JPH02113978A - Printer - Google Patents

Abstract

PURPOSE:To prevent erroneous detection of the thickness of a printing medium by allowing a platen to move to the uppermost position, then allowing it to move downward and monitoring then moving amount. CONSTITUTION:A printing medium 8 stops due to the detection of its tip with a positioning sensor 16. At that time, a platen 10, having moved downward, is parked, and a carrier 3 is pushed down in an arrow B direction in accordance with the thickness of the printing medium 8. If the platen 10 is driven in an arrow C direction, the printing medium 8 is pressed against a card holder 13 in which a pressure sensor 12 is built, a plate 9 on the platen 10 completely shields an optical sensor 1. Then the pressure sensor 12 detects the pressed contact of the printing medium 8 with the card holder 13 on account of the platen 10. Subsequently, the platen 10 moves downward in an arrow D direction and stops at a position where a plate 9 releases the shielding of light against the optical sensor. In this case, it is checked whether the amount of movement of the platen 10 from pressing the printing medium 8 against the card holder 13 to descending again to a stop within the range of a constantly specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a printing device, and particularly to a printing device having a platen that moves according to the thickness of a printing medium.

[Conventional technology]

A conventional printing device has a platen whose distance from the print head can be changed depending on the thickness of the print medium to be printed on.
It has a measuring member whose value a changes according to the thickness of the print medium, and the position of the platen relative to the print head is controlled to be changed using the positions of a total of 811 members as an index.

[Problem to be solved by the invention]

Conventional printing devices such as those described above do not have a means to confirm whether the thickness of the printing medium detected by the measuring member is accurate or not. If the printing medium is caught or wrinkled or folded at the detection location, the printing medium will be detected as being thicker than the correct thickness, which will cause the platen to be misaligned and the printing will be unclear. ing.

(Means for Solving the Problems) In order to solve the drawbacks of the conventional printing device as described above, the present invention includes a sensor, a detection mechanism that changes its position in response to changes in the thickness of a print medium, a member to be detected by the sensor;
The card holder is provided with a platen that is movable in eight directions of the printing operation of the print head, and a card holder that has a pressure sensor that senses the contact pressure with the printing medium.

In other words, the printing device of the present invention includes two pairs of transport rollers that transport the printing medium in the horizontal direction with the print medium sandwiched between them, and an upper roller that is disposed in front of the front transport roller of the two pairs of transport rollers. , a lower roller disposed opposite to and below the upper roller, a carrier that supports the lower roller, a shaft that guides the vertical movement of the carrier, a platen 1- that supports the shaft, and the bracket. a spring mounted between the carrier and pressing the carrier upward; an optical sensor fixed to the carrier; and a leading end disposed above the print medium between the two conveyance rollers. a print head having a card holder on a portion thereof; a pressure sensor attached to the card holder; a platen disposed opposite to and below the print head and movable linearly in the vertical direction; and a plate that blocks the optical path of the optical sensor by downward movement of the platen.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a front view showing an embodiment of the present invention.6 In FIG. 1, a mechanism for detecting the thickness of a print medium 8 is
The carrier 84 includes a carrier 3 to which the optical sensor 1 and the lower roller 2 are attached, and a side roller 4 provided opposite to the lower roller 2. The carrier 3 is vertically slidable along a shaft 6 supported vertically by a bracket 5, and the lower roller 2 is pressed against the upper roller 4 by a spring 7. When the print medium 8 is conveyed between the upper roller 4 and the lower roller 2, it is sandwiched between the front roller 4 and the lower roller 2. The platen mechanism is a platen for the pressure to be detected by the optical sensor 1! -9 and this y! , a platen 10 equipped with a detection plate 9
The diaphragm 10 is provided facing the direction of the printing pad 11 and moves in the printing direction. A card holder 13 incorporating a pressure sensor 12 is attached to the tip of the print head 1. Conveyance rollers 14a and 1.4b and 15a
and 1.5 b sandwich the print medium 8 and transport it. A clearance sensor 16 provided between the card holder 13 and the conveyance roller 15a is a sensor for determining the stop position of the print medium 8.

Next, the operation of the above embodiment will be explained with reference to FIG.

FIG. 2 (a) shows a state in which the printing medium 8 has been fed one yard in the direction of the arrow, and the positioning sensor 16 detects its leading edge and stops. At this time, the platen 10 moves the printing medium 8 In order to make it easier for the printer to be conveyed under the print head 11, it is moved downward and is in a retracted position.
Further, the carrier 3 is pushed down in the direction of arrow B in accordance with the thickness of the print medium 8.

FIG. 2<b> shows a state in which the platen 10 is driven in the direction of arrow C, and the print medium 8 is pressed against the card boulder 13 in which the pressure sensor 12 is installed.

At this time, the plate 1-9 on the platen 10 completely blocks light from the optical sensor 1 on the carrier 3.

In FIG. 2(C), the pressure sensor [2] detects that the print medium 8 is pressed against the card holder 13 by the platen 10, and as a result, the platen 10 is lowered in the direction of the arrow, and the plate 9 is moved to the optical sensor 1. It is in a state where it is stopped at the position where the light is blocked and released.

At this time, the platen 10 transfers the print medium 8 to the card holder J.
It is checked whether the amount of movement from when it comes into contact with pressure point 3 until it descends again and stops is within a certain standard value range. If there is foreign matter or wrinkles at the position where the thickness of the print medium 8 is detected, that is, at the position where it is sandwiched between the upper roller 4 and the lower roller 2, remove the carrier 3.
moves downward than when the print medium has a normal thickness, so if the movement of the platen 10 is controlled using the sensor 1 as a reference, the gap between the platen 10 and the print head 11 becomes larger. Therefore, by raising the platen 10 until it touches the card holder 13, then lowering it, and monitoring the amount of descent at that time, it is possible to judge whether or not the thickness of the printing medium has been accurately measured, and to avoid erroneous detection. It can be prevented.

〔Effect of the invention〕

As explained above, when the printing device of the present invention detects the thickness of the print medium and controls the position of the platen, the platen is moved to the uppermost position and then lowered again to a predetermined position. By monitoring the amount of movement at that time, it is possible to prevent false detection of the thickness of the print medium. Therefore, it is possible to always ensure an accurate gap between the platen and the print head to produce clear images. This has the effect that printing can be performed.

[Brief explanation of the drawing]

Fig. 1 is a front view showing an example of a family of the present invention, Fig. 2(a)
-(c) are front views showing different operating states of the embodiment of FIG. 1; 1... Optical sensor, 2... Lower roller, 3... Carrier, 4... Upper roller, 5... Bracket, 6
... Shaft, 7... Spring, 8... Print medium, 9... Plate, 10... Platen, 11...
・Print 1-head, 12...pressure sensor, 13...
- Card holder, 14a-14b-15a/15b-conveyance roller, 16...sensor.

Claims (1)

[Claims] two pairs of conveyance rollers that convey the printing medium in the horizontal direction with the print medium in between; an upper roller disposed in front of the front conveyance roller of the two pairs of conveyance rollers; a lower roller disposed, a carrier supporting the lower roller, a shaft guiding vertical movement of the carrier, a bracket supporting the shaft, and a carrier mounted between the bracket and the carrier. a spring that presses upward; an optical sensor fixed to the carrier; a print head disposed above the print medium between the two pairs of transport rollers and having a card holder at its tip; a pressure sensor attached to the print head; a platen disposed below the print head and capable of linear movement in the vertical direction; and a platen fixed to the platen and blocking the optical path of the optical sensor by vertical movement of the platen. A printing device comprising: a plate for printing.