JPS63230374A - Printer - Google Patents

Abstract

PURPOSE:To enable a paper to be continuously fed at a high velocity by a single motor and eliminate the need for preparatory operations for a head pressing and releasing operation or a paper-feeding operation, by pressing or releasing a thermal head from a platen only while paper feed is set in a slipping condition by a slipping means at the time of reversion of a paper-feeding direction. CONSTITUTION:The driving force of a motor 24 is switched between two directions by a solenoid 25, which is a drive source for switching, and a switching means 26. When the solenoid 25 is not excited, the driving force of the motor 24 is transmitted to a carriage-moving means 27 to move a carriage which supports a thermal head thereon. When the solenoid 25 is excited, the driving force of the motor 24 is transmitted to a paper-feeding means 29 through a slipping means 28. The slipping means 28 has the function of causing slippage, without feeding a printing paper, for a predetermined amount at the time of reversion of a paper-feeding direction, and only during the slippage, a head pressing and releasing means 30 can be operated to press or release the thermal head from the platen.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a printer, such as a thermal printer using thermal paper or thermal transfer ink ribbon, which performs printing with a print head in pressure contact with a platen loaded with paper. In particular, the present invention relates to a drive system for a serial printer that performs printing by moving a carriage carrying a print head and printing paper in perpendicular directions.

2. Description of the Related Art In general, serial type thermal printers include a carriage moving means for reciprocating a carriage in one direction;
There are three driving means: a paper feeding means that drives the printing paper in a direction perpendicular to the carriage, and a head separating means that presses the thermal head against the platen during printing and separates the thermal head from the platen during non-printing and paper feeding. is necessary.

High-end models are equipped with separate drive sources such as motors and solenoids for each drive, but small and low-priced models are able to switch the driving force of one motor and drive the motors alternately. many.

In this case, a switching means for switching the driving force is required, but the device can be made smaller and lighter and the cost can be reduced.

Hereinafter, a conventional technique for driving the above three means with one motor will be explained based on the drawings.

FIGS. 8 to 10 are block diagrams showing a driving force transmission system for a thermal printer according to the prior art.

A first conventional example shown in FIG. 8 uses only one motor as a drive source. The motor 1 is connected to the carriage moving means 2 via a slipping means 3 that slips the carriage movement by a certain amount when the moving direction of the carriage is reversed. During the slippage of the carriage movement, the cam 4 and the one-way clutch 5 are used to drive the paper feeding means 6 and the head separation means 7.

A second conventional example shown in FIG. 9 uses one motor and one solenoid as drive sources.

The solenoid 8 has a switching means 96A- connected thereto.
, : are used to switch the driving force of the motor 10 in two directions, and when the solenoid 8 is not excited, only the carriage moving means 11 is driven. When the solenoid 8 is energized, the driving force of the motor is further switched between two directions by the switching means 12 according to the previous carriage movement direction. That is, immediately before the solenoid is energized, when the carriage moves in the printing direction, the carriage moving means and the head separation means are simultaneously driven, and when the carriage is driven in the return direction opposite to the printing direction, the paper feeding means is driven. It is driven.

The third conventional example shown in FIG. 10 is published utility model publication 61-
This is shown in No. 8165 and uses one motor and one solenoid. As in the first conventional example, the motor 15 is connected to the carriage moving means 17 via the slip means 16, and to the head separating means 2o via the clutch 19 operated by the solenoid 18. When the solenoid 18 is energized and the clutch 19 is connected during slippage of the carriage movement, the head contact/separation means 2o is driven by 62 and.

Further, the motor 15 is connected to a paper feeding means 22 via an intermittent feeding mechanism 21, and feeds the printing paper by a certain amount in the forward paper feeding direction in response to one reciprocating movement of the carriage.

Problems to be Solved by the Invention However, when driving the paper feeding means, in the first conventional example, the cam operation is repeated within the slip range of carriage movement, and in the third conventional example, the carriage By reversing the reciprocating motion, the paper is fed little by little, making the paper feeding speed extremely slow. In addition, since slip is provided in the carriage movement, each time the carriage is moved after the head approaches and leaves the paper, it is necessary to return the amount of slip to the original amount. However, there was a problem in that the total printing time became long.

Furthermore, in the second conventional example, the driving of the head separating means and the driving of the paper feeding means are switched depending on the direction in which the carriage was moved immediately before, so that 7A is required.

