JPH076706U - Paper thickness measurement sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to a sensor that presses a sheet against a reference plate by a sheet thickness detector that moves by spring force and measures the sheet thickness. Even if there is, it is to secure a paper passage between the reference plate and the paper thickness detector. [Structure] A stopper 10 is provided which can change the pressure angle of the cam 5 when the paper thickness detector 1 is retracted from the paper passage so that the rotational force acting on the cam 5 is in the b direction and prevents the rotational force in the b direction. Therefore, it becomes possible to secure a paper path when the power of the printing device is off.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a paper thickness measuring sensor of a printing device.

[0002]

[Prior art]

 The conventional paper thickness measuring sensor has a structure as shown in FIGS. 4 and 5, and when the paper 6 passes, the cam 5 is rotated in the b direction by the motor 3 to secure the paper passage. As shown in FIG. 5, the paper thickness detector 1 is retracted, and in order to maintain this retracted state, the motor 3 is continuously supplied with a current for giving a holding torque. That is, in the retracted state of the sheet thickness detector 1, the normal direction of the cam surface 5a at the point of application of the rotational force to the cam 5 is the c direction, and the spring force of the compression coil spring 2 causes the normal direction. A force acted on c, and a rotational force in the a direction acted on cam 5.

[0003]

[Problems to be solved by the device]

 According to the above-mentioned conventional technique, the paper 6 cannot be taken in and out when the power of the printing apparatus is off or immediately after the power is turned on until the paper thickness detector 1 is retracted. Had a big problem.

Therefore, if the detent torque, which is the holding torque of the motor when the current is zero, is increased to suppress the spring force, the paper thickness measuring sensor including the motor becomes expensive and becomes large.

Further, if the spring force is weakened so that the retracted state can be maintained even with a small detent torque, an appropriate paper pressing force cannot be obtained, and there arises a problem that the paper thickness measurement value varies.

Further, if a power failure or the like occurs during printing, the sheet thickness detector 1 is accelerated by the spring force of the compression coil spring 2 toward the reference plate 7 and collides with the sheet. If the paper 6 being printed is pressure-sensitive paper, dents may occur, and even one-part paper may be scratched or damaged. In particular, if the user tries to remove the paper 6 in this state, not only will the paper 6 be damaged, but the paper thickness measuring sensor itself will also be damaged.

An object of the present invention is to eliminate these problems of the prior art and provide a paper thickness detector retracting mechanism with good operability.

[0008]

[Means for Solving the Problems]

 As shown in FIG. 2, in the retracted state of the sheet thickness detector 1, the direction of the rotational force acting on the cam 5 by the spring force of the compression coil spring 2 acts on the cam during the sheet thickness detector retracting operation. This can be achieved by forming the shape of the cam so as to be similar to the direction of the generated rotational force.

[0009]

[Action]

 When the force acting in the normal direction of the cam surface 5a in the retracted state of the sheet thickness detector 1 as in the above means is set in the d direction with respect to the cam rotation shaft 12, it acts on the cam 5 in the retracted state of the sheet thickness detector. The rotating force can be in the b direction. Further, by providing the stopper 10 for preventing the rotational force in the b direction, the excessive rotation of the cam 5 can be prevented, so that the sheet thickness detector 1 will not accidentally block the passage. It should be noted that the same effect can be obtained even if the stopper 10 is provided at a position other than the position shown in FIG. 2 as long as it can prevent the cam 5 from excessively rotating.

Further, by setting the force acting in the normal direction of the cam surface 5a in the retracted state of the sheet thickness detector 1 such that the rotational force generated from the vane force is equal to or less than the detent torque of the motor, In the retracted state of the detector, the rotational force acting on the cam 5 in the a direction or the b direction can be weakened, a small motor with a small detent torque can be used, and the paper passage can be secured without the stopper 10. Is.

