JP2639388B2 - Contact device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an approach / separation device used for approaching / separating a platen and a print head of a printer, for example.

[Prior art]

2. Description of the Related Art In an image forming apparatus such as a thermal printer, paper is supplied between a platen and a print head (hereinafter, referred to as a head) which are separated from each other. ing. The contact of the head to and from the platen is controlled by turning the solenoid ON and OFF.
It is done by.

[Problems to be solved by the invention]

However, as described above, since the platen and the head are brought into contact with and separated from each other by turning on and off the solenoid, there are disadvantages in that the contact sound at the start of the press contact is loud or only a constant press contact force is obtained.

[Object of the invention]

According to the present invention, it is possible to reduce the impact at the time of starting the press contact between a first member such as a platen and a second member such as a print head, and to adjust the press contact force between the first member and the second member. It is an object of the present invention to obtain a contacting / separating device that can be used.

[Solution]

That is, in the contact / separation device of the present invention, in the contact / separation device for contacting / separating the first member and the second member, the first member or the second member is supported. A support member that is movable in a direction in which the second member comes into contact with and separates from the other member; a forward / reverse motor that can rotate and stop at an arbitrary position corresponding to the type of recording medium and a home position; The moving member, which is restricted by the rotation of the motor, and gradually moves between the supporting member and the first member and the second member by the elastic restoring force. The elastic member that is pressed against and restored by the elastic restoring force by the movement of the moving member in the opposite direction, and the first member and the second member are moved in the direction in which the first member and the second member contact and separate by controlling the rotation of the motor. While selectively moving the support member, It is characterized in that a drive device for setting in response to pressure contact force of Sawatoki the type of recording medium. Further, the first member is a platen in the image forming apparatus, and the second member is a print head.