In addition, a preparation operation for moving the carriage is required before the head approaches and separates and the paper is fed, which slows down the total printing speed and makes control difficult. Furthermore, since the head detachment operation is performed at the same time as the carriage movement operation, a motor with a large drive torque is required and power consumption is also large. Furthermore, an extra carriage movement section is required to carry out the head detachment operation, resulting in a problem that the apparatus becomes larger.

Therefore, the present invention provides a thermal printer with a high total printing speed, which can feed paper continuously at high speed with a single motor, and does not require preparatory operations for head detachment and paper feeding operations. It provides:

Means for solving the problems and technical means of the present invention for solving the above problems include a driving motor and a driving force of the motor connected to either the carriage moving means or the paper feeding means. a switching drive source for driving the switching means; a slipping means for slipping the paper feed by a certain amount when the paper feeding is reversed between the forward direction and the reverse direction; The thermal head is provided with head contact/separation means that operates only while the thermal head is slipping to bring the thermal head into contact with and away from the platen.

action The effect of this technical means is as follows.

That is, since the driving force of the motor is switched and connected to either the carriage moving means or the paper feeding means by the switching means, paper feeding can be performed continuously;
Paper feeding speed can be increased. However, since a slip is provided in the paper feed rather than the carriage movement, it is possible to immediately shift to the carriage movement operation by simply operating the switching means after the completion of the head contact/separation operation or the paper feed operation. Unlike the third conventional example, there is no need for wasted operation or time to restore the slipped amount.

Further, the carriage movement and paper feed/head contact/separation operation can be switched depending on whether or not the switching means is operated by the switching drive source, and the paper feed and head contact/separation operation can be selected depending on whether or not the paper feed is to be caused to slip. -17. Therefore, there is no need for preparatory operations before performing the desired operation, which improves the total printing speed and simplifies control. In addition, since the three operations of carriage movement, paper feeding, and head separation are performed independently, the drive torque and power consumption are smaller than in the second conventional example, and the extra carriage movement for head separation is unnecessary. There is no need for an interval.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 is a block diagram showing a method of transmitting motor driving force of a thermal printer according to the present invention.

In FIG. 1, the driving force of the motor 24 is controlled by a solenoid 26, which is a switching drive source, and a switching means 26.
The direction can be switched. When the solenoid 25 is not excited, the driving force of the motor 24 is transmitted to the carriage moving means 27 to move the carriage on which the thermal head is mounted. When the solenoid 25 is excited, the driving force of the motor 24 is transmitted to the paper feeding means 29 via the slip means 28. The slip means 28 has a function of slipping the print paper for a certain amount of time when the paper is reversed between the forward and reverse directions, and only during this slip, the head contact/separation means 3Q operates. This allows the thermal head and the platen to be brought into contact and separated from each other.

Hereinafter, the structure of an embodiment of the present invention will be explained using FIGS. 2 to 6.

FIG. 2 is a plan view of the drive unit in the printing state of the thermal printer of this embodiment, FIG. 3 is a vertical sectional view of FIG. be.

In FIGS. 2 and 3, the sun gear 33 of the planetary gear mechanism
is fixed to the motor shaft 32 of the motor 31. The planetary gear mechanism includes a sun gear 33 and a planetary gear 3 that meshes with the sun gear 33.
4. An arm gear 35 that holds the planetary gear 34 and has a gear 35a on its outer periphery; an internal gear 36a that meshes with the planetary gear 34;
and an inner gear 36 having an external gear 36b.

In addition, in FIG. 2, this planetary gear mechanism portion 11.
Only \ represents the BB cross section in Figure 3.

The carriage moving means includes a pulley gear 37 that meshes with the arm gear 35, and a pulley gear 37 that is fixed to the carriage 38.
The timing belt 39 is driven by a pulley portion 371L of No. 7, and a guide shaft 49 that guides the carriage 38.

