JP3001371B2 - Thermal head pressing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head pressing device for moving a thermal head and pressing against a platen when printing on a print medium.

[0002]

2. Description of the Related Art Conventionally, in a thermal head pressing device of this type, when a print medium is transported between a thermal head and a platen, the thermal head is prevented from hindering the transport of the print medium. The platen has been retracted from the platen to a predetermined print standby position, and after the print medium is conveyed, the platen is pressed by moving the thermal head from the print standby position to the print position when printing is performed.

[0003] Specifically, such a device is provided with one print position sensor that turns on when the thermal head is at the print position and turns off when the thermal head is not at the print position. , And retracted to a print standby position where the print position sensor is turned off. Then, when printing is performed, the thermal head is moved from the printing standby position to the platen and moved to the printing position where the printing position sensor is turned on. The replacement of the ink ribbon is also performed when the thermal head is at the print standby position.

[0004]

However, in such a thermal head pressing device, even when the thermal head is at the print standby position, the interval between the thermal head and the platen is narrow, so that the ink ribbon can be easily replaced. In some cases, the ink ribbon may be damaged.

On the other hand, if the thermal head is set so that the printing standby position is far away from the platen, the amount of movement of the thermal head to the platen increases, so that it takes time to start printing and the throughput decreases. Can be

Accordingly, an object of the present invention is to provide a thermal head pressing device that can easily replace a ribbon and can prevent a decrease in throughput during printing.

[0007]

According to the present invention, an ink ribbon is inserted between a platen and a thermal head provided opposite to the platen, and the thermal head is moved to a predetermined print standby position at a distance from the platen. In the retracted state, a print medium for printing is interposed between the platen and the thermal head, and the thermal head is pressed to the platen by moving the thermal head close to the platen and moving to the printing position during printing. In the pressing device, a thermal head contact / separation driving unit for moving the thermal head toward and away from the platen, a standby position detecting unit for detecting whether the thermal head is at a print standby position, and the standby position detecting unit When the thermal head comes close to the platen and the thermal head approaches the platen, the thermal head And print position detecting means for detecting whether or not there, a cover which opens when replacing the ink ribbon
A cover open sensor that detects opening
Cover open sensor detects cover opening instead of lettering
If not, place the thermal head at the specified print standby position.
And the cover open sensor is
When the release of the thermal head is detected, when the ink ribbon is replaced, the thermal head contact / separation driving means is operated in a direction to separate the thermal head from the platen, and the print position detecting means detects that the thermal head is not at the print position, and waits for the printing. When the position detecting unit detects that the thermal head is not at the print standby position, the thermal head retracts the thermal head contact / separation driving unit to retreat the thermal head from the print standby position to the ribbon replacement position further away from the platen. Drive control means.

[0008]

According to the present invention having such a configuration, in printing,
Cover open sensor does not detect cover opening
At this time, with the thermal head retracted to the print standby position, a print medium is interposed between the thermal head and the platen into which the ink ribbon is inserted. Then, when printing is performed on the print medium, the thermal head is brought into contact with the platen by operating the thermal head contact / separation driving means to move the thermal head to the printing position, thereby pressing the thermal head against the platen.

On the other hand, when replacing the ink ribbon,
ー When the open sensor detects the opening of the cover,
Activating the thermal head contact / separation drive means to move the thermal head further away from the platen from the print standby position, the standby position detecting means detects that the thermal head is not at the print standby position, and the print position detecting means When the printer detects that the thermal head is not at the printing position, it stops the thermal head contact / separation driving means to retreat the thermal head from the platen to the ribbon replacement position.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a thermal printer will be described below with reference to the drawings.

FIG. 1 is an assembly perspective view showing a configuration of a thermal head pressing device of a thermal printer according to the present embodiment, and 1 is a platen pressing portion. This platen pressing portion 1
Is composed of a head pressing / releasing mechanism 2 and a head unit 3.