【Example】

An embodiment of the present invention will be described below with reference to the drawings. <Configuration> First, the configuration will be described. As shown in FIG. 1, an image forming apparatus, for example, a digital plate making machine [a plate making machine for perforating a heat-sensitive stencil sheet (hereinafter referred to as a master) using a thermal head] 1 has a main body 2 having an operation section 8 and this main body. A paper feed tray 20 for setting a document to be supplied to the paper feeder 2 and a detachable paper feed cassette 3 for the main body 2 containing the master. An image is formed on a recording medium (master, OHP paper, thermal paper, plain paper, etc.) stored in the printer. In the above description, the master refers to a heat-sensitive stencil sheet obtained by laminating a thermoplastic synthetic resin film and a porous support. Examples of the thermoplastic synthetic resin film include films of polyester, polypropylene, vinylidene chloride-vinyl chloride copolymer, and the like. As the porous support, for example, natural fibers such as Manila hemp, crocodile, Mitsumata, polyester, polyvinyl alcohol, synthetic fibers such as polyacrylonitrile, semi-synthetic fibers such as rayon, porous thin paper, nylon,
Tetoron or silk gauze is used. The paper feed table 20 is provided with paper feed guides 21 and 22 for regulating the side edges of the originals set as shown in FIGS. 1 and 2 movably in the width direction. In the path for feeding the original set on the paper feed table 20 and reading the image, an empty sensor 65, a kick roller 23 for sending the original, and a feed roller for conveying the original sent by the kick roller 23 are provided. 24 are provided. The document following the document conveyed by the paper feed roller 24 is rejected by the separation roller 25. The leading edge of the original set on the paper feed table 20 is regulated by the original stopper 26, and the original leading edge detection sensor 27 (for example, a lever sensor)
The document is fed by a feed roller 29 and a driven roller 30 while confirming the passage by a document trailing edge detection sensor 28 (for example, a lever type sensor). In the transport path, reference reflectors (white reference) 32
Then, the original glass 33 accommodated in the glass pressing plate 35 is provided, and the original is discharged by the discharge lower 31 pressed against the glass pressing plate 35 with an appropriate pressure. The original is illuminated by a light source, for example, a fluorescent lamp 34 provided below the original glass 33 while being conveyed on the original glass 33, and the reflected light from the original illuminated by the fluorescent lamp 34 is reflected by the mirror 4 to change its direction. Is done.
The light supplied through the mirror 4 is an image sensor,
For example, it is input to the image reading unit 5 having a CCD (Charge Coupled Device) 9 and is converted into an electric signal. The image reading section 5 is electrically connected to an image processing section 10 having an A / D converter and the like, and a CPU (central processing unit) 11. The feed roller 24 and the kick roller 23 are driven by a belt and have a speed ratio of 1: 1. The separation roller 25 is pressed against the paper feed roller 24 with an appropriate pressure, and rotates reversely at a speed ratio of about 70% of the paper feed roller 24. However, by a spring clutch (not shown), a mechanism is arranged to rotate in a forward direction when the load is equal to or more than a certain load, and to rotate in a reverse direction when the load is less than a certain load (reverse separation). Has become. It should be noted that a one-way clutch is provided in the paper feed roller 24 so that the original is forcibly conveyed even when the separation roller 25 is pressed. Further, from the output shaft of the original motor (pulse motor) for driving these components, a drive system is divided into two systems (one-way clutch and two-way clutch).
Feed / separation in forward rotation and reading / discharge in reverse rotation. The feed lower 29 and the discharge roller 31 are driven by a belt and have a speed ratio of 1: 1. The driven roller 30 is pressed against the feeding roller 29 with an appropriate pressure, and provides a sheet feeding force. As the above-mentioned image sensor, MOS (Metal Oxide
Semiconductor) image sensor and CID (Charge In)
jection Device) or CPD (Charge Priming Devi)
Other image sensors such as ce) may be used. On the other hand, a path for feeding a recording medium and forming an image includes:
A mounting opening 6 for taking in the recording medium and mounting the paper feed cassette 3 is formed, and the paper feed cassette 3 is set. The paper feed cassette 3 is determined by means for detecting the type of the paper feed cassette 3 set in the mounting port 6 as shown in FIGS. 6 and 7, for example, magnetic sensors 62 and 63. Further, the paper feed cassette 3 is provided with a push-up roller 64 therein and a lever type empty sensor 46 for detecting whether or not there is a recording medium in the paper feed cassette 3, for example. The recording medium set in the paper cassette 3
