JPS61177266A - Home position detector for carrier in printer - Google Patents

Abstract

PURPOSE:To enable a home position to be determined with high accuracy, by a method wherein the exciting phase of a stepping motor is compared with an exciting phase stored in a home position memory, and rotation of the motor is controlled with one pitch as a unit so that both of the exciting phases accord with each other, in a system comprising a switch for detecting a home position for a carrier. CONSTITUTION:At the time of turning ON a power source or in the case of a cover opening operation, the exciting phase of a carrier motor 32 is switched one time to move the carrier 16 one pitch leftward, and the resultant position is set to be a home position. Namely, exciting phase data of the carrier motor 32 at that time are stored into the home position memory HPM. Thereafter, when returning the carrier 16, it is checked whether or not a home position switch 14 is turned ON, and it is also checked whether or not the exciting phase of the motor 32 accords with the exciting phase stored in the memory HPM. Until both of the exciting phase accord with each other, the exciting phase of the motor 32 is switched to minutely move the carrier 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a carrier home position detecting device in a printing device that performs a printing operation by controlling the left and right movement of a carrier equipped with a printing mechanism using a stepping motor.

[Prior Art] Conventionally, home position detection devices of this type are known, such as those using a photo sensor and those using a switch such as a microswitch. The former method has relatively high detection accuracy but also has a high cost I~, whereas the latter method is recently widely used because it is inexpensive.

[Problems to be Solved by the Invention] However, when a switch is used to detect the home position, there is a problem with detection accuracy. That is, the amount of fine movement per pitch of the stepping motor that operates the carrier is required to be approximately 1/1201 nch, and the detection accuracy of the switch is required to satisfy this. By the way 1
/1201nch is 0.212 mm, and in order to satisfy this, the detection accuracy of the switch is required to satisfy ±0.1 mm. However, in the case of microswitches, for example, when a large number of switches are collected, the overall detection accuracy is about ±0.5 mm, and the detection accuracy of one switch is less than half of that, but still cannot satisfy 0.1 mm. For this reason, in conventional systems that use switches to detect the home position, there is a risk that the home position will deviate by one pitch or more, which poses a problem that it cannot be applied to printing devices that require precision.

This invention was made to solve these problems, and is capable of positioning the home position with high precision in a printer that uses a switch to detect the home position of the carrier, and is suitable for printing devices that require high precision. It is an object of the present invention to provide a home position detection device for a carrier in a printing device that can be used satisfactorily.

[Means for Solving the Problems] The present invention provides a printing device that performs a printing operation by controlling the left and right movement of a carrier equipped with a printing mechanism using a stepping motor. , a home position memory, and a detection means for detecting operation of the home position switch when the carrier returns to the home position;
When the detection means detects the operation of the home position switch at the first return when the carrier should be moved to the home position, the carrier is controlled to move a few more pitches and stopped, and the excitation phase of the stepping motor at that time is stored in the home position memory. and means for storing in the home position memory the excitation phase of the stepping motor at that time when the detection means detects the operation of the home position switch at the second and subsequent return to move the carrier to the home position. By comparing the excitation phase with the excitation phase and controlling the rotation of the stepping motor one pitch at a time so that both excitation phases match, the excitation phase of the stepping motor is made to match the excitation phase stored in the home position memory. This is to determine the home position of the carrier.

[Function] In the device of the present invention having such a configuration, the home position is set when the carrier is first returned to the home position, such as when the power is turned on or when the cover covering the printing device is opened and closed. It detects whether the switch operates or not, and if it operates, the carrier is moved a few more pitches, such as one or two pitches, from that state, the excitation phase of the stepping motor at that time is stored in memory, and then the carrier returns to the home position. Each time the carrier returns to the position, the excitation phase of the stepping motor stored in memory is compared with the actual excitation phase of the stepping motor, and the stepping motor is controlled to rotate so that both excitation phases match to determine the home position of the carrier. There is.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described 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 function keys such as keys for inputting characters, symbols, numbers, etc.;
14 is a home position switch for detecting the home position of a carrier, which will be described later; and 15 is a sheet of paper.

As shown in FIG. 2, in the printing device 13, a rotor 18 is rotatably attached to a frame 17 fixed to a carrier 16, and a printing wheel 19 is fixed to the rotor 18. As shown in FIGS. 6-3, the printing wheel 19 has a plurality of spokes 21, 21, .
．． A type body 22 is attached to the tip of the letters 21, . Further, a home position is set on the rotating board 20, and a detection hole 23 is provided at that position. Further, on the inner side of the detection hole 23 of the rotating board 20, a rotation preventing protrusion 24.2 that meshes with the tip of the rotor 18 is provided.
4,... are provided. A recess 25 is provided on the surface of the rotating board 20 of the printing wheel 19 opposite to the surface on which the anti-rotation protrusion 24 is provided, and a wheel motor 26 consisting of a stepping motor is attached to the tip of the rotating shaft of the wheel motor 26 in the recess 25. The convex portion of the connecting member 27 is fitted into the connecting member 27. The wheel motor 26 is connected to the support body 3
3 to the frame 17. A hammer unit 28 is provided on the back side of the type body 22 attached to the tips of the spokes of the printing wheel 19, and a platen 29 on which the paper 15 is wrapped once is provided on the front side.
is provided. Detection hole 23 of the printing wheel 19
A light-emitting element 30 and a light-receiving element 31 are arranged facing each other with the print wheel 19 interposed therebetween at a position where the light passes through. That is, the light emitting element 30 is mounted on the housing of the wheel motor 26, and the light receiving element 31 is attached to the frame 17 to detect passage of the printing wheel 19 through the detection hole 23. A carrier motor 32 consisting of a stepping motor is also attached to the carrier 16.

