JPS63166577A - Gear driver - Google Patents

Abstract

PURPOSE:To eliminate a backlash with a simple construction, by a method wherein a rotating shaft is enabled to displace and an idler gear engaging between a drive gear and a follower gear is pressed to both gears by an elastic member. CONSTITUTION:A friction spring 17 is wound about a cylindrical portion 16g of a shutter gear 16 and engaged with a cutout 15c at an end portion 17a thereof. The cutout 15c is at an angle of degrees corresponding to 1.5 times the tooth of a large gear 15b. If the end portion 17a of the spring 17 moves (idles) within the cutout 15c and the gears relatively rotate through an angle larger than the aforesaid, the gears rotate while being applied with a predetermined braking action by the spring 17. Additionally, two teeth portions 18b of a pressure gear 18 have the teeth traces of the same phase. The gear 18 has the inner diameter substantially larger than that of a shaft 101b supporting them, thus failing to be regulated at the center thereof. A pressure spring 20 is extended between a cylindrical portion 18c of the bottom of a groove portion 18a of a gear 18 and a shaft 101a to pull the gear 18. In this manner, a backlash between each of a PF gear 15, the pressure gear 18, and a PF roller gear 11 is eliminated.

Description

[Detailed Description of the Invention] [Industrial Application Field of the Invention] The present invention relates to a gear drive device, and particularly to a gear drive device that transmits rotation in one direction from a drive gear to a driven gear. Backlash can be removed.

[Prior art and problems to be solved by the invention] Conventionally, a double gear system is often used to remove backlash from gears. This consists of two gears of the same shape sandwiching a mating gear, and the two gears are urged by a spring to rotate in opposite directions. However, this method requires an additional spring and gear, and the teeth of the gears that are rotating in opposite directions must be assembled together, making it expensive due to the increased number of parts and poor assembly. . Furthermore, if an idler gear is required between the drive gear and the driven gear, backlash will occur in one of the gears even if the idler gear is, in principle, a double gear. Therefore, the idler gear has to be a single gear, and both the driving gear and the driven gear have to be double gears, which makes it more expensive and difficult to assemble.

Further, as a method of swinging the gears, there is a method in which the drive gear and idler gear are made swingable, the driven gear is fixed, and the three gears are pressed together with a spring. However, this method requires a rocking plate for holding the gear and a spring for press-fitting, which makes it expensive.

[Means for solving problems]

The present invention for solving the above problems includes a drive gear, a driven gear to which power is transmitted from the drive gear, and an idler gear that meshes with the driven gear, the idler gear comprising: The present invention is characterized in that the rotating shaft is movable and the idler gear is pressed against the drive gear and the driven gear by an elastic member.

〔Example〕

An embodiment of a gear drive device to which the present invention is applied will be described below with reference to the drawings. In addition, in the example described below,
Although a gear drive device applied to a thermal printer will be described as an example, the present invention is not limited to this and can be applied to other gear drive devices.

In the embodiment described below, the backlash of the gear drive device is eliminated, and the inner diameter of the idler gear is made larger than the shaft so that it can move freely in the radial direction, and a groove is provided in the center of the tooth thickness of the idler gear. , is a gear drive device in which backlash is removed only by the spring by directly pressing the groove with a spring and bringing the idler gear into pressure contact with the driving gear and the driven gear.

More specifically, in the embodiment described below, an idler gear is held with a predetermined play in the radial direction. Press the part with a spring. Thereby, the idler gear is brought into pressure contact with both the drive gear and the driven gear so that backlash can be removed at the same time. For this reason, the idler gear is a single integrally molded part (by simply adding one spring to press, it is possible to eliminate backlash, and it is possible to provide a gear drive device that is inexpensive and easy to assemble. .

FIG. 1 is an overall perspective view showing one embodiment of the present invention.

As will be described later, the printer of this embodiment can be loaded with a so-called self-collection ink ribbon cassette, a two-color ribbon cassette, and a normal monochrome printing ink ribbon, making full use of the characteristics of the loaded ribbon to print a single color. Recording/multi-color recording and recording correction can be performed. In the figure, l is a base, and the left side plate 101, the right side plate 102, and the gear receiver have a plate 103. This left side plate 101 has a shaft 10 for holding springs and gears, which will be described later.
1a, 101b-101c are standing. Further, the gear receiver plate 103 is provided with a guide hole 103a for holding the shaft of a bevel gear, which will be described later. Also, on the front side of the base 1, there are grooves 104a-104b, 1 for holding flexible cables (hereinafter abbreviated as flexible cables).
04c is provided. Furthermore, a guide rail 105a is provided on the base bottom plate 105 over the entire width. Further, a rack 2 is provided at a predetermined position on the base l along the printing digit direction (recording direction), and is engaged with a rack pinion of a carrier to be described later during printing. The rack teeth 2a, in which a plurality of rack teeth 2a are lined up at a predetermined pitch, are formed so as to occupy a portion of the lower part of the tooth thickness of the rack 2. A stop tooth 2b is provided at the left end of the rack tooth 2a over the entire width of the rack 2 in the vertical direction. Further, a start tooth 2C is provided with a predetermined width at a position corresponding to the upper portion of the rack tooth 2a, with an interval of one tooth from the stop tooth 2b. Further, the rack 2 is provided with an upper guide surface 2d and a lower guide surface 2e for guiding a carrier, which will be described later. Furthermore, 3 is paper bread,
It is formed integrally with the base l, and has two square holes 3a at predetermined positions (one
(parts not shown) are opened.

Furthermore, 4 is a paper feed roller (hereinafter abbreviated as PF roller), in which a disc-shaped paper guide 4a and a cross-shaped cross-spray 4b are arranged alternately, and are made of a plastic material such as polycarbonate or ABS. is formed. At both ends of this roller 4, there is a guide shaft 4C.
4d is similarly integrally formed, and the left side plate 101
and is rotatably supported by the right side plate 102. Reference numeral 5 denotes a paper feed rubber roller (hereinafter abbreviated as PF rubber roller), which is provided at a predetermined position with a gap between it and the RF crawler, and has rubber wrapped around its circumferential surface. In this embodiment, the RF rubber roller 5 is provided at four locations (two locations are not shown).

