, Ri movable der in the nozzle arrangement direction of the indicia shaped heads, at a position away from the rotary drum to the print head by the movement image forming apparatus characterized by causing. 2. The image forming apparatus according to claim 1 , wherein the plurality of print heads are spirally arranged around the rotary drum. The image forming apparatus according to claim 2 , wherein the holding body is formed in a cylindrical shape, and the plurality of print heads are fixed to an inner peripheral portion thereof.

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