JP2578698B2 - Printer paper presser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper holding device for a printer,
In particular, the present invention relates to an opening / closing drive mechanism for a bail roller for holding a sheet against a platen.

[0002]

2. Description of the Related Art Conventionally, in this type of printer, a print sheet is wound around a platen, and a print head carried on a carriage reciprocating in the axial direction with respect to the platen forms a desired print on the sheet. However, in order to perform printing in a state in which the paper is held in close contact with the platen, the paper is usually pressed against the platen by a bail roller. Such a bail roller is normally rotatably supported at one end of a bail lever, and the bail roller which has been retracted from the platen after paper is fed to the platen is controlled to move to a holding position.

Such a bail roller must be reliably positioned at its holding position after the paper is mounted on the platen. However, when the paper is inserted, the bail roller becomes a hindrance, and the bail roller is inadvertently moved to the holding position. However, there is a problem that if a sheet is inserted in the state described above, a paper jam occurs. Therefore, when the roll paper or sprocket paper is inserted, the user manually retracts the bail roller to the retracted position while the roll paper or the sprocket paper is inserted, and the bail roller is returned to the holding position after the paper is securely wound around the platen. . However, in recent automated printers, it is desired that such bail rollers can be automatically opened and closed, and some automatic opening and closing devices have been proposed in the past. Conventionally, an automatic bail roller opening / closing mechanism generally has a dedicated solenoid or motor for driving a bail lever. After detecting insertion of a sheet by a sensor, the bail roller is driven by a predetermined control program to drive the solenoid or motor. There is a type that opens and closes.

However, in this conventional apparatus, various drive mechanisms are required only for opening and closing the bail roller, and there is a problem that the apparatus becomes large or the price of the printer is increased. Improvements have been required for cost printers.

Further, as a conventional automatic bail roller opening / closing mechanism, an apparatus using a carriage feed driving force instead of a plunger or a dedicated motor has been proposed.

For example, a mechanism disclosed in Japanese Patent Application Laid-Open No. 63-49465 is an example. This mechanism transmits a rotational driving force of a paper feed roller to a rotating cam via a clutch, and a bail which is in contact with the cam. The lever is made freely openable and closable, and the clutch disengagement operation is performed by moving the carriage out of the printing area. This mechanism is convenient because the bail can be automatically opened and closed without using a plunger and a dedicated motor, but has the following disadvantages. That is, (1) When the user tries to open the bail lever in the closed state by manual operation, the bail lever always tries to close due to the urging force of the spring 13 and cannot be held in the open state.

[0007] Therefore, when the user attempts to set the paper by manual operation, it is necessary to keep the bail closed by hand so as not to close, and the operability is extremely poor.

(2) When the bail is open, that is, when the cam lifts the bail, the bail cannot be closed by hand. If it is forcibly operated, the cam mechanism or the bail lever will be damaged.

(3) The arm 9 that engages with the carriage and rotates according to the operation of the carriage is not provided with a portion for absorbing the force, so the amount of movement after the engagement of the carriage with the arm is erroneous. If it is too large, parts will be damaged. In the power-off state, it is rare that the carriage moves until it hits the frame, such as when the user manually operates the carriage for ribbon exchange etc. In such a case, problems such as chipping of the carriage, deformation of the arm, and chipping of the gear occur.

(4) It is necessary to recognize where the cam is stopped when the power is turned on, and to perform an initialization operation to a predetermined position. This is because not only does the carriage, paper feed roller (platen) and bail lever operate unpleasantly every time the power is turned on, but also the paper feed for initialization operation when the power is turned on with the paper inserted. The driving of the rollers causes the set paper to be displaced and causes a problem that normal paper feeding cannot be performed.

Further, the control of the cam requires a detecting means such as an encoder for knowing the rotational position of the cam, which causes an increase in cost.

As described above, although an automatic opening / closing mechanism is achieved without a dedicated driving source, the conventional manual operability of the user is sacrificed, and furthermore, it is easy to be damaged by a slight operation mistake or the like, and the function is not sufficient. It could not be said.