That is, in this embodiment, the guide shafts 4C and 4d, the disc-shaped paper guide plate 4a, and the PF roller 5 are integrally molded, and the PF
The peripheral surface of the roller 5 is coated with rubber to provide high friction.
This increases the conveying power of Further, the guide plate 4a guides the paper 3S with low friction. Here, the diameter of the guide plate 4a is slightly smaller than the diameter of the PF crawler, but may be the same size.

Furthermore, a platen holder 6 is held between the left side plate 101 and the right side plate 102, and grooves 6a are provided at positions facing the guide plate 4a of the PF crawler and the PF rubber roller 5, respectively. There is. Further, in order to guide the leading edge of the sheet S being conveyed, a bent portion 6b is formed in a convex shape at the bottom of the holder 6 facing the gap between the PF crawler and the PF rubber roller 5. That is, the lower tip 6b of this holder 6 intrudes inward from the outer peripheral surfaces of the rollers 4 and 5 in the gap between the PF crawler and the PF rubber roller 5 (as viewed in the cross-sectional direction), and the paper being conveyed is Prevents accidental entry into the gap. Further, the paper guide plate 4a and the PF roller 5 are not disk-shaped (although they may have a shape as shown in FIG. 21 as long as they have an arcuate portion).

A platen 7 made of a sheet such as foamed urethane having an elastic and heat-insulating effect is affixed to a portion of the front surface of the platen holder 6, that is, at a position facing a print head to be described later, along the print/digit direction. A second platen 7 maintains the paper in position during recording by the printhead. 8 is a pinch roller, which is in pressure contact with the PF rubber roller 5, and is lined with rubber so that the leading edge of the paper can easily bite when inserting the paper (the other side of the pinch roller 8 is not shown). The pinch disk 9 is made of a disk-shaped thin plate and is rotatable, and is arranged so that the side surface near the outer periphery of the pinch disk 9 is in contact with the PF rubber roller 5 described above. The pinch disc 9 is pressed by a pinch spring 10, and rotates in synchronization with the PF rubber roller 5 to release the braking force caused by the pressing force when there is no printing paper, such as when printing paper is inserted. The pinch spring 10 also presses the central portion of the pinch roller 8 mentioned above.

Reference numeral 11 denotes a PF crawler layer, which is attached to the rotating shaft 4d of the PF crawler described above and rotates together with it. 12 is a left platen knob, which is integrally attached to the PF crawler. By manually operating this knob 12,
The roller 4 rotates. 13 is a release lever, and the above-mentioned P
It is rotatably fitted to the shaft portion 4d of the F crawler, and is also rotatably attached to the right side plate 102, and the knob 13a
By operating the paper release mechanism, which will be described later, the pinch roller 5 and the pinch disk 9 described above can be released, and the printing paper can be freed.

Further, 14 is a right platen knob, which is integrally attached to the PF crawler. Furthermore, 15 is PF gear or 1
6 is a shutter gear, both of which are rotatably supported by the shaft 101c of the left side plate 101. As shown in FIG. 1(b), the RF gear 15 includes a small gear 15a and a large gear 15.
It has a two-stage gear (b), and a cylindrical portion 15d having a notch 15c in a portion thereof is provided at a position facing the shutter gear 16. Further, as shown in FIG. 10, the shutter gear 16 consists of a feed dog 16a having a normal tooth profile and a shutter tooth 16b having a part of the tooth profile cut away, and the tooth surface 16c is the same as the feed dog 16a.

It is common to shutter tooth 16b, and the other tooth surface is 16d.
and 16e, and an abutment surface 16f is formed (the teeth are shown in a prominent manner in FIG. 1O).

16g is a cylindrical portion around which a friction spring, which will be described later, is wound. A friction spring 17 is wound around the cylindrical portion 16g of the shutter gear 16 with a predetermined tightening force, and its end 17a is connected to the notch 15c of the PF gear 15.
It is designed to engage with. The notch 15c is the large gear 15
The end 17a of the friction spring 7 moves (plays) within this notch 15c, and the PF gear 15 and shutter gear 16 have an angle equivalent to 1.5 teeth of the notch 15c. It is rotatable, and if it rotates more than that angle, a predetermined braking action is applied by the friction springs 17, causing it to rotate. Furthermore, 18 is a pressure gear, with a groove 1 in the center of the teeth 18b.
8a is provided. Furthermore, this pressure gear 18
The tooth traces of the two tooth portions 18b have the same phase. Further, the inner diameter of the pressure gear 18 is considerably larger than the supported shaft 101b, and the center of the pressure gear 18 is not restricted by the shaft 101b. A grip ring 19 is attached to a predetermined position on the shaft 101b to regulate the thrust direction of the pressure gear 18 and prevent the gear 18 from coming off the shaft 101b. A pressure spring 20 is stretched between the cylindrical portion 18c at the bottom of the groove portion 18a of the pressure gear 18 and the shaft 101a. The pressure gear 18 is pulled so as to come into pressure contact with the small gear 15a. This eliminates backlash between the PF gear, the pressure gear 18, and the PF crawler gear 11 (see FIG. 22(a)). In addition,
As an example for removing backlash, there is a second example.
As shown in Figure 2(b) and (C), the torsion spring 20a or tension spring 20b is inserted into the groove 18a.
The same effect can also be obtained.

Further, 21 is a switch, which is attached to the base 1 at a predetermined position. Note that 21a and 21b are contact pieces. Furthermore, 50 is a carrier, which is guided by the rack 2 and guide rail 105a of the base 1 and is slidably attached in the direction of the printing digit. A ribbon cassette 60 is mounted on this carrier 50.

Next, regarding the internal structure of the carrier 50, FIGS.
This will be explained using figures.

In the figure, 501 is a carrier base, and the rack 2
A pair of guide portions 501a are provided on the left and right sides for guiding. Further, a protrusion 501b for turning on the switch 21 is provided at a predetermined position. This will be described further later. Shaft 501c/5 that supports rack rollers, gears, etc.
01d, 501e, and 501", and a shaft 501h having a stepped portion 501g that supports a control lever described later are integrally provided. Furthermore, a groove 501i for supporting a bevel gear described later and a groove 501j for supporting a flexible cable are provided. 502 is a pulse motor, and a shaft 502a is attached to the carrier base 501 to which a motor pinion 503 is fixed.

