JPH0825751A - Gap controlling mechanism for serial printer - Google Patents

Abstract

PURPOSE:To effect sharp printing on sheets different in thickness and having recesses and protrusions on their surfaces. CONSTITUTION:A gap controlling mechanism for a serial printer is provided with a lens 7 for condensing laser beams from a semiconductor laser 5 onto a sheet 10 and for condensing light reflected by the sheet 10 to a light detecting unit, 8, a gap sensor 9 consisting of the semiconductor laser 5 and an optical fiber bundle 6 set between the lens 7 and the light detecting unit 8, and an A/D converting unit 4 for converting the intensity of the reflected light into numerical data. Also, the gap controlling mechanism is provided with a reflected light intensity storage unit 2 for storing the intensity of the reflected light from the sheet 10 irradiated with the laser beams corresponding to the extent of a gap between a printing head and the sheet 10, a gap storage unit 3 for storing the extent of the gap between the printing head of the sheet 10 in a printing column unit, an operation control unit 1 for producing a signal of moving the printing head so that the extent of the gap obtained from the numerical data on the intensity of the reflected light approaches the reference extent of a gap, and a mechanism unit 18 provided with a motor driving section 11 for driving a motor 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gap control mechanism for a serial printer, and more particularly to a gap control mechanism for a serial printer for adjusting a gap between a print head and a sheet.

[0002]

2. Description of the Related Art Conventionally, a gap control mechanism of a serial printer of this type is designed so that the print quality does not deteriorate even when the thickness of a print sheet changes, as disclosed in Japanese Patent Application Laid-Open No. 4-265777. It is used for the purpose.

FIG. 4 is a perspective view showing an example of a gap control mechanism of this conventional serial printer. Referring to FIG. 4, the gap control mechanism of the serial printer includes:
The sheet thickness detecting rollers 102 and 110 that travel on the surface of the sheet 103 to convey the change in the unevenness 104 of the sheet and the movement of the sheet thickness detecting rollers 102 and 110 cause the sheet 10 to move.
Paper thickness detection sensors 105 and 1 for detecting the thickness of 3
11, a sheet thickness detection controller 106 for controlling the print head unit drive motor controller 108 based on signals from the sheet thickness detection sensors 105 and 111 and the head position sensor 107, and a sheet thickness detection controller 106
The print head drive motor controller 108 for operating the print head drive motor 109 according to the command, the print head drive motor 109 for moving the print head 101, and the print head 101 for printing.

Next, the operation will be described. Print head 101
When printing in the B direction from A, the paper thickness detection roller 10
2 runs on the paper 103. When the sheet thickness detecting roller 102 reaches the sheet unevenness 104, the sheet thickness detecting sensor 105 detects the sheet unevenness 104, and the degree and length of the unevenness are taken in by the sheet thickness detecting controller 106. The sheet thickness detection controller 106 detects the sheet unevenness 104 and, at the same time, takes in the head position detected by the head position sensor 107. Next, the print head 10
Immediately before the sheet 1 comes into the paper unevenness 104, a drive signal is sent from the paper thickness detection controller 106 to the print head drive motor controller 108, and the print head drive motor 1
09 is operated to move the print head 101 in the direction of the paper so as to keep the gap between the paper unevenness 104 and the print head 1 constant. When the print head 101 performs printing from the direction B to the direction A, the same operation is performed by the sheet thickness detecting roller 110 and the sheet thickness detecting sensor 111.

[0005]

As described above, in the gap control mechanism of the conventional serial printer, the paper thickness detection roller is brought into contact with the paper and the paper travels in the lateral direction together with the print head. Therefore, the surface of the paper is detected. Dirty due to running traces of rollers. When a copy sheet is used, the trace of travel of the sheet thickness detection roller appears on the second sheet, so the copy sheet cannot be used.

[0006]

A gap control mechanism of a serial printer according to the present invention comprises a detecting means for traveling with a print head, irradiating a light beam toward a paper sheet, and detecting the reflected light intensity thereof, and the reflected light intensity. Numericalizing means for digitizing, reflected light intensity storing means for storing the reflected light intensity of the light beam corresponding to the gap amount between the print head and the paper, and the numerically reflected light intensity. And a moving unit that compares the corresponding gap amount with a reference gap amount and moves the print head so that the gap amount approaches the reference gap amount.

Further, in the gap control mechanism of the serial printer of the present invention, the detecting means emits a laser beam, a semiconductor laser for detecting the laser beam reflected from the paper, and the semiconductor laser. And a lens that collects the laser beam emitted from the sheet onto the paper and collects the reflected light of the collected light from the paper onto the photodetector.

Further, in the gap control mechanism of the serial printer according to the present invention, the detecting means divides one end into two, one of which receives a laser beam emitted from the semiconductor laser and the other of which is connected to the photodetecting section. The other end of the optical fiber bundle is irradiated with the laser beam through the lens, and the reflected light of the laser beam from the sheet is incident through the lens.

