JPH03251703A - Medium thickness detection mechanism - Google Patents

Abstract

PURPOSE:To detect abnormality in thickness by a method wherein carrying of a medium to a mobile roller is detected and a displacement of the movable roller is detected with a magnetic sensor and with a value of the displacement as reference value, an output of the magnetic sensor attributed to the displacement of the movable roller as caused by the medium is judged. CONSTITUTION:An interval between a movable shaft 3 and a drive roller 2 is made equivalent to one sheet of normal medium. A movable arm 4 is made free to turn on a support shaft 5 and one end thereof abuts the movable shaft 3 with a return spring 6. The other end of the movable arm 4 is so formed as to traverse a magnetic sensor 7. An output of the magnetic sensor 7 as given when a medium is detected with a transmission light sensor 8 is held temporarily to be a reference value. An output of the magnetic sensor 7 as given when the medium passes between the drive roller 2 and the movable shaft 3 is compared with the reference value by a judging circuit 1 to judge whether an attached object such as tape exists on the medium or not.

Description

TECHNICAL FIELD The present invention relates to a medium thickness detection mechanism, and more particularly to a medium thickness detection mechanism for detecting the presence or absence of a tape or other deposit on a medium conveyed by a medium conveyance device.

Conventional technology Conventionally, in this type of medium thickness detection mechanism, a rotating shaft is arranged so that the outer circumferential surface touches the bottom surface of the medium being conveyed, and operates only in the vertical direction so that the outer circumferential surface touches the top surface of the medium. A movable shaft is arranged, and the movable shirt I moves upward in the vertical direction when a medium having a deposit such as a tape passes between these rotary shafts and the movable shaft.

When this upward movement of the movable shaft is transmitted to the movable arm, the movement of the movable arm is detected by a magnetic sensor, thereby detecting the presence of deposits on the medium.

In such conventional media thickness detection mechanisms, the rotating shafts and movable shafts placed above and below the conveyance path are positioned by bearings, etc., so the initial position of the movable arm is not constant due to the accuracy and rotation of the bearings. figure,
Furthermore, components such as the magnetic sensor and spring change depending on environmental conditions such as temperature and humidity, and the reference value of the output of the magnetic sensor is not constant, making it difficult to accurately detect the thickness of the medium.

OBJECTS OF THE INVENTION The present invention has been made in order to eliminate the drawbacks of the conventional devices as described above, and an object of the present invention is to provide a medium thickness detection mechanism that can accurately detect the thickness of a medium.

Composition of the Invention A medium thickness detection mechanism according to the present invention includes a movable roller that moves according to the thickness of the medium being conveyed, and a magnetic sensor that detects an abnormality in the thickness of the medium based on displacement of the movable roller. The medium thickness detection mechanism includes a detection means that is provided immediately before the movable roller and detects passage of the medium conveyed to the movable roller, and a detection means that detects conveyance of the medium to the movable roller. a holding means for holding the output of the magnetic sensor when the holding means holds the output of the magnetic sensor, and determining the output of the magnetic sensor when the movable roller is displaced by the medium using the output of the magnetic sensor fully held by the holding means as a reference value. and determining means for detecting an abnormality in the thickness of the medium based on the determination result.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1 and 2 are configuration diagrams showing one embodiment of the present invention. In these figures, the drive roller 2 is disposed at a position where its outer peripheral surface is in contact with the lower surface of a medium (not shown) conveyed through a conveyance path (not shown), and rotates at a constant speed to convey the medium.

The movable shaft 3 is arranged vertically above and corresponding to the drive roller 2, and the distance between the drive roller 2 and the movable shaft 3 is equal to the thickness of one normal medium.

The movable arm 4 is rotatably supported around a support shaft 5, is biased by a return spring 6, and one end thereof is brought into contact with the movable shirt l-3. That is, the movable shaft 3
is positioned by the movable arm 4.

Further, the other end of the movable arm 4 is arranged to cross the magnetic sensor 7.

The transmitted light sensor 8 is arranged just before the drive roller 2 and the movable shaft 3, and is configured to detect the medium passing between the drive roller 2 and the movable shaft 3 immediately before it passes.

The determination circuit 1 temporarily holds the output of the magnetic sensor 7 when the conveyed medium is detected by the transmitted light sensor 8, and uses this held output as a reference value to determine the distance between the drive roller 2 and the movable shaft 3. Based on the output of the magnetic sensor 7 when the medium passes, it is determined whether or not there is any tape or other material attached to the medium.