The paper feeding means includes an idler gear 4Q that meshes with the external gear 36b of the inner gear 36, a paper feeding gear 41 that meshes with this,
Slip gear 42, paper feed roller 43, and paper feed roller 4
3 and a bevel gear 44 that meshes with a bevel gear 420 of a slip gear 42. Both the paper feed gear 41 and the slip gear 42 are rotatably mounted around a shaft 64. When the paper feed gear 41 rotates counterclockwise from the state shown in FIG.
However, as the protrusion 41& presses against the wall 42a, the paper feed roller 243 rotates via the bevel gear 44 and feeds the printing paper (not shown) in the forward direction. Further, when the paper feed gear 41 rotates clockwise, the protrusion 41a slips until it hits the wall 42b of the slip gear 42, and then the protrusion 411L pushes the wall 42b, so that the printing paper is sent in the opposite direction. That is,
A slip means for slipping the paper feed by a certain amount when the paper feed is reversed between the forward and reverse directions is constituted by the paper feed gear 41 and the slip gear 42.

The switching means includes the above-mentioned planetary gear mechanism and the stonova 46.
, and a spring 46, and is driven by a solenoid 47 which is a switching drive source. The stopper 45 is rotatably mounted around a shaft 48 and biased counterclockwise by a spring 46. FIG. 2 shows a state in which the solenoid 47 is not energized, and the rank 45 of the stopper 45
& meshes with the paper feed gear 41 to fix the paper feed means. Also, idler gear 40. The rotation of the inner gear 36 is also fixed. When the motor shaft 32 is rotated in this state, the arm gear 35 rotates and the carriage 38 moves via the pulley gear 37.

13t, when the solenoid 47 is energized, the stopper 45 rotates clockwise, the rack 45b meshes with the gear 35tL on the outer periphery of the arm gear 35, and the carriage moving means connected to the arm gear 35 is fixed. In this state, the motor shaft 32
When rotated, the inner gear 36 rotates, and the paper feed gear 41 is driven via the idler gear 40.

The head separating means includes an inner gear 36 and a pair of oscillator gears 50 and 51 that mesh with an external gear 36b of the inner gear 36;
A pendulum lever 52 that holds a pendulum gear 50, 51 and is rotatably mounted around an inner gear shaft 65, a friction plate 61 made of felt or the like, a spring 62 that presses the pendulum lever 62 against the inner gear 36, A cam gear 53, a cam follower 55 that is driven by the cam portion 53a of the cam gear 53 and rotates around the pulley gear shaft 54, and a head holder drive plate 66 that is rotatably attached to the guide shaft 49 as shown in FIG. , a head holder 58 that holds the thermal head 57, and a head pressure spring 63 suspended between the head holder 58 and the carriage 38.

Note that 59 is a platen for loading printing paper, and 6o is a ribbon cassette containing a thermal transfer ink ribbon (not shown).0 The three operations of the thermal printer of this embodiment configured as above are described below. Explain.

As shown in FIG. 1, the carriage movement operation is performed by rotating the motor without energizing the solenoid.

In FIG. 2, since the solenoid 47 is not energized, the stopper 45 is biased counterclockwise by the spring 46, and the rack 45a engages with the paper feed gear 41, causing the inner gear 36 to move through the idler gear 4o. Fixed. When the motor shaft 32 is rotated in this state, since the inner gear 36 is fixed, the driving force of the motor 31 rotates the arm gear 35 via the sun gear 33 and the planetary gear 34. Then, the carriage 38 is moved left and right via the pulley gear 37 that meshes with the arm gear 35 and the timing belt 3915A.

Note that when the motor shaft 32 is rotated in the direction of arrow E, the carriage 38 moves rightward, and when the motor shaft 32 is rotated in the direction of arrow E, the carriage 38 moves leftward.

Next, the head contact/separation operation will be explained.

FIG. 2 shows the printing state as described above, and at this time, the thermal head 57 is pressed against the platen 59 by the head pressure spring 63 as shown in FIG.

As shown in FIG. 1, the head detachment operation is performed only while the solenoid is energized to rotate the motor and the paper feed is being slipped by the slip means.

When the solenoid 47 is energized from the printing state shown in Fig. 2,
The stopper 45 rotates clockwise, and the rack 46b meshes with the gear 35 & of the arm gear 35 to fix it.