The head unit 3 includes a thermal head 4 having a large number of heating elements (not shown) arranged in a line. Locking members 6 and 6 are attached to the side surface of the thermal head 4.
Cutouts 6a, 6a are formed to removably insert both ends of the platen 5, respectively.

More specifically, both ends of the platen 5 are pivotally supported by a side frame 20 of the printer main body shown in FIG. 3, and concentric portions 5a are provided on both ends thereof. The concentric portions 5a are inserted into the notches 6 of the locking members 6,6.
The platen 5 is disposed at a position facing the arrangement line of the heating elements of the thermal head 4 by inserting it into the thermal head 4.

A mounting piece 8 having a semicircular notch 8a for supporting the head unit 3 on the center shaft 7 of the head pressing / releasing mechanism 2 is mounted above the back surface of the head unit 3. Have been.

The head pressing / releasing mechanism 2 includes a center shaft 7 and a head unit support plate 9 fixed to the center shaft 7. Both ends of the center shaft 7 are pivotally supported by a side frame 20 of the printer main body shown in FIG. 3, and an annular groove 9 is provided substantially in the middle.

The annular groove 9 has the head unit 3
The notch 8a of the mounting piece 8 is rotatably inserted. Thus, the head unit 3 is supported so as to be rotatable back and forth around the center shaft 8.

FIG. 2 is a side view when viewed from the direction of the solid arrow A shown in FIG.
Is omitted. A pair of coil springs 11, 11 are interposed between the head unit support plate 9 and the head unit 3 of the head pressing / releasing mechanism 2 in the longitudinal direction as shown in FIG. 3 is a platen 5 with respect to the head unit support plate 9.
It is urged in the direction of.

On the other hand, a guide hole 9a is provided substantially at the center of the head unit support plate 9 as shown in FIG. 9, and the guide hole 9a moves the head unit 3 in the front-rear direction with respect to the head pressing / releasing mechanism 2. Screw 1 to guide
3 is inserted. The screw 13 is located between the coil springs 11 and 11.

The screw 13 has one end screwed to the back of the head unit 3 and a flange 13a having a diameter larger than the guide hole 9a of the head unit support plate 9 at the other end. Is stopped by the guide hole 9a so that the head unit 3 is prevented from moving toward the platen 5 by a predetermined amount or more.

The head unit support plate 9 of the head pressing / releasing mechanism 2 moves back and forth together with the head unit 3 according to the rotation of the center shaft 7, as shown in FIGS.

An ink ribbon 21 is interposed between the platen 5 and the thermal head 4. The ink ribbon 21 is wound by a ribbon reel (not shown) in a direction indicated by a solid arrow B shown in FIG. Has become.

The platen 5 and the ink ribbon 21
The print medium 22 is set between the ink ribbon guide roller 2 and the print medium 22.
3 and is transported in the direction of the solid arrow A shown in FIG.

As shown in FIG. 10, when the head pressing / releasing mechanism 2 is further rotated from the position where the thermal head 4 of the head unit 3 is in contact with the platen 5, the head unit supporting plate 9 is moved to the coil spring 11, 11, the head unit 3 is pressed. At this time,
The release mechanism 2 stops at a predetermined printing position, and the thermal head 4 presses the platen 3 with a predetermined pressure.

A drive gear 14 is attached to one end of the center shaft 7 of the head pressing / releasing mechanism 2 as a head position detecting body. Teeth 15 are formed on a part of the outer periphery above the drive gear 14, and are connected to a drive shaft of a head lift motor 38 via an intermediate gear (not shown) that meshes with the teeth 15.

The head lift motor 38 and the platen pressing section 1 constitute a thermal head contact / separation driving means.

By driving the head lift motor 38, the driving force is transmitted to the drive gear 14 via each intermediate gear, and the center shaft 7 rotates.

Below the drive gear 14,
A detection notch 16 is provided. This notch for detection 16
Are three positions of the thermal head 4 with respect to the platen 5, that is, a print standby position where the thermal head 4 presses the platen 5 during printing, a print standby position where the thermal head 4 presses the platen 5 before printing, and This is for detecting which of the separated ribbon replacement positions is located.

