JPH08118751A - Method and mechanism for adjusting cap of printer - Google Patents

Abstract

PURPOSE: To adjust a platen to a proper gap position with respect to a printing head in the gap adjusting method and mechanism of a printer. CONSTITUTION: After paper is pressed to a printing head 1 by a platen 2, the platen 2 is separated from the printing head 1 to be set to a definite origin position and further moved to a proper position leaving a proper gap 2 from the printing head 1 to be allowed to approach the printing head 1. By this constitution, the effect of the backlash of a mechanism 6 allowing the platen 2 to approach and separate with respect to the printing head 1 is eliminated and the platen 2 is accurately held to a proper position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gap adjusting device for a printing device, and more particularly to a gap adjusting method for a printing device and a mechanism for the same so that the platen position with respect to a print head can be properly adjusted.

[0002]

2. Description of the Related Art In a printing apparatus such as a dot impact printer, a paper is sandwiched between a print head and a platen, and pins called dot pins are ejected from the print head to perform printing at a desired position on the paper.

A large number of pins are arranged on the print head in the paper transport direction, supported by a shuttle, and the pins are ejected at required positions while moving the shuttle in the paper width direction. An appropriate gap is provided between and to prevent the sheets from jamming and the pins from bending due to contact between the two.

However, if the gap between the print head and the platen becomes too narrow, the force for hitting the pin may cause the pin to buckle and bend, break, or cause a jam. If the distance between the platen and the platen becomes too wide, the tip of the pin may get caught in the paper and may be bent or broken.

Therefore, for example, as shown in FIG. 10, a platen 102 is provided so as to be able to come in contact with and separate from the print head 101 with a sheet sandwiched therebetween, and a spring 104 is provided to an eccentric cam 103 that receives the platen 102 from the side opposite to the print head 101. By operating the lever 106, which is pressed and rotatable about the fulcrum 105 within a predetermined angle range, using the scale provided on the gap scale 107 as a guide, the link 1
Print head 1 by rotating the eccentric cam 103 via 08.
A gap adjusting mechanism is provided so that the gap between 01 and the platen 102 can be adjusted. The scale of the gap scale 107 is formed by using the number of sheets of paper as a guide.

[0006]

However, there are various sheets having different weights, for example, a basis weight of 30 to 130 kg / m ² , and a sheet in which a plurality of sheets having different thicknesses are stacked. Therefore, the correspondence between the gauge scale and the paper thickness is ambiguous.

In practice, the thickness of the paper is judged based on the experience of the operator and is adjusted according to the scale selected corresponding to the thickness, so that the proper gap adjustment is performed for the printer. It is unknown whether or not
Pin breakage or jam may occur.

Therefore, in order to surely prevent the pin breakage and the jam, a test printing is performed to confirm the suitability of the adjustment result. When adjusting according to the scale selected correspondingly, it is difficult to adjust the gap to the optimum value at one time, so the gap adjustment operation and test printing are repeated several times, and it takes a lot of time and effort. I need time.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a gap adjusting method for a printing apparatus and a mechanism therefor, which can perform an appropriate gap adjustment for the printing apparatus. It is a thing.

[0010]

The present invention employs the following means in order to achieve the above object. That is, in the printing apparatus that adjusts the gap between the print head 1 and the platen 2 that is provided so as to be able to come into contact with and separate from the print head 1, after the paper 5 is pressed against the print head 1 by the platen 2, Platen 2 print head 1 to a fixed origin position
After that, the platen 2 is brought closer to the print head 1 to a proper position where a proper gap n2 remains between the platen 2 and the print head 1.

As the proper position, the distance from the position where the platen 2 presses the paper 5 against the print head 1 to the origin position is detected, and the proper gap n2 is subtracted from this distance to obtain the proper position from the origin position. The appropriate pressing distance R-n2 of the platen 2 is calculated according to the appropriate pressing distance R-n2.
Is a position close to the print head 1 from the origin position.

Further, it is desirable that the proper pressing distance R-n2 is an average calculated over a plurality of times. Furthermore,
The position where the sheet 5 is pressed against the print head 1 by the platen 2 is preferably a position other than the position of the perforations of the sheet 5.