504 is a center gear, and the motor pinion 503
A large gear 504a that meshes with the large gear 504a, a small gear 504b provided below the large gear 504b, a bevel gear 504c, and a ribbon drive gear 504d at the top are integrally formed. 504e is a spring clutch post, and 504f is a heladium post. The center gear 504 is supported by the shaft 501f of the carrier base 501 through a hole provided in its lower part, and the root of the ribbon drive gear 504d is guided by a hole in a carrier cover to be described later and is rotatably attached to the upper part. An idler gear 505 is rotatably supported by a shaft 501e, and is connected to the small gear 504b of the center gear 504.
It meshes with. 506 is a carrier pinion, and a pinion tooth 506a having teeth around the entire circumference is provided at the lower part, a single synchronizing tooth 506c is provided at the upper part, and a guide ring 506e is provided at the middle part. Guide ring 5
06e has a notch 506f between the synchronizing teeth 506b and 506c, and the other diameters are equal to or slightly larger than the outer diameter of the pinion tooth 506a. In the height direction of the carrier pinion, the pinion teeth 506a are in a position to mesh with the rack teeth 2a, and the synchronized teeth 506b and
506c and 506d are positioned to mesh with the start tooth 2c.

Further, this guide ring 506e is located at a position where it does not come into contact with the rack teeth 2a and start teeth 2c of the rack,
The stop teeth 2b and the notches 506'' are assembled with their teeth aligned in synchronization.The carrier pinion 506a is rotatably supported on the shaft 501d of the carrier base 501.

Next, the bevel gear unit 55 will be explained.

507 is a bevel gear, and its bevel gear 507a meshes with the bevel gear 504c of the center gear 504. Further, 507b is a bevel gear shaft, and a keyway 507c is provided. Furthermore, a shaft portion 507d into which a stop ring, which will be described later, is press-fitted is formed at the tip thereof. 508 is a ratchet plate, and at the tips of the four arms,
A claw 508a is provided and is molded from an elastic plastic plate such as polyacetal. The ratchet plate 508 is
It has a protrusion on its inner diameter (not shown) that fits into the keyway 507C of the bevel gear 507b, and is attached to the bevel gear shaft 507b so as to be slidable in the axial direction. 509
is a ratchet gear, and the gear part 509a and the ratchet part 5
09b, and a large number of ratchet teeth 509c are formed concentrically on one side of the ratchet portion 509b. A ratchet spring 510 is a compression spring for pressing the ratchet plate 508 and the ratchet gear 509. Furthermore, a stop ring 511 is press-fitted into the shaft portion 507d of the bevel gear shaft 507b, and the ratchet plate 508 and the ratchet gear 509 are pressed by the ratchet spring 510 to prevent the stop ring from coming out. The stop ring 511 is designed to fit into the guide hole 103a of the base l with an appropriate clearance. The rotational force of the center gear 504 is transmitted from the bevel gear 504c to the bevel gear 507a of the bevel gear 507, and then to the ratchet plate 508 through the keyway 507C. Then, the pawl 508a and the ratchet teeth 509C mesh, and the ratchet gear 509
can be conveyed to. Furthermore, the pawl 508a and the ratchet teeth 509 have a sawtooth shape, and transmit rotational force in one direction, but in the opposite direction transmit the rotational force to the elastic force of the arm of the ratchet plate 508.
No power is transmitted by the ratchet spring 510.

Reference numeral 512 denotes a control cam, which has a groove 512a for hooking the end of a clutch spring, which will be described later, and a locking surface 512 and a trigger surface 51 which engage with a control lever, which will be described later.
2c, the locking part with the slope 512d at a predetermined angle A,
There are two locations H (see Figure 5a). The control cam 512 is rotatably inserted into the spring clutch boss 504e of the center gear 504. Also 5
13 is a control lever, 513a is a rotation hole, 51
3b is a spring hook, and 513c is a claw, which is rotatably inserted into the shaft 501h of the carrier base 501. 514
is a control lever spring, which is a compression torsion spring, which presses the control lever 513 so as to rotate toward the control cam 512, and at the same time presses it against the stepped portion 501g of the carrier base. Also 515
is a clutch spring, one end 515a of which is inserted into the groove 512a of the control cam 512. Further, the other end 515b is engaged with a pin of a head cam, which will be described later. The clutch spring 515 is connected to the center gear 50
4 is inserted into the spring clutch boss 504c. Reference numeral 516 denotes a herad cam, and a switching cam 517 for operating a switching lever, which will be described later, is provided at the top. This switching cam 517
are the slope cam 517a, the switching groove 517b, and the cam surface 5.
17c. Furthermore, below the switching cam 517,
A ribbon feed cam 518 is provided. This ribbon feeding cam 518 has notched cams 518a and 51 in a part thereof.
8b and a stop cam 518c are provided. Furthermore, a printing cam 519 is provided at the lower part of the printing cam 519, and a suppressing portion 519a having a large diameter provided in a part of the printing cam 519 presses a head roller, which will be described later, to press the printing head against the platen. Here, the head cam 516 is rotatably attached to the head cam boss 504f of the center gear 504 (a detailed view is shown in FIG. 5(b)).

Next, 60 is a head holder, and the rotating shaft 60a has a vertical axis, and is rotatably held by the shaft 501 of the carrier base 501 and the shaft (not shown) of a carrier cover 70, which will be described later. There is. Also, 60b is a spring shaft, and 60c is an upper and lower 2
The cam roller holding plate is made of a single plate, and has elongated holes 60d at the top and bottom for guiding the cam roller, which will be described later. Furthermore, 60e and 60f are spring-loaded. Reference numeral 61 denotes a heladium spring whose coil portion is held by the spring shaft 60b, one end of which is hooked onto a spring hook 60f of the head holder 60, and the other end hooked onto a groove portion of a cam roller to be described later. Reference numeral 62 denotes a cam roller, which has an outer diameter portion 62a in contact with the helad cam 516, guide shafts 62b and 62c inserted into the elongated hole 60d of the head holder 60 at the top and bottom, and a groove 62d for receiving one end of the helad spring 61. configured. Then, the head cam 516 presses the cam roller 62, and the spring force of the head spring 61 presses the print head 63, which will be described later, against the platen 7. Here, the print head 63 is
It is attached to the head holder 60. Note that the flexible cable pulled out from the print head 63 is
It passes through the carrier 50, is connected to the terminal of the pulse motor 502, and exits from the carrier 50 through the groove 501j of the carrier guide 501, but is not shown in the figure.

