JPS61179768A - Home position detector for printer with print wheel - Google Patents

Abstract

PURPOSE:To detect a home position constantly securely, by setting the relative positions of a light-emitting element, a light-receiving element and a detection hole so that a home position detection level is reached by the time the foregoing type of a specified type as viewed in a fixed rotating direction of a print wheel passes a predetermined position. CONSTITUTION:A rotary base 18 of a printer is provided with the home position detection hole 21 in correspondence with the specified type 20a. At the home position detecting position through which the detection hole 21 of the print wheel 17 passes, are provided the light-emitting element 28 and the light- receiving element 29 opposite to each other, with the print wheel 17 therebetween. As the wheel 17 is rotated in a fixed direction, the level of a signal from the element 29 rises from a moment near the moment the specified type '-' 20a corresponding to the home position is located at a central position. The rising condition continues about to the moment the foregoing type '.' 20b of the specified type 20a in the rotating direction (a) is located at the central position, and the home position can be detected at the timing at which the specified type '-' 20a is located at the central position.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a home position detection device for printing KM equipped with a printing wheel.

[Prior Art] Conventionally, as shown in FIG. 8, this type of home position detection device has a home position detection hole 3 provided in correspondence with a specific character 2 of a print wheel 1, and the detection hole 3 is When a light-emitting element and a light-receiving element are arranged facing each other with a print wheel in between at a predetermined position to pass through, and the detection hole 3 is located exactly in the center of the optical path 4 between the light-emitting element and the light-receiving element, as shown by the solid line in the figure. As the ninth factor, a device is known in which a light-receiving element output waveform as shown in the solid line graph is obtained and the home position is detected.

[M4f:i] However, due to the structure of the printing wheel, it is difficult to provide the detection hole 3 near the base of the spoke with type attached to the tip. It will be placed closer. For this reason, even if the distance between adjacent types can be relatively large, the distance will be quite small at the location where the detection hole is provided, and even if the detection hole is at the position of the type next to the home position, the light receiving element will be connected to the light emitting element. There is a problem with detecting light from Therefore, for example, if the printing wheel 1 rotates from the left side as shown by the dotted line in Figure 8, the output waveform of the light receiving element may become a waveform as shown by the dotted line in Figure 9, which corresponds to the home position. There is a problem in that home position detection is performed not only when the printed character "-" passes, but also when the printed character "," to the right of the printed character "," passes by. On the other hand, if the printing wheel 1 rotates from the right side as shown by the single point MIA in FIG. There is a problem in that the home position is detected not only when the corresponding printed character "-" but also when the printed character ", j" to the left of it passes.For this reason, conventionally, the output level of the light receiving element that determines the home position cannot be adjusted. There was a problem in which the home position was incorrectly detected.

This invention was made in order to solve such problems, and in a device that detects a home position by detecting a detection hole provided in a print wheel using a light emitting element and a light receiving element, the home position detection is performed using a light emitting element and a light receiving element. It is an object of the present invention to provide a home position detecting device for a printing device equipped with a printing wheel that can always be reliably detected.

[Means for Solving the Problems] This invention provides a 11J that is mounted on a carrier and moves left and right.
10 In a printing device that performs printing by rotationally driving a printing wheel by a stepping motor, there is a home position detection hole provided corresponding to a specific character on the printing wheel, and a predetermined position through which this detection hole passes. A light-emitting element and a light-receiving element are arranged facing each other with a print wheel in between, and when a specific type of character reaches a predetermined position by this pixel element, one rotational direction of the print wheel is set in advance. The positional relationship between the light emitting element, the light receiving element, and the detection hole is set in advance so that the output level of the light receiving element is at the home position detection level until the adjacent type passes a predetermined position, and the printing wheel is controlled by a stepping motor. The device is provided with means for rotating the light receiving element in one rotation direction and detecting the position where the output level of the light receiving element rises to the home position detection level as the home position.

[Function] In the apparatus of the present invention having such a configuration, the printing wheel is rotated in one rotation direction by the stepping motor, and the position where the output level of the light receiving element obtained at that time rises to the home position detection level is detected. All you have to do is decide on your home position.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, the present invention will be described as applied to an electronic typewriter.

FIG. 1 is a perspective view showing the external appearance, and 11 is a housing, 12 is a keyboard provided with various keys for inputting letters, symbols, numbers, etc., and 13 is a printing wheel that constitutes the main part of the present invention. 14 is paper.

Said printing '35r! 113, as shown in FIG. 2, a rotor 16 is rotatably attached to the frame 15, and a printing wheel 17 is fixed to the rotor 16.

The printing wheel 11 is connected to the rotary substrate 1 as shown in FIG.
A plurality of spokes 19, 19, . . . are attached around the 8, and a type body 20 is attached to the tip of each spoke 19, 19, . Further, the rotating board 18 is provided with a home position detection hole 21 corresponding to a specific type 20a. Further, on the inner side of the detection hole 21 of the rotary substrate 18, there are provided anti-rotation protrusions 22, 22, . . . that mesh with the tip of the rotor 16. A recess 23 is provided on the surface of the rotating board 18 of the printing wheel 17 opposite to the surface on which the anti-rotation protrusion 22 is provided, and a wheel motor 24 consisting of a stepping motor is attached to the tip of the rotating shaft of the wheel motor 24 in the recess 23. The convex portion of the coupling member 25 is fitted. A hammer unit 26 is provided on the back side of the type body 20 attached to the tips of the spokes of the printing wheel 11, and a platen 21 on which the paper 14 is wound is provided in front. A light emitting element 28 and a light receiving element 29 are disposed facing each other with the printing wheel 17 interposed therebetween at a home position detection position through which the detection hole 21 of the printing wheel 17 passes. That is, the light emitting element 28 is attached to the housing of the wheel motor 24, and the light receiving element 29 is attached to the frame 15, so as to detect passage of the printing wheel 11 through the detection hole 21 at the home position. There is.