The gap adjusting mechanism 3 includes a contact / separation mechanism 6 which is driven by a motor 4 to bring the platen 2 into and out of contact with the print head 1 with the paper 5 interposed therebetween, and a torque limiter 12 interposed in the contact / separation mechanism 6. The motor 4 is rotated in the direction in which the platen 2 approaches the print head 1 to separate the platen 2 from the initial position to the pressing position for pressing the paper 5 against the print head 1, and then the motor 4 is rotated in the reverse direction to move the platen 2 to the platen 2. 2 is separated from the print head 1 at an origin position by a certain distance, and the motor 4 is further rotated to subtract the proper gap n2 from the distance from the press position to the origin position to set the platen 2 at the origin position by an appropriate press distance R-n2. And a contact / separation control unit 20 for bringing the print head 1 closer to the print head 1.

Further, the origin position is detected by an origin sensor 18 which detects that the platen 2 has reached the origin position from the pressing position. The contact / separation control unit 20 rotates the motor 4 in a direction in which the platen 2 approaches the print head 1 to initially move the platen 2 from an initial position to a pressing position for pressing the paper 5 against the print head 1. Means 20a, reverse rotation control means 20b for rotating the motor 4 in the reverse direction after the initial movement to move the platen 2 to the origin position which is a certain distance away from the print head 1, and obtains the movement distance, and the reverse movement. The calculating means 20c for calculating the proper pressing distance R-n2 by subtracting the proper gap n2 from the distance from the pressed position to the origin position, and further, the platen 2 is moved to the proper pressing distance R-n from the origin position.
Adjustment movement control means 2 for moving only 2 toward the print head 1 side
It consists of 0d.

Further, in the present invention, the paper 5 is the print head 1.
The sheet detecting means 5 for detecting the presence or absence of the sheet 5 at a stage before driving the contact / separation mechanism 6 based on the output of the sheet sensor 17 for detecting whether the sheet 5 is located between the platen 2 and the platen 2.
It is desirable to have 2. Further, it is desirable to operate the contacting / separating mechanism 6 while the paper is in a tensioned state. Therefore, when the paper detection means detects the presence of a paper, the paper detection means 52 slightly reverses the paper supply tracker and / or slightly rotates the paper discharge tracker with respect to the paper feed control means. Provide a function to issue instructions.

Further, it is desirable to provide a restarting means 50 for restarting the gap adjusting mechanism 3 when a predetermined predetermined condition is satisfied during the printing operation. The restarting means 50 changes a predetermined time, the number of printing lines reaches a predetermined value, the printing of one hopper ends, the end of one job, or the temperature of the platen changes by a certain value or more (or less) from the previous start. It is started every time.

Further, a print density control means 34 for controlling the print density corresponding to the paper thickness is provided with a function of calculating the paper thickness based on the detected distance between the pressed position and the origin position. It is preferable that the structure is provided. The print density control means 34 is an overlapping print control means for printing the same print data at the same position on the paper 5 a number of times determined by the paper thickness, and a head drive current control means for controlling the drive current of the print head 1 according to the paper thickness. It is possible to employ a printing speed control means for controlling the printing speed and the excitation time according to the paper thickness.

Further, according to the present invention, the power holding means 40 for holding the power for a predetermined time when the power switch is turned off.
Then, the power holding means 40 may be provided with a releasing means 41 for moving the platen 2 from the print head 1 by a predetermined distance when the power supply switch OFF is detected.

Although the case where the platen 2 moves with respect to the print head 1 has been described above, the present invention can be naturally applied even when the print head 1 moves with respect to the platen 2.

[0020]

[Operation] Generally, in the contact / separation mechanism 6 for contacting and separating the platen 2 with respect to the print head with the paper sandwiched therebetween, a minute clearance is provided between the parts contacting each other in order to facilitate the operation thereof. When the operation direction is reversed, the driven-side component loosens with respect to the driving-side component, that is, backlash occurs.

It is possible to separate the platen 2 from the position where the sheet is pressed against the print head 1 by the platen 2, that is, the platen 2 can be directly separated from the print head 1 to the proper position. Backlash occurs due to the reversal of the operation direction of the contact / separation mechanism 6 at the position, and after moving the platen 2 to the proper position, the platen 2 further moves in the direction of separating from the print head 1 within the range of this backlash. However, an error may occur in the position control, which is disadvantageous in improving the gap adjustment accuracy.

In the method of the present invention, after pressing the sheet against the print head 1 by the platen 2, the platen 2 is once separated from the print head 1 to a certain origin position, and the operation of the contact / separation mechanism is reversed at the origin position. Therefore, as shown in FIG.
Backlash N ₁ in the reverse direction at the same amount as the backlash N ₀ by operation inversion at the pressing position is generated at the home position, the platen while being offset backlash N ₁ at the origin position and Bakurasshi N ₀ at the pressing position 2 can be separated from the proper position, and the platen 2 separated from the proper position can be prevented from moving from the proper position in a direction away from the print head 1.

