JPS5812874B2 - serial printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a serial printer that can easily detect printing errors.

A type wheel is provided, the head is rotated by a motor to select the type, and the print head consisting of the type wheel and the motor is made to run along the platen,
In serial printers that operate a hammer at the printing position to impact the selected type onto the print medium on the platen via an ink ribbon to print, if there is an error in type selection, incorrect printing will occur. This is a fatal printer malfunction.

In particular, it is difficult to detect misprinted numbers simply by visually inspecting the printed matter.

Conventionally, in order to prevent this, some methods have been used, such as taking into account the layout of the print wheel and arranging kana characters between numbers to make it easier to detect incorrect printing due to misalignment of Ichiu printing, but this method This method has the drawback that the amount of selected characters (the number of characters between the current position and the desired character) increases, which reduces the effective printing speed of the printer.

This is because the printing speed of a serial printer is proportional to the amount of selected characters.

The present invention improves these points, allows continuous arrangement of numbers, etc., without reducing printing speed, and makes it possible to detect malfunctions in character selection at the time of erroneous printing and to notify the outside. .

The present invention relates to a serial printer having a type wheel that is transversely fed along a platen and rotated to select type. In addition to an annular position detection track in which each pair of bright and dark areas corresponds to each type position, a mode of detecting whether there is a bright area in the pair of bright areas and dark areas and whether there is a dark area in the next pair of bright areas and dark areas. Then, the bright and dark areas with twice the bright and dark pitch alternate,
The present invention is characterized by the provision of annular error detection tracks aligned corresponding to the bright and dark portions of the position detection track, which will now be described in detail with reference to the drawings.

Referring to Fig. 1, numeral 1 is a type wheel, which has two stages of 64 characters per rotation, for a total of 128 characters, and is rotated forward and backward by motor 2 to select the type (the desired type faces the platen). to be done)

A transducer 3 is attached to the rotating shaft of the motor 2, and outputs a position signal of one pulse for each printed character.

4 is a circuit that receives the output of the transducer and performs waveform shaping; 5 and 6 are input and output ports of the microprocessor 7; and IF is an interface with a host computer or the like.

The transducer 3 includes a slit disk 11 and a floodlight 1
2, and a light receiver 13.

Details of the slit disk 11 are shown in FIG.

As shown in FIG. 2, the slit disk 11 has four tracks A to D each having a bright and dark pattern of a different width, and A is a speed detection track consisting of an extremely large number of narrow bright and dark stripes.

B is a position detection track, which has a large number of bright and dark stripes that are considerably wider than the bright and dark stripes, for example (5 to 6 times).

C is a rank of typo detection added according to the present invention, which detects the bright part of track B (this is referred to as white W) and the following dark part (
(This is referred to as black B) One bright part or one dark part is provided alternately for each one.

In other words, track C has twice the pitch of bright and dark stripes as track B.

Track D is for a home position mark and has one bright portion h indicating the home position.

As mentioned above, the type wheel rotates forward and backward, and each row of 64 type characters is arranged in halves to the left and right of a specific type character in the center, usually the @ sign.

A bright area h indicates the position of this at mark.

1- in the rows of bright area h1 and dark area h2 of position detection track B.
A pair of emitter and receiver 1 3a, 1 3b at 80° different positions
are placed, and the light and dark patterns of track B facing these emitters and receivers are in opposite phases, that is, the bright parts are the emitters and receivers 13.
When facing the light emitter/receiver 13. Opposite b.

In Figure 3, track B is drawn in two lines, and the bright part h
1. The dark area h2 is shown shifted by 180°.

As can be easily inferred from Figure 3, depending on such a bright/dark pattern and the emitter/receiver arrangement, an alternating waveform can be obtained in which each adjacent bright and dark area (corresponding to one character position) forms one cycle. and if passed through an appropriate filter, the fourth
A sine wave SW as shown in the figure is obtained.

This is the position signal.

Point STP is the stopping point, and printing is performed with this point STP correctly facing the platen.

The point STP is located at the center of the bright part W1 and the dark part B of the track C.

Note that in the above explanation, bright areas refer to areas through which light passes, and dark areas refer to areas through which light does not pass.

Type selection guidelines are provided in the patent application filed by the applicant on May 5, 1982.
It is detailed in ``Print selection method in serial printers'' in No. 4, 5, 7, etc., but to give an overview, first, a print selection command is sent from the central processing unit 1, and the printer uses this command based on this command. A multi-bit binary signal is calculated and generated which indicates the amount of rotation of the type wheel from the current position to the desired (printed) type character in terms of the number of characters between.

