JPH07106655B2 - Printer paper thickness detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention sets the thickness of paper in order to set the head gap by a platen position adjusting mechanism that moves the platen toward and away from the print head. The present invention relates to a paper thickness detecting method for a printer having a paper thickness measuring mechanism for measuring.

[Conventional technology]

In a printer that performs printing with a wire dot type print head that faces the platen and reciprocates in the axial direction together with the carriage, the distance from the paper surface on the platen to the tip of the print head (hereinafter referred to as the head gap). If not properly maintained, the print quality may be deteriorated due to the distance being too far away, or the wire may be broken in the print head due to being too close or the ink may not adhere to the ink ribbon, resulting in poor space operation of the carriage. Therefore, in order to avoid these, it is necessary to always maintain an appropriate head gap.

Therefore, the operator has to perform operation or confirmation so that the distance from the surface of the paper to the tip of the print head has an appropriate value each time the paper is loaded, which is very inconvenient.

Therefore, in order to eliminate such inconvenience, the present applicant has proposed the printer of Japanese Utility Model Application No. 62-152217.

This printer drives a paper thickness measuring mechanism that measures the paper thickness of the paper used, a platen position adjusting mechanism that adjusts the position of the platen with respect to the print head, and a platen position adjusting mechanism that is based on the measured values of the paper thickness measuring mechanism. By providing a calculating means for calculating the operation amount of the driving means, it is possible to automatically set an appropriate head gap. The details will be described below with reference to FIGS. 4 to 8.

FIG. 4 is a plan view showing the printer, and FIG. 5 is a sectional view taken along line AA of FIG.

As shown in both figures, a print head is provided so as to face the platen 1.
Is mounted on a carriage 5 guided by guide shafts 3 and 4 so as to be able to reciprocate in parallel with the axial direction.

The platen position adjusting mechanism 6 is a side plate 7a, 7b of the printer.
By a shaft 8 rotatably supported on the shaft 8, cams 9a and 9b fixed on the shaft 8 at a predetermined interval, and a spring provided so as to press the platen 1 against the cams 9a and 9b. Biasing members 10a, 10b and a gear 1 fixed to one end of the shaft 8
2 and a motor 11 for rotating the shaft 8 via the gear 12.

The platen 1 has side plates 7a and 7a at both ends so that the platen 1 can move horizontally in a direction perpendicular to the moving direction of the print head 2.
It is supported by b, and both end portions of the guide shafts 3 and 4 are also fixed to the side plates 7a and 7b.

On the other hand, a disc-shaped slit disk on the gear 12 side
A slit 13 is fixed to the shaft 8 and detects a slit (not shown) provided in the slit disk 13. Light reception /
A sensor 14 composed of a light-receiving element is arranged, and both of them are controlled by the control means described later by the platen position adjusting mechanism 6
Used to control the motor 11 of the.

The sheet thickness measuring mechanism 15 is arranged on the insertion side (lower side in this example) of the sheet 16 with respect to the platen 1, and faces the reference plate 17 arranged in the sheet passage.

In addition, on the discharge side of the paper 16 (the upper side in this example), the paper 16
A paper feeding mechanism 28 composed of a tractor belt having sprocket pins fitted with sprocket holes provided at regular intervals is arranged on both sides of the paper feeding mechanism 28, and the paper feeding mechanism 28 is a transmission voltage member such as a timing belt. It is connected to the motor 30 via the motor 29, and the feed of the paper 16 printed by the print head 2 via the ink ribbon 31 at the time of line feed or discharge is driven by the motor 30 via the power transmission member 29. It is designed to be performed by the paper feeding mechanism 28.

FIG. 6 is a side view showing the paper thickness measuring mechanism 15 in detail,
FIG. 7 is a front view of the slit disk which is the constituent element.

As shown in FIG. 6, the paper thickness measuring mechanism 15 includes a lead nut 20 rotatably supported by a boss 19 fixed to a fixing plate 18 provided on a base frame (not shown) of the printer, A gear 21 attached to one end of the lead nut 20, a motor 22 for rotating the lead nut 20 via the gear 21, and a male screw portion 23a at one end, and the male screw portion 23a is provided inside the lead nut 20. A guide frame 25 provided on the fixed plate 18 for guiding the screw shaft 23, which is screwed to the female screw 20a so that it can be moved back and forth, toward and away from the reference plate 17 by rotation so as to move toward and away from the reference plate 17. And a disc-shaped slit disk 26 fixed to the lead nut 20 on the gear 21 side.
And the sensors 27a, 27b corresponding to this slit disk 26.
It is composed of and.

