JPH1052954A - Apparatus for detecting head end of paper in printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely clamp a head end of a paper to a platen by means of a clamp blade even when the head end is inclined. SOLUTION: A controller judges that a paper 58 is set at a paper insertion opening when a sensor 54 is changed from OFF to ON. The controller then sends the paper 58 in a forward direction by a regulated distance, checks which of sensors 55a, 55b and 55c is turned ON, and recognizes that the paper 58 is present between the sensors turned ON. Thereafter, the controller moves the paper 58 in the opposite direction and obtains where the sensors 55a, 55b and 55c are turned OFF. The controller obtains an inclination of the paper 58 from a position where all of the sensors 55a, 55b and 55c are turned OFF. The amount of the paper 58 to be fed to a clamp blade 16 is determined on the basis of the inclination and a position of the sensor 55c which is turned OFF first. Accordingly, a head end of the paper 58 enters the clamp blade 16 with a suitable margin R left at a delay part F.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting the leading edge of a sheet in a printer such as an ink jet printer.

[0002]

2. Description of the Related Art A long paper sheet such as roll paper inserted into a paper insertion slot is conveyed onto a platen, and the leading end of the long paper sheet is sandwiched between a plate-shaped clamp blade extending in the width direction of the platen and a platen. The present applicant has developed a printer in which long paper is clamped to a platen so that the non-printable area of the paper is made as small as possible.

[0003]

In the above-described apparatus, when there is only one sensor for detecting the sheet, when the sheet is inclined, one sensor 55a is provided at one point of the leading end of the sheet 58 as shown in FIG. Since only the width of the sheet 58 is detected, the clamp blade 16 may not be able to grasp the entire width of the sheet 58 in some cases. An object of the present invention is to solve the above problems.

[0004]

In order to achieve the above object, the present invention conveys a sheet inserted into a sheet insertion slot onto a platen, and attaches a plate-shaped clamp blade extending in the width direction of the platen to the platen. In a printer in which the leading end of the sheet is clamped and clamped between the clamp blade and the platen, a plurality of sheets are provided between the sheet insertion port and the platen at a predetermined interval in the width direction of the sheet. A plurality of paper detection sensors are provided, the inclination of the paper is detected by the sensors, and the feed amount of the paper to the clamp blade is determined based on the inclination.

[0005]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Reference numeral 2 denotes a platen composed of a drum, which is rotatably supported by the body of the printer. The platen 2 is connected to a motor controlled in the forward and reverse rotation directions by a printer controller. In the present invention, the platen 2 is not particularly limited to a drum, and its moving direction is not particularly limited to a rotating direction. A substantially central portion of a clamp side plate 6 (the other clamp side plate is not shown) is rotatably fitted to a rotating shaft 4 protruding from both ends of the platen 2. A synchronous shaft 8 is provided on each one of the pair of clamp side plates 6.
Is rotatably hung, and synchronization gears 10 are fixed to both ends of the synchronization shaft 8.

[0006] The pair of synchronization gears 10,
At both ends of the platen 2, a gear 11 fixed along the outer peripheral surface thereof is engaged. A support arm 12 is rotatably supported by the pair of clamp side plates 6 in a plane perpendicular to the rotation center axis of the platen 2. Both ends of a thin plate-like clamp blade 16 extending in the direction perpendicular to the paper of FIG. 3 are fixed to one side of the support arm 12. At both ends of the clamp blade 16,
A gear 18 is fixedly opposed to the gear 11 of the platen 2. A clamp blade driving actuator 20 composed of a solenoid is fixed to each of the pair of clamp side plates 6, and a connecting pin 24 is fixed to an output shaft 22 of the actuator 20. At both ends of the clamp blade 16, mounting plates 26 are fixed.
The connecting pin 24 is slidably fitted in a long hole penetrated through the hole.

