JPH05270083A - Printer - Google Patents

Abstract

PURPOSE:To close a bail lever without using a special purpose drive source by transmission-engaging a sheet feed gear with a ball gear through an idle gear by swinging an idle lever, and normally disposing the idle lever at a refuged position apart from the feed gear and the bail gear by a return spring. CONSTITUTION:A bail lever 18 is self-held at a platen 10 by a toggle spring 22 at both opening and closing positions. A bail gear 21 is provided at the lever 18, and transmission-engagement of a sheet feed gear 13 with the gear 21 is executed through an idle gear 23 by swinging an idle lever 24. The lever 14 is normally disposed at a refuged position apart from the gears 13, 21 by a return spring 26. This refuged position is positioned by a stopper 11b. When the lever 18 is manually moved to an opening position, a positioning pawl 21a is simultaneously rotated to rotatably position the gear 23 in contact with the gear 23, and the engagement of the gear 23 with the gear 23 is effectively executed by swinging the lever 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper pressing device for a printer, and more particularly to a bail roller opening / closing drive mechanism for pressing and holding a paper against a platen.

[0002]

2. Description of the Related Art Conventionally, in a printer, a print sheet is wound around a platen, and a print head carried by a carriage reciprocating in the axial direction with respect to the platen carries out desired printing on the sheet. Since printing is performed in a state in which the sheet is held in close contact with the platen, normally, the sheet is pressed against the platen by the bail roller. Such a bail roller is usually rotatably supported at one end of the bail lever, and after the paper is fed to the platen, the bail roller retracted from the platen is moved to the holding position.

Such a bail roller must be surely positioned at the holding position after the sheet is mounted on the platen. However, when the sheet is inserted, the bail roller becomes a hindrance, and the bail roller is inadvertently pressed by the bail roller. There was a problem that a paper jam would occur if the paper was inserted in the position. Therefore, when the roll paper or the sprocket paper is inserted, the user manually retracts the bail roller to the retracted position while the roll paper or sprocket paper is inserted, and then manually returns the bail roller to the holding position after the sheet is securely wound around the platen. ..

However, in the recent automated printers, it is desired that the bail roller can be opened and closed automatically, and various automatic opening / closing devices have been proposed. The conventional automatic bail roller opening / closing mechanism generally has a dedicated solenoid or motor for driving the bail lever, which drives the solenoid or motor by a predetermined control program after detecting the insertion of a sheet by a sensor. The bail roller is opened and closed.

However, in this conventional apparatus, various driving mechanisms are needed only for opening and closing the bail roller, which causes a problem that the apparatus becomes large and the price of the printer rises, and the size and the cost of the printer are reduced. It is an obstacle to cost reduction.

As a conventional automatic bail roller opening / closing mechanism, there has been proposed a device utilizing a carriage feed driving force instead of a plunger or a dedicated motor. For example, as disclosed in Japanese Patent Laid-Open No. 63-49465,
The rotation driving force of the paper feed roller is transmitted to the rotating cam via the clutch, and the bail lever connected to this cam can be opened and closed freely. This is performed by the moving operation of. This mechanism is convenient because it can open and close the bail automatically without using a plunger or a dedicated motor, but it has the following drawbacks.

That is, when the user tries to open the closed bail lever by manual operation, the bail lever always tries to close due to the urging force of the spring,
Cannot hold in open state. Therefore, when the user attempts to manually set the paper, it is necessary to hold the bail with the hand so that the bail does not close, and the operability is extremely poor. The bail cannot be closed manually when the bail is open, that is, when the cam lifts the bail. Forcibly operating it will damage the cam mechanism or the bail lever. Since the arm that engages with the carriage and rotates according to the movement of the carriage does not have a part that absorbs force, if the amount of movement after the carriage engages with the arm is mistakenly too large, parts will be damaged. Invite.

