JPH11240214A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation apparatus which can correctly detect a side end part of a paper even in the presence of paper dust, etc., on a platen and form good images in a breadthwise direction of the paper. SOLUTION: A paper width detection sensor 9 is set at a carriage 8 driven in a direction nearly orthogonal to a direction in which a paper 1 is transferred, and a through hole 11 as a part to be detected by the paper width detection sensor 9 is formed at a platen 2 opposite to the carriage 8. Even when paper dust of the paper 1, etc., are present on the platen 2, the paper dust, etc., slips penetrating the platen 2 through the through hole 11, and the through hole 11 is not covered with the paper dust, etc. Accordingly, the paper width detection sensor 9 is prevented from making wrong detection due to the paper dust, correctly detecting the through hole 11 at all times thereby correctly detecting a side end part of the paper 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus in which a head is mounted on a carriage driven in a direction substantially perpendicular to a direction in which a recording medium is conveyed.

[0002]

2. Description of the Related Art Conventionally, in an ink jet type image forming apparatus or the like, a platen for receiving a sheet as a recording medium in a recording section, and ink is applied to the sheet which is opposed to the platen and received on the platen. A head for ejecting and forming a predetermined image. The head is mounted on a carriage that is driven in a direction substantially perpendicular to the direction in which the sheet is conveyed, and ejects ink from selected nozzles in a direction substantially perpendicular to the direction in which the sheet is conveyed with the carriage. It is scanned so as to form a desired image on a sheet.

In such an image forming apparatus, the carriage is provided with a side end of the paper in a direction substantially perpendicular to the direction in which the paper is transported, that is, a paper width detection sensor for detecting the width of the paper. The image is formed so as to correspond to the width of the sheet to be used. This paper width detection sensor is composed of a non-contact type optical sensor having a light emitting unit that emits light toward the platen side and a light receiving unit that receives light reflected from the platen side. Is located at the side edge of the paper, that is, when it is positioned at the boundary between the paper and the platen, the reflectance of the light reflected from the surface of the paper and the light reflected from the surface of the platen is By detecting the difference, the side edge of the sheet is detected. Therefore, when the paper is white, the platen is usually painted black or a black tape is attached on the platen to minimize the reflection of light on the platen and detect light at the light receiving section. When a sheet is present, when light is no longer detected by the light receiving unit, it is detected as a side edge of the sheet.

[0004]

However, in an image forming apparatus having such a sheet width sensor, paper dust or the like generated from the sheet may adhere to the platen, and the sheet width detection sensor may Paper dust or the like adhering to the detected portion may be erroneously detected as paper. In this case, it is not possible to accurately detect the side end of the sheet, and therefore, there is a problem that an appropriate image cannot be formed in the width direction of the sheet.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and an object of the present invention is to accurately detect a side edge of a sheet even if there is paper dust on the platen. An object of the present invention is to provide an image forming apparatus capable of forming a good image in the width direction of a sheet.

[0006]

According to an aspect of the present invention, there is provided a platen for receiving a recording medium, and a predetermined image formed on the recording medium facing the platen. And a carriage mounted with the head and driven in a direction substantially perpendicular to the direction in which the recording medium is conveyed. A recording medium width detection sensor for detecting a side end in a direction substantially orthogonal to the direction in which the recording medium is conveyed, and the platen is detected by the recording medium width detection sensor. A detected part is provided,
The detected portion is formed by a gap formed to penetrate the platen.

According to such a configuration, the recording medium width detecting sensor for detecting the side end of the recording medium in a direction substantially perpendicular to the direction in which the recording medium is conveyed is provided so as to penetrate the platen. The gap formed is detected as a detected portion. Therefore, even if paper dust or the like generated by the recording medium is on the platen, the paper dust or the like falls through the platen from the gap in the detected portion and does not cover the detected portion.

[0008] The invention described in claim 2 is the first invention.
In the invention described in (1), the detected portion is formed by a through hole penetrating the platen. By forming the detected part by the through hole penetrating the platen, the detected part can be favorably formed by simple processing. According to a third aspect of the present invention, in the second aspect of the present invention, the through hole is formed such that a receiving surface side for receiving the recording medium is small, and a surface opposite to the receiving surface side is large. It is characterized by that. By forming the through hole such that the receiving surface side receiving the recording medium is small and the surface on the opposite side to the receiving surface side is large, paper powder and the like that have entered the through hole can easily fall off. it can.