The support arm 12 has an engaging recess 32 for engaging with a pin 30 of a side plate 28 fixed to the body. A guide rail (not shown) is disposed on the body of the printer in parallel to the platen 2 in the direction perpendicular to the paper of FIG. 3 and a carriage 34 is movably mounted on the guide rail. An ink jet print head 36 is mounted on the carriage 34, and an ink discharge unit 38 of the ink jet print head 36 faces the surface of the platen 2 with a slight gap. The carriage 34 is configured to be driven in a reciprocating direction along a guide rail by a motor controlled by a controller. 40
Is a sheet pressing means for pressing a sheet against the surface of the platen 2, and is constituted by a thin blade. The paper pressing means 40 is supported by a printer body via a support member 42.

The paper pressing means 40 is lightly elastically contacted with the surface of the platen 2 above the ink discharge section 38 so that the paper can move, and forms a nip with the platen 2. Reference numerals 44 denote pinch rollers rotatably supported at both ends of a plurality of shafts 46. Each of the shafts 46 is arranged at a predetermined distance from each other in parallel with the longitudinal direction of the platen drum 2. Each of the shafts 46 is supported by one of leaf springs 48, and the other of the leaf springs 48 is fixed to a printer body. A pair of pinch rollers 44 supported at both ends of each shaft 46 are loosely fitted into cutouts 50 formed in the lower part of the clamp blade 16 and are in elastic contact with the surface of the platen 2 in this state.

A pinch roller 52 is rotatably disposed substantially 90 degrees rearward (upstream side) of the printing section of the platen 2, and the pinch roller 52 is in contact with the platen drum 2 at a predetermined pressure. The pinch roller 52 and the platen drum 2 constitute a sheet conveying unit. Reference numeral 54 denotes a light reflection type optical sensor for detecting a sheet, which is disposed in front of the pinch roller 52 and is supported by the machine.
Behind the sensor 54, light reflection type optical sensors 55a, 5a for detecting a sheet at a predetermined interval in the width direction of the sheet.
5b and 55c are arranged, and each is supported by the fuselage. Reference numeral 56 denotes a paper guide disposed in front of the pinch roller 44. The paper guide 56 has a guide surface extending in the width direction of the long paper conveyed by the platen 2. It is configured to guide. At one end of the paper guide 56, a stopper portion 56a for colliding engagement with the other end rising portion 16a of the clamp blade 16 is formed.

Each drive unit of the printer is configured to be controlled by a controller. Next, the operation of the present embodiment will be described. When the start switch of the printer is turned on, the platen roller 2 rotates clockwise in FIG. When the leading end of the long sheet 58 such as a roll sheet is inserted into the nip between the pinch roller 52 and the platen 2, the long sheet 58 is conveyed clockwise in conjunction with the rotation of the platen 2 in FIG. . When the leading end of the long sheet 58 passes below the sensor 54, the sensor 54 detects the leading end of the long sheet 58. When the sensor 54 changes from OFF to ON, the controller determines that the sheet 58 has been set in the sheet insertion slot (see FIG. 1A). Next, the controller feeds the paper 58 in the clockwise direction in FIG. 3 by the specified amount i, and checks which of the sensors 55a, 55b, and 55c is turned on. Recognize that there is.

Next, the controller rotates the platen 2 in the reverse direction to move the paper 58 in the reverse direction.
The position where 55b and 55c are turned off is obtained (FIG. 1b,
c). At this time, the controller operates the sensors 55a, 5
From the position where both 5b and 55c are turned off, the paper 58
Of the sheet 58 toward the clamp blade 16 is determined based on the inclination and the position of the sensor 55c which is initially turned off. Next, the long paper 58 is conveyed to the nip between the paper holding means 40 and the platen drum 2, and the long paper 58 is moved by the paper holding means 40 near the printing section and behind the printing section. 2 is pressed against the surface. When the leading end of the paper 58 passes through the paper pressing means 40 and enters the inside of the clamp blade 16 with an appropriate margin R in the delay portion F as shown in FIG. Stop rotation.