In the power-off state, when the user manually operates the carriage to replace the ribbon, or when the carriage motor is out of step and the carriage position is misaligned, the carriage moves until it hits the frame. This is not rare, and in such a case, problems such as the protrusion of the carriage being chipped, the arm being deformed, and the gear teeth being chipped may occur. Furthermore, it is necessary to initialize the cam to the stop position when the power is turned on. This is because not only does the carriage, paper feed roller (platen), and bail lever cause annoying movements each time the power is turned on, but also when the power is turned on with paper already inserted, the paper feed for initialization operation Due to the driving of the rollers, the set paper may be misaligned or the paper may not be fed normally. Further, this cam control requires a detection means such as an encoder for knowing the rotational position of the cam, which is a factor of cost increase.

Although the mechanism disclosed in the above-mentioned Japanese Patent Laid-Open No. 63-49465 achieves an automatic opening / closing mechanism without a dedicated drive source, it sacrifices the manual operability of the user and further makes a small operation. It was easy to break due to mistakes, etc., and it was never a sufficient function.

In addition to this, as a simpler structure while ensuring manual operability, it is disclosed in Japanese Patent Laid-Open No. 63-428.
Some are disclosed in Japanese Patent Publication No. 79. This has a mechanism to hold the bail open by manually opening the bail lever.When the carriage moves out of the print area, the carriage collides with a release mechanism that releases the open hold state. , The bail lever is returned to the closed state. This is so that printing can be done from the top of the paper, but since the carriage is always moving outside the printing area at the moment the bail lever is closed, there is a slack in the left and right when the bail is closed. However, there is a problem in that skewing occurs in the subsequent paper feeding and the printing is bent, which causes so-called skew.

This skew phenomenon is well known,
Generally, when performing the closing operation of the bail, the carriage is temporarily moved to the vicinity of the center of the paper (this operation is generally called centering), and the paper is roughly removed by a guide provided on the print head or the carriage. Skew is prevented by closing the bail while supporting each side equally. Therefore, in the above-mentioned conventional example, although the mechanism is simple, there is a drawback in that since the carriage is a mechanism that cannot be centered, a fatal defect of sheet skew is caused.

The present invention has been made to solve the above problems, and automatically closes the bail lever without using a dedicated drive source, and does not impair the operability manually. An object of the present invention is to provide a printer that does not cause damage to parts or the like. A further object of the present invention is to provide a high-quality printer at a low price, which eliminates an annoying initialization operation when the power is turned on. Another object of the present invention is to provide a high-quality printer which is capable of reliably setting a sheet without causing skew of the sheet and is free from malfunction.

[0013]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and includes a platen for winding a sheet,
A paper feed gear that drives the platen to rotate, a carriage that carries the print head back and forth along the axial direction of the platen, and a paper supported by a bail lever that is swingably supported by the printer base frame. The bail roller to be pressed to the platen, the toggle to position and hold the bail lever in the holding position where the bail roller is pressed against the platen and the retracted position retracted from the platen, and to receive the force to rotate and drive the bail lever provided on the rotation support part of the bail lever. Bail gear, the idle gear that can be moved to both the drive position that is supported by the rotatable idle lever and that connects the paper feed gear and the bail gear, and the retracted position that is retracted from both, and the idle lever to the retracted position of the idle gear. A return spring that gives a return biasing force to the The carriage includes a positioning tab for positioning the dollar gear at a rotational position, and a pressing piece provided on the carriage for engaging the idle lever and moving the idle gear to the drive position when the carriage moves out of the printing area. The drive force of the paper feed gear is transmitted to the bail gear via the idle gear by moving out of the printing area, and the idle gear is self-held in the drive position by the gear drive force until the bail gear moves to the holding position. It is characterized by.