It is sent out by the kick roller 42, separated by the paper feed roller 43 and the separation roller 44 toward the recording medium conveyance path,
Will be fed. The transport path includes a rear end detection sensor 45, a platen 52, a thermal head 47 that is brought into contact with and separated from the pretenn 52, a head holder 51 that supports the thermal head 47, and a front end detection sensor 55 (for example, a transmission type Sensor)
A front / back detection sensor 56 provided alongside the sensor 55 to detect the front and back of the master, a registration lever 57,
Paper discharge rollers 58 and 59 are provided. The kick roller 42 has a one-way clutch interposed. The speed ratio of the paper feed roller 43 and the kick roller 42 is 1: 1 by belt drive. The separation roller 44 has a reverse rotation speed ratio of 0.7: 1 with respect to the feed roller 43. Separating roller 4
Reference numeral 4 reverses and separates by a spring clutch similarly to the document transport system. The thermal head 47 is supported by a head holder 51 via a head bracket 82 and a head pressing plate 85 as shown in FIGS. The head holder 51 is attached to a rotating shaft 81. A head cam 78 is attached to the rotating shaft 81, and the head 47 and the platen 52 come into contact with each other by the rotation of the head cam 78. The drive mechanism for the head cam 78 and the head holder 51 is attached to a bracket 76. That is, a pulse motor 71 serving as a driving source, a gear 83 attached to a rotation shaft of the pulse motor 71, and a gear 72 meshing with the gear 83.
A gear 84 provided coaxially with the gear 72; a gear 73 meshed with the gear 84; a gear 87 provided coaxially with the gear 73; a gear 75 meshed with the gear 87; A head pressing spring 90 stretched between a cam pin 88 provided on the cam gear 75 and a gear pin 89 provided on the cam gear 75,
A lever sensor 91 (home position sensor) for detecting the rotation state of the cam gear 75 is provided. The cam gear 75 has an arc-shaped gear portion 75A and an arc-shaped concave portion 75B.
It has. The paper feed cassette 3 includes a push-up plate 41 which presses the recording medium accommodated in the kick roller 42 as shown in FIG. 2 by the urging force of the push-up roller 64, and magnetic sensors 62 and 63 as shown in FIGS. Magnet housings 60, 61 at positions corresponding to
According to whether or not magnets are housed in the magnet housing portions 60 and 61 (see the following table), the type of the sheet feeding cassette 3 can be distinguished as shown in FIG. Each paper feed cassette 3 is provided with a partition plate whose mounting position can be changed so as to correspond to the paper size. The design is also made in consideration of the respective friction coefficients of the recording medium. Further, when the plain paper feed cassette 3 is attached to the mounting opening 6, the thermal transfer ribbon 7 is attached to the head 47 and the platen 52.
Used between them. In this case, a ribbon feeding mechanism is required. Further, the printing processing conditions are varied depending on the type of the recording medium, for example, as follows. (1) Setting of print start position (Cueing) In the master to be the printing master, the reinforcing ears to be attached to the printing press are fed empty, and printing is started with a small amount of margin on thermal paper or the like. (2) Front and back detection The dedicated master has front and back detection holes to detect front and back. Thermal paper or the like kills this front / back detection function. (3) Determination of printing conditions Control of printing pressure: strong for master, weak for thermal paper. This is because there is a lot of energy for printing (plate making). Control of print pulse width and number of pulses: Control is performed according to the energizing time of the thermal head and how to apply energizing pulses, that is, whether printing (plate making) with one pulse or multi-pulse. Switching of normal image / reverse image ... The type of the paper feed cassette 3 set in the mounting slot 6 is determined, and switching is performed between printing (plate making) with a normal image and printing (plate making) with a reverse image. In other words, the master of the printing original plate becomes a reverse image (a normal image if printed),
Thermal paper is printed as a normal image. Appropriate gamma correction is applied to each sheet of external data (read data). (4) Setting and discharging of printing end position The end of the paper is detected, the printing (plate making) end position is set, and discharging is performed as appropriate. <Operation> In such a configuration, this device operates as follows. First. Place the document face down on the feed tray 20 and
21 and 22 are adjusted to the original width, and the original is aligned with the original stopper 26 and set. At this time, empty sensor 65 is ON
Then, it is detected that the document is set on the paper feed table 20. On the other hand, when the paper feed cassette 3 is mounted in the mounting opening 6 in step S1 as shown in FIG.