[0009]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, and FIG. 2 is a perspective view showing a mechanism portion of this embodiment.
Referring to FIGS. 1 and 2, the gap control mechanism of the serial printer of this embodiment includes a semiconductor laser 5 that emits a laser beam, a photodetector 8 that detects a laser beam reflected from a sheet 10, and a semiconductor laser. The laser beam emitted from the light source 5 is focused on the paper 10, and the focused light of the paper 1
A lens 7 for condensing the light reflected by the laser beam 0 on the photodetector 8, one end of which is divided into two parts, one of which receives a laser beam irradiated from the semiconductor laser 5 and the other is connected to the photodetector 8, A laser beam is irradiated through a lens 7 and a gap sensor 9 composed of an optical fiber bundle 6 which receives reflected light of the laser beam from the paper 10 through the lens 7; and converts the reflected light intensity into numerical data. A / D converter 4; print head 1
4 and the reflected light intensity storage unit 2 that stores the reflected light intensity of the laser beam corresponding to the gap amount between the paper 10 and the paper 10, and the gap storage that stores the gap amount between the print head 14 and the paper 10 in print column units. Part 3 and; A
The gap amount is obtained from the numerical data of the reflected light intensity from the / D converter 4, and the gap amount is compared with the reference gap amount to generate a signal for moving the print head 14 so that the gap amount approaches the reference gap amount. An arithmetic control unit 1 for
Carriage 1 that moves laterally on the front 15 and the rear 16 of the guide shaft, and the front 15 and the rear 16 of the guide shaft that are mounted in parallel
3, a print head 14 fixed to the carriage 13 for printing, a drive gear 17 attached to an eccentric shaft in front of the guide shaft 15 for changing the gap by rotation, and a step motor for rotating the drive gear 17. 12 and a mechanism unit 18 including a motor drive unit 11 that drives the step motor 12.

Next, the operation of this embodiment will be described with reference to FIGS. The semiconductor laser 5 emits irradiation light 21 according to a signal from the arithmetic and control unit 1. The irradiation light 21 passes through the optical fiber bundle 6 and is collected by the lens 7 to
Hit The reflected light 22 which is irregularly reflected on the paper 10, condensed again by the lens 7 and passed through the optical fiber bundle 6 is detected by the light
Be led to. The intensity of the reflected light 22 detected by the light detector 8 is converted into numerical data by the A / D converter 4 and sent to the arithmetic and control unit 1. The arithmetic control unit 1 reads the gap amount corresponding to this numerical data from the reflected light intensity storage unit 2, and writes this gap amount into the address of the gap storage unit 3 corresponding to the current position of the gap sensor 9. The arithmetic control unit 1 reads the gap amount corresponding to the current position of the print head 14 from the gap storage unit 3, and sends the movement amount and the forward or reverse rotation signal to the motor drive unit 11 based on the comparison with the current gap amount. The step motor 12 rotates normally or reversely to rotate the drive gear 17, and the carriage 13 moves forward or backward to fix the print head 1 fixed to the carriage 13.
The gap amount between the sheet 4 and the sheet 10 is kept constant.

The intensity of the reflected light 22 is, as shown in FIG.
Since the same gap amount changes depending on the quality and color of the paper 10, a reference value suitable for each paper is set as follows. First, the arithmetic and control unit 1 causes the stepping motor 12 to rotate forward through the motor driving unit 11 to hit the print head 14 against the paper 10. Then, set the stepping motor 12 to 50
Reverse by the gap amount of micrometer. The intensity of the reflected light 22 and the gap amount at that time are stored in the reflected light intensity storage unit 2.
Write in. This is repeated until the gap between the print head 14 and the paper 10 becomes 5 mm. This data is used as a reference value for the reflection intensity and the gap amount of each sheet.

In the above-described embodiment, the optical fiber bundle 6 is installed between the semiconductor laser 5, the lens 7 and the photodetection section 8. However, the semiconductor laser 5 is not installed.
It is also possible to arrange such that the laser beam from is directly focused on the sheet 10 by the lens 7 and the reflected light is made incident on the photodetection section 8 by the lens 7.

[0013]

As described above, according to the present invention,
It travels with the print head, irradiates a light beam toward the paper, detects the reflected light intensity, digitizes this reflected light intensity, and compares this value with the reference gap amount so that this value approaches the reference gap amount. By moving the print head to, clear printing can be performed even on paper with irregularities on the surface.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a perspective view showing a mechanism section of the embodiment.

FIG. 3 is a diagram illustrating a relationship between a difference between sheets, a gap amount, and a reflected light intensity.

FIG. 4 is a perspective view showing an example of a gap control mechanism of a conventional serial printer.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 arithmetic control unit 2 reflectance storage unit 3 gap storage unit 4 A / D conversion unit 5 semiconductor laser 6 optical fiber bundle 7 lens 8 light detection unit 9 gap sensor 10 paper 11 motor drive unit 12 step motor 13 carriage 14 print head 15 Before the guide shaft 16 After the guide shaft 17 Drive gear 18 Mechanism 21 Irradiation light 22 Reflected light

Claims (3)

[Claims] 1. A detection unit that travels together with a print head and irradiates a light beam toward a sheet to detect a reflected light intensity thereof, a digitizing unit that digitizes the reflected light intensity, and a gap between the print head and the sheet. The reflected light intensity storage means for storing the reflected light intensity of the light beam corresponding to the gap amount of the sheet, and comparing the gap amount corresponding to the numerically reflected reflection light intensity with a reference gap amount. A gap control mechanism for a serial printer, comprising: a moving unit that moves the print head so that the gap amount approaches the reference gap amount. 2. The detection means includes a semiconductor laser that emits a laser beam, a photodetector that detects the laser beam reflected from the sheet, and the laser beam emitted from the semiconductor laser on the sheet. The gap control mechanism of the serial printer according to claim 1, further comprising: a lens that collects the condensed light on a sheet and reflects the condensed light reflected by the paper to the light detection unit. 3. The detecting means has one end divided into two, one of which receives a laser beam emitted from the semiconductor laser, the other of which is connected to the photodetector, and the other end of which is connected via the lens. 3. The gap control mechanism for a serial printer according to claim 2, further comprising an optical fiber bundle that irradiates a laser beam and makes reflected light of the laser beam from the paper sheet incident through the lens.