Reference numeral 64 denotes a head return spring, which guides a coil portion to the rotating shaft 60a of the head holder 60, and has one end attached to the spring hook 60.
e1 and the other end is hung on the carrier base 501.

70 is a carrier cover, and a ribbon cassette 80 which will be described later
The guide pins 70a and 70 are used to guide the cassette 80.
b and 70c, and is further provided with a claw 70d for pressing the ribbon cassette 80 against the guide pin and preventing it from coming off. 70e is an index, and 70f is a shaft that holds a switching cover, which will be described later. In this embodiment, three types of cassettes can be exchangeably loaded into the cassette loading section 70: a self-collection ink ribbon cassette 80a, a two-color ribbon ink ribbon cassette 80b, and a normal one-color ink ribbon cassette 80c, which will be described later. .

Reference numeral 71 denotes a switching lever, which is rotatably held by the shaft 70f, has a pressing pin 71a at its tip, and has a slide shaft 71b1 and a rotation stopper shaft 71c erected at the other end.

A switching slider 72 is slidably held on the slide shaft 71b of the switching lever 71, and the U groove 72a engages with the rotation stopper shaft 71c to restrict the rotation direction. Note that the switching slider 72 has a claw 72d formed at its lower part. Further, 73 is a switching slider spring that constantly pushes down the switching slider 72. Reference numeral 74 denotes a switching lever spring, which is stretched between the switching lever 71 and the carrier cover 70, as shown in FIG.
1 is biased in the counterclockwise direction of the arrow (direction of arrow B).

In FIG. 4, reference numeral 75 denotes a ribbon idle gear which meshes with the ribbon drive gear 504d of the center gear 504, but since it is held on the shaft of a ribbon lever which will be described later, the mesh is released by rotation of the ribbon lever. be able to. Also, 76 is a ribbon lever, and the carrier cover 70
The ribbon lever 76 is rotatably held on the shaft 76a, and the ribbon idle gear 75 is held on the shaft 76a. It is in contact with the outer periphery.

A ribbon lever spring 77 biases the ribbon lever 76 clockwise (in the direction of arrow C).

78 is the friction clutch shaft, carrier cover 70
is press-fitted into the 79 is the friction clutch (3rd
In the figure), a lower gear portion (not shown) meshes with the ribbon idle gear 75, and power is transmitted to the take-up spool 79a with a predetermined friction. Since the center of rotation of the ribbon lever 76 is the same as that of the friction clutch 79, even if the ribbon idle gear 75 rotates, the ribbon lever 76 does not disengage from the gear of the friction clutch.

Further, 80 is a ribbon cassette, 801 is a ribbon cassette bottom, and 802 is a ribbon cassette lid. Next, the internal structure of the ribbon cassette 80 will be explained using FIGS. 8 and 9. In the figure, 803 is a ribbon pancake, and the ribbon pancake 803 and the ink ribbon R are guided in the order of the arrows, pass through the front of the print head 63, and are guided through a delay roller 804, a delay lever 805, and a guide roller 806. , is wound onto a winding core 810.

The take-up core 810 is fitted with the take-up spool 79a on the carrier 50 described above, and the rotational force of the take-up spool 79a is transmitted. The delay lever 805 is made of a material with bending resistance such as polypropylene.
05a is provided. This bent portion 805a is sufficiently thin and can be bent with a slight force. Further, 807 is a delay lever return spring, and the delay lever 805
is always kept in a retracted state. Reference numeral 808 denotes a delay spring, which is disposed between the slider 809 and the delay lever 805. When the slider 809 is pressed, the delay lever 805 is projected forward (toward the platen) via the delay spring 808, and the delay spring 808 is disposed between the slider 809 and the delay lever 805. roller 80
4 is pressed against the platen 7. In addition, delay lever 8
05, there is a pin (not shown) that is guided by a diagonal slit formed in the ribbon cassette lower part 801 and the ribbon cassette lid 802.
Therefore, when pressing the platen 7, the delay roller 804 advances diagonally to the left along the slit and presses at a position away from the print head 63 (see FIG. 9). The shape of this cassette may be changed depending on the type of ribbon to be stored, or it may have the same shape as long as a display is attached.In short, the guide pin 70a
It is sufficient if the carrier cover 70 can be guided by the pots b and C and locked by the claws 70d.

FIG. 13 is a block diagram of the configuration of an output device when the printer of this embodiment is installed in an electronic typewriter, and the operation of the printer of this embodiment is controlled by this output device. Here, the motor 502 and the thermal bed 63 are connected to the thermal head driver THD and motor driver MD via the flexible board 22.

Further, the switch 21 is connected to the detection section.

Note that 1014 is a power switch, 1015 is a keyboard, and 1070 is a liquid crystal display section. Further, in this embodiment, the keyboard 1015 is provided with a correction button a and a color designation button b. Therefore, as will be described later, when a self-collection ribbon cassette (one ribbon with printing and correction functions) is installed in the carrier 50, the delay roller 804 can be adjusted by turning on the correction button a. A modification (lift-off or cover lap) of the record can be made in particular. Furthermore, the applicant of the present invention has provided an ink ribbon cassette equipped with an ink ribbon disclosed in Japanese Patent Application No. 59-260403 or Japanese Patent Application No. 60-298831 (printing in multiple colors is possible with one ribbon) in a carrier 50. When the color selection button b is turned on when the delay roller 804 is installed on the
By protruding or retracting, it is possible to print in a color (for example, blue) different from the basic color (for example, black).

Next, FIG. 13 will be explained in detail.