2, 63 are turned ON and OFF, and the type of the recording medium is determined. Then, in step S2, a flag (start position of the processing procedure) is set for each recording medium. The presence or absence of the recording medium is detected by the empty sensor 46. The push-up roller 64 pushes up the push-up plate 41 by mounting the paper feed cassette 3, and the recording medium is pressed against the kick roller 42. Further, except for the printing state, the sensor 91 is ON as shown in FIG.
The operation has ended. When the sensor 91 is turned off by an external force, the state returns to this state when the power is turned on. When the sensor 91 is in the state shown in FIG. 3, the gear pin 89 pushes up the head cam 78, and the platen 52 and the thermal head 47 are separated. When the start switch of the operation unit 8 is pressed in such a state, a solenoid (not shown) is turned on, and at the same time as the kick roller 23 is lowered (own weight), the document stopper 26 is also lowered, and a document motor (not shown) (Pulse motor) starts to rotate. When the leading edge of the document turns on the leading edge detection sensor 27, the document is fed by a certain amount. At this time, the leading edge of the document hits the rolling contact portion between the feed roller 29 and the driven roller 30 to form a registration loop and correct skew. Thereafter, the document motor rotates in the reverse direction, and the feed roller 29 and the discharge roller 31 start feeding the document. At the time when the original is conveyed by a fixed amount so as to mesh with the paper feed roller 29 and the driven roller 30, the solenoid is turned off, the kick roller 23 is raised, and the document stopper 26 is also raised. The original motor rotates reversely and the original trailing edge detection sensor 28 is turned on, and then feeds a certain amount.
Start reading (after issuing m). The light source uses a fluorescent light 34, through the original glass 33,
Perform illumination reading. At the time of reading, the reference reflection plate 32 is read and shading correction is performed. That is, when the start switch is ON, the variation in the length direction of the light of the fluorescent lamp 34 is read and the base color of the reference reflecting plate 32 is read and electrically corrected. However, when correcting to distinguish the background from the image, the data (base color of the document) at the center of the document at the leading edge (about 3 mm) of the document is read and the slice level is changed. A fixed amount of reading is performed after the document trailing edge detection sensor 28 is turned off (the document runs out), and then the document is discharged by being accelerated and conveyed for a certain time. On the other hand, when the printing process starts in step S3, the kick roller 42 is rotated by driving the recording medium motor, and the recording medium in the cassette 3 is fed. Then, the sheet is separated into one by a sheet feed roller 43 and a separation roller 44,
And the thermal head 47. Thereafter, when the leading end detection sensor 55 detects the leading end, the leading end is sent after a predetermined amount and stopped. For this reason, the leading end of the recording medium strikes the registration lever 57 to remove the skew. When the recording medium motor stops, the pulse motor 71 rotates and the registration lever 57 retracts. The rotation of the pulse motor 71 causes the cam gear 75 to rotate clockwise by a predetermined amount via the gears 83, 72, 84, 73, 87. Accordingly, the gear pin 89 moves from the point A to the point B as shown in FIG. Therefore, the cam pin 88 is attracted by the tension of the spring 90, and the head cam 78 rotates clockwise about the shaft 81, so that the thermal head
47 contacts the platen 52. When the pulse motor 71 further rotates, the pressure contact force of the thermal head 47 increases. Thereafter, if the recording medium is the master in the vicinity of the feed of about 15 mm (step S4), front and back detection is performed in step S5. If it is determined in step S6 that the surface is upside down, an error occurs in step S7, the mode is switched to the discharge mode in step S8, and the plate is discharged without performing plate making. In step S9, cueing (control of the printing plate making start position) is performed according to the type of the recording medium. Then, in step S10, the printing and plate making method according to the recording medium is selected, and in step S11, the printing and plate making operation is started. At that time, it is asked whether or not it is a master in step S12, and if it is a master, the image is sent out as a reverse image in step S13,
If it is not the master, the image is sent out as a normal image in step S14. Then, in step S15, the thermal head 47 is energized, and printing and plate making are performed. When the rear end of the recording medium is detected by the sensor 45, after printing a predetermined amount and making a plate, the recording medium motor is accelerated, and the pulse motor 71 is rotated in reverse to weaken the tension of the spring 90 (the head 47 and the platen 52 While reducing the pressing force of). In step S16, it is determined whether all printing and plate making have been completed. If not completed, the process returns to step S12, and if completed, stops in step S17.

