JPS5812872B2 - small printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small printer that selectively prints a type ring having characters, symbols, etc. around it.

An object of the present invention is to detect the stop position of a motor and the end of one printing cycle with a single detector without increasing the number of detectors.

Another object of the present invention is to always stabilize the completion time of one printing cycle.

A conventional small printer will be explained with reference to a schematic structural diagram in FIG. 1 and a time chart diagram in FIG. 2.

Reference numeral 1 denotes a printer driving motor, and a series of printing operations is started when the motor starts to be energized.

2 is a motor gear, 3 is a reduction gear that roughly rotates once per printing cycle, 4, 5, 6, and 11 are transmission gears, and 7 has a tooth part and a notch part of the bottom diameter on a part of the circumference. An intermittent drive gear provided, 8 is an intermittent gear with a part of the gear cut out, 9 is a type wheel disposed on the intermittent gear and has type letters on the circumference from which arbitrary characters can be selected by a type wheel selection mechanism, 10 1 is a coil spring having one end fixed to the intermittent gear 8 and the other end fixed to the frame, and 12 is a printing gear, which has the same rotation ratio as the intermittent drive gear 7.

13 is a crankshaft engaged with the printing gear; 14 is a printing roller that is engaged with the crankshaft 13 and prints while rolling over the type on the type wheel; 15 is printing paper; and 16 is a ribbon.

The state shown in the figure shows the standby state.

The printer drive motor 1 is driven by the print command shown in FIG. 2, and the intermittent drive gear 7 starts rotating in the direction of arrow 17, and the teeth on the intermittent drive gear 7 and the teeth on the intermittent gear 8 start to mesh. 8 rotates while winding up the coil spring 10 in the direction of arrow 18.

When the intermittent gear 8 rotates, the type wheel 9 also begins to rotate and a character is selected by the type wheel selection mechanism.

When the intermittent drive gear 7 continues to rotate and the character selection is completed, the intermittent drive gear 7 and the intermittent gear 8 are disengaged, and the intermittent gear 8 is in a state where the coil spring 10 is wound up because it is the part 19 of the intermittent drive gear 7 where the teeth are not cut. It is locked.

At this time, the printing roller 14 is rotating in synchronization with the intermittent drive gear 7, and when the selection of the type wheel is completed and the intermittent gear 8 is locked, the printing roller rolls over the selected type and prints on the printing paper 15. do.

When the printing is completed, the locking of the intermittent gear 8 is completed due to the notch in the bottom diameter of the intermittent drive gear 7, and the coil spring 10 returns to the standby position.

At the same time, the type wheel also returns to its standby position.

Paper feeding is performed by a paper feeding mechanism after printing is completed.

A magnet 2 is installed on the reduction gear 3 during paper feeding or before and after paper feeding, taking into account the printer's mechanical load and motor inertia.
0 and reed switch 2 installed on the printer frame, etc.
1 generates a stop command as shown in FIG. 2, and with this stop command, the printer drive motor 1 is de-energized and electrically braked to a sudden stop, and the intermittent drive gear 7 is stopped at a predetermined standby position. .

When the printer drive motor 1 stops, paper feeding ends, and the intermittent gear 8 and type wheel 9 return to their standby positions, the next printing command is given.

Printing is performed by repeating the above steps.

The stop command has the following functions as shown in FIG.

A creates a motor drive signal that starts with a print command and ends with a stop command, and in C, the end of one print cycle is at the type wheel 9.
Since is α time from the trailing edge of the dense timing signal R generated at the time of return, or β time from the leading edge of the stop command, using the latter, the β time counter calculates the time after the stop command is generated. The end of one printing cycle is detected by inputting and measuring a clock sufficiently smaller than the β time.

d resets the character counter and synchronizes the timing signal with the type on the type wheel 9, even if the printer stops at any position other than the standby state (for example, if a power outage occurs while the printer is in operation) This enables synchronization (resulting from the occurrence of

b is a motor control circuit, 42 is an ON-OFF control transistor, 43 and 44 are drive transistors connected by Darlington, 48 is a stop transistor that applies electrical braking to the motor 1, and 41 is an input terminal for a motor drive signal, which is a low level When the motor 1 is driven by the drive transistor 43. 44, and is controlled to a constant rotational speed by a mechanical governor or the like during the type wheel selection process.

When 41 is applied with a high level due to a stop command, 42
The ON-OFF control transistor is conductive, and the drive transistors 43 and 44 are cut off because the supply of base current is stopped, cutting off current to the motor 1, and at the same time, the stop transistor 4 is turned off.
8 is brought into conduction to short-circuit the terminals of the motor 1, causing it to suddenly stop.

Such stop signals require parts such as reed switches and permanent magnets, which increases the price, increases the price due to assembly adjustments, and requires installation space, which limits the printer shape and layout.Furthermore, the reed switch is a mechanical contact. It had some drawbacks such as reduced reliability.

The present invention eliminates these drawbacks and allows the timing signal from the type position detector to play the above-mentioned basic role.