As shown in FIG. 7, the slit disk 26 is provided with a plurality of outer peripheral slits 26a for detecting the rotation angle at equal angles in the circumferential direction, and inside the outer peripheral slit 26a, home position detection is performed. There is one home slit 26b for use with this outer slit 26a, home slit
Sensor composed of light emitting / light emitting element so as to detect 26b
a and 27b are arranged.

FIG. 8 is a block diagram showing a conventional control system having the above-mentioned configuration.

In the figure, 32 is a main control unit and 33 is a paper thickness measuring mechanism control unit, which controls the drive of the motor 22.

Reference numeral 34 denotes a platen position adjustment mechanism control unit, which controls driving of the motor 11.

Reference numeral 35 denotes a print mechanism control unit, which controls the drive of the print head 2.

A carriage mechanism control unit 36 controls driving of a carriage motor 37 which is a driving source of a moving mechanism of the carriage 5.

A paper feed mechanism control unit 38 controls driving of the motor 30.

Reference numeral 39 is an arithmetic circuit as an arithmetic means.

Next, the operation of the above configuration will be described.

First, when the operator inserts the paper 16 inserted through the paper insertion opening of the printer between the contact 24 of the paper thickness measuring mechanism 15 and the reference plate 17 and attaches it to the paper feeding mechanism 28, the paper is fed. The paper thickness measuring mechanism 15 measures the paper thickness of 16.

That is, the paper thickness measuring mechanism control unit 33 drives the motor 22, rotates the lead nut 20 and the slit disk 26, and brings the contact 24 into contact with the reference plate 17 via the paper 16. The determination that the contact 24 has come into contact with the reference plate 17 via the paper 16 is determined when there is no change in the output of the sensor 27a corresponding to the outer peripheral slit 26a for detecting the rotation angle of the slit disk 26, or when the motor 22 is disconnected. The paper thickness measurement mechanism control unit 33 determines that the adjusted case is a contact.

After the contactor 24 contacts the reference plate 17 via the paper 16 and the contact determination condition is satisfied, the control circuit 32a reversely rotates the motor 22 to separate the contactor 24 from the paper 16 and to detect the home slit. The outer peripheral slit 26a at the rotation angle of the slit disk 26 until the sensor 27b detects the home slit 26b is counted by the sensor 27a for detecting the outer peripheral slit, and there is no paper 16 stored in advance in the counted value and a memory (not shown). By comparing with the case numbers,
Measure the thickness of paper 16.

This measured value is sent to the arithmetic circuit 38, which
Based on the measured value, 38 calculates the operating rotation angle of the shaft 8 and the cams 9a, 9b which is an appropriate head gap for the paper 16 and sends the calculation result to the platen position adjusting mechanism control unit 34.

In response to this, the platen position adjustment mechanism control unit 34 receives the motor 11
First, the platen 1 is moved in a direction separating from the print head 2 so that the head gap is maximized, and the position of the slit disk 13 after the movement is used as a reference position to set the shaft 8 and the cams 9a, 9b. The motor 11 is driven until the number of slits corresponding to the calculation result of the operation rotation angle is detected by the sensor 14. As a result, the cams 9a, 9b push the platen 1 in pressure contact with the cams 9a, 9b to bring them closer to the print head 2 by a lift amount corresponding to the number of slits, thereby setting an appropriate head gap for the paper thickness of the paper.

[Problems to be Solved by the Invention]

However, according to the conventional technique having the above-described configuration, if the paper has a uniform thickness, the proper head gap can be automatically set for each paper even if the paper thickness of the used paper is different. There is a problem that it is not always possible to set an appropriate head gap when using papers that are partially the same in thickness even if they are the same. This will be described in more detail with reference to FIG.

9 (a) and 9 (b) are a plan view and a side view showing a sheet having an uneven portion. The sheet shown in FIG. 9 has perforations A for separating the sheet after printing and folding the sheet. A fold line B, a hole C for separating the sheets and then binding the sheets, and a corner cut D for separating and organizing the sheets are provided in advance.

Since the paper thickness of the portion having the perforations A, the folds B, the hole C, the portion having the corner cuts D is different from that of the other portions, when the printer is mounted on the printer, the paper thickness measuring mechanism 15 is used. Even if the paper thickness is measured, the proper head gap is not always set.

That is, the printed portion of the paper is perforated A, fold B, hole
Although there is no C or corner cut D, the perforation A or the fold B is thicker than the paper thickness of the part to be printed, and the part of the paper to be printed with the hole C or the corner cut D is the paper. Thin compared to thickness.