Note that this diagram only shows the connection relationship between each block.
Detailed control lines are omitted. The part surrounded by the dotted line is the CPU unit.

The CPU is a central processing unit that reads programs and various data from a ROM, etc. (described later), performs necessary calculations and judgments, and performs various controls. Further, the CPU may be composed of a plurality of CPUs. The ROM is a read-only memory and stores various programs for the CPU to operate, character codes, dot patterns (character generator, CG), various data necessary for printing, etc. TRAM is read/write memory, and is a working area where the CPU temporarily stores data and calculation results while executing instructions.
Keyboard 1015 and external interface unit IFu
It consists of a buffer area for storing various input data, a text area for saving documents, etc., and is backed up by a battery, so even if the main power is turned off when the power switch is turned off, the Data can be saved even if the main power is turned off.

The CPU unit also has a thermal head driver THD.
, the printer unit Pu via the motor driver MD and the detection unit Su.

The thermal head driver THD is controlled by the CPU.
It is provided in the aforementioned printer unit Pu. The thermal head 63 is driven, and the motor driver MD drives the motor 502 under the control of the CPU.

The detection unit Su transmits information from a limit sensor (not shown) provided in the printer unit Pu to the CPU.

The power source PSu supplies a mold source VH for driving (heating) the thermal head 63, a power source VM for driving the motor 502, and a power source VCC for other logic circuits.

Further, the controller GA performs various controls such as changing the voltage and current of the power source VH for driving the thermal head 63 and changing the heating time and duty of the thermal head 63 under the control of the CPU.

The CPU unit also has a keyboard connector K B C
A keyboard 1015 for inputting various data necessary for printing 2 editing, etc. is connected via the keyboard 1015.

Further, a liquid crystal display section 1070 for displaying data and information input from the keyboard 1015 is connected to the CPU unit via an LCD connector LCDC.

Note that instead of the liquid crystal display section 1070, a zero-cell display device such as a CRT may be used.

The CPU unit has an interface connector IFC.
R3232C for controlling this recording device by an external control device and communicating with external devices.

Interfaces such as Centro interface and modem can be connected.

In addition, the CPU unit is connected to a ROM for operating special functions and for printing with a separate unit via the cartridge connector CAC.
A cartridge and a RAM cartridge for expansion memory for storing documents, data, etc. can be connected.

Furthermore, although not shown in this figure, an audio output device such as a buzzer may be provided.

Now, in the above configuration, the operation of the printer controlled by the above-described output device will be explained.

First, the up and down movements of the head will be explained. When the motor 502 rotates forward, the motor pinion 503 also rotates forward (in the direction of the arrow), and the motor pinion 503 also rotates forward (in the direction of the arrow).
03 also rotates (in the direction of arrow B). At this time, the clutch spring 515 wound around the spring clutch boss 504e of the center gear 504 also rotates synchronously. Since one end 515a of the clutch spring 515 is integrated with the control cam 512, the control cam 512 also rotates in synchronization with the center gear 504. In addition, the claw 513c of the control lever 513
slides on the slope 512d of the control cam 512, comes into contact with the locking surface 512b, and the control cam 512
stop rotating. When the control cam 512 stops, one end 515a of the clutch spring 515 is stopped, and the one end 515a loosens, causing the clutch spring 515 to stop.
is released, so it stops without periodically rotating with the center gear 504.

Note that at this time, the center gear 504 continues to rotate. Assuming that the locking portion where the control cam 512 and the control lever 513 are currently locked is A, the head cam 519 at this time is in the position shown in FIG. 11(a), and the pressing portion 519
a is pressing the cam roller 62, and the print head 63 is pressed against the platen.

In addition, the notch part of the ribbon feed cam 518 (notch cam 518
a-518b) to the ribbon arm 76b of the ribbon lever 76.
(correspondingly), and the ribbon idler gear 75 meshes with the ribbon drive gear 504d of the center gear 504. Therefore, the rotational force of the ribbon drive gear 504d is transmitted to the friction clutch 74 via the ribbon idler gear 75.
can be conveyed to.

Here, as described above, since the center gear 504 continues to rotate, the carrier 50 is constantly moving on the rack 2 through communication with the small gear 504b, idler gear 505, and carrier pinion 506.

Then, head up (the thermal head 63 is placed on the platen 7)
When the motor 502 is rotated in the opposite direction by a predetermined pulse, the center gear 504 also rotates in the opposite direction (in the opposite direction to arrow B), and the control cam 512 is also synchronized by the loosening torque of the clutch spring 515. and rotate. At this time, the claw 513c of the control lever 513 is
The trigger surface 512c of the control cam 512 pushes it outward in the circumference. Next, when the control lever 513 is rotated in the forward rotation direction, the control lever 513 that has been thrown out is unable to lock the locking surface 512b of the locking portion A that has been locked so far, and the control cam 512 is rotated in the normal direction. It can be rotated and then rotated to the stop B. Here, Figure 11 (
As shown in b), the head cam 519 is connected to the cam roller 6.
2 is released, and the thermal head 63 is separated from the platen 7. Also, since the ribbon lever 76 and the ribbon arm 76 are in contact with the outer peripheral surface of the ribbon feed cam 518,
The ribbon idler gear 75 is separated from the ribbon drive gear 504d, and the friction clutch 74 does not rotate and does not wind up the ribbon R.

As described above, by rotating the motor 502 in the reverse direction, the control cam 512 and the control rail /<-51
3 is repeated, the print head 63 moves down in the direction of the platen 7, and then moves up in the direction away from the platen 7. Note that if the carrier 50 moves in the opposite direction due to the trigger when the head is up, the ribbon R may become loose or dirty, or the motor load may increase. The carrier 50 does not move in the opposite direction when the trigger is reversed.

Next, the operation of the switching lever 71 will be described (see FIG. 11).

As mentioned above, in normal head down mode, the control cam 512 is moved up to A by applying - at B.
rotates and stops. At this time, the switching lever 71 has a switching slider 72 slidably attached to one end of the switching lever 71, which passes through the slope cam 517a of the switching cam 517 provided at the top of the spacing cam 516, and passes over the top surface of the switching groove 517b. Since the head cam 516 stops when positioned above the cam surface 517c, the switching lever 71 does not rotate (FIG. 23(a)).

