JPS62128778A - Position detection system in printer - Google Patents

Abstract

PURPOSE:To make it possible to accurately detect the position of a printing head, by storing the output of a photosensor at the time of saturation and that at the time of shielding and detecting a relative position from said outputs and the output of the present photosensor. CONSTITUTION:A value calculated by dividing the sum of the sensor output (saturated output) of a photosensor 7 when a slit is fully opened and the sensor output when the slit is fully closed by 2 is set to S. At first, a platen 1 is raised under such a state that no paper 40 is present until sensor output comes to a value S+DELTAs and fallen if said sensor output reached said value and the angle R1 of rotation of a stepping motor 17 obtained when the sensor output reached the value S is stored. next, the paper 40 is allowed to interpose between the platen 1 and a printing head 5 and the same operation is performed. When the platen 1 is falling, the angle R2 of rotation of a motor 17 when sensor output reached the value S is stored. The difference between the values R1, R2 is based on the thickness of the paper 40 and a head gap is regulated on the basis of said difference.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention provides a printer device having a head gap adjustment function that stores an output when a photo sensor is saturated and an output when the photo sensor is shielded, and combines these with the current photo sensor. The current vertical position of the print head can be detected based on the output of the sensor.

[Industrial application field]

The present invention relates to a printer device having a head gap adjustment function, particularly a print head vertical position detection method% method. FIG. 3 is a cross-sectional view showing details of the upper guide portion. In Fig. 3, 1 is a platen;
2 is a guide rod, 3 is an L-shaped guide rail, 4 is a carrier, 5 is a print head, 6 is a cam, and 7 is a photosensor. Guide rod 2 is platen l
The L-shaped guide rail 3 is mounted parallel to the guide rod 2. The carrier 4 runs back and forth along the guide 2.3. The platen 1 includes a paper feed roller 1 that is pivoted to the frame of the device.
It is swingably supported by an arm 12 on a shaft 11 of 0,
It is attached to the print head 5 so as to be able to approach and separate from it.

Rollers 3 are pivotally attached to both ends of the platen 1, and the platen 1, which is urged downward by its own weight or a spring, is supported by the rollers 13 coming into contact with the cams 6. The cam 6 is fixed to a camshaft 14, and the camshaft 14 is
A gear 15.1 is mounted on a shaft at a fixed position on a frame (not shown).
6 to a stepping motor 17. Therefore, when the cam 6 is rotated by the stepping motor 17, the platen 1 is pushed by the cam 6 and moves up and down. The contour curve of the cam 6 is a curve in which the amount of elevation of the platen 1 and the rotation angle of the cam 6 are proportional. The carrier 4 is slidably and rotatably supported by a guide rod 2 attached to a fixed position on the frame, and a roller 20 and a slider 21 are mounted on the upper part of the guide rod 2.
The guide rail 3 is held between the two. This guide structure on the upper part of the carrier is shown in FIG.
The sliding body 21 is biased toward the guide rail 3.
is clamped to allow movement of the carrier 4 along the guide rod 2 and to restrict rotation of the carrier 4 around the guide rod 12. Reference numeral 23 in FIG. 4 is a sleeve that holds the sliding body 21 in a manner that it can be freely extended and retracted, and 24 is a spring retainer.

The print head 5 has an arm 4 extending horizontally below the carrier 4.
Therefore, when the carrier 4 rotates around the guide long 12, the print head 5 moves toward and away from the platen 1. The rotation of the carrier 4 around the guide Ron 12 is regulated by a roller 20 and a sliding body 21 biased by a spring 22. That is, the print head 5 is urged toward the platen 1 by the spring 22, and its advancing end position is regulated by the rollers 20.

A detection piece 30 is fixed to the upper part of the carrier 4,
A sensor 7 having a pair of opposing light emitting device 31 and light receiving device 32 is arranged at a position slightly apart from the position of the tip of the detection piece 30 in a steady state. This sensor 7 is
The distance between the detection piece and the detection piece can be finely adjusted using an adjustment screw or the like.

FIGS. 5 and 6 are diagrams illustrating head gap adjustment in the printer device described above.

The paper 4o whose thickness has not been detected is supplied between the print head 5 and the platen 1 with the platen 1 lowered to the lowest end. When the paper 40 stops at a predetermined cue position, the stepping motor 17 is driven to rotate the cam 6 in the direction in which the platen 1 is raised. Then, the platen 1 moves the paper 4 between it and the print head 5.
o is pressed, and further rises to push up the print head 5.

That is, when the platen 1 pushes up the tip of the printing plate 5, a rotation moment shown by arrow A in FIG. 5 acts on the carrier 3, compressing the spring 22 and rotating the carrier 4 in the direction of the arrow A. Due to this rotation, the detection piece 3o fixed to the carrier 4 moves toward the sensor 7, and the print head 5
When the detection piece 3o is pushed up to the position where it is, the sensor 7 detects the detection piece 3o. The amount of movement of the print head 5 at this time may be small, and the sensor 7 is preferably provided sufficiently close to the detection piece 3o.

After the detection signal is emitted from sensor 7, stepping
The motor 17 is rotated several more pulses, and then the stepping motor 17 is reversed to lower the platen 1. Then, the drive pulses applied to the stepping motor 17 are counted from the moment the detection piece 3o leaves the sensor 7, that is, the moment the detection signal from the sensor 7 disappears, and the count value becomes a preset value. The stepping motor 17 is then stopped. The above value to be set is based on the amount of movement of the detection piece 30 from when it leaves the sensor 7 until it reaches its advancing end position, and the play (head gap) between the print head 5 and paper 40 necessary for printing. This is the number of pulses corresponding to the sum of .