Therefore, when the operator mounts the paper, the portion where the paper is printed is not always positioned at the measurement position by the paper thickness measuring mechanism 15 while avoiding the portions having different paper thicknesses, and the perforation A, the fold B, The part with hole C and corner cut D may be measured by the paper thickness measuring mechanism 15,
In this case, an appropriate head gap cannot be obtained.

In view of the above problems, the present invention provides a method of performing paper thickness measurement at a portion having the original thickness of the paper regardless of the setting position of the paper, so that the perforations, folds, holes, corner cuts, etc. It is an object of the present invention to provide a method for accurately detecting the thickness of a sheet having an uneven portion in addition to the thickness.

[Means for Solving the Problems]

In order to achieve the above object, the present invention discriminates between the measurement in the uneven portion and the measurement in the original thickness portion, and when it is determined that the measurement is performed in the uneven portion, the position is changed and the measurement is performed again. .

That is, the present invention relates to a platen that supports a sheet, a print head that prints while reciprocating in parallel along the platen, a sheet feeding mechanism that feeds the sheet, and a print head from the surface of the sheet on the platen. In a paper thickness detection method for a printer that has a head gap adjustment mechanism that adjusts the distance to the tip of the paper and a paper thickness measurement mechanism that measures the paper thickness of the attached paper, One half of the thickness of the thinnest is determined as a judgment value in advance, the thickness of the attached paper is measured at two points, and the absolute value of the difference between the measurement results at the two points and the judgment value are determined. Compare, if the absolute value is equal to or less than the judgment value, determine the average value of the measured values as the paper thickness, if the absolute value is not equal to or less than the judgment value, the thickness of the mounted paper The above two points Re-measure at two points, the absolute value of the difference between the measurement results of the two re-measured points and the above-mentioned judgment value are compared, and if the difference is equal to or smaller than the judgment value, the average value of the re-measured values is printed. It is characterized in that it is determined as the thickness of.

[Action]

With the above configuration, the present invention measures the thickness of the mounted paper at two points while shifting the facing position of the paper and the paper thickness measuring mechanism by the paper feeding mechanism, and the measurement results of the two points are measured. The difference absolute value is compared with a determination value corresponding to 1/2 of the thickness of the thinnest sheet to be used by the printer.

Then, if both of the measured two points are the original thickness portion of the paper that does not cover the uneven portion, the absolute value is equal to or less than the determination value, and in this case, the measurement is performed in the original thickness portion. As a judgment, the average value of the measured values is determined as the paper thickness.

On the other hand, if both or one of the two measured points is on the uneven portion, the absolute value will not be equal to or less than the judgment value. In this case, it is determined that the measurement is on the uneven portion and re-measurement is performed. I do.

The re-measurement is performed at two points different from the above two points while shifting the facing position of the sheet and the sheet thickness measuring mechanism by the sheet feeding mechanism.

Then, the absolute value of the difference between the two remeasured measurement results is compared with the judgment value, and if the difference is equal to or smaller than the judgment value, the average value of the remeasured values is determined as the paper thickness. be able to.

〔Example〕

 Embodiments will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a control system of a printer to which an embodiment of the present invention is applied.

Since the mechanical structure of this printer is the same as that of the apparatus described with reference to FIGS. 4 to 7, the description thereof will be omitted and the reference numerals will be used as they are.

In FIG. 1, reference numeral 32 is a main controller, and 33 is a paper thickness measuring mechanism controller, which controls the drive of the motor 22.

Reference numeral 34 denotes a platen position adjustment mechanism control unit, which controls driving of the motor 11.

Reference numeral 35 denotes a print mechanism control unit, which controls the drive of the print head 2.

A carriage mechanism control unit 36 controls driving of a carriage motor 37 which is a driving source of a moving mechanism of the carriage 5.

A paper feed mechanism control unit 38 controls driving of the motor 30.

Reference numeral 40 is a paper thickness comparison / calculation circuit, and 41 is a paper thickness / platen position calculation circuit.

In such a configuration, the present paper thickness detection method is carried out as follows.

FIG. 2 is an explanatory diagram showing measurement points on the paper 16 in this embodiment, and FIG. 3 is an operation flowchart of this embodiment.

First, when the sheet 16 inserted by the operator from the sheet insertion port of the printer is passed between the contact 24 of the sheet thickness measuring mechanism 15 and the reference plate 17 and attached to the sheet feeding mechanism 28 (S1). The sheet thickness measuring mechanism control unit 33 measures the sheet thickness at the position a on the sheet 16 from the operation of the sheet thickness measuring mechanism 15 (S2).

