JP2715487B2 - Paper thickness detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention detects the thickness of a sheet mounted on a platen by moving the printer head to a position where the printer head presses the sheet. The present invention relates to a paper thickness detecting device.

[Prior Art] Conventionally, in a general printer, a thin plate-shaped ribbon mask is provided between an ink ribbon and a sheet in order to prevent sheet contamination due to unnecessary contact between the sheet and the ink ribbon during printing. The reason why the ribbon mask is provided between the ink ribbon and the paper sheet also depends on the following circumstances. In a paper thickness detector that presses the printer head against paper,
In order to ensure the reliability of the detection result of the paper thickness, the printer head is pressed against the paper with a force of 2 [kg] to 4 [kg], but with such a large force only via the ink ribbon. When the printer head is pressed against the paper, unnecessary ink adheres to the paper, and the paper becomes dirty. Therefore, the ribbon mask is provided between the platen on which the paper is mounted and the printer head, thereby preventing ink from adhering to the paper.

[Problems to be Solved by the Invention] However, in the conventional paper thickness detecting apparatus using the above-described ribbon mask, the problem that the paper is stained with unnecessary ink can be avoided, but the paper end is attached to the ribbon mask when the paper is loaded. There is a new problem that the ribbon mask is caught or the running load of the ink ribbon is increased by the ribbon mask.

An object of the present invention is to solve the above-mentioned problem and to enable extremely good detection of the paper thickness.

Configuration of the Invention [Means for Solving the Problems] The paper thickness detecting device of the present invention is configured to move the printer head to a position where the printer head presses the paper with the thickness of the paper mounted on the platen. In the paper thickness detection device for detecting, a transparent or an area of the same or similar color as the paper ground color is formed on the ink ribbon positioned between the printer head and the paper, and the printer head is moved to the paper side. An ink ribbon driving means for positioning the area of the ink ribbon on the front surface of the printer head is provided.

[Operation] In the paper thickness detecting apparatus of the present invention having the above-described configuration, when the printer head is moved to the paper side for paper thickness detection, the ink ribbon driving means is the same as or similar to the transparency of the ink ribbon or the paper ground color. Is located on the front of the print head. Therefore, even if the printer head presses the paper, no ink adheres to the paper, or even if ink adheres, the difference between the ink color and the paper ground color is not clear, and the paper is not stained.

The detection of the paper thickness may be performed by measuring the position where the printer head presses the paper and stops.
By retreating the printer head by a predetermined distance with the stopped position as the origin, the paper thickness detection and the accompanying positioning of the printer head may be performed together.

[Embodiment] Hereinafter, a paper thickness detecting device of a dot impact type printer as one embodiment of the present invention will be described. FIG. 1A is a perspective view showing a schematic configuration of the paper thickness detecting device.

As shown in the figure, this paper thickness detecting device is a flat platen P
Printer head 1 for printing on paper S attached to
An ink ribbon 2 positioned between the printer head 1 and the paper S, an ink ribbon driving mechanism 3 for driving the ink ribbon 2 when detecting the paper thickness, and a head transport mechanism 4 for transporting the printer head 1 back and forth. Prepare.

The printer head 1 includes, for example, 24 head wires, and performs printing by independently driving each head wire. Printer head 1 of the embodiment
In FIG. 1, the distal end surface is formed so as to form the same surface as each head wire 11 as shown in FIG. 1 (B).

As shown in FIG. 1 (A), the ink ribbon 2 has a colorless region 23 above a black ink band 21.
The colorless region 23 can be formed by forming a boundary line 24 by microwaves on the ribbon base of the ink ribbon 2 and impregnating only the black ink band 21 with black ink. The width of the colorless area 23 is formed to be slightly larger than the vertical dimension of the front end face of the printer head 1.

The ink ribbon driving mechanism 3 includes a guide member 31 for positioning the ink ribbon 2 on the front surface of the printer head 1 and a solenoid 33 for driving the guide member 31 downward (in the direction of arrow Z).
And a compression spring 35 interposed between the guide member 31 and the solenoid 33 to urge the guide member 31 upward. The guide member 31 has a slit 31 having substantially the same width as the width of the ink ribbon 2.
a at both sides of the printer head 1. The guide member 31 is attached to the tip of the drive shaft 33a, and the solenoid 33 is fixed on the carriage 41. Solenoid 33
Since the drive shaft 33a is sucked for a certain distance by energization, the position of the ink ribbon 2 with respect to the printer head 1 can be switched up and down by turning the solenoid 33 on and off.

