JPH06143626A - Thermal recorder - Google Patents

Abstract

PURPOSE:To provide a thermal recorder in which print density and image quality can be ensured without increasing the number of components and without sacrificing the assembling performance. CONSTITUTION:The thermal recorder comprises a platen roller (hereinafter referred to PR) 2 loaded through bearings 7 inserted into a pair of bearing parts 8 cut in the opposite side plates 3, a thermal head(hereinafter referred to as TH) comprising a heat plate 4 supported by the opposite side plates while projecting slightly therefrom and a row of heating elements mounted thereon, and a leaf spring 5 for urging the TH against the PR2. The thermal recorder further comprises a reference part for positioning TH comprising a side edge part 9a at the U-cut part of the side plate 3 serving as a stopper for retaining the upper end part of the heat plate 4 in the TH which is displaced through rotation of the PR2 and a protrusion 10 for retaining the rear side of the heat plate 4 in the vicinity of lower end part thereof. Length L of the side plate 3 for fixing the TH1 is set longer than the length LTH' of a diagonal on the cross-section of the TH but shortet than the length LTH of the TH added with about half of the width of nip being formed when the TH is pressed against the PR2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal recording apparatus used in an image recording apparatus such as a small facsimile and a copying machine which uses a thermal recording method as a printing method, and particularly to a thermal recording apparatus characterized by a thermal head supporting mechanism. Regarding the device.

[0002]

The present applicant has proposed Japanese Patent Application No. 2-284488 as a thermal recording apparatus of this type. This includes a platen roller in which bearings fitted to shaft portions at both ends are respectively inserted and mounted in a pair of U-shaped notches formed in opposite portions of the both side plates, and a gap between the both side plates. A thermal head having a slightly longer length and supported by both side plates respectively, and a heating element array mounted on the radiator plate, and an upper side of the back surface of the radiator plate so that the thermal head is in pressure contact with the platen roller. A leaf spring that presses near the end, a U-shaped cut edge of the side plate that serves as a stopper that holds the upper end of the heat sink of the thermal head that is displaced by the rotational force when the platen roller rotates, and the lower end of the back surface of the heat sink. Of a thermal recording device having a thermal head positioning reference part consisting of a protrusion that holds the vicinity of the part, an explanation of the operation, a recording paper detection and a pressure release lever It is to the description of the release detection.

[0003]

By the way, of the objects that have a recording unit of a thermal recording system like a conventional small-sized fax machine and release the pressure contact state between the thermal head and the platen roller to the extent that a gap is opened, cut the side plate. The platen roller, the bearing, and the thermal head are positioned by providing a notch, and the positioning of the thermal head and the platen roller is such that the thermal head is moved against the end face of the side plate by moving the thermal head by the rotation of the platen roller. When rotating the thermal head for replacement or processing such as recording paper jam, the thermal head up / down restriction notch of the side plate is set with a margin with respect to the diagonal length of the cross section of the thermal head. If it goes down, the friction load, the change in friction between the thermal head and the paper due to temperature and humidity, Or become unstable return to the proper position of the thermal head due to a cause such that the parts deviate heater protrusion of the thermal head, it happened that does not return. Further, if the restoration is not completed completely, there are cases in which the print density is lowered, the print density is different, the print is missing, and the like.

When a metal such as aluminum is used for the heat dissipation plate of the thermal head and mild steel is used for the side plates, the heat dissipation plate is scratched due to rubbing due to the movement of the thermal head.
When the position of the side plate and the thermal head in the main scanning direction changes due to vibration or the like, friction at this portion increases, which may affect the movement of the thermal head.

In view of the above problems, it is an object of the present invention to provide a thermal recording apparatus capable of reliably obtaining print density and image quality without increasing the number of constituent parts and without compromising the assembling property. .

[0006]

In order to achieve the above-mentioned object, the present invention has a pair of U-shaped notch bearing portions formed at opposite portions of both side plates and fitted to both end shaft portions. A thermal head including a platen roller having bearings inserted therein, a heat radiating plate having a length slightly longer than the distance between the both side plates and being supported by the both side plates, and a heating element array mounted on the heat radiating plate. And a leaf spring that presses the vicinity of the upper end of the back surface of the heat dissipation plate so that the thermal head presses against the platen roller, and a stopper that presses the upper end of the heat dissipation plate of the thermal head that is displaced by the rotational force when the platen roller rotates. Thermal head having a U-shaped cutout edge of the side plate and a projection for pressing near the lower end of the back surface of the heat dissipation plate In recording device, cross-sectional diagonal length of about half the value following the thermal head plus the nip width formed when pressing the length L of the thermal head mounting portion of the side plate to the platen roller to the length L _TH of the thermal head L _TH '
It is configured as the first means described above.