FIG. 4 is a block diagram showing the circuit configuration, and 41 is a CPU.
(Central processing unit), 42 is a ROM (read only memory) that stores program data, 43 is a RAM (RAM) provided with a key buffer K [3F, wheel return timer PWT, -th flag NF, home position memory HPM, etc. random access memory). The cPU 41, the ROM 42, and the RAM 43 are connected by a pass line 44.

Further, 45 is an I10 port, 46 is a keyboard interface, and 47 is a programmable timer.

The cpu 41, the I10 port 45, and the keyboard interface 46 are connected by a pass line 48. The programmable timer 47 generates a timing clock signal CLK for excitation phase switching when the wheel motor 26 rotates.
The signal CLK is supplied to the motor drive circuit 49 that rotationally drives the wheel motor 26, and the CP
It is also supplied to U41. The c p U 41 sends a direction signal D to the motor drive circuit 49 via the 110 ports 1 to 45 for determining the rotation direction of the print wheel 19.
A rotation instruction signal ENA for instructing the rotation of the IR1 print wheel 19 and a clear signal CLR for setting the excitation phase of the wheel motor 26 at the home position to a preset excitation phase are supplied, respectively. In addition, the above C
The P U 41 controls the motor drive circuit 50 of the carrier motor 32 that controls the movement of the carrier 1G via the I10 boat 45, and also controls the motor drive circuit 52 of the paper feed motor 51 that controls the feeding of the paper 15. ing. Further, the CPU 41
Signals from the home position switch 14 and the light receiving element 31 are taken in through the 10 port 45.

FIG. 5 is a general flowchart in which the CPU 41 controls each part. When the power is turned on, first the RAM 43 is
(The first flags N and F are set to "1" in this initial cell 1~).

), then control is performed to restore the carrier motor 32, wheel motor 26, and paper feed motor 51, that is, to return them to their home positions. Next, it is checked whether the cover provided on the printing section is open. If the cover is open, wait until the cover is closed, and when the cover is closed, set the first flag NF to "1" and then start the carrier motor 32.
and restore the wheel motor 26.

Next, it is checked whether the wheel motor 26 is in the RFDY state. This is because if the wheel motor 26 is not in the RFDY state, the wheel motor 26 is rotating and there is no point in checking the home position. RED
, if it is in the Y state, it is then checked whether the wheel motor address is zero. This is because if the wheel motor address is not zero, it is determined that the spokes 21 of the print wheel 19 have not returned to the home position, and the home position detection is passed. If the address is zero, then it is checked whether the light receiving element old detects light from the light emitting element 30 or not. If no light is detected, it is determined that there is a discrepancy between the data home position and the actual home position of the printing wheel 19, and the wheel motor 26 is restored.

When these series of checks are completed, it is next checked whether the wheel return timer PWT has timed up, and if the time has expired, the wheel motor 26 is returned to the home position. This is to return the printing wheel 19 to the home position when it is stopped for a predetermined period of time in the final printing state.

Next, it is checked whether there is data in the key buffer KBF. If there is data, it processes that data, that is, performs key processing. In this key processing, carrier 1
6 may return, the carrier motor 32 also performs glue store processing. Next, the state of the beat key is checked, and if the key is ON, a repeat operation is performed. If the carrier 16 returns during this repeat operation, the carrier motor 32 is also restored.

This completes the overall check and returns to the cover open check.