Below the drive gear 14, a transmission type optical sensor 17 is provided. This optical sensor 17
A standby position sensor 18 as standby position detecting means for detecting whether the thermal head 5 is at the print standby position or not.
And a print position sensor 19 as a print position detecting means for detecting whether or not the thermal head 4 is at the print position.

The optical sensors 18 and 19 have light emitting portions 18a and 19a and light receiving portions 18b and 19b, respectively, and the detection notch 16 of the drive gear 14 is provided with the light emitting portions 18a and 19a and the light receiving portions 18b and 18b. 19b.

FIG. 3 is a side view when viewed from the direction of the solid arrow B shown in FIG. The standby position sensor 18 is fixed to the side frame 20 of the printer main body so as to be located below the center shaft 7 in the vertical direction as shown in FIG. The print position sensor 19 is fixed to the side frame 20 of the printer main body so as to be spaced apart from the standby position sensor 18 along the outer periphery of the detection notch 16.

Notch 16 for detecting drive gear 14
Is notched by a predetermined circumferential length along the outer circumference of the drive gear 14. The output of the optical sensor 17 changes depending on the position of the detection notch 16 with respect to the optical sensor 17, and the position of the head pressing / releasing mechanism 2 is detected by detecting the output of the optical sensor 17. You can do it. As a result, the position of the thermal head 4 can be indirectly detected.

That is, the sensors 18 and 19 are turned on when the detection notch 16 is detected at each position, and turned off when the detection notch 16 is not detected. , The position of the thermal head 4 is detected.

The positional relationship between the sensors 18 and 19 and the notch 16 for detection and the positional relationship between the thermal head 4 and the platen 5 will be specifically described below with reference to FIGS.

FIGS. 6 to 8 show solid arrows B shown in FIG.
Drive gear 15 and each sensor 1 when viewed from the direction
9 and 11 are schematic diagrams showing the platen pressing portion 1 and the platen 5 when viewed from the direction of the solid arrow A shown in FIG.

When the standby position sensor 18 is off and the print position sensor 19 is on, each sensor 1
The positional relationship between 8, 19 and the notch 16 for detection is as shown in FIG. 6, and the positional relationship between the thermal head 4 and the platen 5 at this time is as shown in FIG. That is, this position is the print standby position.

Also, the standby position sensor 18 is on,
When the print position sensor 19 is off, the positional relationship between the sensors 18, 19 and the detection notch 16 is as shown in FIG. 7, and the thermal head 4 and the platen 5 at this time are as shown in FIG.
And the positional relationship is as shown in FIG. That is, this position is the printing position.

Further, when both the standby position sensor 18 and the print position sensor 19 are off, each sensor 18,
The positional relationship between 19 and the notch 16 for detection is as shown in FIG. 8, and the positional relationship between the thermal head 4 and the platen 5 at this time is as shown in FIG. That is, this position is the ribbon replacement position where the space between the thermal head 4 and the platen 5 becomes the largest when the ink ribbon 21 is replaced.

FIG. 4 is a block diagram showing a schematic configuration of this embodiment. Reference numeral 31 denotes a CPU (central processing unit) constituting a control unit main body, and 32 stores program data for the CPU 31 to control each unit. ROM (read only memory), 33 is a RAM (random access memory) provided with a memory or the like used by the CPU 31 for various data processing, and 34 is an I / O port. The CPU 3
1 is electrically connected to the ROM 32, the RAM 33, and the I / O port 34 by the bus line 30.

The I / O port 34 has a cover open sensor 36 for detecting that a cover (not shown) of the printer main body has been opened for ink ribbon exchange and the like, a head driver 37 for driving the thermal head 18,
Motor driver 39 for driving head lift motor 38
And a motor driver 42 for driving a platen motor 41 for driving the platen 5.

The CPU 31 performs a process as shown in FIG. 5 when performing a printing operation based on print data from an externally connected host computer, for example. That is, the CPU 31 first performs a predetermined initial operation based on the initial settings of the printer main body in ST1.