In addition, since the gap adjustment is automatically performed in this manner, it is not necessary to perform the troublesome manual adjustment of the gap and the test printing for confirming the suitability of the result. In the apparatus of the present invention, the motor 4 is rotated in the direction in which the platen 2 is separated from the print head 1 by the initial movement control means 20a of the contact / separation control means 20 to press the platen 2 from the initial position to press the paper against the print head 1. Move to. The motor 4 is driven so as to move the platen 2 by a distance larger than the distance from the initial position to the pressing position, and the torque limiter 12 escapes the excessive driving after the platen 2 reaches the pressing position.

Thereafter, the reverse rotation control means 20b of the contact / separation control means 20 causes the motor 4 to rotate in the reverse direction so that the platen 2 is rotated.
Is separated from the pressing position to the origin position which is a certain distance from the print head 1. Further, the calculating means 20c calculates an appropriate pressing distance by subtracting an appropriate gap from the distance from the pressing position to the origin position, and then the adjusting moving means 20.
The method of the present invention is carried out by rotating the motor 4 by d to bring the platen 2 closer to the print head 1 from the origin position by the proper pressing distance.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The gap adjusting method and mechanism of a printing apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a principle view of the present invention, FIG. 2 is a side view of the present invention, FIG. 3 is a functional block diagram of the present invention, FIG. 4 is a flow chart of the present invention, and FIG. [Fig. 6] is an operation explanatory view of the present invention.

As shown in FIGS. 1 and 2, the gap adjustment of the printing apparatus according to the embodiment of the present invention is performed by using the print head 1 and the platen 2 which can be brought into contact with and separated from the print head 1. A gap adjusting mechanism 3 of a printing apparatus for adjusting a gap between the two, including a motor 4 and a contact / separation mechanism 6 which is driven by the motor 4 to move the platen 2 to and from the print head 1 with the paper 5 interposed therebetween. .

The contacting / separating mechanism 6 has a pair of cams 7 that are in contact with both ends of the platen 2, a gear train 8 that interlocks the cams 7 with the motor 4, and a pair of springs that press the platen 2 against the cams 7. 9, a rotary shaft 11 for supporting the final gear 10 of the gear train 8 and the cam 7 as shown in FIG.
A torque limiter 12 is interposed between and.

The initial gear 1 of the gear train 8
Two reduction gears 14 are provided between the gear 3 and the final gear 10.
15 and one intermediate gear 16 are provided. Also, paper 5
2 is fed into the paper feed tractor 42 from the lower left of FIG.
The paper is fed between the print head 1 and the platen 2 at the same timing as the operation of the print head 1 to perform line-by-line printing, and then the paper is ejected from between the print head 1 and the platen 2 by line feed. Is sent out in the upper right direction, and is finally conveyed to the discharge tray or the discharge stacker of the printing apparatus.

The rotation direction and rotation amount of the motor 4 are controlled by the contact / separation control means 20 shown in FIG. 3 as follows. In the following description, the distance is equivalent to the pulse number.

First, when the power of the printing apparatus is turned on, the ROM
3 to the memory 31 shown in FIG. 3 with an initial value n1 and an appropriate gap value n2 according to the paper thickness (n1 and n2 will be described in detail later).
Is written.

After writing to the memory 1, the restarting means 50 obtained from the upper control means or described later is used.
When the activation signal S ₁₀ obtained by the above is input to the initial setting means 51, the initial setting means 51 first sets the initial value n1 in the register 24 from the memory 31 and clears the counter (FIG. 4, step). S1). Here, the initial value n1 represents the initial moving distance of the platen 2 by the number of pulses, and is set to a value larger than the maximum distance between the print head 1 and the initial position of the platen 2.

Then, based on the outputs of the paper sensor 17 and the end sensor 41 shown in FIG.
However, by detecting that the paper 5 is between the print head 1 and the platen 2, the adjustment start instruction signal S ₁ is input to the initial movement control means 20a of the contact / separation control means 20 (FIG. 4, step S2). ).

The initial movement control means 20a includes the counter 22, register 24, comparison section 23 and drive control section 29 shown in FIG.
Composed of Upon receiving the adjustment start instruction signal S ₁ , the drive control unit 29 of the initial movement control means 20a starts the driver 25 in the normal rotation (for example, the normal rotation signal "1") to rotate the motor 4 in the normal direction, and the counter 22 to start.