[0014]

According to the above construction, the bail roller is once manually opened when inserting the paper, and the bail roller open position is self-held by the toggle spring. During the opening operation of the bail roller, the positioning claw provided on the bail gear rotates together with the bail gear and stops at the position where it comes into contact with the teeth of the idle gear that is biased by the spring to the stopper, and rotationally positions the idle gear. , Keep that state. Then, when the paper is sucked in, the front end of the paper is correctly detected by a predetermined sensor or the like, and when the front end of the paper passes the bail roller position by a predetermined amount of paper feed, the carriage moves out of the printing area and is pressed against the pressing piece. Force the idle lever to move from its retracted position to the drive position. By this movement to the drive position, the idle gear enters the mesh with the bail gear and the paper feed gear,
Since the idle gear is rotationally positioned by the positioning tabs in advance, the idle gear smoothly meshes with the bail gear and the paper feed gear without causing a gear meshing error due to the contact between the gear tooth tips. Then, the paper feed driving force is transmitted to the bail gear, and the bail lever rotates. In this state, once the idle gear meshes with the drive position, the idle gear is sandwiched between the paper feed gear and the bail gear even if the drive is stopped, and the idle gear is no longer disengaged by the biasing force of the return spring. Self-held by. Therefore, if necessary, the carriage does not need to hold the idle lever in the pressed state in this bail gear coupling state, and can freely move to any position for centering or other purposes. Then, when the paper feed gear drives the bail gear via the idle gear and the bail lever goes over the neutral position of the toggle spring, the toggle spring instantly rotates the bail lever to the holding position for pressing the bail roller against the platen. Therefore, the drive force of the toggle spring provides a reliable bail roller pressing position, and the bail gear rotates at high speed prior to the idle gear, so that the idle gear no longer performs a self-holding action to the drive position in the drive gear train. Instead, the bail gear kicks back to the retracted position, and it is possible to return to the original retracted position. Therefore, a reliable automatic bail roller closing action can be performed, and the carriage can move freely without merely requiring the subsequent holding action by merely moving the bail lever to the drive position.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing a main part of a paper pressing device of a printer according to the present invention. As is well known, the platen 10 has both ends supported by a printer base frame 11, a paper feed gear 13 is fixed to the platen shaft 12, and a driving force from a main motor (not shown) is transmitted to the paper feed gear 13. ing. A carriage stay 14 is fixed to the printer base frame 11 in parallel with the platen shaft 12.
A carriage 15 is reciprocally held on the carriage stay 14. As is well known, a print head 16 is carried on the carriage 15, and the print head 16 shown in the figure comprises a wire dot head. While the carriage 15 is reciprocated, a desired wire is driven at each position of the platen facing the carriage 15 to print on the paper. The desired printing action.

Reference numerals 15-a and 15-b are paper guides formed on the carriage located on both sides of the print head to guide the paper along the platen. Further, in order to firmly and closely hold the sheet on the platen 10, a bail roller 17 is rotatably provided at a holding position and an open position with respect to the platen 10, and the bail roller 17 performs the bail operation in order to perform this rotating action. A roller shaft 19 supported on the tip of the lever 18 is rotatably provided. The bail lever 18 is rotatably supported by the printer base frame 11 by a support shaft 20.

A feature of the present invention is that the bail roller 17 can be manually moved to the open / close position and the bail roller 17 is moved from the open position of FIG. 1 to the platen 1.
The pressing position to be pressed to 0 is subject to the automatic closing action using the driving force of the paper feed gear 13. Therefore, as is apparent from this embodiment, the bail lever 18 is used.
The bail gear 21 is formed on the side of the rotation support end of, and the bail gear 21 in the embodiment is a gear having about 3/4 circumference. Further, the bail gear 21 in the present invention
A positioning claw 21a is provided on the shaft, and is integrally rotatable with the bail lever 18 about the support shaft 20 as a rotation center.