Through the above operations, the head gap is set according to the thickness of the paper 4o, but the reason why the platen 1 is raised several more pulses after the sensor 7 detects the detection piece 3o during the above operation is This is to avoid malfunctions due to hysteresis caused by play in the support mechanism of the print head 5, and the origin of the set value count is set at the position where the detection piece 30 leaves the sensor 7 when the platen 1 is lowered. This is to ensure that the detection accuracy of the sensor is more accurate and to prevent the occurrence of errors due to the above-mentioned history phenomenon or reversal of the stepping motor 17.

[Problems with conventional technology]

The conventional device as described above has the disadvantage that the position at which the detection piece 30 leaves the sensor 7 cannot be accurately detected. The sensor 7 consists of a horseshoe-shaped container, slits formed in opposite legs of the container, a light emitter disposed in one leg facing the slit, and a slit in the other leg. and a light receiver placed facing the. FIG. 7 is a diagram illustrating a conventional position detection method using a sensor. In FIG. 7, the left side shows a state where the slit is fully closed, and the right side shows a state where the slit is fully open. Further, the sensor detection range may be considered as the width of the slit in the detection piece moving direction. Assuming that the slit is closed by the detection piece 30, from this state the detection piece 3
Suppose that 0 moves in the direction of opening the slit. Then, the output of the photodetector gradually increases, and when the slit is fully opened, the output does not increase any further. It is assumed that the detection piece 30 leaves the sensor 7 when the output of the photoreceiver exceeds the slice level. Incidentally, there are variations in the characteristics of the sensor 7, and the position detection method shown in FIG. 7 has the disadvantage that the detached position of the detection piece 30 cannot be detected accurately. As shown in FIG. 7, when the sensor output is large, the slice level is reached sooner, and when the sensor output is small, the slice level is reached later.

[Purpose of the invention]

The present invention is based on the above consideration, and provides a positioning system in which the print head position can be accurately detected in a printer device having a head gap adjustment function in which the print head also moves up and down when the platen moves up and down. The purpose is to provide a detection method.

[Means to achieve the purpose]

Therefore, the position detection method in the printer device of the present invention is suitable for saturation of the photosensor in a printer device having a head gap adjustment function that can measure the position of the print head based on the relative position between the photosensor and the detection piece. The present invention is characterized in that the output at the time and the output when the photosensor is shielded by the detection piece are stored, and the relative position is detected based on these and the current output of the photosensor.

[Embodiments of the invention]

Hereinafter, the present invention will be explained with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention. Note that the mechanical parts of the printer device are omitted from the illustration. In Figure 1,
51 is an amplifier circuit, 52 is an AD comparator, 53 is a microprocessor, and 54 is a driver. The amplifier circuit 51 amplifies the output of the transmission type photosensor 7. The AD converter 52 converts an analog electrical signal from the amplifier circuit 51 into a digital electrical signal. The microprocessor 53 has the function of controlling the stepping motor 7. The driver 54 amplifies the drive signal from the microprocessor 53 and supplies it to the stepping motor 7. The microprocessor 53 stores the output of the sensor 7 when the slit of the sensor 7 is fully closed by the detection piece 30 and the output of the sensor 7 when the slit of the sensor 7 is fully opened, and stores these values and the current output. Based on the output of the sensor 7, the position of the detection piece 30 with respect to the sensor 7 can be accurately known.

FIG. 2 is a diagram illustrating the position detection method of the present invention. The sensor detection range is, for example, 0. , /mm to 1 mm, and each time one pulse is applied to the stepping motor 7, the detection piece 30 moves by 0.01 mm. paper 4
The thickness of 0 is approximately 0.05 mm. Let S be the value obtained by dividing the sum of the sensor output when the slit of the sensor 7 is fully opened (saturated output) and the sensor output when the slit of the sensor 7 is fully closed by 2. Microprocessor 1 is
When the current sensor output becomes equal to the value S, the detection piece 30
It is determined that the sensor 7 has reached the intermediate position of the slit.

The thickness of the paper 40 is measured as follows.

First, in the absence of paper 40, the platen 1 is raised until the sensor output reaches the value S+ΔS, and when this value is reached, the platen 1 is lowered and the sensor output reaches the value S.
The rotation angle R1 of the stepping motor 17 when the rotation angle R1 is 1 is memorized. Next, the paper 40 is placed between the platen 1 and the print head 5.
and perform similar operations. Platen 1
The rotation angle R2 of the stepping motor 17 when the sensor output reaches the value S while the motor is falling is stored. value R
The difference between 1 and R2 indicates the thickness of the paper 40. The head gear is adjusted based on the measured thickness of paper 40.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, it is possible to always detect at the same position even when there are variations in the photosensor and output changes. The accuracy of detection is absorbed by the number of steps of the steering motor, and it is possible to detect a position with a positive value.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram explaining the position detection method of the present invention, FIG. 3 is a perspective view of an example of a printer device that can adjust the head gap, and FIG. The figure is a cross-sectional view showing details of the upper guide portion of the carrier, Figures 5 and 6 are diagrams explaining head gap adjustment in a printer device, and Figure 7 is a diagram explaining a position detection method using a conventional sensor. It is. 1...Platen, 5...Print head, 7...Photo sensor, 17...Stepping motor, 3o...
・Detection piece, 40...Paper, 51...Amplifier circuit, 5
2... AD converter, 53... Microprocessor, 54... Driver.

Claims (1)

[Claims] In a printer device that has a head gap adjustment function that allows the position of the print head to be measured based on the relative position between the photosensor and the detection piece, the output of the photosensor at saturation and the photosensor are shielded by the detection piece. 1. A position detection method for a printer apparatus, characterized in that the relative position is detected based on the outputs of the photosensors and the current outputs of the photosensors.