As another example, Japanese Patent Application Laid-Open No. 63-4 / 1988 discloses a simpler configuration while ensuring manual operability.
No. 2879 is known. The present invention has a mechanism for manually opening the bail lever and holding the bail in the open state.When the carriage moves out of the printing area, the carriage collides with a release mechanism for releasing the open holding state. , The bail lever is returned to the closed state. The present invention allows printing from the upper end of the paper, but has the following disadvantages. In other words, the carriage always moves out of the printing area at the moment when the bail lever is closed, so that when the bail is closed, the paper is left and right biased, and skew occurs in the subsequent paper feed, and the printing is bent. This is a problem of causing skew. This phenomenon is a well-known phenomenon. Generally, when performing an operation of closing a bail, the carriage is temporarily moved to a position near the center of the sheet (this operation is generally called centering), and the print head or The skewing is prevented by closing the bail in a state where the paper is supported substantially equally in the left and right directions by a guide or the like provided on the carriage. Therefore, in this example, although a simple mechanism is used, the mechanism in which the carriage cannot be centered causes a fatal defect of paper skew.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and automatically performs a closing operation of a bail lever without using a dedicated driving source, while not impairing manual operability. It is another object of the present invention to provide a printer which eliminates the danger of damage to parts and the like. A further object of the present invention is to provide a high-quality printer at a low price, which eliminates an unsightly initialization operation at power-on. Also,
It is a further object of the present invention to provide a printer of high print quality that enables the paper to be set without skew of the paper.

[0015]

In order to achieve the above object, the present invention provides a platen on which a sheet is wound, a paper feed gear for driving the platen to rotate, and reciprocatingly moving along the axial direction of the platen. In a paper holding device for a printer, comprising: a carriage carrying a print head; and a bail roller supported by a swingable bail lever and pressing a sheet against a platen surface, a holding position at which the bail roller is pressed against the platen and a platen. A toggle spring for positioning and holding at an open position separated from the
A bail gear provided at a rotation support portion of the bail lever for receiving a force for rotating the bail lever; a driving position supported by a rotatable idle lever for connecting the paper feed gear and the bail gear; An idle gear that can move to both of the retracted positions, a return spring that applies a return biasing force to the idle lever toward the retracted position of the idle gear, and a return spring that is provided on the carriage, and that moves when the carriage moves out of the print area. A pressing piece that engages with the idle lever and moves the idle gear to a driving position;
Wherein the idle gear includes the paper in a driving position.
Transmitting the driving force of the feed gear to the bail gear,
Driving force from the paper feed gear and driving to the bail gear
Is held in the driving position by the driving reaction force of the force, while
The biasing force of the toggle spring moves the bail lever to the paper holding position.
When working in the opposite direction, the biasing force
Due to these driving forces and the driving reaction force from the paper feed gear.
It is arranged at a position that receives a return force to the escape position.

[0016]

Therefore, according to the present invention, the bail roller is manually opened once when the sheet is inserted, and the bail roller opening position is self-held by the toggle spring.

When the sheet is sucked, the leading end is correctly detected by a predetermined sensor or the like. When the leading end of the sheet passes the bail roller position by a predetermined amount of paper feeding, the carriage moves out of the printing area, and The idler lever is forcibly moved from the retracted position to the drive position by the pressing piece. In this driving position, the idle gear meshes with the paper feed gear and the bail gear, and the paper feed driving force is transmitted to the bail gear, and the bail lever rotates.

In this state, once the idle gear is engaged at the driving position, the idle gear is caught between the paper feed gear and the bail gear even if the drive is stopped, and is no longer released by the return biasing force of the return spring. Self-holding in the drive position without any

Therefore, if necessary, in this bail gear coupling state, the carriage does not need to hold the idle lever in the pressed state, and can be freely moved to an arbitrary position for centering or other purposes.

When the paper feed gear drives the bail gear via the idle gear and the bail lever exceeds the neutral position of the toggle spring, the toggle spring instantaneously rotates the bail lever to a holding position for pressing the bail roller against the platen. Therefore, the driving force of the toggle spring provides a reliable bail roller holding position, and the bail gear rotates at a high speed prior to the idle gear, so that the idle gear no longer performs a self-holding operation at the drive position in the drive gear train. It is not possible to kick back to the retracted position by the bail gear, and it is possible to return to the original retracted position.

Therefore, according to the present invention, a reliable bail roller automatic closing operation can be performed with a simplified structure,
In addition, there is an advantage that the carriage can be freely moved merely by moving the idle lever to the driving position and not requiring a subsequent holding action.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a main part of a paper holding device of a printer according to the present invention. As is well known, both ends of the platen 10 are supported by a printer base frame 11, and 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.