[0011]

【Example】

 The present invention will be described below with reference to the accompanying drawings. In FIG. 1, a paper thickness detector 1 opposes the acting force of a compression coil spring 2, and a cam gear 5 rotated by a motor 3 and a motor gear 4 and a power transmission shaft fixed to the paper thickness detector 1 as shown in FIG. It moves back and forth between the reference plate 7 and the paper guide 8 via 9. The space between the reference plate 7 and the paper guide 8 is a passage for the paper 6.

In the state shown in FIG. 2 in which the sheet thickness detector 1 is retracted from the sheet path for printing, the force acting in the normal direction of the cam surface 5a at the contact portion between the power transmission shaft 9 and the cam surface is applied. The direction of the rotational force acting on the cam gear 5 is changed to the direction d with respect to the cam rotation axis, and the stopper 10 for blocking the rotational force in the direction b is provided to prevent the passage of the paper when the power is off. Can be secured.

In this embodiment, the notch is provided in the cam gear 5 as a means for allowing the force of the cam 5 to move in the direction of b. However, the present invention is not limited to this, and the force acting on the cam 5 is directed in the direction of b. Anything will do.

Further, in the cam 5 of this embodiment, even if the motor is not energized due to an unexpected accident such as a power failure, the cutout portion of the cam surface 5a is a flat surface, so that the power source shaft 9 is not affected. Since it remains held and does not rotate, there is no fear that the sheet thickness detector 1 will come out in the sheet passage.

[0015]

[Effect of device]

 According to the present invention, by changing the pressure angle at the point of application of the rotational force to the cam, the direction of the rotational force due to the spring force is changed, and a stopper for blocking the rotational force is provided. It is possible to prevent the paper thickness detector from blocking the paper passage when the power of the printing device is turned off, and it is possible to improve the operability such that the paper can be taken in and out.

Further, since the spring force is not suppressed by the detent torque of the motor, an inexpensive small motor can be used, and the sensor body can be manufactured at low cost and the size can be reduced.

In addition, it is possible to prevent the adverse effect that the force for pressing the paper is weakened and the stability of the sensor measurement value is sacrificed due to the downsizing of the sensor body.

Even if a power failure or the like occurs during printing, the paper thickness detector does not project and the printing paper is not damaged.

Further, since the holding torque for preventing the paper thickness detector from obstructing the paper path is unnecessary during the motor is not operating, it is not necessary to supply power to the motor except when the sensor is operating, Power consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view showing a state in which a sheet thickness detector is projected in a sheet thickness detection sensor of the present invention and a state in which it is attached to a printer main body.

FIG. 2 is a plan view showing a retracted state of a sheet thickness detector in the sheet thickness detection sensor of the present invention.

FIG. 3 is a perspective view showing a paper thickness detector driving mechanism in the paper thickness detection sensor of the present invention.

FIG. 4 is a plan view showing a protruding state of a sheet thickness detector of a conventional sheet thickness detection sensor.

FIG. 5 is a plan view showing a retracted state of a sheet thickness detector of a conventional sheet thickness detection sensor.

[Explanation of symbols]

1 is a paper thickness detector, 2 is a compression coil spring, 3 is a motor,
4 is a motor gear, 5 is a cam gear, 6 is a paper, 7 is a reference plate, 8 is a paper guide, 9 is a power transmission shaft, 10 is a stopper, 11 is a paper thickness detector bearing, and 12 is a cam rotation shaft.

Claims (2)

[Scope of utility model registration request] 1. A paper thickness detector that reciprocates in a paper passage between a reference plate and a paper guide by rotation of a cam via a motor, and presses the paper thickness detector against the reference plate by a spring force. In a paper thickness measuring sensor of a printing device for measuring the thickness of a paper passing through the paper passage, the paper thickness detector is provided in order to secure a passage through which the paper can be taken in and out even when the power is off. A paper thickness measuring sensor, which is provided with a mechanism for holding it in a retracted state. 2. The mechanism for holding in a retracted state,
With the paper thickness detector retracted, the direction of the rotational force acting on the cam by the spring force is the same as the direction of the rotational force applied to the cam during the paper thickness detector retracting operation. 2. The paper thickness measuring sensor according to claim 1, wherein a cam shape is formed.