When the motor shaft 32 is rotated in the direction of arrow E in this state, the inner gear 36 is rotated counterclockwise via the planetary gear 34. Pendulum lever 52, friction plate 61 and spring 62
As a result, the pendulum gear 60 is rotated in the same direction as the rotation of the inner gear 36, and the pendulum gear 60 is pressed against and engaged with the gear portion 53b of the cam gear 63, as shown in FIG. Subsequently, when the motor shaft 32 is rotated in the direction of arrow E, the cam gear 53 rotates counterclockwise, and the cam follower 55 rotates clockwise around the pulley gear shaft 54 by the cam portion 531L. The movement of the cam follower 56 is caused by the movement of the head holder driving plate 56 and the head holder 58 shown in FIG.
The thermal head 57 is separated from the platen 59 by rotating it counterclockwise against the pressure.

The cam gear 63 includes a cam portion 53a and a gear portion 53°53b.
, 53 (1 and a notch 630 are provided,
When the cam gear 53 is rotated a certain amount counterclockwise by the pendulum gear 5o, the pendulum gear 50 and the cam portion 53t of the cam gear 53 are disengaged, resulting in the state shown in FIG. 6. FIG. 6 shows the end of the head detachment operation. In addition, in FIG. 6, the part of the planetary gear mechanism is omitted.

17 Bay 7 The press-contact operation between the thermal head 67 and the platen 59 is opposite to the above-described head detachment operation.From the state shown in FIG. 6, the solenoid 47 is energized and the motor shaft 32 is moved in the direction of the arrow in FIG. This is done by rotating the That is, when the motor shaft 32 is rotated in the direction of the arrow, the inner gear 36 rotates clockwise and the pendulum lever 62 also rotates clockwise. Then, the pendulum gear 51 meshes with the gear portion 53d of the cam gear 63, the cam gear 63 rotates clockwise to the position shown in FIG. 2, and the head holder drive plate 66 and the head holder 68 return to the state shown in FIG. 4. The thermal head 67 is pressed against the platen 69 by the head pressure spring 63 .

During the above-described head separation operation, the inner gear 36 rotates, so the paper feed gear 41 rotates via the idler gear 4o. However, between FIG. 2 and FIG.
, 42b, the slip gear 42, the bevel gear 44 connected thereto, and the paper feed roller 43 do not rotate, and the paper is not fed.

Next, the paper feed 9 operation will be explained.

From the state where the head detachment operation is completed in Fig. 6, solenoid 4
i excited 7! 1. When the inner gear 36 is further rotated counterclockwise by the motor 31, the idler gear 40
The paper feed gear 41 is rotated counterclockwise via the . Then, the protrusion 41a of the paper feed gear 41 is connected to the wall 4 of the slip gear.
2a, the slip gear 42 also rotates in the same direction, and a bevel gear 420 rotates a paper feed roller 43 fixed to a bevel gear 44 to feed the printing paper in the forward direction.

Further, when the solenoid 47 is energized and the inner gear 36 is rotated clockwise from the printing state (head pressure contact state) shown in FIG. 2, the paper feed gear 41 is rotated clockwise, and the protrusion 4
11L pushes the wall 42b of the slip gear,
Paper feed roller 43 rotates to feed the printing paper in the opposite direction. However, if the thermal head 67 is pressed against the platen 69 and the printing paper is fed while sandwiching it, there is a risk that the printing paper 19A will be fed diagonally. , it is necessary to move the thermal head 57 out of the range of the printing paper.

Note that since the notch 53C is provided in the cam gear 53, even if the inner gear 36 rotates and the pendulum gear 5o or 51 rotates during paper feeding operation, the cam gear 53 is not driven and the head separation state does not change. do not have. That is, the head detachment operation is performed only during the slippage of paper feeding.

As described above, according to this embodiment, the driving force of the motor 31 is switched by the flenoid 4, the stopper 45, and the spring 46 to connect it to either the carriage moving means or the paper feeding means. can be performed continuously and at high speed. However, due to the provision of a slip in the paper feed,
If the solenoid 47 is de-energized after the head approaches and separates and the paper is fed, the carriage movement operation can be started immediately, so there is no need to waste time or to restore the amount by which the paper feed has slipped. do not have.

Furthermore, compared to the second conventional example, no preparatory operation is required before performing a desired operation, the total printing speed is improved, and control is simple.

Furthermore, since the three operations of carriage movement, head contact/separation, and paper feeding are performed independently, both driving torque and power consumption are small, and an extra carriage movement section for head contact/separation is not required.