The carriage stay 1 is mounted on the printer base frame 11.
4 is fixed parallel to the platen shaft 12, and a carriage 15 is held on the carriage stay 14 so as to be able to reciprocate. A print head 16 is carried on the carriage 15 as is well known, and the print head 16 shown in the figure is formed of a wire dot head. The desired printing action is performed on the top. 15-
Reference numerals a and 15-b denote paper guides formed on a carriage located on both sides of the print head to guide the paper along the platen.

A bail roller 17 is rotatably opposed to a pressing position and an opening position with respect to the platen 10 in order to firmly hold the sheet in close contact with the platen 10. A roller shaft 19 supported at the tip of the bail lever 18 is rotatably provided. The bail lever 18 is mounted on the support shaft 2.
Reference numeral 0 denotes a rotatable support on the printer base frame 11.

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 in FIG.
0 is to be provided to an automatic closing operation using the driving force of the paper feed gear 13 to the holding position where the bail lever 18 is pressed as shown in FIG.
The bail gear 21 is formed on the rotation support end side of the bail gear, and the bail gear 21 in the embodiment is formed of a gear having about 3/4 circumference.

The bail lever 18 of the present invention
1 is held by the toggle spring 22 at both the open position in FIG. 1 and the pressing position where the platen 12 and the bail roller 17 described below are pressed. That is, the toggle spring 22
Means that the bail lever 18 is closer to the open position than the neutral point
Sometimes this is biased towards the open position while the bail lever
-18 is located at the presser position from the neutral point.
Bias toward the presser position. Thus, toggle spring 2
2 changes the direction of the biasing force at the neutral point.

[0028] have idle gear 23 is provided for transmitting the driving force of the paper feed gear 13 to Beirugiya 21
You. When the idle gear 23 is in the driving position and the paper feed gear
A when transmitting the driving force from the
The positional relationship between the gears is as follows. That is,
The bail lever 1 is driven by the rotational driving force of the paper feed gear 13.
8 from the open position to the holding position against the toggle spring 22
When driving the paper feed gear 13
The force acting on the tooth surface of the gear 23 and the idle gear 23
The force acting on the bail gear 21 is applied to the tooth surface as a reaction force.
Of the idle gear 23 in the paper feed gear
Acts so as to be drawn between the hole 13 and the bail gear 21
Each gear is arranged in a position. Further, the idle gear 23 is rotatably supported by the swinging end of the idle lever 24, the idle lever 24 is rotatably printer base frame 11 by a shaft 25 journalled. Further, an elastic receiving arm 24a extends from the root side of the idle lever 24 in the embodiment, and a carriage 15 described later.
Can be engaged with the pressing piece. Further, a return spring 26 shown by a broken line is hung on the idle lever 24, and constantly urges the idle lever 24 with a weak urging force in the clockwise direction in FIG.

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

FIG. 6 shows the configuration of the control unit of the above embodiment. A CPU 40 for controlling printing and paper feeding of the printer is provided. The CPU 40 includes a ROM 41 storing a control program and the like. , A RAM 42 for storing print data received from a host computer, operation information during operation, and the like, and an I / F (interface) 43 for connecting the printer to an external host computer.
Is connected. Further, the print head 16, the carriage motor 44, and the paper feed motor 45 are each connected to a CPU via a drive circuit. Also, the paper sensor 28,
Each output signal of the bail SW 30 is also input to the CPU 40 and its state is monitored by a program, and a command such as a page break or line feed from the operation panel 46 is input.

The embodiment of FIG. 1 is constructed as described above, and the operation of opening and closing the bail lever will be described below with reference to the respective operating states of FIGS.

FIG. 2 shows a state of the printer when paper insertion is started. The bail roller 17 is in a closed state, that is, in a holding position where the bail roller 17 is pressed against the platen 10. This holding position is self-held by the toggle spring 22. On the other hand, the idle gear 23 is also held at the retracted position rotated clockwise by the return spring 26. In this state, the idle gear 23 is moved to the paper feed gear 13 and the bail gear 21.
It is understood that the user has retreated to a position away from both. A pinch roller 29 is in pressure contact with the platen at the paper insertion opening, and the paper
00 is set.

