JPS5833827B2 - printer protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a printer comprising a type wheel with a plurality of type fingers and a print hammer that strikes a desired type finger of the type wheel. This relates to a printer protection system in which if one end of the type wheel enters the type wheel, this is immediately detected by a type wheel detector and the rotation of the type wheel is stopped.

FIG. 1 is a block diagram showing an embodiment of a printer protection system according to the present invention.

In the figure, 1 is a type wheel equipped with a plurality of type fingers 1a to 1n;
As shown in FIG. 2, each has type 2 on one side and magnetic bodies 3a and 3b on the other side.

4 is a printing paper; 5 is a platen; 6 is a first detector that detects the hole 7 through which the type wheel 1 passes every rotation and sends out a home pulse; 8 is the type finger 1a to 1;
9 is a drive source such as a servo motor that rotates the type wheel 1 continuously or intermittently; 10 is an input terminal for printing data; a data register for temporarily storing print data; 12 an index register for counting the scan pulse; 13 a data register 1;
A matching circuit matches the contents of index register 12 with the contents of index register 12; 14 is a hammer magnet energized by the output signal of this matching circuit; 15 is rotatably supported by 15a; one end is attached to the hammer magnet; 14, the other end facing the type finger, 16
11 constitutes a reset spring of the hammer 15, and 11 constitutes a hammer detector, which is attached to the other end of the hammer 15, and an induced voltage is generated by the movement of the magnetic bodies 3a, 3b of the type fingers 1a to 1n, A finger proximity detector 18 detects when the hammer 15 that has entered the rotation locus approaches these type fingers 1a to 1n. When receiving the output signal of the detector 17, that is, indicating that the end of the hammer 15 has entered the rotation locus of the type wheel 1, an abnormality detection circuit immediately sends a stop signal and stops the drive source 900 rotations. It is.

Next, the operation of the above configuration will be explained, but the explanation of the operation of detecting the desired type fingers 1a to 1n of the type wheel 1 and printing at the desired position will be omitted.

One of the desired type fingers 1a to 1n is selected without hesitation, and after the printing operation of the marker 15 is completed, the rotation of the type wheel 1, that is, the rotation of the type fingers 1a to 1n, causes the magnetic material 3a, 3b to be selected. is finger proximity detector 1
7, an induced voltage is generated only from the movement of the magnetic body 3a, and the waveform shown in FIG. 3A is sent out from the finger proximity detector 17.

Similarly, when the printing operation of the hammer 15 continues, the finger proximity detector 17 sends out a waveform shown at the beginning of FIG.

On the other hand, when the end of the hammer 15 enters the rotation locus of the type wheel 1, for example, the desired type fingers 1a to 1
After one of n is selected and the printing operation of the hammer 15 is completed, the rotation of the type wheel 1, that is, the rotation of the type finger, moves the magnetic body 3a, and the magnetic body 3b of the next type finger moves within the rotation trajectory. It approaches the end of Noma 15, which entered the area.

Therefore, the finger proximity detector 17 can detect the approach of the magnetic body 3b.

The detected waveform in that case can be shown in FIG.

Therefore, the abnormality detection circuit 18 receives a detection signal from the magnetic body 3b from the finger proximity detector 17 that is present even after a predetermined period of time has elapsed since the activation signal of the sensor 15, and sends out a stop signal.

This stop signal stops the rotation of the drive source 9, that is, the rotation of the type wheel 10, thereby preventing contact or collision between the hammer and type fingers.

Note that if the magnetic bodies 3a and 3b are made of permanent magnets and the finger proximity detector 11 is made of a Hall effect element, the structure of the detection circuit is also favorable.

FIG. 4 is a side view showing another embodiment of the printer protection system according to the present invention.

In the figure, 19 constitutes a light source, and 20 constitutes a hammer detector, which is a photodetector into which the reflected light from the printing hammer 15 enters when one end of the printing hammer 15 enters the rotation locus of the type wheel 1. be.

Therefore, one of the desired type fingers 1a to 1n is selected, and the printing operation of the hammer 15 causes the light from the light source 19 to be reflected by the hammer 15 and input to the photodetector 20.

Therefore, the abnormality detector 18 does not send out one output signal due to the cooperation of the output signal of the photodetector 20 and the energizing signal of the hammer 15, even though the energizing signal of the hammer 15 is no longer present. , when there is an output signal from the photodetector 20, an abnormal signal is sent, the rotation of the drive source 9 is stopped, and contact or collision between the type finger 1a of the type wheel 1 and the printing mark 15 is prevented. I can do it.

Here, it is preferable to use a light emitting diode as a light source and a light receiving transistor as a photodetector from the viewpoint of reliability and response speed.

As explained above in detail, according to the printer protection system according to the present invention, even if one end of the hammer enters the rotation locus of the type finger of the type wheel, contact or collision between the hammer and the type finger can be avoided. There are effects such as being able to.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the printer protection system according to the present invention, FIG. FIG. 4 is a block diagram showing another embodiment of the printer protection system according to the present invention. DESCRIPTION OF SYMBOLS 1... Type wheel, 1a-1n... Type finger, 2... Type, 3a and 3b... Magnetic material, 4...
・Print paper, 5... platen, 6... first detector,
7...JL. 8... Second detector, 9... Drive source, 10... Input terminal, 11... Data register, 12... Index register, 13... - number circuit, 14... Hammer Magnet, 15... Hammer, 16... Reset spring, 17... Finger proximity detector, 18...
Abnormality detection circuit, 19... light source, 20... photodetector.

Claims (1)

[Claims] 1 In a printer equipped with a type wheel having a plurality of type fingers and a print hammer that strikes a desired type finger of the type wheel by selectively energizing a hammer magnet, An error detection circuit that detects that the output signal of the hammer magnet is present even after a predetermined period of time has elapsed from the energization signal of the hammer magnet. A protection device for a printer, characterized in that the rotation of a type wheel is immediately stopped in response to an output signal of the abnormality detection circuit.