[0009]

FIG. 1 is a perspective view of a main part of an ink jet type image forming apparatus showing an embodiment of the image forming apparatus of the present invention, and FIG. 2 is a sectional side view of the main part in FIG. . In FIG. 1, a platen 2 for receiving a sheet 1 as a recording medium is provided in a main body of the ink jet type image forming apparatus. In the transport direction of the paper 1 (indicated by the arrow 3), a driving roller 4 for feeding the paper 1 is disposed upstream and downstream of the platen 2 and opposed to the driving roller 4 with the paper 1 therebetween. Press rollers 5 are provided.
The drive roller 4 is rotated by a roller drive mechanism including a motor and a gear train (not shown), and sequentially moves the paper 1 sandwiched between the drive roller 4 and the pressing roller 5 in the direction of arrow 3. Such a driving roller 4, a pressing roller 5, and a roller driving mechanism constitute a sheet feeding device.

At a position facing the platen 2, a head 6 having a nozzle for discharging hot melt ink, that is, ink that is solidified at room temperature and melted into a liquid state by heating, is disposed. The head 6 is mounted on a carriage 8 together with an ink tank 7 containing hot melt ink. The carriage 8 is moved by two guide bars 14 and 15 provided in parallel with the platen 2 in a direction substantially orthogonal to the direction in which the sheet 1 is conveyed (hereinafter, referred to as the width direction of the sheet 1). The paper 1 is supported in such a manner that the paper 1 can be driven in the width direction by a carriage driving mechanism (not shown).

The head 6 is scanned in the width direction of the sheet 1 by driving the carriage 8 while ejecting the molten hot liquid ink from the selected nozzles to form a desired image on the sheet 1. To form When one scan is completed, the paper 1 is fed by the paper feeder, and the next row of the paper 1 on which the image is formed is the head 6.
Is located at an opposing position. By sequentially repeating the image forming operation, desired image information is formed on the sheet 1.

In the image forming apparatus of this embodiment, the carriage 8 has a sheet for detecting the widthwise side edge of the sheet 1 in order to detect the width of the sheet 1 to be used. A width detection sensor 9 is provided. As shown in FIG. 2, the paper width detection sensor 9
The surface of the carriage 8 facing the platen 2 is provided below the head 6 (downstream in the transport direction of the sheet 1) so as to face the platen 2.
The paper width detection sensor 9 includes a light emitting unit (not shown) that emits light toward the platen 2 side, and a light receiving unit that receives light reflected from the light emitting unit reflected on the platen 2 side. (Not shown) and a non-contact type optical sensor having:
The widthwise side edge of the sheet 1 can be detected.

On the other hand, as shown in FIG. 1, when the sheet width detecting sensor 9 is scanned in the width direction of the sheet 1 by driving the carriage 8, the sheet width detecting sensor 9 is scanned. A through-hole 11 is formed on the axis 10 facing the sheet as a detected portion of the sheet width detection sensor 9. As shown in FIG. 2, the through hole 11 penetrates the platen 2, has a diameter such that light emitted from the light emitting unit of the sheet width detection sensor 9 can pass, and has a receiving surface 12 The taper shape is such that the diameter of the side 13 is small and the diameter of the surface 13 on the side opposite to the receiving surface 12 is large. The through holes 11 are formed as a pair in the width direction of the paper 1, and the length between the pair of through holes 11 is
Paper width standards (for example, 54 inches, A0, etc.) are used. Then, such a pair of through holes 11
Are formed in a plurality of pairs so as to correspond to the respective standards (A0, A3, A4, etc.). As shown in FIG. 1, when the sheet 1 is received on the platen 2,
Of the plurality of through holes 11, a pair of through holes 11 corresponding to the standard of the width of the sheet 1 used at that time appear at both ends in the width direction of the sheet.