FIG. 4 is a block diagram showing the circuit configuration, and 31 is a CPU
(Central processing unit), ROM that stores program data
(read-only memory), RAM (random access memory) with memory for data processing, and an I10 board with a built-in A/D conversion circuit.

The microprocessor 31 includes the keyboard 12;
A wheel (PW) motor 24, a carrier (CA) motor 32, a vapor feed (PF) motor 33, and the light emitting element 28 and light receiving element 29 are connected.

The microprocessor 31 is a CPU when the power is turned on.
Said wheel motor 924 via I10 boat by
IIIIO is performed as shown in the flowchart of FIG. That is, when the initial processing is completed, the signal from the light receiving element 29 is read, and if the signal level is already at the home position detection level, accurate home position detection cannot be performed. Rotate the printing wheel 17 by 8 characters in the opposite direction to the one rotation direction at the time, and remove the home position detection hole 21 from the optical path between the light emitting element 28 and the light receiving element 29.
0 Also, when the signal level is not at the home position detection level, or after rotating in the opposite direction by 8 characters as described above, the wheel motor 24 is rotated by one character of the print wheel 17 in a preset rotation direction. Check the signal level from the light receiving element 29 again. This signal level check is repeated until the signal level from the light receiving element 29 reaches the home position detection level, and when the signal level from the light receiving element 29 reaches the home position detection level, it is determined that the signal level has risen, and the current The position of the print wheel 17 is defined as the home position.

In the embodiment of the present invention having such a configuration, the light emitting element 28
The positional relationship between the optical path A of the light-receiving element 29 and the home position detection hole 21 is the sixth position when detecting the home position.
The result will be as shown in the figure. The signal level change from the light receiving element 29 at that time is as shown in FIG. That is, when the printing wheel 17 rotates in one direction as shown by the arrow in the sixth factor, the light receiving element 29
The signal level rises, and the next character in the direction of rotation
" 20b continues to rise until it reaches the center. Therefore, the next printed character "," in the opposite direction to the rotation direction.
When J20C is located at the center, the signal level of the light receiving element 29 is at a low level. Therefore, if the home position is detected by the rise of the signal level of the light receiving element 29, the home position can be detected at the timing when the specific character "-J" 20a is located in the center. Therefore, the adjacent character "," 20b There is no risk of erroneously detecting the home position when the position is at the center. Also, when another adjacent printed character "," is located in the center, the signal level of the light receiving element 29 is at low level, so
At this time, there is no risk of erroneously detecting the home position.

In this way, home position detection is always performed only when the specific printed character "-" is located at the center, making it possible to accurately detect the home position.

Although the above embodiment has been described in which the present invention is applied to a printing device of an electronic typewriter, the present invention is not necessarily limited to this, and may be applied to a single printing device.

〔Effect of the invention〕

As detailed above, according to the present invention, the home position is detected by detecting the detection hole provided in the print wheel using the light emitting element and the light receiving element, and the home position can always be detected reliably. It is possible to provide a home position detection device for printing KM equipped with a printing wheel.

[Brief explanation of the drawing]

Figures 1 to 7 show embodiments of this invention.
The figure is a perspective view showing the external appearance, Figure 2 is a sectional view of the main part, Figure 3 is a diagram showing the printing wheel, Figure 4 is a block diagram showing the circuit configuration, and Figure 5 is a home position detection process by a microprocessor. 6 is a diagram showing the positional relationship between the optical path of the light emitting element and the light receiving element and the home position detection hole of the printing wheel, and FIG. 7 is a diagram showing the change in the signal level from the light receiving element in FIG. 6. Figure 8 shows the conventional optical path between the light emitting element and the light receiving element and the position 111r of the home position detection hole of the print wheel! ! The fourth factor is a diagram showing the change in the signal level from the light receiving element in FIG. 8, and the ninth factor is a diagram showing the change in the signal level from the light receiving element in FIG. 13...Print H[, 11...Print wheel, 21...
...Home position detection hole, 24...Wheel motor, 28...Light emitting element, 29...Light receiving element, 31
...Microprocessor. Applicant's agent Patent attorney Takehiko Suzue Figure 6
Figure 7 Figure 8 Figure 9

Claims (1)

[Claims] In a printing device that performs a printing operation by rotationally driving a printing wheel mounted on a carrier and controlled to move left and right by a stepping motor, a home position detection hole provided in the printing wheel corresponding to a specific type;
A light-emitting element and a light-receiving element are arranged opposite to each other with the print wheel interposed in between at a predetermined position through which the detection hole passes, and the pixel element allows the specific type to reach a predetermined position and then move the print from the type in advance. The light emitting element, the light receiving element, and the detection hole are set in advance so that the output level of the light receiving element becomes the home position detection level until the next printed character passes a predetermined position in the direction of one rotation of the print wheel. means for setting the positional relationship between the two, and rotating the printing wheel in one rotational direction by the stepping motor, and detecting the position where the output level of the light receiving element rises to the home position detection level as the home position. What is claimed is: 1. A home position detection device for a printing device equipped with a printing wheel.