In order to achieve the above-mentioned object, according to the present invention, a pair of U-shaped notched bearing portions formed at opposite portions of both side plates are respectively inserted with bearings fitted to both end shaft portions. The mounted platen roller, a thermal head including a heat radiating plate having a length slightly longer than the distance between the both side plates and supported by the both side plates, and a heating element array mounted on the heat radiating plate; A leaf spring that presses the vicinity of the upper end of the back surface of the heat dissipation plate so as to press the roller, and a U-shaped side plate that serves as a stopper that presses the upper end of the heat dissipation plate of the thermal head that is displaced by the rotational force when the platen roller rotates. A thermal recording apparatus comprising: a thermal head positioning reference portion including a cutout edge portion and a protrusion that presses near the lower end portion of the back surface of the heat sink. In the thermal head, a concave portion is formed on the ridgeline before and after the heat radiating plate in the conveying direction, and the length of the thermal head mounting portion of the side plate is equal to the length of the thermal head or slightly longer than the thermal head. is there.

In order to achieve the above object, according to the present invention, in the first means or the second means, a member having a hardness higher than that of the protrusion of the side plate supporting the lower portion of the thermal head is larger than the protrusion. Or a third means for increasing the hardness of the heat dissipation plate than the protrusion.

In order to achieve the above-mentioned object, according to the present invention, in the first means or the second means, a power supply line for applying an applied voltage for printing with a thermal head and a signal line for sending print data are thermally provided. Connect to the recording paper side of the head,
The wire rod is sandwiched between the inside of the device body and the thermal head, which is a fourth means.

[0010]

With the first means, the moving amount of the thermal head in the carrying direction is set to the length of the thermal head plus about half of the nip width of the platen roller. When the platen roller is restored, the uneven portion near the heater is always overlapped with the nip portion of the platen roller, so that it is easy to restore by the force of rotation. Even when the platen roller does not recover only by the force of rotation, the heater is installed in the nip part to assist the recovery due to the friction load due to the sticking of the recording paper thermal head during printing. Even if it is not, there is an effect that a certain concentration can be secured.

According to the second means, since the rotation space for releasing the pressure of the thermal head is formed by taking a corner of the heat radiating plate of the thermal head, the length of the thermal head vertical regulation notch of the side plate and the thermal The head lengths can be made almost equal, and the return to the normal writing position of the thermal head is positioned by returning the pressure release lever regardless of the rotation of the platen roller, and the axis of the thermal head heater and the platen roller can be easily set. As a result, the image quality including the print density can be secured.

By the third means, a member having a hardness higher than that of the supporting portion of the side plate is attached to the heat dissipation plate of the thermal head or the hardness of the heat dissipation plate itself is increased. Even if the thermal head moves in the carrying direction or the direction perpendicular to the carrying direction (main scanning), it does not interfere with the side plate support portion and does not hinder the thermal head recovery.

By the fourth means, the thermal head is urged by the elasticity of the signal line and the power source line in the direction of returning to the normal position, so that the thermal head can be assisted without providing a member for urging the thermal head. Is possible.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory view showing a schematic structure of a first embodiment of the present invention, FIG. 2 is an enlarged explanatory view of a main part, and FIG. 3 is an explanatory view showing a dimensional relationship. .

As shown in these figures, the thermal head 1, the platen roller 2, the plate spring 5, the bearing 7 of the platen roller 2, the pressure release lever 6, the drive system and other components are supported by the side plates 3 at both ends thereof. And are positioned by the side plates 3, respectively.

That is, the bearing 7 of the platen roller 2 is regulated in the vertical direction by the bearing portion 8 formed by further cutting in a U-shape at the bottom of the U-shaped cut portion 9 of the side plate 3 provided in the equipment body. The axis of the platen roller 2 rotatably supported by and the heater position of the thermal head 1 have a predetermined distance when the heat radiating plate 4 of the thermal head 1 contacts the side edge 9a of the U-shaped notch 9 of the side plate 3. The distance (e in FIG. 1) from the end surface of the heat dissipation plate 4 to the heater is set so as to be located.