The count value of the counter 22 is the comparison unit 2
3 is compared with the initial value n1 set in the register 24,
When the comparison unit 23 detects that the count value has become equal to the initial value n1, the drive control unit 29 instructs the driver 25 to stop the motor 4 (for example, the normal rotation signal “0”) and the counter 22 is cleared. Then, a reverse rotation instruction (reverse rotation signal “1”) is issued, and the reverse rotation moving means 20b of the contact / separation control means 20 is activated (FIG. 4, steps S3 → S4).

Although the initial position of the platen 2 has not been determined in the above, the maximum distance from the print head 1 is known, so the initial value n1 is α from the maximum distance (pulse number) between the print head 1 and the platen 2. The value is higher by the number of pulses. Therefore, after the platen 2 reaches the pressing position, the motor 4 excessively rotates by at least α pulses, but the torque limiter 11 interposed in the contact / separation mechanism 6 releases the rotation of the excessive pulse, and the platen 2 is rotated. The paper 5 is surely pressed against the print head 1 with a predetermined pressure.

The reverse moving means 20b is the drive control unit 29.
And a counter 22. As described above, when the reverse rotation moving means 20b is activated, the drive control unit 29 of the reverse rotation moving means 20b reverses the motor 4, and the counter 22 sequentially increments in accordance with this reverse rotation. This procedure is shown in Figure 1.
It continues until the origin signal S ₀ from the origin sensor 18 shown in FIG. ₂ is detected (S5 → S6 → S7), and by this origin detection, as will be described later, the count value of the counter 22 is fetched into the calculating means 20c (FIG. 4, step S5 → S6 →
S7 → S8).

Here, the origin sensor 18 is constructed so as to be able to detect that the platen 2 is separated from the print head 1 to the origin, which is a predetermined distance away from the pressing position by the cam 7 and the rotating shaft 11 rotating in the reverse direction. Good.

That is, for example, as shown in FIG. 1, while the platen 2 is separated from the pressing position to the origin position by the light shielding plate 19 fixed to one end of the rotary shaft 11 of the cam 7, the optical path is blocked and the platen 2 is the origin. It can be composed of a photo interrupter whose optical path is opened when the position is reached.

[0040] When the platen 2 is the origin sensor 18 is spaced apart from to the home position is output origin signal S _0, the raw point signal S ₀
Is input to the drive control unit 29, and the motor 25
Is stopped (reverse rotation signal “0”) and the counter 22 is stopped (step S8 in FIG. 4).

Further, the origin signal S ₀ is also input to the computing means 20c, whereby the computing means 20c takes in the count value R of the counter 22, that is, the distance from the pressed position to the origin position, and thereafter, Instruct the counter to clear.

The calculating means 20c subtracts the proper gap n2 fetched from the memory 21 from the count value R fetched from the counter 22 to obtain the proper pressing distance R-n2.
Is calculated, the proper pressing distance R-n2 is set in the register 27, and the calculation end signal S ₂ is sent to the drive controller 2
9 to input the adjustment movement control means 20d (FIG. 4, step S9).

The adjustment movement control means 20d comprises the counter 22, the register 27, the comparison section 26 and the drive control section 29. When the adjustment movement control means 20d is activated, the operation end signal S ₂ is drive control means is input 2
Reference numeral 9 issues a normal rotation instruction to the driver 25 to rotate the motor 4 in the normal direction and count up the counter 22. The count value of the counter 22 is stored in the register 2 in the comparison unit 26.
7 is compared with the set value (R-n2), the motor 4 is R-n
When two pulses are normally rotated, the drive control unit 29 causes the driver 25 to
A stop instruction is output to the driver 2 which has received this stop instruction.
5 stops the motor 4 so that the separation control means 2
The operation of 0 ends (FIG. 4, step S10).

The outline of the operation of the platen 2 can be shown by a time chart as shown in FIG. 6, but here, while the platen 2 is separated from the pressing position to the origin position (t ₁ −
The count value R counted by the counter 22 at t ₂ ) corresponds to the backlash N ₀ of the contact / separation mechanism 6 that occurs when the rotation direction of the motor 4 is switched at the pressing position and the distance from the pressing position to the origin position. Contains the number of pulses.

When the motor 4 is rotated in the forward rotation direction with the number of pulses obtained by subtracting the appropriate gap n2 from the count value R (timing t ₂ ), first, the contact / separation accompanying switching of the rotation direction of the motor 4 at the origin position is performed. Backlash N of mechanism 6
_{After 1} (= N ₀ ) is resolved, the platen 2 will start moving from the origin position.