In addition, since the planetary gear mechanism and the stopper 45 are used as the switching means, the means for moving the carriage and feeding the paper is always connected in gear to the sun gear 33 fixed to the drive motor shaft 32 and then disconnected. Since there is no interference, the switching operation is reliable and reliability can be improved.

A second embodiment of the present invention will be described below.

This embodiment is a thermal printer configured such that the thermal head is always separated from the platen when a paper feeding operation is performed.

FIG. 7 is a plan view of the drive unit in the printing state of the thermal printer of this embodiment.

In FIG. 7, the shapes of the slip gear 66, pendulum lever 67, pendulum gears 68, 69, cam gear 70, and cam follower 71 are different from those in FIG. 2, which shows the printed state of the first embodiment on page 21. It is different and the pendulum gear 68
．． 69 and a pendulum idler 72 that meshes with the cam gear 7o.
73 has been added ○For other parts, see Part 1.
This is the same as the embodiment shown in FIG. 7, and the planetary gear mechanism portion is omitted in FIG. In addition, in the printing state shown in FIG. 7, the thermal head 6 as shown in FIG.
7 is pressed against the platen 69.

The operation of this embodiment will be explained below.

The carriage moving operation is exactly the same as in the first embodiment, so the explanation will be omitted.

When the solenoid 47 is energized from the state shown in FIG.
The arm gear 36 is fixed in the same manner as in the embodiment.

In this state, when the motor rotates the inner gear 36 counterclockwise, the pendulum lever 67 rotates in the same direction as the inner gear 36, the pendulum gear 68 meshes with the pendulum idler 72, and the cam gear 22''-70 is rotated. Rotate clockwise.The rotation of the cam gear 70 is as follows:
When the notch portion 70b rotates to the position of the pendulum idler 72, it is disengaged and stops. As a result, as in the first embodiment, the movement of the cam portion 70a of the cam gear To is transmitted to the head holder 68 via the cam follower 71 and the head holder drive plate 66, and the thermal head 57 separates from the platen 59.

At this time, that is, from the printed state shown in Fig. 7, the inner gear 3
The state in which the head is removed by rotating 6 counterclockwise is called a first head removal state.

During this head detachment operation, the paper feed gear 41 rotates counterclockwise via the idler gear 40, but as in the first embodiment, the protrusion 412L is connected to the wall 66a of the slip gear 66.
Since it does not hit, paper feeding is not performed.

From the first head detached state, the inner gear 36
When rotated counterclockwise, the protrusion 4 of the paper feed gear 41
1a hits the wall 661L of the cam gear 66, which rotates the bevel gear (not shown) and the paper feed roller 23 and the bevel 43, allowing the printing paper to be fed in the forward direction.

Furthermore, when the inner gear 36 is rotated 9 clockwise from the first head detached state, the pendulum lever 67 also rotates in the same direction, and the cam gear 7o is rotated counterclockwise via the pendulum gear 69 and the pendulum idler 72. rotate around. Then, when the cam gear 7o is turned to the position shown in FIG. 7, the head is brought into pressure contact state.

Next, from the printing state shown in FIG. 7, when the solenoid 47 is excited and the inner gear 36 is rotated clockwise, the cam gear To
rotates counterclockwise 9 at the groove where the notch 70d is located at the pendulum idler 73 and stops. As a result, the thermal head 57 also separates from the platen 59. This state is called the second head detached state.

During this time, the paper feed gear 41 rotates clockwise, but since the protrusion 41a does not hit the wall 66b of the slip gear 66, the paper is not fed.

When the inner gear 36 is further rotated clockwise from this second head detached state, the protrusion 411L of the paper feed 9 gear 41 hits and pushes the wall 66b of the slip gear 66, so that the printing paper is sent in the opposite direction. It is something that can be done.

As described above, according to this embodiment, the thermal head 57 can be separated from the platen 59 before paper is fed in both the forward and reverse directions. As a result, there is no need to move the thermal head 57 outside the range of the printing paper when feeding the paper in the opposite direction as in the first embodiment.

In addition, 1. In the second embodiment, a planetary gear mechanism and a stopper are used as the switching means to ensure switching, and a solenoid is used as the switching drive source, but these are, for example, an electromagnetic clutch, a motor, a cam, etc. This can also be achieved by means of

Further, regarding the carriage movement, paper feeding, and head separation means, various structures have been put into practical use in the past and are not limited to the structure of this embodiment.