The drive gear (not shown) is rotatably supported by the studs provided on the side plate 3, and the stud position is set so that the gear pitch distance can be secured.

The pressure release lever 6 is rotatably attached to the bearing 7. By rotating the pressure release lever 6 in the direction B in FIG. 2 about the axis of the platen roller 2, the cam portions at both ends of the pressure release lever 6 are rotated. The pressure of the thermal head 1 on the platen roller 2 can be released by 6a pressing the heat dissipation plate 4. When the recording paper (roll paper 13) is set in this way, a gap is created between the thermal head 1 and the platen roller 2 and the recording paper is inserted.
The arrow A indicates the rotation direction of the platen roller 2,
0 is a protrusion, 11 is a left and right position regulating bent portion, 12 is a motor,
13 is roll paper, and 14 is a main body base.

At the contact portion between the thermal head 1 and the platen roller 2, the nip (NIP) width depends on the outer diameter, the rubber thickness, the rubber hardness of the rubber material wound around the shaft core material of the platen roller 2 and the pressure of the leaf spring 5. (Width of crush at the contact portion of the platen roller 2 due to the pressure of the leaf spring 5) is different. Further, in the case of the thermal head 1 having a rectangular cross section as shown in FIG. 2, the length L of the mounting portion of the side plate 3 (width of the U-shaped cut-in portion 9) is rotated when the pressure of the thermal head 1 is released. In order to do so, the mounting portion length L which is equal to or greater than the diagonal length L _TH ′ of the cross section of the thermal head 1 is required. From this, in this embodiment, the length L of the side plate mounting portion is approximately equal to the length L _TH of the thermal head, which is about half the nip width L _NIP (L _NIP / 2: the thermal head 1 in the normal printing state).
The heater position and the distance to the sheet feeding side end of the nip) or less and the nip width L _NIP is formed so as to be longer than the cross-sectional diagonal length L _TH 'of the thermal head 1. Set by. To summarize this, L
_This is a condition under which L _NIP satisfying _TH '≦ L ≦ L _TH + L _NIP / 2 can be obtained.

According to the first embodiment thus constructed, the shaft portions at both ends are fitted to the pair of U-shaped notch bearing portions 8 formed at the portions of the side plates 3 facing each other. From the platen roller in which the bearings 7 are inserted and mounted, the heat radiating plates 4 each having a length slightly longer than the distance between the both side plates and supported by the both side plates, and the heat generating element array mounted on the heat radiating plate 4. Thermal head 1, a leaf spring 5 that presses the vicinity of the upper end of the back surface of the heat dissipation plate 4 so that the thermal head 1 comes into pressure contact with the platen roller 2, and a thermal displacement that is caused by the rotational force when the platen roller 2 rotates. The side edge portion 9a of the U-shaped notch 9 of the side plate which serves as a stopper for pressing the upper end of the heat dissipation plate 4 of the head 1 and the heat dissipation plate 4
In a thermal recording apparatus having a thermal head positioning reference portion composed of a protrusion 10 for pressing near the lower end of the back surface of the thermal head 1, the length L of the side plate 3 where the thermal head 1 is attached is defined as the length of the thermal head 1. Platen roller 2 on L _TH
Since the cross-sectional diagonal length L _TH ′ of the thermal head 1 is set to a value equal to or less than a value obtained by adding about half of the nip width formed when pressed to the platen, the movement amount of the thermal head 1 in the transport direction is set to the length of the thermal head 1 by the platen. Since the amount is about half of the nip width of the roller 2, when the thermal head 1 is released from the pressure and then returned to the proper position, the nip portion of the platen roller 2 must be overlapped with the uneven portion near the heater. It becomes easy to restore by force. Further, even when the platen roller 2 does not recover only by the rotation force, the heater is provided in the nip portion to assist the recovery due to the frictional load due to the sticking of the recording paper thermal head 1 during printing. The effect is that a certain concentration can be ensured even if it has not been restored.

FIG. 4 shows a second embodiment. In this second embodiment, as shown in FIG. 4, the nip width is reduced in order to reduce the nip width in order to reduce the drive load and the structure of the equipment. a recess 1a diagonal of the head 1 and the like chamfered or or R processing, L ≦ by a L _TH '≦ L _TH
It is also possible to set L which is L _TH .

FIG. 5 shows a third embodiment. In this third embodiment, a member 15 having a higher hardness than the material of the side plate 3 is provided on the back surface of the thermal head 1 facing the lower fulcrum portion of the side plate 3. By fixing by bonding, screwing, etc.
It is possible to prevent the occurrence of scratches in this portion and reduce the friction load.