[0046] Thus, the offset and the backlash N ₁ in backlash N ₀ and the origin position in the pressing position is a direction reverse magnitude is the same as each other, the platen 2 is precisely the proper position, i.e., the print head 1 The sheet 5 is sandwiched between the platen 2 and the platen 2 and is moved to a position where the proper gap n2 is placed.

At the proper position, the spring 9 moves the platen 2
Is pressed against the cam 7, there is no risk that the platen 2 will move from the proper position toward the print head 1, and
There is no risk that the platen 2 will be separated from the print head 1 from the proper position unless the motor 4 is rotated in the reverse direction.

In FIG. 6, the adjustment start signal S₁
When occurs₀When starting reverse rotation from t ₁By the time of initial movement
Excess pulse time of (the torque limiter is operating
Time) is included. Also, it moves from reverse to normal again.
Time t₂The calculation processing by the calculation means 20c is extremely short.
It's a good time, so it's ignored.

Thus, the platen 2 is accurately held at the proper position, the gap can be properly adjusted with respect to the printing apparatus, and the dot pin can be surely prevented from bending, breaking, and jamming. It will be.

Further, since the proper gap adjustment is automatically performed in this manner, it is not necessary to perform the troublesome manual work of the gap adjustment and the test printing for confirming the adequacy of the adjustment result.

Further, the calculating means 20c fetches the origin value X corresponding to the distance between the origin position and the position of the platen 2 pressed against the print head 1 without pinching the paper 5 from the memory 31, and the origin value X is obtained. It has a function of calculating the paper thickness t by subtracting the count value R of the counter 22 from the.

The sheet thickness t is calculated at the same time as the step of calculating each appropriate pressing distance (step S9), and is stored in the memory 3
1 and then, after the gap adjustment procedure is completed, as shown in FIG. 3 or 7, it is output to the density control means 34 as necessary, and used for controlling the print density.

As the print density control means 34, the number of times the pin is hit at the same position is determined in correspondence with the paper thickness t, and the thicker the paper thickness t, the greater the number of times the pin is hit. , Printing current control means for controlling the drive current that defines the strength of hitting the pins of the print head 1 corresponding to the paper thickness t, and printing for controlling the printing speed and excitation time of the print head 1 corresponding to the paper thickness t A speed control means or the like can be considered.

FIG. 8 shows a flow chart in the case where the above-mentioned overlay printing control means 34a is adopted. When printing is performed a plurality of times, the number of times of printing n is set and the number of times n is sequentially decremented each time the pin is driven, and when it becomes zero, it is confirmed whether there is a next line, and the next step (restart step ) (FIG. 8, steps 211 to S2)
16).

In the case of the above-mentioned overprinting control means, the thicker the paper thickness is, the more the number of times of overprinting is increased. In the case of the printing current control means, the thicker the paper thickness is, the larger the current value is.
Further, in the case of the printing speed control means, the thicker the paper thickness, the longer the excitation time and the slower the printing speed, so that the printing density can be adjusted to an appropriate value.

By the way, when the paper thickness is calculated by the calculating means 20c in this manner, the thinner the paper 5 is, the thinner the paper thickness is detected due to the rigidity or elasticity of the print head 1, the platen 2 and the paper 5. It has been found.

Since the presence of such a detection error is not preferable for the gap adjustment and the printing paper density adjustment, in the present invention, the detection error is empirically obtained and the paper calculated as described above is used. It is preferable to correct the proper gap n2 and the origin value X at the time of gap adjustment based on the thickness.

Further, in the above embodiment, the distance from the pressing position to the origin position is detected once, and the calculating means 20c calculates the appropriate pressing distance based on the detected distance. However, an error may occur in the proper pressing distance calculated by the detection error of the distance from the pressing position to the origin position.

In order to reduce this error and improve control accuracy, in the above embodiment, the contact / separation control means 2 is used.
To 0, the function of repeatedly separating the platen from the pressing position to the origin position and then reciprocating the platen between the origin position and the pressing position a plurality of times to repeatedly detect the distance from the pressing position to the origin position is calculated. The means 20c may be provided with a function of calculating an average value of the distances from the pressing position to the origin position a plurality of times and subtracting the appropriate gap from the average value to calculate the appropriate pressing distance.

Further, the gear adjustment of the printing device may not be sufficient once performed when the printing device is started. For example, when the printing apparatus is continuously operated, the print head 1 is heated and thermally expanded, so that the gabb becomes narrower than an appropriate value, and the gap may need to be readjusted.