Next, in ST2, it is determined whether or not the cover open sensor 36 detects that the cover of the printer body has been opened. At this time, if it is determined that the cover open sensor 36 does not detect that the cover of the main body is opened, the head lift motor 38 is driven in a direction in which the thermal head 4 is retracted from the platen 5 in ST3.

Then, it is determined whether or not the thermal head 4 is at the print standby position. That is, the standby position sensor 1
It is determined whether 8 is off and the print position sensor 19 is on. When it is determined that it is not at the print standby position, the operation returns to the operation of ST3, and when it is determined that it is at the print standby position, the head lift motor 38 is stopped at ST5.

Subsequently, in step ST6, a print command from the host computer is awaited, and at this time, it is confirmed whether a print medium is set. Then, the print medium is set,
If it is determined that the print command has been received, the head lift motor 38 is driven in a direction in which the thermal head 4 approaches the platen 5 in ST7.

Then, it is determined whether or not the thermal head 4 is at the printing position. That is, it is determined whether the standby position sensor 18 is on and the print position sensor 19 is off. When it is determined that it is not at the printing position, the operation returns to ST7, and when it is determined that it is at the printing position, the head lift motor 38 is stopped at ST9.

Next, in ST10, a predetermined printing operation is performed based on the printing data from the host computer. Then, in ST11, it is determined whether or not the printing is completed. If it is determined that the printing is completed, the process returns to ST2, and if it is determined that the printing is not completed, the process returns to ST10.

On the other hand, if it is determined in ST2 that the cover open sensor 36 has detected that the cover of the printer main body has been opened, in ST12 the head lift is moved in the direction in which the thermal head 4 is retracted from the platen 5. The motor 38 is driven.

Then, in ST13, it is determined whether or not the thermal head 4 is at the ribbon replacement position. That is, it is determined whether or not both the standby position sensor 18 and the print position sensor 19 are off. When it is determined that it is not at the ribbon replacement position, the operation returns to ST12, and when it is determined that it is at the ribbon exchange position, the head lift motor 38 is stopped at ST14 and the process returns to ST2 (thermal head drive control). means).

In this embodiment having such a configuration, when performing a printing operation, after a predetermined initial operation is completed, if the cover of the printer body is not opened, the thermal head 4 moves in a direction to retract from the platen 5. .

When the detection notch 16 of the drive gear 14 reaches the position shown in FIG. 6 for each of the sensors 18 and 19, that is, the standby position sensor 18 is turned off and the print position sensor 19 is turned on. The thermal head 4 stops. At this time, the thermal head 4
The print standby state is established at the print standby position shown in FIG.

In this state, when a print medium is set and a print command is transmitted from the host computer to the printer main body, the thermal head 4 moves in a direction further approaching the platen 5. When the notch for detection of the drive gear 14 with respect to each of the sensors 18 and 19 is at the position shown in FIG. 7, that is, when the standby position sensor 18 is turned on and the print position sensor 19 is turned off, The head 4 stops. At this time, the thermal head 4
The platen 5 is elastically pressed at the printing position as shown in FIG. In this state, a predetermined printing operation is performed based on print data from the host computer.

On the other hand, when the cover of the printer body is opened at the time of ribbon exchange, the thermal head 4
From the print standby position, and further away from the platen 5 from the print standby position.

When the notch 16 for detecting the drive gear 14 for each of the sensors 18 and 19 reaches the position shown in FIG. 8, that is, when both the standby position sensor 18 and the print position sensor 19 are turned off, the thermal head 4 stops. At this time, the thermal head 4 is at the ribbon replacement position as shown in FIG.

When the ribbon is replaced in this state and the cover of the printer body is closed after the ribbon replacement, the thermal head 4 moves in the direction approaching the platen 5, and the thermal head 4 waits for printing as shown in FIG. At the position, the print standby state is set again.

As described above, when the ribbon is replaced, the position of the thermal head 4 with respect to the platen 5 is further moved from the print standby position to the ribbon replacement position which is further away from the platen 5, so that the interval between the thermal head 4 and the platen 5 increases. Therefore, the ribbon can be easily replaced. Thereby, damage to the ink ribbon 21 is reduced.