This signal causes the type wheel drive motor to rotate. Since the letter decreases by 1 every time the letter rotates by one character position, if it is converted to DA, it will become a step wave that gradually decreases, and this will cause the speed (
or position) command.

This position command is matched with the actual speed signal obtained from track A by a differential amplifier, and the difference, which is greater than a predetermined value, is applied to the truncated motor to drive the type wheel.

Generally, the difference is large at the beginning of startup, so the difference signal is truncated to a constant value, driving the motor at maximum torque.

When the motor speed exceeds the speed command, the motor is braked.
In this way, the motor decelerates in accordance with the gradually decreasing speed command.

When near the stop position, specifically when it comes to point P or P2, it switches to fine control, and from track B to 0? Position signal SW
Position control according to the following starts and stops accurately at the stopping point STP.

The type is selected in this manner, and then the hammer motor operates to strike out the selected type toward the platen for printing.

As is clear from the above description, character selection is performed by integrating position signals, so if even one cycle (one pulse) of the position signal is not counted, a character selection error will occur.

Although it is conceivable that a position signal counting error occurs over a plurality of pulses, in reality, a single pulse counting error is most common.

In this case, characters adjacent to the desired characters will be printed.

However, according to the present invention, this can be detected very easily by checking the bright and dark areas of track C using a light emitting and receiving device.

In other words, it is clear from Figure 3 (of course, Figure 2 may also be used) that if the position of track C for a type is a bright area, then the position of track C corresponding to the adjacent type is a dark area; By looking at the bright and dark areas, you can easily tell whether the print is correct or whether it was printed next to it.

That is, since 64 types of type are arranged on each side of the type wheel, the selection of type can be commanded using, for example, 7-bit digital information.

Depending on whether the most significant bit is "1" or "0", either the upper or lower print character is commanded, and the remaining 6 bits command one print character on the circumference.

As is clear from this, in the least significant bit of the character selection command, "1" and "0" alternately appear for each character starting from the character at the home position up to the 64th character.

Therefore, it is possible to make the bright part of track C correspond to the printed character whose least significant bit is "1", and to make the dark part of track C correspond to the printed character whose least significant bit is "0".

Thus, by storing the type selection command and checking the contents of the least significant bit of the type selection command and the brightness of track C after printing, erroneous printing can be easily detected.

For example, the least significant bit of the printing command is "0"("1"), and a bright (dark) part is detected from track C after printing.
This means that a printing error has been made.

Of course, only track C can only check odd and even numbers.
If the next to the next, then the next to the next, etc. are printed, it is determined to be correct.

To prevent this, it is sufficient to increase the number of test tracks, and FIG. 3 shows an example in which a track E is provided, which has bright and dark parts with twice the pitch as track C.

The detection signals from the detection track are velocity, position track A,
The waveform is shaped by the circuit 4 along with the signals from B, etc., and the microprocessor sensor 7 stored in the inlet port 5 captures this at the time after printing, and if an abnormality is detected, it is sent to the output port 6 and via the interface IF. The information is sent to the host computer, etc.

As explained in detail above, according to the present invention, printing errors can be immediately detected by a simple means of providing an error detection drag with coarse brightness and darkness on the slit disk of the type wheel position and speed detector than the position detection track. is possible,
Since numbers, etc. can be arranged closely on the type wheel, the type density can be increased compared to the method of placing kana characters between the numbers, and the type selection time can be shortened and the printing speed can be increased. can do.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a plan view of a perforation disk, and FIGS. 3 and 4 are diagrams for explaining the operation. In the drawing, 1 is a type wheel, 2 is a motor, 3 is a transducer, 11 is a rotating disk, B is a position signal track, and C
1 is a track for detecting incorrect printing, and 12 and 13 are an emitter and a light receiver.

Claims (1)

[Claims] 1. In a serial printer equipped with a type wheel that is transversely fed along a platen and rotated to select type, a slit disk of a transducer attached to the rotating shaft of the type wheel has bright and dark areas arranged alternately. In addition to annular position detection tracks in which each pair of light and dark areas corresponds to each type position, in such a manner that there is a light area in one pair of light and dark areas and a dark area in the next pair of light areas and dark areas, A serial printer characterized in that an annular typographical error detection track is provided in which bright and dark areas with twice the pitch of the bright and dark areas are arranged alternately in correspondence with the bright and dark areas of the position detection track.