The measurement in this case is performed in the same manner as in the conventional case, and the details thereof have already been described in the related art, and therefore the description thereof is omitted here.

Now, as shown in FIG. 2, the paper thickness at the position a obtained by the measurement is set as the measured value t ₁ and stored in the storage unit of the main control unit 32 (S3).

Next, the paper feed mechanism control unit 38 drives the motor 30 to drive the paper.
16 is fed in the forward direction by a predetermined fixed amount (S
4) Measure the paper thickness at position b in the same way as at position a (S
5) The paper thickness obtained by this measurement is set as the measured value t ₂ and stored in the storage unit of the main control unit 32 (S6).

Here, the interval between the positions a and b and l, this interval l dimension l _C of the holes C, is set to be larger than the dimension l _D corner-cut D. That is, the interval is set so that at least one of the positions a and b is the printed portion of the paper. In reality, the interval l is 4.23
mm to 8.47 mm (1/6 to 1/3 inch) is suitable.

Next, the measured values t ₁ and t ₂ are sent from the main control unit 32 to the paper thickness comparison / arithmetic circuit 40, and the paper thickness comparison / arithmetic circuit 40 compares / calculates the paper 16 by the following procedure. Thickness t
To decide.

First, the paper thickness comparison / arithmetic circuit 40 compares the absolute value of the difference between the measured values t ₁ and t ₂ with a predetermined judgment value H, and mainly controls whether or not the following expression (1) is satisfied. The unit 32 determines (S7).

| t ₁ −t ₂ | ≦ H (1) Here, the judgment value H is 1/2 of the thickness of about 0.06 mm of one sheet (continuous weight 34 kg) of the thinnest generally used sheet of paper. Is 0.03 mm, and as a result of the above determination, when the condition of the expression (1) is satisfied, the average value using the two values of the measured values t ₁ and t ₂ is determined as the thickness t of the paper 16. .

That is, it is the paper 16 that satisfies the above equation (1).
Indicates a portion that is not affected by the perforations A, the folds B, the holes C, and the corner cuts D, in other words, the thickness portion of the paper that is the portion to be printed. Therefore, in this case, t = (t ₁ + t ₂ ) / 2 is detected as the thickness t of the portion of the paper 16 to be printed (S8).

On the other hand, when either the measurement position a or the measurement position b of the paper 16 is the perforation A or the fold B or the hole C or the corner cut D, the perforation A or the fold B is concerned.
Alternatively, the hole C and the corner cut D may affect the condition of the formula (1). In this case, in the same manner as described above, the paper feed mechanism control unit 38 drives the motor 30 to feed the paper 16 in the forward direction by a predetermined constant amount (S10), and moves the paper to the positions c and d on the paper 16. The paper thickness is measured, and the paper thickness obtained by this measurement is stored in the memory of the main control unit 32 as measured values t ₃ and t ₄ (S11 to S1).
Five). In this case, the distance between c and d is also l.

Then, in the same manner as described above, the absolute value of the difference between the measured values t ₃ and t ₄ is compared with a predetermined judgment value H (S16), and the following equation (2) similar to the equation (1) is also obtained. The main control unit 32 determines whether or not it is satisfied.

| t ₃ −t ₄ | ≦ H (2) As a result, when the condition of the expression (2) is satisfied, an average value using two values of the paper thickness t ₃ and t ₄ is printed on the paper 16. It is determined as the thickness t of the portion to be formed (S8).

That is, here, the value of the difference between the measured values at the positions c and d and the judgment value H are compared and calculated, but the positions c and d are positions not affected by the holes C with the perforations A and the folds B and the corner cuts D. Therefore, if t = (t ₃ + t ₄ ) / 2 is detected as the thickness t of the paper 16, this thickness t becomes the value of the portion of the paper to be printed.

After detecting the paper thickness of the portion of the paper 16 to be printed in this way, the paper feed mechanism control unit 38 reversely rotates the motor 30 to feed the paper 16 in the forward direction by the paper feeding mechanism 28. And the paper 16 is returned to the position where it is initially mounted, whereby the paper thickness detection operation is completed.

If the condition of the expression (2) is also not satisfied, it is displayed by an unillustrated display means to the operator that the mounted paper 16 is not applicable to the printer or erroneous detection due to measurement error or the like, or An alarm sound is generated and notified, and necessary measures such as paper replacement and remeasurement are performed (S17).