Then, the bail lever 18 in the present invention
Is self-held by the toggle spring 22 both in the open position of FIG. 1 and in the holding position where the platen 10 and the bail roller 17 described later are pressed. In order to transmit the driving force of the paper feed gear 13 to the bail gear 21, the idle gear 23
The idle gear 23 is pivotally supported on the swing end of an idle lever 24, and the idle lever 24 is pivotally supported on the printer base frame 11 by a shaft 25. An elastic receiving arm 24a extends from the root side of the idle lever 24 in the embodiment and can engage with a pressing piece 27 of the carriage 15 described later. Further, a return spring 26 indicated by a broken line is hooked on the idle lever 24 to constantly urge the idle lever 24 with a weak urging force in the clockwise direction of FIG. Further, the biased idle lever 24 is attached to the printer base frame 1.
It contacts the stopper 11b (FIG. 2) provided on the No. 1 and stops at the retracted position.

In the embodiment, the carriage 15 has a pressing piece 27 having a slope at a left end thereof.
The pressing piece 27 can protrude from the opening window 11a provided in the printer base frame 11 to press the receiving arm 24a of the idle lever 24.

FIG. 7 is a block diagram showing the arrangement of the control unit of the printer described above. A CPU 40 for controlling printing and paper feeding is provided, and the CPU 40 has a ROM 41 storing a control program and a host. A RAM 42 for storing print data received from a computer and calculation information for the next operation, and an I / F (interface) for connecting this printer to an external host computer.
43 is connected. Further, the print head 16, the carriage motor 44, and the paper feed motor 45 are each connected to the CPU 40 via a drive circuit. Further, the output signals of the paper sensor 28 and the bail SW 30 are also input to the CPU 40 so that their states are monitored by a program, and commands such as page breaks and line feeds are input from the operation panel 46.

The present embodiment is constructed as described above, and the bail lever opening / closing action will be described below with reference to the respective operating states shown in FIGS. FIG. 2 shows a state of the printer when the sheet insertion is started, and the bail roller 17 is in a closed state, that is, in a holding position where it is pressed against the platen 10. This pressing position is self-held by the toggle spring 22. On the other hand, the idle gear 23 is also the idle lever 2
4, the spring 11 is urged clockwise by the return spring 26, and the idle lever 24 is brought into contact with the stopper 11b so that the idle gear 24 is held at a predetermined retracted position. In this state, the idle gear 23 serves as both the paper feed gear 13 and the bail gear 21. It is understood that they are retreating to a position away from. A pinch roller 29 is in pressure contact with the platen at the paper insertion port, and the paper 100 with its leading edge aligned is set in this pressure contact portion.

In the present invention, the opening action of the bail roller 17 when the sheet is inserted, that is, the movement to the escape position is performed manually. This escape action is shown in FIG. 3, and the bail roller 17 is manually moved as shown by an arrow A. At the same time, the bail lever is displaced by the spring force of the toggle 22 and the stopper 31 positions and holds the open position. At this time, the bail SW30 is turned from OFF to ON, and the tip end of the positioning claw 21a provided on the bail gear 21 comes into contact with the tooth tip of the idle gear 23 in the retracted position, thereby completing the rotational positioning of the idle gear 23 at the same time. To do. In this positioning state, the idle gear 23 and the bail gear 21 are caused by the swing of the idle lever 24.
The teeth of the idle gear 23 are surely meshed with the teeth of the bail gear 21 during the meshing operation with the. Since the idle gear 23 is only weakly urged by the return spring 26, even if the tip of the positioning tab 21a collides with the tooth tip of the idle gear 23, no problem such as breakage occurs.