5A Furthermore, although this embodiment describes a thermal printer, it can also be applied to other types of printers in which the print head is pressed against the platen during printing, and the print head is separated from the platen during non-printing and paper feeding. Needless to say.

Effect of the invention According to the present invention, the following effects can be obtained.

First, since a switching means is provided for connecting the driving force of the motor to either the carriage moving means or the paper feeding means, paper feeding can be performed continuously at high speed.

Second, since the slip is provided in the paper feed rather than the carriage movement, it is possible to immediately shift to the carriage movement operation by simply operating the switching means after the head separation/paper feeding operation. Unlike the third conventional example, there is no need to waste operating time to restore the slipped amount.

Thirdly, since the radial contact/separation operation is performed only while the paper feed is slipping, a preparatory operation is required before performing the desired operation as in the second conventional example, and the total printing Speed is increased and control is also simplified.

Fourth, since the three operations of carriage movement, paper feeding, and head separation are performed independently, the drive torque and power consumption are smaller than in the second conventional example, and the extra carriage movement required for head separation is unnecessary. No interval required. Conversely,
Since it can be driven by a smaller motor and the carriage movement section can be shortened, the device can be made more compact.

To summarize the above, according to the present invention, a printer that prints with the print head in pressure contact with the platen, such as a thermal printer, can be driven by one motor and one solenoid, and can continuously feed paper. Accordingly, it is possible to provide a compact and inexpensive printer that can perform high-speed printing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a motor driving force transmission system of a printer according to the present invention, and FIGS. 2 to 6 are diagrams showing the structure of a printer according to an embodiment of the present invention. is a plan view of the drive unit in the printing state;
The figure is Figure 2A - longitudinal cross-sectional view of a person, Figure 4 is Figure 2C
5 is a plan view showing the state immediately after the solenoid 47 is energized and the motor shaft 32 is rotated in the direction of the arrow from the printing state shown in FIG. FIG. 7 is a plan view of the drive unit in the printing state of the printer in the second embodiment, and FIG.
1 to 10 are block diagrams showing a conventional printer motor driving force transmission system. 24... Motor, 25... Solenoid, 26... Switching means, 27... Carriage moving means, 28... Slip means ,2
9... Paper feeding means, 3°... Head separation means, 31... Motor, 33... Sun gear, 34... Planetary gear, 36...
Arm gear, 36... Inner gear, 38...
... Carriage, 41 ... Paper feed gear, 42
...Slip gear, 45...Stopper, 47...Solenoid, 50.51...
・Pendulum gear, 52...Pendulum lever, 53・
...Cam gear, 67 ... Thermal head, 59 ... Platen, 66 ... Slip gear, 67 ... Pendulum lever, 68.69.
...Pendulum gear, 70...Cam gear.

Claims (4)

[Claims] (1) A print head, a carriage on which the print head is mounted, a platen on which print paper is mounted, a carriage moving means for reciprocating the carriage in one direction along the platen, and movement of the print paper on the carriage. a paper feeding means for driving in a direction perpendicular to the direction; a driving motor; a switching means for connecting the driving force of the motor to either the carriage moving means or the paper feeding means; and a driving means for driving the switching means. a switching drive source that causes the paper feed to slip by a certain amount when the paper feed is reversed between the forward direction and the reverse direction; and a slip means that operates only while the paper feed is slipping by the slip means to perform the above-mentioned printing. A printer comprising head contact/separation means for bringing the head into contact with/separating from the platen. (2) As a switching means, a motor shaft, a carriage moving means, and a paper feeding means are respectively coupled to the three rotating parts of the planetary gear mechanism, and either one of the carriage moving means and the paper feeding means is selectively fixed. 2. A printer as claimed in claim 1, further comprising a stop connected to said switching drive source in such a manner as to allow said switching drive. (3) The head separating means includes a connecting gear connected to the slipping means, a pair of pendulum gears that mesh with the connecting gear and are rotatably attached around the axis of the connecting gear, and the pendulum gear. Claim 1, comprising: a cam gear having an engaging gear portion, a gear notch portion, and a cam portion; and a head contact/separation mechanism driven by the cam portion of the cam gear to connect and separate the print head and the platen. Printer listed. (4) The printer according to claim 1, wherein the print head is always separated from the platen by the head separating means when paper is fed without the slip means operating.