Further, the print standby position is set separately from the ribbon exchange position, and when the ribbon exchange is not performed, the thermal head 4 is moved from the print standby position to the print position and printing is performed as in the conventional case. It is not necessary to set the position to a position far away from the platen 5, and it can be set to the same position as in the related art, so that a decrease in throughput during printing can be prevented.

Further, a stand-by position sensor 18 is provided in addition to the print position sensor 19, and the position of the detection notch 16 of the drive gear 14 with respect to these sensors 18 and 19 is detected by a combination of the outputs of these sensors 18 and 19. This makes it possible to indirectly detect three positions of the thermal head 4 with respect to the platen 5, that is, a print position, a standby position, and a ribbon replacement position.

[0057]

As described above in detail, according to the present invention, it is possible to provide a thermal head pressing device that can easily replace a ribbon and can prevent a decrease in throughput during printing.

[Brief description of the drawings]

FIG. 1 is an assembly perspective view showing a configuration of a thermal head pressing device of a thermal printer according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram when the thermal head pressing device shown in FIG. 1 is viewed from a direction of a solid arrow A shown in FIG.

3 is a schematic configuration diagram when the thermal head pressing device shown in FIG. 1 is viewed from a direction of a solid arrow B shown in FIG.

FIG. 4 is a block diagram showing a configuration of the thermal head pressing device shown in FIG.

FIG. 5 is a flowchart showing thermal head drive control performed by the CPU shown in FIG. 4;

FIG. 6 is a diagram showing a positional relationship between a notch for detecting a drive gear and each sensor when the thermal head shown in FIG. 1 is at a print standby position.

FIG. 7 is a diagram showing a positional relationship between a notch for detecting a drive gear and each sensor when the thermal head shown in FIG. 1 is at a printing position.

FIG. 8 is a diagram showing a positional relationship between a notch for detecting a drive gear and each sensor when the thermal head shown in FIG. 1 is at a ribbon replacement position.

9 is a diagram showing a positional relationship between the thermal head and a platen when the thermal head shown in FIG. 1 is at a print standby position.

10 is a diagram showing a positional relationship between the thermal head and a platen when the thermal head shown in FIG. 1 is at a printing position.

FIG. 11 is a diagram showing a positional relationship between the thermal head and a platen when the thermal head shown in FIG. 1 is at a ribbon replacement position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 4 ... Thermal head 5 ... Platen 14 ... Drive gear 16 ... Notch for detection 18 ... Stand-by position sensor 19 ... Printing position sensor 21 ... Ink ribbon 22 ... Printing medium 31 ... CPU 37 ... Head driver

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 25/304 B41J 2/32 B41J 25/312 B41J 25/316

Claims (1)

(57) [Claims] An ink ribbon is inserted between a platen and a thermal head provided opposite to the platen, and the thermal head is retracted to a predetermined print standby position separated from the platen. A thermal head that presses the thermal head against the platen by interposing a print medium for printing between the platen and the thermal head and moving the thermal head to the platen and moving to a printing position during printing. In the pressing device, a thermal head contact / separation driving unit for moving the thermal head toward and away from the platen; a standby position detecting unit for detecting whether the thermal head is at a print standby position; When the thermal head is disposed separately from the position detecting means and approaches the platen, A print position detecting means for detecting whether the thermal head is at a print position, and a cover which is opened when the ink ribbon is replaced are opened.
A cover open sensor that detects that the cover is open ,
When the release is not detected, the thermal head
To the print standby position of
When the open sensor detects the opening of the cover, the thermal head contact / separation driving means is operated in a direction to separate the thermal head from the platen, and the print position detecting means detects that the thermal head is not at the print position. And when the standby position detecting means detects that the thermal head is not at the print standby position, the thermal head contact / separation driving means is stopped to further separate the thermal head from the platen from the print standby position. And a thermal head drive control means for retracting to the ribbon replacement position.