Therefore, in the present invention, as shown in FIGS. 3 and 7, when the predetermined condition is satisfied even during printing, the start signal S ₁₀ is output to restart the gap adjusting mechanism. It is desirable to provide the restarting means 50 (FIG. 7, steps S22a → 22b). As the above conditions,
For example, whether the temperature of the platen 2 has changed by a predetermined value or more, the printing time has passed a certain time, the number of printing lines has reached a predetermined number, the printing of one hopper has finished, or one shovel has finished. , Etc. can be used. It is also possible to combine a plurality of conditions among the above.

In order to realize the restart by the temperature of the platen 2, the temperature sensor is embedded in the platen 2, and the restart means 50 is set to the temperature when the temperature of the temperature sensor last started the gap adjusting mechanism. The system is configured to restart when the temperature is higher or lower than a predetermined temperature.

Particularly, the gap adjusting mechanism 3 is provided for each number of print lines.
When the restarting means 50 for restarting the sheet is provided, the thickness of the sheet is partially different by giving the correspondence relationship between the line position and the sheet thickness and operating the restarting means 50 in a predetermined row. That is, the gap between the print head 1 and the platen 2 is increased in the thick portion of the so-called stepped medium and decreased in the thin portion so that the proper gap can always be maintained against the change in the sheet thickness. As a result, it is possible to reliably prevent jamming, pin bending, and pin breakage even in a stepped medium that easily causes jamming, pin bending, and pin breakage.

In order to facilitate the paper insertion work, it is necessary to release the gap adjusting mechanism when the power is turned off.
Therefore, in addition to detecting the power switch OFF, a power supply holding unit 40 that holds the power supply for a while without turning off the power supply even if the power supply switch is turned OFF is provided, and when the power supply holding unit 40 detects the switch OFF, the drive control unit 2
The reverse rotation instruction is issued by 9 (FIG. 7, steps S23a → S23b).

As a result, as shown in FIG. 7, the releasing means 41 operates to release the gap adjusting mechanism, that is,
The gap between the platen 2 and the print head 1 is widened. The releasing means 41 is also made up of the counter 22, the comparing section 26, the register 27, and the driving means 29 of the contact / separation control means 20, and the reverse rotation distance is, for example, the step of adjustment movement (FIG. 4, step S10). The platen is returned to the origin position as a distance corresponding to the R-n2 pulse number set in the register 27.

Regarding the adjustment work by the gap adjusting method or apparatus of the present application, when the pressing position of the platen 2 on the paper becomes the perforated portion of the continuous paper, the gap adjustment is performed at a portion thinner than the actual paper pressure. become. By the way, since the perforation of the paper is located at a predetermined distance from the position of the leading edge of the paper, the existing sensor is used so that the end sensor 41 detects the leading edge of the paper and then transfers the paper at a distance where the perforation is not located at the pressing position. It is preferable to instruct the paper feeding means. However, this method is effective only when setting the paper.

If the sheet is loosened, it may cause an erroneous detection of the proper pressing position or the sheet thickness. Therefore, it is possible to give tension to the sheet when operating the gap adjusting mechanism of the present invention. Hope. Therefore, the paper detection means 52 is configured to output the adjustment start instruction signal S ₁ and at the same time instruct the paper feed control means originally provided in this type of printing apparatus to perform paper tension processing. Is desirable.

The above-described paper tension processing is, for example, to slightly reverse the paper supply tracker 42, slightly rotate the paper discharge tracker 44, or both. .

Although the above description has been made only for the case where the platen 2 moves with respect to the print head 1, the present invention will be described with reference to FIG.
As shown in FIG. 5, it can be naturally applied to the case where the print head 1 moves with respect to the platen 2.

[0070]

As described above, the device of the present invention is
After pressing the sheet of paper against the print head with the platen, the platen can be separated from the print head to a certain origin position, and thereafter, the platen can be moved closer to the print head to a proper position where a proper gap remains with the print head. it can.

According to the present invention, by reversing the operation of the contact / separation mechanism at the origin position, the backlash in the opposite direction is generated at the origin position by the same amount as the backlash caused by the reversal of the operation of the contact / separation mechanism at the pressing position. Then, the platen can be moved to the proper position with the backlash at the pressing position and the backlash at the origin position being canceled out, and the platen that has moved to the proper position is separated from the print head from this proper position. The effect of preventing movement is obtained.

Further, since the gap adjustment is automatically performed in this way, the effect that the manual gap adjustment and the test printing for confirming the adjustment result are unnecessary can be obtained.