A partially enlarged view of FIG. 3 is shown in FIG. In the state shown in FIG. 3, when the bail lever 18 is opened, the bail SW30 is turned from OFF to ON, and the paper feed operation is started under the control of the CPU 40. First, the paper feed motor 45 is driven and the paper starts to be sucked. The paper sensor 28 provided at a predetermined position detects the leading edge of the paper 100,
After that, the position of the leading edge of the paper 100 can be correctly known by counting the paper feed drive pulses. A predetermined amount of paper is fed according to the setting of the print start desired position by the user, the paper setting is completed, and the printer goes online. The leading edge of the paper is located in the printing section in front of the print head, and upper edge printing is possible. Upon receiving a print command from the host computer, printing and line feed are started. When the paper advances after the printing and line feed of several lines is executed, and the cumulative amount of feed since the paper sensor 28 detects the leading edge of the paper exceeds a predetermined amount, the CPU 40 judges this and performs the bail closing operation. ..

FIG. 4 shows a state in which the leading end position of the sheet 100 has reached the above-mentioned predetermined position, and this leading end position has passed between the bail roller 17 and the platen 10 and has reached the position where the bail can be closed. The CPU 40 sends a drive pulse to the carriage motor 44 to move the carriage 15 in the direction indicated by arrow B in FIG. As shown in FIG. 4, the pressing piece 27 of the carriage 15 engages with the elastic receiving arm 24a of the idle lever 24 and pushes up the receiving arm 24a in the direction of arrow C by the slope thereof, and as a result, the idle gear 23 moves the paper feeding gear 13 And the bail gear 21 can be moved to a position where they mesh with each other.

At this time, as shown in FIG. 6, the idle gear 23 has already been rotationally positioned by the positioning claw 21a and then enters the meshing operation (moves in the direction of arrow C). Smooth connection can be achieved without connection mistakes due to gear edge contact. In this state, the CPU 40 slightly rotates the paper feed motor 45 to rotate the paper feed gear 13 forward. Due to the slight rotation of the paper feed gear, the idle gear 23
Is securely meshed between the paper feed gear 13 and the bail gear 21, and is held at the drive position. Therefore, even if the carriage 15 or the pressing piece 27 is separated from the receiving arm 24a, the idle gear 23 can maintain the state of FIG. Of course, the biasing force of the return spring 26 is set to be weaker than the gear rotation holding force.

Further, in the embodiment, the receiving arm 2
Since 4a has elasticity, it is designed so that an excessive force is released by a bending action so that an unnecessary force is not applied to the idle gear 23 when it is pressed by the pressing piece 27 of the carriage 15. Next, the carriage 15 moves toward the center of the paper, and the paper guides 15-a and 15-b support the deflection from the back surface of the paper 100 to cope with the subsequent bail closing operation. FIG. 5 shows the operation of closing the bail lever 18, and when the paper feed motor 45 is driven in the normal direction, the bail lever 18 rotates in the direction of arrow D by the drive transmission of the idle gear 23. When the bail lever 18 exceeds the neutral point of the toggle spring 22, the toggle spring 22
Almost instantly moves the bail lever 18 to its bail roller 17
Moves at a high speed toward a position where it is pressed against the platen 10, and the bail roller 17 itself sandwiches the paper 100 and surely moves toward the closed position.

At this time, a characteristic of the present invention is that the bail gear 21 kicks back the idle gear 23 toward the retracted position as shown by the arrow E as the bail lever 18 rotates at high speed. The idle lever 24 is swung quickly to the retracted position by both the kicking back force and the return biasing force of the return spring 26. Therefore, the apparatus itself returns to the state shown in FIG. 2 from the state of FIG. 5, and at this time, the sheet 100 has already advanced to the position where it is sandwiched between the platen 10 by the bail roller 17 as shown in the figure, unlike FIG. The bail roller closing operation is surely completed.

Next, the initialization operation when the power of the printer is turned on will be described. When the power is turned on, it is assumed that the idle lever 18 is held in the drive position as the state of the mechanism, and the paper feed motor 45 is slightly reversed. Due to this slight reverse rotation, the meshing of the idle gear 23 in the holding state is released, the bail lever 18 is returned to the retracted position, and the clutch mechanism is in the initial state. Subsequent operations are performed in the same manner as a known printer.