In this check process, the carrier motor 32 is restored based on FIG. 6. That is, first, it is checked whether the home position switch 14 is ONL. If it is ONL, the switch 14 is already turned on before the home position is determined, and the home position cannot be determined in this state. Therefore, the carrier motor 32 is operated to the extent that the carrier 16 is turned off and the home position switch 14 is no longer in the ON state. and move it to the right by a predetermined pitch. Home position switch 14
is in the OFF state, operate the carrier motor 32 to move the carrier 16 to the left by one pitch, and read the state of the home position switch 14 after a predetermined delay time that takes into account mechanical delays, vibrations, etc. It's crowded. If this switch 14 is in the OFF state, the same control is repeated again. If this switch 14 is in the ON state, it is subsequently checked whether the first flag NF is set to "1", and if NF = 1, it is determined that the home position has been determined for the first time, and the carrier The motor 32 is operated to move the carrier 16 to the left by one pitch. In addition,
The movement pitch at this time may be two pitches, or just several pitches. This one-pitch movement control is performed because the home position is set to a position further shifted to the left by one pitch after the home position switch 14 is turned on. When this 1-pitch movement control is completed, check whether the home position switch 14 is turned on again, and turn it on.
If so, it is determined that this is the home position, and the data of the excitation phase of the carrier motor 32 at that time is stored in the home position memory HPM. Then, the -th flag NF is cleared to "O". If the home position switch 14 is turned off at this time, it is determined that the switch has not operated correctly, and the carrier 16 is moved by one pitch again, and the home position detection control is repeated. Also, in checking the flag NF, NF
If it is not equal to 1, it is determined that the home position is being detected for the second time or later, and the excitation phase data stored in the home position memory HPM and the current carrier motor 3 are
Compare with the excitation phase of No. 2. If the two match, it is determined that the carrier 16 is at the home position, and this process ends. Further, if the two do not match, it is determined that the current carrier 16 has not come to the home position correctly, and the carrier motor 32 is operated one pitch again to check the excitation phase again. This check is repeated until both excitation phases match.

In the embodiment of the present invention having such a configuration, when the power is turned on, when the cover is opened and closed, and when the key is processed,
Restoration processing of the carrier motor 32 is performed during each repeat operation. In this restoration process, it is first checked whether the home position switch -14 = 14 is in the ON state, and if it is
If so, the carrier 16 is moved to the right by a predetermined pitch and the home position switch 14 is removed. When the home position switch 14 is in the OFF state, the excitation phase of the carrier motor 32 is switched only once, and the carrier 16
1 pitch to the left and check whether the home position switch 14 is turned on. This process is repeated until the home position switch 14 is turned on. When the home position switch 14 is turned on, it is then checked whether the first flag NF is set to 11''. When the power is turned on or the cover is opened, NF = 1, so at this time, the excitation phase of the carrier motor 32 is switched only once to move the carrier 16 to the left by one pitch and set it as the Baum position. Set. That is, the excitation phase data of the carrier motor 32 at that time is stored in the home position memory HPM.
When the motor 6 returns, the carrier 32 checks whether the home position switch 14 is turned on or not, and if the switch 14 is turned on, the excitation phase of the carrier motor 32 is further changed to the excitation phase stored in the home position memory HPM. It is checked whether they match, and the excitation phase of the carrier motor 32 is switched until the excitation phase of the carrier motor 32 matches the excitation phase of the memory, and the carrier 16 is moved by a small amount. In this way, the carrier 16 is always positioned with respect to the once set home position not only by the ON operation of the home position switch 14, but also by adjusting until the excitation phase of the carrier motor 32 matches, so even if the home position is detected by using a micro Highly accurate positioning is possible even when using switches such as

It should be noted that although the embodiment described above is an example in which the present invention is applied to an electronic typewriter device, the present invention is not necessarily limited thereto, and may be applied to a single printing device.

[Effects of the Invention] As detailed above, according to the present invention, the home position can be positioned with high precision in a device that uses a switch to detect the home position of the carrier, and is suitable for printing devices that require precision. It is possible to provide a carrier home position detection device in a printing device that can be used satisfactorily.

[Brief explanation of the drawing]

Figures 1 to 6 show embodiments of this invention.
Figure 2 is a perspective view showing the external appearance, Figure 2 is a sectional view of main parts, Figure 3 is a diagram showing the printing wheel, Figure 4 is a block diagram showing the circuit configuration, Figure 5 is a flow chart showing general processing by the CPU, FIG. 6 is a flowchart showing the carrier motor glue store process in FIG. 13...Printing device, 14...Home position switch, 16...Carrier, 32...Carrier motor, 41...CPU (central processing bag fit), 42...
ROM (read only memory), 43...RA
M (random access memory), NF...-th flag, HPM... home position memory, 50
...Motor drive circuit.

Claims (1)

[Claims] A printing device that performs a printing operation by controlling the left and right movement of a carrier equipped with a printing mechanism using a stepping motor includes a home position switch that detects the home position of the carrier, a home position memory, and a home position memory of the carrier. detection means for detecting operation of the home position switch upon return;
When the detection means detects the operation of the home position switch at the first return to move the carrier to the home position, the carrier is further controlled to move by several pitches and stopped, and the stepping motor is excited at that time. means for storing the phase in the home position memory; and excitation of the stepping motor when the detecting means detects the operation of the home position switch during the second and subsequent returns to move the carrier to the home position. means for comparing the excitation phase stored in the home position memory with the excitation phase stored in the home position memory, and controlling the rotation of the stepping motor one pitch at a time so that both excitation phases match; A home position detection device for a carrier in a printing device, characterized in that the home position of the carrier is determined by matching an excitation phase stored in a position memory.