Further, in the present invention, if the procedure for operating the gap adjusting mechanism is set to be performed for a fixed period of time every time one shovel is completed or every time printing on one hopper is completed, the platen is removed with the lapse of time. Even if the gap of the print head changes, it can be dealt with. Furthermore, if the gap can be adjusted for each predetermined number of rows, it becomes possible to cope with a stepped medium.

In the present invention, based on the paper thickness,
When using the print density adjustment means that can adjust the print density,
Even if the paper thickness is large or small, a uniform print density can be secured.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention.

FIG. 2 is a side view of the present invention.

FIG. 3 is a functional block diagram of the present invention.

FIG. 4 is a flow chart of the present invention.

FIG. 5 is an operation explanatory diagram of the present invention.

FIG. 6 is a time chart of the present invention.

FIG. 7 is a flow chart of another embodiment of the present invention.

FIG. 8 is a flow chart of overlay printing according to the present invention.

FIG. 9 is a side view of another embodiment of the present invention.

FIG. 10 is a perspective view of a conventional example.

[Explanation of symbols]

 1 print head 2 platen 3 gap adjusting mechanism 4 motor 5 paper 6 contact / separation mechanism 12 torque limiter 17 paper sensor 18 origin sensor 20 contact / separation control means 20a initial movement control means 20b reverse rotation control means 20c computing means 20d adjustment movement control means 33 Judgment means 34 Print density control means 40 Power supply holding means 41 Release means 41 50 Restart means 52 Paper detection means n2 Proper gap R-n2 Proper pressing distance

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location B41J 11/26 11/42 KM 29/38 C // B41J 25/308 (72) Inventor Fujimoto Hiroshi Hyogo Prefecture, Kato-gun, Shrine Town, Saho No. 35 (no street number) In Fujitsu Shuttle Machine Co., Ltd. (72) Inventor Daigo Uchikoshi, Kato-gun, Shrine Town, Kato District, Hyogo Prefecture, No. 35 (no street number) In Fujitsu Shuttle Machine Co., Ltd. (72) ) Inventor Mitsunori Hiraishi No. 35 Saho, Shrine-cho, Kato-gun, Hyogo Prefecture (No house number) In Fujitsu Shuhei Co., Ltd. (72) Inventor, Kazuhiro Tamada No. 35 Saho, Shaho-machi, Kato-gun, Hyogo Prefecture (No house number) In-house (72) Inventor Shingo Ashida 35, Saho, Shrine-cho, Kato-gun, Hyogo Prefecture (No street number) In Fujitsu Aki Co., Ltd.

Claims (23)