As described above, according to the illustrated embodiment, after the bail roller 17 is manually opened, the paper feed driving force is effectively used as the bail lever driving force in the idle gear controlled by the carriage. , The bail roller automatic closing action can be achieved.

In the above embodiment, the positioning claw is formed integrally with the bail gear, and the positioning claw positions the idle gear by opening / closing the bail lever. However, the invention is not limited to this. A pin or the like may be planted at an appropriate position where it interferes with the tooth tip of the idle gear, so that the idle gear may be rotationally positioned by the retracting operation of the idle lever.

[0031]

As described above, according to the present invention,
With the simplified structure, the bail roller can be surely automatically returned to the closed position.

Further, the number of parts is reduced as compared with the conventional mechanism, and the operability of manual operation is maintained even though the structure is simple,
In addition, it is possible to provide a highly reliable printer in which parts are not damaged. Even when compared as an automatic paper setting operation, the operation of the paper feed SW in a conventional printer or the like can be performed only by replacing it with a manual operation for opening the bail lever. Full automatic using a dedicated drive source for the bail. The operability is almost the same as that of the formula, and it is a very useful invention in practice. Further, even in the coupling mechanism for transmitting the paper feed driving force to the bail gear, a mechanism with no coupling error is realized, and higher reliability can be provided to the printer.

Further, since it is possible to center the carriage at the moment when the bail lever is closed, it is possible to prevent the occurrence of skew.

Further, as compared with the conventional mechanism using the cam for the bail operation, it is an excellent one that does not require annoying operation of the initialization operation when the power is turned on.

[Brief description of drawings]

FIG. 1 is a perspective view of essential parts showing a preferred embodiment of a paper feeding device of a printer according to the present invention.

FIG. 2 is an operation explanatory view showing a state immediately before inserting a sheet in the present embodiment.

FIG. 3 is an operation explanatory view showing a sheet insertion state after the bail roller is manually opened in the present embodiment.

FIG. 4 is an operation explanatory view showing a state in which the idle gear is engaged with both the paper feed gear and the bail gear by moving the carriage out of the printing area.

FIG. 5 is an operation explanatory view showing a state in which the bail lever is rapidly moved to the bail roller closed position by the toggle spring and the idle gear is kicked back.

6 is a partially enlarged view of FIG.

FIG. 7 is a block diagram showing a mechanism of a control unit of this embodiment.

[Explanation of symbols]

 10 Platen 11b Stopper 13 Paper Feed Gear 15 Carriage 16 Print Head 17 Bail Roller 18 Bail Lever 21 Bail Gear 21a Positioning Claw 22 Toggle Spring 23 Idle Gear 24 Idle Lever 26 Return Spring 27 Pressing Piece 100 Paper

Claims (1)

[Claims] 1. A platen for winding a paper sheet, a paper feed gear for rotationally driving the platen, a carriage for reciprocating along the axial direction of the platen to carry a print head, and a printer base frame for swinging movement. In a printer including a bail roller that presses the sheet supported by the supported bail lever against the platen surface, and a toggle that positions and holds the bail lever at a holding position where the bail roller is pressed against the platen and a retracted position retracted from the platen, A bail gear that is provided on the rotation support portion of the bail lever and receives a force for rotationally driving the bail lever, a drive position that is supported by a rotatable idle lever and that connects the paper feed gear and the bail gear, and a retract that is retracted from both. Idle gear that can be moved to both positions, and the idle gear A return spring that gives a return biasing force to the lever toward the retracted position of the idle gear, a positioning claw that positions the idle gear located at the retracted position to a rotational position, and a carriage provided on the carriage and moved outside the printing area. And a pressing piece that engages with the idle lever to move the idle gear to a drive position, and the drive force of the paper feed gear is transmitted to the bail gear via the idle gear when the carriage moves out of the printing area. A printer characterized in that the idle gear is self-held in a driving position by a gear driving force until the bail gear moves to a holding position.