Next, the controller operates the actuator 2
0 is turned on. As a result, the output shaft 22 of the actuator 20 is sucked, the mounting plate 38 is pulled toward the center of the platen 2, and the clamp blade 16 is brought into close contact with the surface of the platen 2 from above the long paper 58 (FIGS. 4 and 4). 8). At this time, the gear 18 on the clamp blade 16 meshes with the gear 11 on the platen 2. In this state, since the clamp blade 16 is long, there is almost no force for fixing the sheet 58 on the platen drum 2. Next, platen 2
Starts rotating clockwise.

In synchronization with the clockwise rotation of the platen 2,
The clamp blade 16 rotates clockwise. At this time,
The pinch roller 44 rides on the clamp blade 16. As a result, the clamp blade 16 is pressed by the pinch roller 44, and fixes the long sheet 58 below the clamp blade 16 to the platen 2. On the other hand, the carriage 34 moves along the rail, and the print head 36 moves.
Thus, printing is performed on the long paper 58. Further, the platen 2 rotates clockwise, and the clamp blade 16
Is released from the pinch roller 44 and the long sheet 58 is gripped by the nip between the pinch roller 44 and the platen 2, the controller turns off the actuator 20.

As a result, the clamp blade 16 separates from the platen 2 and the engagement between the gears 18 and 11 is released. In this state, the rising portion 16a at one end of the clamp blade 16 is, as shown in FIG.
6, the engaging recess 32 of the support arm 12 engages with the pin 30, and the position of the clamp blade 16 is regulated, so that the clamp blade 16 functions as a paper guide. The long paper 58 gripped by the pinch roller 44 and the platen 2 is guided by the paper guide 56 by the clockwise rotation of the platen 2 and is conveyed to the discharge port.

When printing is completed, the controller turns on the actuator 20 to bring the clamp blade 16 into close contact engagement with the platen 2 and remove the engagement recess 32 from the pin 30. Next, the platen 2 is rotated reversely by a predetermined rotation angle to return the clamp blade 16 to the standby position shown in FIG. Thereafter, the actuator 20 is turned off, and the clamp blade 16 returns to the initial state.

[0016]

Since the present invention is constructed as described above, there is an effect that the leading edge of the sheet can be securely clamped by the clamp blade.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the operation of an ink jet printer.

FIG. 2 is a diagram illustrating the operation of the ink jet printer.

FIG. 3 is an explanatory side view of the ink jet printer.

FIG. 4 is an explanatory side view of the ink jet printer.

FIG. 5 is an explanatory side view of the ink jet printer.

FIG. 6 is an explanatory side view of the ink jet printer.

FIG. 7 is an explanatory plan view of a part of the ink jet printer.

FIG. 8 is a side view illustrating the operation of inkjet printing.

FIG. 9 is a side view illustrating the operation of inkjet printing.

FIG. 10 is a plan view of a part of the clamp blade.

[Explanation of symbols]

 2 Platen drum 4 Rotating shaft 6 Clamp side plate 8 Synchronous shaft 10 Gear 11 Gear 12 Support arm 14 Axis 16 Clamp blade 18 Gear 20 Actuator 22 Output shaft 24 Connecting pin 26 Mounting plate 28 Side plate 30 Pin 32 Engagement recess 34 Carriage 36 Print head 38 Ink ejection unit 40 Paper pressing means 42 Supporting member 44 Pinch roller 46 Shaft 48 Leaf spring 50 Notch 52 Pinch roller 54 Sensor 55a Sensor 55b Sensor 55c Sensor 56 Paper guide 58 Long paper

Claims (1)

[Claims] 1. A sheet inserted into a sheet insertion slot is conveyed onto a platen, and a plate-shaped clamp blade extending in a lateral width direction of the platen is pressed against the platen, and a tip of the sheet is clamped by the clamp blade and the platen. A plurality of paper detection sensors are provided between the paper insertion slot and the platen at predetermined intervals in the width direction of the paper, and the inclination of the paper is detected by the sensors. The sheet leading edge detecting device detects the amount of the sheet fed to the clamp blade based on the detected inclination.