Now, here, when rotating the switching lever 71, when the switching slider is positioned on the upper surface of the switching groove 517b of the switching cam 517, as shown in FIG. 23(b), the motor 502
When the reverse rotation operation (second trigger) is performed, the switching groove 517
b engages with the claw 72d of the switching slider 72, the switching lever 71 is pushed out of the groove (in the direction of the outer periphery), and as a result, the switching lever 71 rotates in the direction A in FIG. 23(c). At this time, since the switching slider 72 is pressed downward by the switching slider spring 73, the switching slider 72 comes into contact with the cam surface 517c. Then, due to the rotation of the switching cam, when the switching slider 72 is positioned at its maximum outer circumferential surface, the head-down operation ends and stops, so the switching lever 71 rotates in the direction of arrow A, and the pressing pin 71a moves toward the platen 7. Figure 23 (d)
). At this time, the cassette with delay lever 805 (2
Colored ribbons and self-collection ribbons) have a delay.
Since the lever 805 is pushed in the direction of the platen 7 by the pressing pin 71a, the delay roller 804 is pressed against the platen 7 (see FIG. 9).

When the head is up (by rotating the motor 502 in the reverse direction (applying a trigger) and rotating the head cam 516, it will come off the maximum diameter part of the switching cam 517, so the switching lever 71 will rotate in the direction of arrow B in FIG. 4). The pressure on the director lever 805 by the above-mentioned suppressing pin 71a is also released, and the lever 805 returns to its initial position.

As described above, according to this embodiment, the delay lever 805 can be extended and retracted at any point in the recording process, that is, regardless of where the carrier 50 is in the recording area, the recording speed can be improved. be able to.

As described above, as the carrier 50 moves, the head moves up and down, the ribbon is wound up, and the switching lever is moved in and out. In this embodiment, all operations are performed by the motor. The control is performed by rotating 502 in the opposite direction by a predetermined amount.

Now, the paper feeding operation will be described next.

First, the rotation of the motor 502 mounted on the carrier 50 is as follows.
This is transmitted to the bevel gear 507, and the bevel gear 507 always rotates in synchronization with the motor 502.

Now, when the motor 502 is reversely rotated, the carrier 50 moves toward the home position (left side in the figure) while rotating the bevel gear in the C direction. First, the ratchet gear 509a and the shutter gear 16 are engaged, and the shutter gear 16 is rotated. Rotate in direction D. At this time, the tooth surface 16e of the shutter gear 16 and the ratchet gear 509a are meshing with each other, and due to the movement of the carrier 50, the tooth surface 16e and the ratchet gear 509a are engaged deeply in the tooth thickness direction from meshing, but they come into contact with the abutting surface 16f and stop. At this time, since the shutter gear 16 is subjected to the braking action (friction) of the friction spring 17, the tooth surface of the ratchet gear 509 and the tooth surface 16e of the shutter gear are always in contact with each other without being repelled. Here, the carrier 5o moves further, but the ratchet spring 510 is compressed, and the ratchet gear 509 and ratchet plate 508 both move on the bevel gear shaft 507b of the bevel gear 507, but the rotational force is transmitted by the keyway 507c. (Figure 12 (a'
)). On the other hand, the carrier pinion 506 is disengaged from the stop tooth 2b of the rack 2, and the guide ring 506 is disengaged from the stop teeth 2b of the rack 2.
6e is rotating while contacting the stop tooth 2b (FIG. 12(a)). Also, a little before the carrier pinion 506 comes off from the stop tooth 2b, the contact piece 2 of the switch 21
1a and 21b are pressed by the protrusion 501b of the carrier 50 and are electrically connected. By detecting conduction of the switch 21, it can be confirmed that the carrier 50 has come to a predetermined position. When the switch 21 is turned on and the motor 502 is reversely rotated by a predetermined amount, the carrier 50 stops when the stop tooth 2b and the carrier pinion 506 are disengaged. However, carrier pinion 506 is still rotatable. Therefore, when the carrier pinion 506 is stopped at a predetermined position and the motor is then rotated forward, the carrier pinion 506 rotates in the E direction (Fig. 12(b)), but before the stop tooth 2b and the notch 506' engage. Then, stop the forward rotation (Fig. 12(b)).

At this time, the ratchet gear 509 rotates in the F direction, so it slides on the abutment surface 16 of the shutter gear 16, passes between the feed teeth 16a, and meshes with the teeth of the PF gear 15 (see Fig. 12). b')) At this time, the ratchet gear 50
9, the ratchet plate 508 also moves.

When the PF gear 15 and the ratchet gear 509 mesh here, the load on the ratchet gear 509 increases, so that the pawls 508a to 508d of the ratchet plate 508 and the ratchet gear 5
The ratchet teeth 509c of 09 are disengaged and the rotational force of the motor 502 is released. The ratchet plate 508 releases force in the F direction, but transmits force in the C direction, so if the motor 502 is rotated in the reverse direction again with the ratchet gear 509 and the PF gear 15 engaged, the PF gear 1
5. Rotational force is transmitted to the breather gear 18 and the PF crawler layer 11, the PF crawler rotates, and the printing paper S can be fed by the frictional force between the paper feed rubber roller 5 and the printing paper. After feeding the printing paper S by a predetermined amount, when the motor 502 is rotated forward, the ratchet 5
08 is disengaged and the rotational force of the motor 502 is not transmitted to the PF gear 15, so the carrier pinion 506 rotates in the direction of arrow C without the PF crawler rotating in the reverse direction.