FIG. 6 shows a fourth embodiment. In this fourth embodiment, a wire material such as a power supply line for applying an applied voltage for printing by the thermal head 1 and a signal line for sending print data. 16 are arranged, and the thermal head 1 is attached to the side edge portion 9a of the U-shaped cut portion 9 by the elasticity of these wire rods 16.
The thermal head 1 can be used as an assisting means for returning the thermal head 1 to a predetermined position by urging the thermal head 1 (direction C) by pressing it against (direction D). In addition, 17 is a connector, 1
Reference numeral 8 is a control board.

The constitutions not particularly explained in the second to fourth embodiments are the same as those in the first embodiment.

According to the second embodiment, the bearings 7 fitted to the shaft portions at both ends are inserted into the pair of U-shaped notch bearing portions 8 formed at the portions of the both side plates 3 facing each other. The thermal head 1 is composed of a platen roller 2 mounted on the radiator plate 4, a radiator plate 4 having a length slightly longer than the distance between the both side plates 3 and supported by the both side plates, and a heating element array mounted on the radiator plate 4. And a leaf spring 5 that presses the vicinity of the upper end of the back surface of the heat dissipation plate 4 so that the thermal head 1 comes into pressure contact with the platen roller 2, and heat dissipation of the thermal head 1 that is displaced by the rotational force when the platen roller 2 rotates. The thermal head positioning reference portion includes a side edge portion 9a of the U-shaped cutout portion 9 of the side plate that serves as a stopper that presses the upper end portion of the plate 4, and a protrusion 10 that presses near the lower end portion of the back surface of the heat dissipation plate 4. In the thermal head 1 of the thermal recording apparatus, a concave portion 1a formed by C chamfering, R processing, a step, etc. is formed on the ridgeline before and after the heat radiating plate 4 in the conveying direction, and the length L of the side plate 3 at the mounting portion of the thermal head 1 is set. Since the length L _TH of the thermal head 1 is made equal to or slightly longer than the length L _{TH of} the thermal head 1, a rotation space for releasing the pressure of the thermal head 1 is provided with a heat dissipation plate 4 of the thermal head 1.
Since it is done by removing the corners of the thermal head, the length of the thermal head vertical regulation notch of the side plate (U-shaped notch 9
Width L) and the length L _TH of the thermal head 1 can be made substantially equal. Therefore, the return of the thermal head 1 to the normal writing position is performed by returning the pressure release lever 6 without depending on the rotation of the platen roller 2, and the axes of the heater of the thermal head 1 and the platen roller 2 are easy. Therefore, the image quality including the print density can be secured.

Further, according to the third embodiment, with respect to the protrusion 10 of the side plate 3 which supports the lower portion of the thermal head 1, a member 15 having a hardness higher than that of the protrusion 10 is attached to the radiator plate 4, and heat dissipation is performed. Since the hardness of the plate 4 is made larger than that of the protrusion 10, the thermal head 1 is not scratched by the movement of the thermal head 1, and the side plate 3 is supported even if the thermal head 1 moves in the transport direction or the transport right angle (main scanning) direction. It does not interfere with the return of the thermal head 1 by interfering with the parts.

Further, according to the fourth embodiment, a power supply line for applying an applied voltage for printing by the thermal head 1 and a signal line for sending print data are connected to the recording paper side of the thermal head 1. Since the wire 16 is sandwiched between the inside of the device body and the thermal head 1, the thermal head 1 can be urged by the elastic force of the wire 16 of the signal line and the power supply line in the normal position returning direction. Therefore, it becomes possible to assist the thermal head 1 without separately providing a member for biasing the return.

[0028]

According to the first aspect of the present invention, the amount of movement of the thermal head in the conveying direction is set to the amount of the length of the thermal head plus about half the nip width of the platen roller. After that, when the platen roller is returned to the proper position, the uneven portion near the heater is always overlapped with the nip portion of the platen roller, which makes it easy to return by the force of rotation. In addition, even if the platen roller does not recover only by the rotation force, the heater is installed in the nip area to assist the recovery due to the friction load due to the sticking of the recording paper thermal head during printing.
The effect is that a certain concentration can be ensured even if it has not been restored.