[Effects of the embodiment]

(1) Since the motor is used without using a solenoid for contacting and separating the thermal head 47 and the platen 52, the thermal head 47 can be pressed against the platen 52 at a low speed by adjusting the rotation speed of the motor. For this reason, the contact noise at the start of the pressure contact can be significantly reduced, and the impact on the head 47 is small, so that the damage of the head 47 at the start of the pressure contact can be prevented. (2) A head pressing spring 90 is interposed between the cam pin 88 of the head cam 78 and the gear pin 89 of the cam gear 75, and
5 is pressed against the platen 52, so that the gear pin 89 moves from the state where the gear pin 89 is located at the point A (the head 47 and the platen 52 are separated) to the point B as shown in FIG. After touching 52, the tension of the spring 90 changes depending on where the point C is set depending on the rotation amount of the motor 71,
The pressing force of the head 47 against the platen 52 can be set (variable) with a predetermined width.

[Modification]

As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, For example, the following modifications are possible. (1) In the above embodiment, the head was pressed against the platen. However, the platen may be pressed against the head, or the head and the platen may be pressed against each other. (2) In the above embodiment, the head holder 51 with the shaft 81 as the center,
Although the head 47 is pressed against the platen 52 by rotating the head cam 78, a mechanism for moving the head 47 in parallel may be used. (3) In the above-described embodiment, one end of the spring 90 is supported by the gear pin 89, and the head cam 78 is pushed up at the time of releasing the pressure contact. (4) Although the pulse motor is used as the motor in the above embodiment, a DC motor may be used. In this case, for example, it is necessary to provide a sensor at the home position, a sensor at the weak pressure position, and a sensor at the high pressure position. (5) In the above-described embodiment, the description has been given of the device for moving the printing portion of the digital plate making machine. However, the automatic document feeder supplies the document onto the platen of an image processing device such as a copying machine or an image reader. The present invention can also be applied to a device for contacting and separating a paper roller and a reverse rotation roller. If described with reference to FIG. 2, the paper feed roller 24 and the separation roller 25 are configured to come into contact with and separate from each other. Further, the present invention is also applicable to the approach and separation of a paper bail where paper is pressed against a platen of a printer.

【The invention's effect】

As described above, according to the present invention, the support member that supports the first member or the second member and is movable in the direction in which the first member and the second member come into contact with or separate from each other is changed to a type of recording medium. Since the motor is moved to a corresponding arbitrary position and the home position by a forward / reverse rotatable motor capable of stopping rotation, it is possible to reduce an impact at the time of starting the pressure contact between the first member and the second member. At the same time, in the image forming apparatus, a clear recorded image can be obtained even when the recording medium is changed. In addition, the support member is moved via a moving member that moves while being constrained by the rotation of the motor in conjunction with the motor, and the moving member is also constrained to that position while the motor is stopped, so that image forming is performed. In the apparatus, a clear recorded image can always be obtained without the contact pressure between the first member and the second member fluctuating due to vibration or the like during image formation.

[Brief description of the drawings]

FIG. 1 is a side view showing the external appearance of a digital plate making machine, FIG. 2 is a cross-sectional view schematically showing the internal structure of the digital plate making machine, FIGS. FIG. 6 is a schematic side view showing a mounting portion of a sheet cassette, FIG. 7 is a schematic sectional view showing a mounted state, and FIG. 8 is a perspective view showing a plurality of sheet cassettes. FIG. 9 is a flowchart showing the operation of the digital plate making machine. 1 ... digital plate making machine, 3 ... paper feed cassette 47 ... head, 51 ... head holder 52 ... platen, 71 ... pulse motor 75 ... cam gear, 78 ... head cam 90 ... head holding spring

Continuation of the front page (72) Inventor Naoki Kobayashi 3167 Yamamiya-cho, Kofu-shi Nippon Seimitsu Kogyo Co., Ltd. (56) References JP-A-61-130076 (JP, A) JP-A-62-19476 (JP, A JP-A-62-251174 (JP, A) JP-A-62-22846 (JP, U)

Claims (2)

(57) [Claims] 1. A contact / separation device for contacting / separating a first member and a second member, wherein the first member or the second member is supported, and the first member or the second member is supported.
A support member that is movable in the direction in which the member and the second member come into contact with and separate from each other; a forward / reverse motor that can rotate and stop at an arbitrary position corresponding to the type of recording medium and a home position; A moving member that moves while being restricted by the rotation of the motor in conjunction with the motor; and a moving member that moves in one direction and is gradually elastically deformed between the supporting member and the first member and the second member by the elastic restoring force.
The first member and the second member are brought into contact with and separated from each other by controlling the rotation of the motor. And a drive device for selectively moving the support member in a direction to be set and setting a pressing force at the time of contact in accordance with the type of the recording medium. 2. An apparatus according to claim 1, wherein said first member is a platen in an image forming apparatus, and said second member is a print head.