And the start tooth 2C of rack 2 and the synchronization tooth 506b
After the rack teeth 2a and pinion teeth 506a come into contact with each other, the carrier 50 starts moving rightward (the first
Figure 2 (C)). Note that as the carrier 50 moves, the PF
Gear 15, shutter gear 16 and ratchet gear 509
is out of engagement. While the ratchet gear 509 and the PF gear 15 are disengaged, the ratchet 508 operates to release the rotational force. In addition, since the guide hole 103a of the left side plate 103 and the stop ring 511 press-fitted into the bevel gear 507 are fitted, the ratchet gear 5
PF gear 15 when 09 and PF gear 15 are engaged
The spacing between the ratchet gear 509 and the ratchet gear 509 can be maintained accurately. Furthermore, when the amount of paper feed is large, in this device, the amount of paper feed at one time is less than one revolution of the carrier pinion 506, so by alternately rotating the motor 502 in forward and reverse directions and continuously feeding the paper, 50 allows continuous paper feeding without moving. Also, the forward and reverse rotation of the motor 502 (
When reversing, backlash occurs between the motor pinion 503 and the PF gear 15, so in order to compensate for the backlash during reverse rotation, a predetermined amount of pulses is added to the number of pulses calculated from the gear ratio. Perform paper feed.

This backlash correction is always performed by rotating the motor 502 in the reverse direction before performing the paper feeding operation.

As described above, according to this embodiment, the driving force of the motor 502 can be arbitrarily taken out and used for conveying the paper S, so that the motor 502 can also be used to make the apparatus smaller and lighter.

Note that the pressure gear 18 is a pressure spring 20.
Since it is constantly pressing against the PF gear 15 and PF roller 11, backlash is eliminated.

In addition, when the pressure gear 18 is feeding paper under a heavy load, the PF gear 15 is arranged to bite in the direction in which the pressure spring 20 is pulling, so the spring force of the pressure spring 20 may be weak, and the motor 50
The increase in the load of No. 2 is slight.

Next, the initialization (initial position setting) of the printer when the power is turned on will be explained.

FIG. 14 shows a timing chart.

First, when the switch 2I is OFF, the carrier 50 reversely rotates the motor 502 to return to the home position. At this time, if the print head 63 remains down, the head cam 51
Since the head 6 rotates in the opposite direction, the head 63 is separated from the platen 7. At this time, 1, the stop cam 5 of the ribbon feed cam 518
When the ribbon lever arm 76b of the ribbon lever 76 comes into contact with the ribbon lever arm 76C, the clutch spring 515 is released and the head cam 516 stops rotating. Note that the center gear 504 and the carrier 50 are provided with movement.

When the protrusion 501b of the carrier 50 presses the contact piece 21a and the switch 21 is turned on, the carrier 50 is ramped down by a predetermined amount and stopped. Next, carrier 5
0 in the positive direction, detect the OFF of switch 21,
From there, if the motor 502 is rotated in the forward direction with a prescribed pulse, the index will point to the first digit and the carrier 50 will stop. During this time, the head 63 is lowered and raised to remove slack from the ribbon R. Also, when the power is turned on, switch 2
1 is ON, first rotate the motor 502 in the forward direction, move the carrier 50 to the right, confirm that the switch 21 is turned OFF, remove the slack in the ribbon as described above, and then move the carrier 50 to the right. Adjust the index to In other words, the operation starts from part A in the timing chart of FIG.

Next, the printing operation will be explained. FIG. 15 is a timing chart of printing operation.

First, when the power switch 1014 is turned on, the printer is initialized as described above, and the carrier 50 stops at the first digit. And keyboard 1015 (Fig. 13)
Enter characters, symbols, etc., and press the return key to start printing. First, the motor 502 is reversely rotated to return the carrier 50 by a predetermined amount (a). Next, move the carrier 50 to the right by a predetermined amount (b) and hit the control cam 512's B locking part with the control lever/<-513, and then start the reverse rotation (trigger operation) of the motor 502 (c). and lower the head 63. Here, during the return operation of the carrier 50, the control lever 1
3 and the control cam 512 are the stop cam 518c of the ribbon feed cam 518 and the ribbon arm 76 described above.
b are in contact with each other, so that the pawl 513c is positioned just before the slope 512d of the control cam 512, as shown in FIG. 16(a). By performing the forward rotation b, the control cam 512 and the control lever 513 come into contact with each other, and the trigger operation is activated (Fig. 16(b)).Next, the motor 502 is rotated in the reverse direction (A). The bird applies -) and performs a head-down motion (d). At this time, the head-down is completed with d,
Run-up before printing is performed at d2, and printing (voltage is applied to the head) is performed at d3. Then, at d4, a run-up after printing is performed, and the printing operation is completed.

At this time, as the head is slowly lowered over time, the print head 63 comes into pressure contact with the platen 7.
Since the shape of each cam of the head cam 516 is set so that the friction clutch rotates after the ribbon R starts to be fed out, problems such as dirt at the beginning of printing do not occur.

Now, the reverse rotation (B) rigger) of the motor 502 is applied to raise the head f, but at this time as well, the ribbon R also stops winding after the head 63 is raised, so the ribbon pulled out when the head is lowered is Since the ribbon is rolled up, there is no ribbon slack. Incidentally, since the head is raised instantaneously, it is possible to prevent the trailing edge of printing from becoming dirty.

Now, after the head is up, the carrier 50 is returned to the left, and after detecting that the g2 switch 21 is ON, the g2 motor is further rotated by a predetermined amount. At this time, as described above, the movement of the carrier 50 is stopped. By performing forward rotation H here,
Until now, the meshing with the PF gear 15 has been restricted by the shutter gear 16, but it is now released, and the PF gear 15 and the ratchet gear 509 mesh. Next, by performing the reverse rotation i of the motor 502, the PF gear 15 and the PF roller gear 11 are rotated, and a predetermined amount of printing paper is deposited. When the motor 502 rotates forward (j) after paper feeding, the carrier pinion 506 and the rack teeth 2a mesh after a predetermined amount of rotation, and the carrier 5o moves to the right, points to the first digit, and stops.

The above describes normal printing.

Next, printing with the first layer ink of the self-collection ribbon or the so-called two-color ribbon (the ribbon disclosed by the applicant in Japanese Patent Application No. 59-260403 or No. 60-298831) will be described. Note that the ink layer is in a stacked relationship with the first layer and the second layer. In this case, the ribbon cassette is selected using the keyboard 1015 and the ribbon mode is switched, but the ribbon mode is automatically switched using a dedicated changeover switch or a contact provided on the carrier by providing a detection hole in the ribbon cassette. You can go. Now, in printing with the first layer ink of a self-collection ribbon or a two-color ribbon, it is necessary to peel the ribbon R from the paper S at a steep angle after the print head 63 is heated. For this reason, the winding timing of the ribbon R varies (taking into consideration the case, the run-up d2 after the head is down is increased) to take up the slack in the ribbon R fed out from the head 63. A timing chart of the motor 502 is shown.As shown in the figure, a' when returning to the carrier.
The only difference is d2' when the head is down.