According to the second aspect of the present invention, since the pivoting space for releasing the pressure of the thermal head is formed by taking a corner of the heat radiating plate of the thermal head, the thermal head up / down regulating notch of the side plate is formed. The length and the length of the thermal head can be made almost equal. Therefore, the return of the thermal head to the normal writing position is done by returning the pressure release lever regardless of the rotation of the platen roller, and the heater of the thermal head and the axis of the platen roller can easily come out. It is possible to secure the image quality including.

According to the third aspect of the invention, a member having a higher hardness than the supporting portion of the side plate is attached to the heat dissipation plate of the thermal head, or the hardness of the heat dissipation plate itself is increased. The thermal head is not scratched, and even if the thermal head moves in the transport direction or the transport right-angle (main scanning) direction, it does not interfere with the support portion of the side plate to prevent the thermal head from returning.

According to the fourth aspect of the invention, since the thermal head is biased in the normal position restoring direction by the elastic force of the wire of the signal line and the power source line, a member for biasing the thermal head for restoring is separately provided. It becomes possible to perform auxiliary urging without providing the above.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a first embodiment according to the present invention.

FIG. 2 is an enlarged explanatory view of a main part of the first embodiment according to the present invention.

FIG. 3 is an explanatory diagram showing a dimensional relationship of the first embodiment according to the present invention.

FIG. 4 is an explanatory diagram showing a main part of a second embodiment according to the present invention.

FIG. 5 is an explanatory diagram showing a main part of a third embodiment according to the present invention.

FIG. 6 is an explanatory diagram showing a main part of a fourth embodiment according to the present invention.

[Explanation of symbols]

 1 Thermal Head 2 Platen Roller 4 Heat Sink 3 Side Plate 5 Leaf Spring 6 Pressure Release Lever 7 Bearing 8 Bearing 9 U-shaped Notch 10 Protrusion 13 Roll Paper 15 High Hardness 16 Wire

Claims (4)

[Claims] 1. A platen roller in which bearings fitted to shaft portions at both ends are respectively inserted and mounted in a pair of U-shaped notched bearing portions formed in opposite portions of the both side plates, and the both side plates. A thermal head comprising a heat radiating plate having a length slightly longer than the space between them and supported by the both side plates, and a heating element array mounted on the heat radiating plate;
A leaf spring for pressing the vicinity of the upper end of the back surface of the heat dissipation plate so that the thermal head is in pressure contact with the platen roller;
A U-shaped cut edge portion of the side plate, which serves as a stopper for holding the upper end portion of the heat dissipation plate of the thermal head, which is displaced by the rotational force of the platen roller when it rotates, and a projection which holds near the lower end portion of the back surface of the heat dissipation plate. And a thermal head positioning reference portion comprising a nip formed when the length L of the thermal head mounting portion of the side plate is pressed to the platen roller by the length L _TH of the thermal head. A thermal recording device characterized in that the cross-sectional diagonal length L _TH ′ of the thermal head is set to a value equal to or less than a value obtained by adding about half of the width L _NIP . 2. A platen roller in which bearings fitted in shaft portions at both ends are respectively inserted and mounted in a pair of U-shaped notched bearing portions formed in opposite portions of the both side plates, and the both side plates. A thermal head comprising a heat radiating plate having a length slightly longer than the space between them and supported by the both side plates, and a heating element array mounted on the heat radiating plate;
A leaf spring for pressing the vicinity of the upper end of the back surface of the heat dissipation plate so that the thermal head is in pressure contact with the platen roller;
When the platen roller rotates, it is displaced by the rotational force of the thermal head. A protrusion that holds the edge of the U-shaped cut portion of the side plate that serves as a stopper that holds the upper end of the heat sink and a portion of the heat sink near the lower end of the back surface of the heat sink. In a thermal recording apparatus having a thermal head positioning reference section consisting of, a concave portion is formed on a ridge line before and after the heat radiating plate in the conveying direction, and the length of the thermal head mounting portion of the side plate is set to the length of the thermal head. A thermal recording device characterized by being made equal or slightly longer than the thermal head. 3. The protrusion according to claim 1 or 2, wherein the protrusion of the side plate supports a lower portion of the thermal head.
A heat-sensitive recording apparatus characterized in that a high hardness portion having a hardness higher than that of the protrusion is provided on the heat dissipation plate. 4. The apparatus according to claim 1, wherein a power supply line for applying an applied voltage for printing with the thermal head and a signal line for sending print data are connected to a recording paper side of the thermal head, A thermal recording apparatus, wherein the wire is sandwiched between an inner side and the thermal head.