Next, the operation of detecting the widthwise side edge of the sheet 1 by the sheet width detection sensor 9 and the through hole 11 will be described. First, when the carriage 8 is driven, the paper width detection sensor 9 is scanned in the width direction of the paper 1 together with the head 6. When the paper width detection sensor 9 is scanned in a range facing the paper 1, The light emitted from the light emitting unit of the width detection sensor 9 is reflected by the paper 1 and the reflected light is received by the light receiving unit. Then, the sheet width detection sensor 9 detects the sheet 1
Is located at the side end of the sheet 1 and faces the through hole 11 that appears at the boundary between the sheet 1 and the platen 2. At this time, the light emitted from the light emitting unit of the paper width detection sensor 9 is
Since the light passes through the through-hole 11 and cannot be received by the light receiving unit, the side edge of the sheet 1 is detected.

The paper width detection sensor 9 and the through hole 1
By detecting the end of the sheet 1 in the width direction by using the sheet No. 1, even if the paper dust of the sheet 1 is on the platen 2,
In the through-hole 11, paper powder or the like falls through the platen 2 from the hole. Therefore, the through hole 11 is not covered with such paper dust. Therefore, the paper width detection sensor 9 does not make an erroneous detection due to such paper dust, but can always accurately detect the side end of the paper 1 by accurately detecting the through hole 11, and can detect the width of the paper 1. A good image in the direction can be formed.

Further, since such a through-hole 11 can be satisfactorily formed in the platen 2 by a simple processing, the production cost does not increase so much. Further, the through hole 11 is tapered so that the diameter of the receiving surface 12 receiving the paper 1 is small and the diameter of the surface 13 opposite to the receiving surface 12 is large. Paper dust or the like that has entered the inside becomes more likely to fall off, and it is possible to effectively prevent paper dust or the like from clogging in the through hole 11 while falling off. If the diameter of the receiving surface 12 receiving the paper 1 is reduced by the taper and the diameter of the surface 13 opposite to the receiving surface 12 is increased, such a shape can be formed by relatively simple processing. Can be formed.

In the present embodiment, the detected portion of the paper width detecting sensor 9 is formed by the through hole 11,
If it is a gap formed so as to penetrate the platen 2,
Not limited to the through holes 11, for example, the platen 2 may be divided into two, and the two divided platens 2 may be formed at predetermined intervals in the width direction of the paper to form a gap.

[0018]

As described above, according to the first aspect of the present invention, even if paper dust or the like generated by the recording medium is on the platen, the paper dust or the like in the detected portion is not covered by the gap. , Penetrates through the platen, and does not cover the detected part. Therefore, the recording medium width detection sensor can always accurately detect the detected portion. Therefore, the recording medium width detection sensor can always accurately detect the side edge of the recording medium, and can form a good image on the recording medium in a direction substantially orthogonal to the direction in which the recording medium is transported. .

According to the second aspect of the present invention, since the detected portion is formed by the through-hole penetrating the platen, the detected portion can be favorably formed by simple processing. Therefore, the detected part can be formed easily and reliably, and the manufacturing cost can be reduced. According to the third aspect of the present invention, the through hole is formed such that the receiving surface side for receiving the recording medium is small and the surface on the opposite side to the receiving surface side is large. Paper powder and the like that have come off can be easily dropped off. Therefore, it is possible to effectively prevent paper dust and the like from being clogged in the middle of falling through the through hole.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of an ink jet type image forming apparatus showing an embodiment of the image forming apparatus of the present invention.

FIG. 2 is a side sectional view of a main part in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Paper 2 Platen 6 Head 8 Carriage 9 Paper width detection sensor 11 Through hole 12 Receiving surface 13 Surface opposite to receiving surface side

Claims (3)

[Claims] 1. A platen for receiving a recording medium, a head opposed to the platen for forming a predetermined image on the recording medium, and a head on which the head is mounted and in which the recording medium is conveyed. An image forming apparatus comprising: a carriage driven in a direction substantially orthogonal to the image forming apparatus; wherein the carriage has a side end of the recording medium in a direction substantially orthogonal to a direction in which the recording medium is conveyed. A recording medium width detection sensor for detecting is provided, and the platen is provided with a detected part detected by the recording medium width detection sensor, and the detected part is formed so as to penetrate the platen. An image forming apparatus characterized by being formed by a gap formed. 2. The image forming apparatus according to claim 1, wherein the detected part is formed by a through-hole penetrating the platen. 3. The through hole according to claim 2, wherein the receiving surface side receiving the recording medium is small, and the surface on the side opposite to the receiving surface side is large.
An image forming apparatus according to claim 1.