After the paper thickness comparison / arithmetic circuit 40 detects the thickness t as described above, the head gap is set based on the thickness t in the same manner as in the conventional case (S9). That is, the paper thickness / platen position calculation circuit 41 calculates the operating rotation angles of the shaft 8 and the cams 9a and 9b, which serve as an appropriate head gap for the paper 16 based on the thickness t, and the main controller 32 Sends the calculation result to the platen position adjusting mechanism controller 34.

In response to this, the platen position adjusting mechanism control unit 34 drives the motor 11 of the platen position adjusting mechanism 5, and first moves the platen 1 in a direction in which the platen 1 is separated from the print head 2 so as to maximize the head gap. Rear slit disc
With the position of 13 as a reference position, the motor 11 is driven until the number of slits corresponding to the calculation result of the operation rotation angles of the shaft 8 and the cams 9a, 9b is detected by the sensor 14. As a result, the cams 9a and 9b push the platen 1 which is in pressure contact with the cams 9a and 9b to approach the print head 2 by a lift amount corresponding to the number of slits, thereby setting an appropriate head gap for the paper thickness of the paper.

The printer to which the present invention is applied does not necessarily have to include the platen position adjusting mechanism 5 and the sheet thickness measuring mechanism 15 shown in the figure. For example, as disclosed in JP-A-63-249673. , Paper thickness to detect the paper thickness of the paper by moving the print head with respect to the platen to adjust the head gap and counting slits such as the rotation angle of the slit disk that rotates in conjunction with the movement of the print head. It can also be applied to a printer equipped with a measuring mechanism.

〔The invention's effect〕

As described in detail above, according to the present invention, 1/2 of the thickness of the thinnest sheet to be used by the printer is predetermined as a determination value, and the thickness of the attached sheet is set to 2 points. And compare the absolute value of the difference between the measurement results of the two points with the judgment value, and if the absolute value is equal to or less than the judgment value, determine the average value of the measured values as the paper thickness. If the absolute value is not equal to or less than the judgment value, the thickness of the loaded paper is re-measured at two points different from the above two points, and the absolute value of the difference between the measurement results at the two re-measured points. When the difference is less than or equal to the judgment value, the average value of the remeasured values is determined as the thickness of the paper, so the measurement in the uneven portion and the original thickness portion are performed. If it is determined that the measurement was made on the uneven part, It is possible to perform the measurement again changed.

This makes it possible to measure the thickness of the paper at the original thickness of the paper regardless of the paper setting position.
There is an effect of providing a method for accurately detecting the thickness of a sheet having an uneven portion in addition to the original thickness such as perforations, folds, holes, and corner cuts.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control system of a printer to which an embodiment of the present invention is applied, FIG. 2 is an explanatory view showing measuring points on a sheet in the embodiment, and FIG. 3 is an operation flowchart of the embodiment. 4, FIG. 4 is a plan view showing a printer having a paper thickness measuring mechanism, FIG. 5 is a sectional view taken along the line AA of FIG. 4, FIG. 6 is a side view showing the paper thickness measuring mechanism, and FIG. Is a front view of a slit disk, FIG. 8 is a block diagram of a conventional example, and FIGS. 9 (a) and 9 (b) are a plan view and a side view showing a sheet having an uneven portion. 32 …… Main control unit 33 …… Paper thickness measurement mechanism control unit 34 …… Platen position adjustment mechanism control unit 38 …… Paper feed mechanism control unit 40 …… Paper thickness comparison / arithmetic circuit 41 …… Paper thickness / Platen Position calculation circuit

Claims (1)

[Claims] 1. A platen for supporting a sheet, a print head for printing while reciprocating in parallel along the platen, a sheet feeding mechanism for feeding a sheet, and a print head from the surface of the sheet on the platen. A paper thickness detection method for a printer that has a head gap adjustment mechanism that adjusts the distance to the leading edge and a paper thickness measurement mechanism that measures the paper thickness of the loaded paper. Predetermine 1/2 of the thickness of the thinnest as a judgment value, measure the thickness of the loaded paper at two points, and compare the absolute value of the difference between the measurement results at the two points with the judgment value. However, if the absolute value is less than or equal to the judgment value, the average value of the measured values is determined as the thickness of the paper.If the absolute value is not less than or equal to the judgment value, the thickness of the mounted paper is determined. Different from the above two points Re-measure at two points and compare the absolute value of the difference between the two re-measured results with the judgment value. If the difference is equal to or less than the judgment value, the average value of the re-measured values is printed. A method for detecting the sheet thickness of a printer, characterized in that it is determined as the thickness of the sheet.