In the present invention, the opening operation of the bail roller 17 when the sheet is inserted, that is, the movement to the open position, is performed manually. FIG. 3 shows this opening operation, and the bail roller 17 is manually operated as shown by an arrow A. is moved, the opening position is held by the toggle spring 22. In the state shown in the drawing, when the bail lever 18 is opened, the bail SW 30 is turned from OFF to ON, and the paper feed operation is started under the control of the CPU 40 in response thereto. First, the paper feed motor 45 is driven, and the paper starts to be sucked. The leading edge of the sheet 100 is detected by a sheet sensor 28 provided at a predetermined position,
Thereafter, the position of the leading edge of the paper 100 can be always known correctly by counting the paper feed drive pulse. A predetermined amount of paper is fed according to the setting of the user's desired print start position, the paper is set, and the printer is brought online. The leading edge of the sheet is positioned in the printing section in front of the print head, and upper end printing is possible.

When a print command is received from the host computer, printing and line feed are started. After the print line feed of several lines is executed, the paper advances, and when the total feed amount after the paper sensor 28 detects the leading edge of the paper exceeds a predetermined amount, the CPU 4 determines
0 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 has passed between the bail roller 17 and the platen 10 to reach a position where the bail can be closed. The CPU 40 sends a drive pulse to the carriage motor 44 to move the carriage 1 in the direction indicated by the arrow B in FIG.
Move 5 When the carriage 15 moves further to the left than the left end of the print area and stops, the pressing piece 27 of the carriage 15 engages with the elastic receiving arm 24a of the idle lever 24 as shown in FIG. As a result, the idle gear 23 can be moved to a position where it meshes with both the paper feed gear 13 and the bail gear 21. In this position
The idle gear 23 receives the driving force of the paper feed gear 13
Rotate. At this time, the paper feed gear 21 and the idle gear
The force acting between 23 is the common pitch circle of the two gears.
Work that crosses the tangent with the pressure angle in the gear specifications
Face the direction of the service line. In FIG. 4, the idle gear 23
Is the driven side, so the driving force from the paper feed gear 13 is
To move the idle gear 23 almost in the upper right direction in the figure.
The power to work works. On the other hand, the idle gear 23 is a bail gear.
The toggle spring 22 moves the bail lever 18 to the open position.
And rotate in the direction of the arrow in the figure against the urging force.
That is, the idle gear 23 becomes the drive gear, and the bail
The gear 21 is a driven gear. Therefore, at this time
The idle gear 23 is a reaction force for driving the bail gear 21.
The pressure angle to the common tangent to the pitch circle of the two gears.
It receives a driving reaction force in the direction of the acting line having an inclination. This drive
Move the idle gear 23 almost to the left in the figure.
It is the direction to be moved. And in this embodiment,
From the paper feed gear 13 added to the idle gear 23
The resultant force of the driving force and the driving reaction force from the bail gear 21 is
Pull the dollar gear 23 between the other two gears 13 and 21
I'm working on it. As a result, idle gear 2
3 is held at a position where it meshes with the other two gears 13 and 21
Is done. In this state, the CPU 40 controls the paper feed motor 4
5 is slightly rotated 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 the driving force and the driving reaction force between the gears described above.
And held at the drive position. Therefore, the idle gear 23 can maintain the state shown in FIG. 4 even if the carriage 15, that is, the pressing piece 27 is separated from the receiving arm 24a.

Of course, the urging force of the return spring 26 is set weaker than such a gear rotation holding force.

In the embodiment, the receiving arm 2
Since the pressing member 4a has elasticity, an excessive force is released by a bending action so that an excessive force is not applied to the idle gear 23 when the pressing member 27 of the carriage 15 is pressed.

Next, the carriage 15 moves toward the center of the sheet, and the paper guides 15-a and 15-b support the bend from the back of the sheet 100 to cope with the subsequent closing operation of the bail. FIG. 5 shows the operation in which the bail lever 18 is closed. When the paper feed motor 45 is driven to rotate forward, 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 the bail roller 17
Is moved at a high speed toward the position where it is pressed against the platen 10, and the bail roller 17 itself reliably moves to the closed position with the paper 100 interposed therebetween.