The printing state in this case is shown in FIGS. 19(a) and 19(b).

In the figure, 900 is a substrate of the ink ribbon R, and 901 is a multilayer ink layer. Further, 63a is a heat generating portion of the head 63, and B1 is a recorded image.

Next, the collection operation of the self-collection ribbon will be explained using the timing chart shown in FIG.

First, the carrier 50 is returned by manually rotating the motor 502 in the reverse direction a using an erase key a provided on the keyboard 1015. Next, set the control lever 513 at b and apply the reverse rotation (Al-rigger) C of the motor 502 to start head-down. Further d. Switch with slider 7
2 is at the position of the switching groove 517b of the helad cam 516 (therefore, the reverse (C) rigger) of the motor 502 for rotating the switching lever 71 is applied.

The reverse rotation C' (C trigger) of the motor 502 is the reverse rotation C' (C trigger) of the motor 502 during normal head-up and head-down.
Since the amount of reversal is greater than that of A/B trigger), carrier 50
moves slightly in the opposite direction, but since the head 63 is not yet pressed against the platen 7, there is no adverse effect on printing. Now, by reversing the motor 502 (C trigger), the switching lever 7
1 rotates slightly, and the switching slider 72 moves to the switching cam surface 5.
It fell to 17c and the set was complete.

Next, as the motor 502 rotates in the normal direction d1, the head 63 continues to move downward and comes into pressure contact with the platen 7. At this time, the switching lever 71 and the pressing pin 71a also rotate to press the slider 809 of the ribbon cassette 80 and press the delay roller 804 against the platen 7 via the delay lever 806 (see FIG. 20(a)).

Next, at the position of the printing part Bl, an electric current is applied to the head 63 to heat the heat generating part 63a to make the ink in a semi-molten state, and then the printing part Bl is peeled off from the paper S d3 (see FIG. 20(b)). Here, since a run-up after printing is required until the delay roller 804 passes the printing portion Bl, the run-up d4 is larger than that during self-correction printing.

Next, the motor 502 is reversed (B trigger) e, and the head 63 is raised f. Simultaneously with the raising of the head 63, the switching lever 71 is also reset, and the delay roller 804 also releases its pressure contact with the platen 7. Note that the above-described collection operation may be performed only once, but the collection operation may be repeated once again, taking into consideration the smoothness of the paper S, the difference in type, etc.

Next, when printing the second layer of ink when using the two-color ribbon described above, as in the case of erasing the self-collection ribbon, the delay lever 804 is extended to prevent the ribbon R from peeling off from the paper S after printing. It suffices to delay it, and on the timing chart, it suffices to perform the same operation as erasing. In other words, when printing, if the motor 502 is reversed (triggered) when the head is down as reverse c (A) rigger) or reverse c' (C) rigger), the delay roller 804 presses against the platen 7, and the ribbon R The timing of peeling from the paper S can be delayed.

〔Effect of the invention〕

As described above, the present invention provides a gear drive device that can eliminate backlash with a simple structure.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is an overall perspective view showing an embodiment of the present invention, Fig. 2 is a sectional view of an embodiment of the invention, Fig. 3 is an exploded perspective view of the carrier portion thereof, and Fig. 3 is an exploded perspective view of the carrier portion thereof. Figure 4 is a sectional view of the carrier part, Figure 5 is an enlarged perspective view of the control plate and head cam, and Figure 6 is an enlarged perspective view of the control plate and head cam.
7 are left and right side views of an embodiment of the present invention, FIGS. 8 and 9 are internal plan views of a ribbon cassette of an embodiment of the present invention, and FIG. 1O is an embodiment of the present invention. 11 is a state diagram for explaining the operation of the control plate and head cam, and FIG. 12 is a state diagram for explaining the operation of the carrier pinion and paper feeding mechanism in one embodiment of the present invention. , FIG. 13 is a block diagram of an output device of an electronic typewriter using the printer of the present invention, FIG. 14 is a timing chart of carrier initialization, and FIG.
Fig. 5 is an overall timing chart showing the operation of the printer of this embodiment, Fig. 16 is a state diagram showing the operation of the control board, Fig. 17 is a timing chart during printing of self-collection ribbon, and Fig. 18 is a self-correction ribbon timing chart. Erasing the collection ribbon. Figure 18 is a timing chart when printing the collection ribbon. Figure 18 is a timing chart when erasing the self-collection ribbon. Figure 19 is a diagram showing how the ribbon is peeled off from the paper during printing. Figure 20. 21 is a partial perspective view of another embodiment of the paper feeding device; FIG. 22 is a perspective view of an embodiment for removing backlash; FIG. FIG. 23 is a state diagram for explaining the operation of the switching lever. In the figure, l...Base, 2...Rack, 4...
PF crawler 5...PF rubber roller, 7...
Platen, ll...PF crawler, 15...PF
Gear, 16...Shutter gear, 18...Pressure gear, 21...Switch, 22...Flexible cable, 50...Carrier, 502...Motor, 506...Carrier pinion, 512... Control plate, 515...Clutch spring, 516...Head cam, 55...Bevel gear unit, 63...Print head, 71...Switching lever 71
... Press pin, 80 ... Ribbon cassette, 804 ... Delay roller, 805 ... Delay lever.

Claims (2)

[Claims] (1) A drive gear, a driven gear to which power is transmitted from the drive gear, and an idler gear that meshes with the driven gear, the idler gear making it possible to displace the rotating shaft, and
A gear drive device characterized in that the idler gear is pressed against the drive gear and the driven gear by an elastic member. (2) The idler gear has two gears A and B having the same shape and the same phase of teeth, and a cylindrical boss formed between the gears A and B. The gear drive device according to the scope item (1).