The head transfer mechanism 4 includes a carriage 41 to which the printer head 1 is attached, guide shafts 43 and 45 arranged in parallel to support the carriage 41, and a front guide shaft 43.
And a gear assembly 50 connected to one end of the gear assembly. At the rear of the carriage 41, a U-shaped slide guide portion 41a is formed as a mechanism for moving the printer head 1 forward and backward, and a slide portion attached to the guide shaft 45 is formed here.
41b is slidably fitted.

The gear assembly 50 drives an eccentric shaft 51 provided at one end of the guide shaft 43, a driven gear 53 having a coaxial center with the eccentric shaft 51, a driving gear 55 meshing with the driven gear 53, and a step of driving the driving gear 55. The motor 57 is provided. Also, the gear assembly 50
A friction clutch (not shown) is provided. In the friction clutch, the force of pressing the paper by the printer head 1 is set to a set value (2).
[Kg] to 4 [kg]), a slip occurs, and the transmission of the rotation of the step motor 57 is interrupted.

An electronic control device for controlling the driving of each of the above-described elements is described in the second section.
Shown in the figure. The electronic control unit 6 includes a well-known CPU 61, a ROM 63,
An input / output port 67 for inputting print data from an external word processor or the like, an ink ribbon drive circuit 69 for the solenoid 33 of the ink ribbon drive mechanism 3, a printer head 1 and gear assembly A printing drive means 71 for 50 step motors 57 is provided.

The detection of the paper thickness by the paper thickness detection device of the embodiment configured as described above will be described with reference to the flowchart of FIG. When a print command is issued from an external word processor or the like, the apparatus determines whether the sheet S mounted on the platen P is a new sheet (step 100). If it is determined that the paper thickness has already been detected and the printing has been continued, the detection of the paper thickness is terminated, and the process proceeds to a later printing process or the like.
If it is determined that the sheet is new paper, the ink ribbon driving mechanism 3
Is turned on by turning on the solenoid 33 (step 110). Thus, the solenoid 33 sucks the drive shaft 33a in the direction of the arrow Z in FIG. 1A against the urging force of the compression spring 35, and positions the guide member 31 at its lower limit.

The operation state of the apparatus corresponding to step 110 is shown in FIGS. 4A and 4B as a schematic side view. The lowering limit of the guide member 31 is a position where the height of the center 23d of the colorless area 23 of the ink ribbon 2 is the same as the height of the center 1a of the leading end of the printer head 1, as shown in FIG. 4 (B). .

Next, the step motor 57 is rotated in the forward direction by a predetermined number of steps D1 (step 120). The rotation of the step motor 57 is transmitted via the driving gear 55 and the driven gear 53, and further via a friction clutch (not shown) to rotate the eccentric shaft 51.
The rotation of the eccentric shaft 51 moves the guide shaft 5 in the direction of arrow Y shown in FIG. 1A, and moves the printer head 1 of each carriage 41 toward the sheet S. As the movement proceeds, the printer head 1 moves the paper S through the colorless area 23 of the ink ribbon 2 as schematically shown in FIG.
Press. When the force of pressing the paper S by the printer head 1 reaches a set value (2 kg to 4 kg), the printer head 1 is rotated by the friction clutch (not shown) even if the step motor 57 further rotates. The printer head 1 does not advance any further, and stops in a state where the leading end of the printer head 1 presses the sheet S. In this state, the thickness of the paper S is indirectly detected based on the positional relationship between the platen P, the ink ribbon 2 and the printer head 1. The predetermined number of steps D1 for the step motor 57 is such that the printer head 1 is advanced from the initial position shown in FIG.
This is a numerical value sufficient to press the sheet S with a set force.