At this time, a characteristic of the present invention is that the bail gear 21 kicks the idle gear 23 back to the retracted position as shown by an arrow E with the bail lever 18 rotating at a high speed. Idle lever 2
4 is quickly rotated to the retracted position by both the kickback force and the return biasing force of the return spring 26. This is further elaborated
Then it becomes as follows. The bail lever 18 rotates
When the biasing force of the toggle spring 22 exceeds the neutral point, the toggle
The biasing force of the spring 22 pushes the bail lever 18 toward the holding position.
Work in the direction, which allows the idle gear 23
The relationship between the drive and the drive of the device 21 is reversed. Therefore,
The idle gear 23 is rotated by the biasing force of the toggle spring 22.
It is driven by the rotating bail gear 21. But
The idle gear 23 and the bail gear 21 at this time
In FIG. 5, the force acting in between is as follows.
Acts to move the idle gear 23 almost in the lower right direction.
Good. Therefore, the paper feed gear added to the idle gear 23
13 and the driving force from the bail gear 21
The resultant force is to change the idle gear 23 from the other gears 13, 21
Work in a direction away from it, thereby meshing the three gears
The condition is resolved. Further, the biasing force of the toggle spring 22 is
Quickly rotate the bail lever 18 to the holding position
So the idle gear 23 is kicked back by the bail gear 21
You. Then, the kick-back operation and the biasing of the return spring 26 are performed.
It is turned to the retracted position by the force and returned by the return spring 26.
It is held in the leverage position.

Therefore, the apparatus itself returns from the state shown in FIG. 5 to the state shown in FIG.
In contrast, as shown in the figure, the bail roller 17 is advanced to the position where it is sandwiched between the bail roller 17 and the platen 10, so that 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 24 is held at the driving position as the state of the mechanism, and the paper feed motor 45 is slightly reversed. Due to this slight reverse rotation, the engagement of the idle gear 23 in the holding state is released, the idle lever 24 returns to the retracted position, and the clutch mechanism is brought into the initial state. Subsequent operations are performed in the same manner as in 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 by the idle gear controlled by the carriage. Thus, the bail roller automatic closing action can be achieved.

[0043]

As described above, according to the present invention,
The bail roller can be reliably automatically returned to the closed position with a simplified structure.

In addition, the number of parts is reduced as compared with the conventional mechanism, and the operability by manual operation is maintained while the structure is simple.
In addition, it is possible to provide a highly reliable printer that does not cause component damage or the like. When compared with the automatic paper setting operation, the operation of the paper feed SW in a conventional printer or the like can be performed only by replacing the manual operation of opening the bail lever. This is an invention that can realize almost the same operability as an automatic type and is very useful in practical use.

Further, since the carriage can be centered at the moment when the bail lever is closed, the occurrence of skew can be prevented.

Further, as compared with the conventional mechanism using a cam for the bail operation, the present invention is excellent in that an unsightly operation of the initialization operation at the time of turning on the power is not required.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part showing a preferred embodiment of a paper presser of a printer according to the present invention.

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

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

FIG. 4 is an operation explanatory diagram 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 print area.

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

FIG. 6 is a block diagram illustrating a mechanism of a control unit according to the embodiment.

[Explanation of symbols]

 Reference Signs List 10 platen 13 paper feed gear 15 carriage 16 print head 17 bail roller 18 bail lever 21 bail gear 22 toggle spring 23 idle gear 24 idle lever 26 return spring 27 pressing piece 100 paper

Claims (1)

(57) [Claims] 1. A platen on which a sheet is wound, a paper feed gear for driving the platen to rotate, a carriage reciprocating along the axial direction of the platen and carrying a print head, and supported by a swingable bail lever. A bail roller for pressing the sheet against the surface of the platen, a toggle spring for positioning and holding the bail lever at a holding position at which the bail roller is pressed against the platen and an escape position retracted from the platen. A bail gear provided on the rotary support portion for receiving a force for rotating the bail lever; a drive position supported by the rotatable idle lever to connect the paper feed gear and the bail gear; and a retracted position retracted from both. An idle gear that can move freely between the two, and idle the idle lever A return spring for applying a return biasing force toward the retracted position of the a, a pressing piece provided on the carriage and engaging the idle lever to move the idle gear to the driving position when the carriage moves out of the printing area. And wherein the idle gear transmits the driving force of the paper feed gear to the bail gear at the driving position, and at this time, the idle gear is held at the driving position by the driving force from the paper feeding gear and the driving reaction force of the driving force to the bail gear. On the other hand, when the biasing force of the toggle spring acts on the bail lever in the direction of the paper holding position, the biasing force is arranged at a position receiving the driving force from the bail gear by this biasing force and receiving the return force to the retracted position. paper printer push
For example apparatus.