[Claims] 1. A gap adjusting method for a printing apparatus, which adjusts a gap between a print head and a platen which is capable of coming into contact with and separated from the print head, wherein the paper is pressed against the print head by the platen. A method for adjusting a gap in a printing apparatus, wherein the platen is separated from the print head to an origin position, and thereafter, the platen is brought closer to the print head to a proper position where a proper gap remains between the platen and the print head. 2. The proper position is a distance from the position where the platen presses the paper to the print head to the origin position, and the proper gap is subtracted from this distance to determine the proper position from the origin position to the proper position. 2. The gap adjusting method for a printing apparatus according to claim 1, wherein the pressing distance is calculated, and the platen is located at a position closer to the print head from the origin position according to the appropriate pressing distance. 3. The press of the paper against the print head and the separation to the origin position are repeated a plurality of times, and the distance from the position where the paper is pressed against the print head to the origin position is detected a plurality of times, which is detected. The gap adjusting method for a printing apparatus according to claim 2, wherein the appropriate pressing distance is calculated based on an average value of the distances. 4. The gap adjusting method for a printing apparatus according to claim 1, wherein the sheet is pressed against the print head by the platen in a state where the perforation is not located at the position where the platen is pressing the sheet against the print head. 5. The print head is pressed against the platen and separated to the origin position instead of the procedure of pressing the platen against the print head, separating to the origin position, and approaching the print head. 5. The gap adjusting method for a printing apparatus according to claim 1, wherein a procedure of approaching the print head is adopted. 6. A gap adjusting mechanism of a printing apparatus, which adjusts a gap between a print head and a platen which is provided so as to sandwich and sandwich a sheet relative to the print head, wherein the platen is sandwiched by a motor driven by a motor. The contact / separation mechanism for contacting / separating with the print head, the torque limiter interposed in the contact / separation mechanism, and the motor in the direction in which the platen approaches the print head presses the platen from the initial position onto the print head. After separating to the pressing position, rotate the motor in the reverse direction to separate the platen to the origin position that is a certain distance from the print head, and further rotate the motor to subtract the appropriate gap from the distance from the pressing position to the origin position. A gap adjusting mechanism for a printing apparatus, comprising: a contact / separation control unit that brings the platen closer to the print head from the origin position by an appropriate pressing distance. . 7. An origin sensor for detecting that the platen has reached the origin position from the pressing position.
The gap adjusting mechanism of the printing apparatus according to [1]. 8. The contact / separation control means rotates the motor in a direction in which the platen approaches the print head to initially move the platen from the initial position to a pressing position for pressing the paper against the print head. After the initial movement, the motor is rotated in the reverse direction to separate the platen from the print head to the origin position which is separated from the print head by a predetermined distance, and the reverse movement control means for obtaining the movement distance, and the origin from the pressing position obtained by the reverse separation. 8. A calculation means for calculating a proper pressing distance by subtracting a proper gap from a distance to a position, and an adjusting separation controlling means for further moving the platen from the origin position to the print head side by the proper pressing distance. The gap adjusting mechanism of the printing apparatus according to [1]. 9. The contact / separation control means has a function of reciprocating the platen between a pressing position and an origin position a plurality of times to detect a distance from the pressing position to the origin position a plurality of times, 9. The printer according to claim 8, wherein the means has a function of calculating an average value of the distances from the pressing position to the origin position of the plurality of times and subtracting an appropriate gap from the average value to calculate the appropriate pressing distance. Gap adjustment mechanism. 10. The presence / absence of a sheet is detected at a stage before driving the contact / separation mechanism based on an output of a sheet sensor that detects whether or not the sheet is positioned between the print head and the platen. 9. The gap adjusting mechanism according to claim 6, further comprising a sheet detecting unit for performing the sheet adjusting operation. 11. When the paper detection means detects the presence of paper, the paper detection means slightly reverses the paper supply tracker and / or slightly discharges the paper discharge tracker with respect to the paper feed control means. The gap adjusting mechanism for a printing apparatus according to claim 10, further comprising a function of issuing a normal rotation instruction. 12. The printer according to claim 6, further comprising restarting means for restarting the gap adjusting mechanism when a predetermined predetermined condition is satisfied during the printing operation. Gap adjustment mechanism. 13. The gap adjusting mechanism for a printing apparatus according to claim 12, wherein the restarting means restarts the gap adjusting mechanism at regular intervals. 14. The gap adjusting mechanism for a printing apparatus according to claim 12, wherein the restarting unit restarts the gap adjusting mechanism every time the number of continuous printing lines reaches a predetermined value. 15. The gap adjusting mechanism for a printing apparatus according to claim 12, wherein the restarting means restarts the gap adjusting mechanism every time printing of one hopper is completed. 16. The gap adjusting mechanism for a printer according to claim 12, wherein the restarting means restarts the gap adjusting mechanism after one job is completed and before the next job is started. 17. The gap adjusting mechanism for a printer according to claim 12, wherein the restarting means restarts the gap adjusting mechanism when the temperature of the platen changes by a predetermined value or more. 18. A print density control means for controlling the print density corresponding to the paper thickness, wherein the calculation means has a function of calculating the paper thickness based on the detected distance between the pressed position and the origin position. The gap adjusting mechanism of the printing apparatus according to claim 8, further comprising: 19. The gap adjusting device for a printing apparatus according to claim 18, wherein the print density control means comprises overlay print control means for printing the same print data at the same position on the paper for a number of times determined by the paper thickness. 20. The gap adjusting mechanism for a printing apparatus according to claim 18, wherein the print density control means comprises a head drive current control means for controlling a drive current of the print head according to the sheet thickness. 21. The gap adjusting mechanism for a printing apparatus according to claim 18, wherein said print density control means comprises print speed control means for controlling a print speed and an excitation time according to said paper thickness. 22. Power supply holding means for holding the power supply for a predetermined time when the power switch is turned off, and release means for separating the platen from the print head by a predetermined distance when the power supply holding means detects the power switch off. The gap adjusting mechanism for a printing apparatus according to claim 6, which is provided. 23. The print head is pressed against the platen and separated to the origin position in place of the structure in which the platen is pressed against the print head, separated to the origin position, and approached to the print head. The gap adjusting mechanism for a printing apparatus according to any one of claims 6 to 22, wherein a mechanism for approaching the print head is adopted.