When the thickness of the paper S is detected in this manner, the step motor
57 is rotated backward by the predetermined number of steps D2 (step 130). The rotation of the step motor 57 is transmitted via the main driving gear 55 and the driven gear 53 and a friction clutch (not shown) as in the case of the forward movement, and rotates the eccentric shaft 51 in the opposite direction. The guide shaft is rotated by the rotation of the eccentric shaft 51 in the opposite direction.
Reference numeral 43 moves in the direction opposite to the Y direction, and moves the printer head 1 together with the carriage 41 backward from the sheet S. The predetermined number of steps D2 for driving the step motor 57 is such that the printer head 1 is retracted until the distance between the printer head 1 and the paper S becomes an optimal distance for printing (about 0.2 [mm] in this embodiment). Is a numerical value corresponding to.

After this, when the solenoid 33 is de-energized and turned off (step 140), the biasing force of the compression spring 35 raises the guide member 31 and positions the guide member 31 at its upper limit. As shown in FIG.
When 140 is completed, the black ink band 21 is positioned on the front surface of the printer head 1, and the printer head 1 is positioned at a position spaced from the sheet S by an optimal gap for printing.

The paper thickness detecting device of the embodiment configured as described above presses the printer head 1 against the paper S via the colorless area 23 of the ink ribbon 2 and detects the paper thickness of the paper S. No ink is attached to S, and the paper S is not stained. Further, since the ribbon mask is not used as in the related art, the loading of the paper S can be always performed smoothly, and the running resistance of the ink ribbon 2 can be reduced and the load on the running motor can be reduced. Further, in the embodiment, the front end surface of the printer head 1 is
Since the printer head 1 is pressed against the sheet S, no pressing point of the head wire 11 remains at all, and the sheet S can be maintained in a better condition. .

Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment. For example, the colorless region 23 of the ink ribbon 2 may be provided below the black ink band. Further, an area having the same or similar color as the paper S ground color may be formed on the ink ribbon 2 instead of the colorless area. For example, in a printer that performs multicolor printing, the fifth
As shown in FIGS. 7A and 7B, a general multicolor ink ribbon 85 has a black area 85a, a cyan area 85b, a magenta area 85c, and a yellow area 85d. For example, the paper thickness detection may be performed by positioning the yellow region 85d in front of the printer head 1. The ink adhering to the paper S is yellow only, and the difference in color from the ground color of the paper S is slight, so that the ink is inconspicuous. As the ink ribbon driving mechanism 3, a mechanism for positioning the multi-color ink ribbon in multiple stages may be used in addition to a mechanism for positioning the ink ribbon at two positions like the solenoid 33.

Effect of the Invention As described in detail above, the paper thickness detection device of the present invention detects the paper thickness by pressing the printer head against the paper via the transparent or formed on the ink ribbon and the same or similar color as the paper ground color. With such an extremely simple configuration, there is an excellent effect that no ink adheres to the sheet at the time of detection and the sheet is not stained. Therefore, the present invention does not require the use of a ribbon mask as in the related art,
There is an effect that the paper can always be smoothly loaded, and the running resistance of the ink ribbon can be reduced and the load on the running motor can be reduced.

[Brief description of the drawings]

FIG. 1 (A) is a schematic perspective view of a paper thickness detecting device as one embodiment of the present invention, FIG. 1 (B) is an enlarged cross-sectional view of a tip portion of the printer head, and FIG. FIG. 3 is a block diagram, FIG. 3 is a flowchart showing the outline of the paper thickness detection, FIGS. 4 (A) to (D) are schematic diagrams showing the process of the paper thickness detection, and FIGS. It is the schematic which shows an Example apparatus and its ink ribbon. DESCRIPTION OF SYMBOLS 1 ... Printer head 2 ... Ink ribbon 3 ... Ink ribbon drive mechanism 4 ... Head transfer mechanism 6 ... Electronic control device

Claims (1)

(57) [Claims] An apparatus for detecting the thickness of a sheet mounted on a platen by moving the printer head to a position at which a printer head presses the sheet, comprising: An area of transparent or the same or similar color as the paper ground color is formed on the ink ribbon located therebetween, and when the printer head is moved to the paper side, the area of the ink ribbon is placed on the front surface of the printer head. A paper thickness detecting device comprising an ink ribbon driving means for positioning.