FIG. 4 shows a type selection mechanism of a small printer according to the present invention, and the same mechanical parts as in FIG. 1 are designated by the same numbers as in FIG. 1.

Due to the rotation of the intermittent rotation drive gear 7, the intermittent gear 8 rotates in the direction A of the arrow 18 while winding up the coil spring 10.

When the intermittent gear 8 rotates, the type wheel 9 also rotates, and the intermittent gear 8
The detection plate 3 of the type wheel position detector 32 is locked to the shaft 31 of the type wheel position detector 32.
5 also rotates.

A slit portion 36 is installed on the detection plate 35 so as to be synchronized with the character position on the type ring 9, and a light emitting element 33 such as a light emitting diode is installed.
The position of the character on the type wheel 9 is detected by the light receiving element 34 such as a phototransistor, and the type wheel selection pawl 37 is engaged with the type wheel locking pawl 38 by energizing the trigger electromagnet corresponding to the character position. Select 9.

When character selection on the type wheel is completed, the intermittent drive gear 7 and the intermittent gear 8 are disengaged, and the intermittent gear 8 is locked with the coil spring 10 wound up due to the uncut portion 19 of the intermittent drive gear 7. There is.

The last slit 36-13 is wider than the others, so
The timing signal remains at high level.

At this time, the printing roller 14 is rotating in synchronization with the intermittent drive gear 7, and when the selection of the type wheel is completed and the intermittent gear 8 is locked, the printing roller 14 rolls over the selected type to suppress printing.

When printing is completed, the locking of the intermittent gear 8 is completed due to the notch of the bottom circle diameter of the intermittent drive gear 7, and the coil spring 10 moves the intermittent gear 8, the type ring 9, and the detection plate 3 in the direction of arrow 18 B.
5 to the standby position.

Paper feeding is performed by a paper feeding mechanism after printing.

In the time chart diagram in Figure 5 and the circuit diagram in Figure 6, a indicates the detection of synchronization between the type on the type wheel and the timing signal, b indicates the creation of a stop command and motor drive signal, and C indicates the duration of one print cycle. This shows how to detect the end.

In a, the 13th timing signal is the reference timing signal, and since the pulse width is larger than the normal timing signals up to the 12th and the width is longer than σ time, a counter is provided to detect σ time, and the pulse width is set to σ Detects that there is more time.

Since the character counter is reset from the σ time counter output Cout-1 to the print command, synchronization with the timing signal can be obtained.

The stop command for b is γ from the 13th leading edge of the timing signal.
Since it corresponds to time, the time after the 13th timing signal is detected by the γ time counter and the stop finger + (Cou
t-2) is obtained, and a motor drive signal (6) is obtained from the print command to the stop command.

The stop command can be determined by a 14th or 15th timing signal, and can also be taken out from the output of a character counter.

One print cycle in C ends after β time has elapsed since the stop command, so the time after the stop command is generated is measured with the β time counter, and the time from the print command to the output of the β time counter is considered as one print cycle. do.

As mentioned above, the reference signal is set continuously with the timing signal, and one detector (type position detector) is used to determine the motor stop position and the end of one print cycle based on this reference signal. Detection becomes possible, and moreover, one printing cycle time can always be stabilized.

[Brief explanation of the drawing]

FIG. 1 is a structural diagram of a conventional printer, in which 1 is a drive motor, 9 is a type wheel, 20 is a permanent magnet, and 21 is a reed switch. Figure 2 is a time chart diagram of a conventional printer, and Figure 3 is a circuit diagram in which a is a motor drive signal, b is a motor control circuit, and C is a circuit diagram.
1 shows an example of a circuit for detecting one printing cycle, and d shows an example of a circuit for obtaining synchronization between printed characters and a timing signal. FIG. 4 shows an embodiment of the printer according to the present invention, in which 32 is a character position detector, 35 is a detection plate, and 36-13 is a wide slit. FIG. 5 is a time chart diagram of the printer according to the present invention, and FIG. 6 is a circuit diagram, where a detects a reference timing signal,
3 shows an example of a circuit for synchronizing printed characters and a timing signal, b shows a motor drive signal, and C shows an example of a circuit for detecting one print cycle.

Claims (1)

[Scope of Claims] 1. A selection step in which a type wheel supported on a type wheel shaft rotates as the motor rotates, and the type to be printed is selected from among the type placed around the type wheel; In a printer in which one printing cycle is completed by completing a printing process for printing the selected type and a return process for returning the type wheel to its original standby state, the first rotation of the type wheel spindle corresponds to the position of the type. a timing signal and a reference signal having a pulse width longer than the pulse width of the timing signal in succession to the timing signal, and generating an irregular signal corresponding to the position of the type at the second rotation of the type wheel shaft; a detector; a first counter that counts from the reference signal to a time at which power to the motor is cut off to detect a position at which power to the motor is cut off; a second counter that detects when the printer returns to the standby state and one printing cycle is completed.