FIG. 3 is a block diagram showing the configuration of the determination circuit 1 shown in FIG. 1. In the figure, when the transmitted light sensor 8 detects the conveyed medium, "1" is output as a detection signal, so the AND gate 11 of the determination circuit 1 opens, and the output of the magnetic sensor 7 is transmitted through the AND gate 11. It is held in register 12.

That is, the output of the magnetic sensor 7 immediately before the medium passes between the drive roller 2 and the movable shaft 3 is held in the register 12.

The comparator 13 detects subsequent changes in the output from the magnetic sensor 7 using the value held in the register 12 as a reference value, and when the medium passes between the drive roller 2 and the movable shaft 3, the magnetic sensor When the output value of 7 changes, it is detected and an abnormality notification is output to a host device (not shown).

FIG. 4 is a flowchart showing the operation of one embodiment of the present invention. The operation of one embodiment of the present invention will be explained using these FIGS. 1 to 4.

When the leading edge of the medium conveyed on the conveyance path in the conveyance direction (direction of arrow A) passes the transmitted light sensor 8, the output of the magnetic sensor 7 is held in the register 12 of the determination circuit 1 (step 21 in FIG. 4). The output of the magnetic sensor 7 is compared with the comparator 13 using this output as a reference value (step 22 in Figure 4).
.

When the medium passes between the drive roller 2 and the movable shaft 3, if there is an adhesive such as tape on the medium, the movable roller 3 is pushed upward in the vertical direction, which causes the movable arm 4 to be supported. It rotates about the axis 5 by the excess thickness of the medium.

When the amount of rotation of the movable arm 4 is detected by the magnetic sensor 7, the output value of the magnetic sensor 7 fluctuates, and the fluctuation in the output value of the magnetic sensor 7 is detected by the comparator 13. It is determined whether or not.

When the comparator 13 detects adhesion of an adhering substance to the medium, an abnormality notification is sent to the host device (step 23 in Fig. 4).
).

When the medium has passed between the drive roller 2 and the movable shirt l-3, the movable arm 4 is urged by the return spring 6 to return to its initial position, and the movable shaft 3 also returns to its initial position.

In this way, the output of the magnetic sensor 7 is held in the register 12 of the determination circuit 1 when the transmitted light sensor 8 disposed immediately before the drive roller 2 and the movable shaft 3 detects that the medium has been conveyed. By comparing the output of the magnetic sensor 7 with the comparator 13 using the output as a base value and detecting an abnormality in the thickness of the medium, the drive roller 2
Abnormalities in the thickness of the medium can be determined based on the output of the magnetic sensor 7 just before the medium passes between the movable shaft 3 and the movable shaft 3. The thickness of the medium can be detected without being affected by changes in the initial value of the output of the sensor 7.

Therefore, it is possible to accurately detect the medium thickness.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, the output of the magnetic sensor immediately before detecting an abnormality in the thickness of the medium to be conveyed is held, and the output of the magnetic sensor is used as a reference value to detect the medium. By determining the output of the magnetic sensor when the movable roller is displaced and detecting abnormalities in the thickness of the medium based on the results, it is possible to accurately detect the thickness of the medium. .

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are configuration diagrams showing one embodiment of the present invention,
3 is a block diagram showing the configuration of the determination circuit shown in FIG. 1, and FIG. 4 is a flow chart 1 showing the operation of an embodiment of the present invention.
It is. Explanation of symbols of main parts 1... Judgment circuit 2... Drive roller 3... Movable shaft 4... Movable arm 6... Return Spring 7... Magnetic sensor 8... Transmitted light sensor 11... AND gate 12... Register 13... Comparator

Claims (1)

[Claims] (1) A medium thickness detection mechanism including a movable roller that moves according to the thickness of the medium being conveyed, and a magnetic sensor that detects an abnormality in the thickness of the medium based on displacement of the movable roller, a detection means provided immediately before the movable roller for detecting passage of the medium conveyed to the movable roller; The output of the magnetic sensor when the movable roller is displaced by the medium is determined using the holding means for holding the medium and the output of the magnetic sensor held by the holding means as a reference value, and the thickness of the medium is determined based on the determination result. A medium thickness detection mechanism characterized by comprising: a determination means for detecting an abnormality in thickness.