JPS5963B2 - small printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a selection process for selecting a type wheel having printed characters such as letters, symbols, etc. around it, a printing process for printing the selected type, and a return process for aligning and returning the type wheel to a standby position. Regarding small printers that undergo

A conventional small printer will be explained with reference to a schematic structural diagram in FIG. 1 and a time chart 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 rotates approximately once per printing cycle, 4, 5, 6, and 11 are transmission gears, and 7 is provided with a tooth portion and a notch portion of the diameter of the tooth bottom in a part of the circumference. intermittent gear, 9
10 is a coil spring having one end fixed to the intermittent gear 8 and the other end fixed to the frame; 10 is a coil spring having one end fixed to the intermittent gear 8 and the other end to the frame; is a printing gear and 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 9; 15 is printing paper; and 16 is a ribbon.

The state shown in the figure shows the standby state. The printer and drive motor 1 are driven by the printing command shown in FIG. 2, and the intermittent drive gear T starts rotating in the direction of the arrow IT, so that the teeth on the intermittent drive gear T and the teeth on the intermittent gear 8 mesh with each other. The starting intermittent gear 8 is indicated by the arrow 18
It rotates while winding up the coil spring 10 in the direction of. When the intermittent gear 8 rotates, the type wheel 9 also starts rotating and a timing signal (T0 to T12) is generated, leading to a selection process in which a character is selected by the type wheel selection mechanism. Intermittent drive gear T
continues to rotate, and when the character selection is completed, the intermittent drive gear T and the intermittent gear 8 are disengaged, and the intermittent gear 8 becomes the intermittent drive gear T.
Because of the uncut portion 19 of the coil spring 10, the coil spring 10 is locked in a wound state. 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 9 is completed and the intermittent gear 8 is locked, the printing roller 114
is a printing process in which the selected characters are printed on the rolling printing paper 15. 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 9 also returns to its standby position in a return process. At this time, the timing signal is unrelated to the selection, and a return signal R whose cycle is unstable is generated. Paper feeding is performed by a paper feeding mechanism after printing is completed. Considering the mechanical load of the printer, motor inertia, etc., a detector is constructed from a magnet 20 installed on the reduction gear 3 and a reed switch 21 installed on the printer frame, etc., during or before and after paper feeding. A stop command as shown in FIG. 2 is generated, and with this stop command, the printer drive motor 1 is de-energized and electrically controlled to suddenly stop, and the intermittent drive gear 7 is stopped at a predetermined standby position.

When the printer drive motor 1 stops and paper feeding ends, and the intermittent gear 8 and type wheel 9 return to their standby positions, the printer waits for the next printing command. This completes one printing cycle, and printing is performed by repeating this process. The stop command has the following functions as shown in FIG.

In a, a motor drive signal is created that starts with a print command and ends with a stop command, and in c, the end of one printing cycle is α time from the trailing edge of the dense timing signal R generated when the type wheel 9 returns, or a stop command. Since it is β time from the leading edge of , using the latter, the β time counter measures the time since the stop command was issued using a clock that is sufficiently smaller than β time as input, and detects the end of one printing cycle. do. d
This function sets the character counter and synchronizes the timing signal with the type on the type wheel 9, even if the printer is stopped at any position within the standby position (for example, if a power outage occurs while the printer is in operation). synchronization). b is the motor control circuit, 4
2 is an 0N-0FF control transistor, 48 is a stop transistor that applies electrical control to the motor 1, 41 is an input terminal for a motor drive signal, and when the level is low, the motor 1 is driven by the conduction of the 1 drive transistors 43 and 44; During the selection process, the printing type is controlled at a constant rotation speed by a mechanical governor or the like. When a high level is applied to the input terminal 41 in response to a stop command, the 0N-0FF control transistor 42 becomes conductive, and the drive transistors 43, 44 stop supplying base current and are cut off, cutting off the power to the motor 1. At the same time, the stop transistor 48 is made conductive to short-circuit the terminals of the motor 1, causing it to stop abruptly. Such stop signals require parts such as reed switches and permanent magnets, which increases the price, increases the price due to assembly adjustments, increases the price due to assembly adjustments, and requires installation space, which limits the printer shape and layout.
Additionally, reed switches have several drawbacks, such as reduced reliability due to mechanical contacts. Another drawback is that the printing speed per printing cycle is reduced. That is, when used in an electronic desktop calculator or the like, the clock of the β time counter is made of an astable multivibrator, so there are variations due to variations in elements, temperature characteristics, etc. Therefore, the number of stages of the β time counter is determined so that β time can be obtained even if the clock cycle is the minimum, and therefore, a normal clock requires a waiting time longer than β time. This results in the printer's original printing speed being less than that in the normal case and the same in the maximum case. The object of the present invention is to use a shutter means to shut off the signal emitted from the slit corresponding to the position of the type on the detection plate during the return stroke of the type wheel, thereby easily preventing unnecessary signals from being generated when the type wheel returns. The objective is to obtain a highly reliable detection mechanism. Next, examples of the present invention will be described. 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 drive gear 7, the intermittent gear 8 meshes with the arrow 1
It rotates while winding up the coil spring 10 in the direction A of 8. When the intermittent gear 8 rotates, the type wheel 9 also rotates in the same direction due to the spring 39 (Figure b) inserted into the type wheel 9, and the detection plate of the type position detector, which is locked to the shaft 31 of the intermittent gear 8, 35 also rotates. The type position detector is composed of a light emitting element 33 such as a light emitting diode, a light receiving element 34 such as a phototransistor, a detection plate 35, and shutter means 50. Type wheel 9
A detection plate 35 (
The synchronizing member) has a slit 36 corresponding to the position of the type,
It has a wide slit 36-s that is installed near the standby position and has no relation to the position of the type. Slit 3 of detection plate 35
6 detects the character position on the type wheel 9 using a light emitting element 33 such as a light emitting diode and a light receiving element 34 such as a phototransistor, and connects the type wheel selection claw 37 to the type wheel by energizing the trigger electromagnet corresponding to the character position. The type ring 9 is selected by engaging the stop pawl 38. When character selection on the type wheel 9 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 by the uncut portion 19 of the intermittent 1 drive gear 7. are doing. At this time, the printing roller 14 is rotating in synchronization with the intermittent 1 drive gear 7, and when the selection of the type wheel 9 is completed and the intermittent gear 8 is locked, the printing roller 14 rolls over the selected type and presses the recording paper 15. and print. When printing is completed, a wide slit 36-, which is unrelated to the slit 36 corresponding to the character position, is installed near the standby position of the detection plate 35 of the character position detector.
The protrusion 36-1 provided at s engages with the protrusion 53-a of the shutter means 50 having the shutter 51, and
Since the frame and the shutter means 50 having the shutter portion 51 are engaged by the spring member 54, the stopper 52 provided on the shutter means 50 is rotated in the frame (not shown) by the action of the spring member 54. The optical axis of the light-emitting element 33 such as a light-emitting diode and the light-receiving element 34 such as a phototransistor is blocked by firmly hitting the Due to the notch, the coil spring 10 causes the lock to be opened by arrow 18 B.
The type ring 9, the intermittent gear 8, and the detection plate 35 are returned to the standby position in the direction, and a wide slit 36-s unrelated to the slit 36 corresponding to the type position installed near the standby position of the detection plate 35 is inserted. The projection 36-1 (FIG. c) provided on the shutter means 50 has a shutter portion 51.
3-b (invisible part in the drawing), and B of arrow 55
Since the frame and the shutter means 50 having the shutter portion 51 are engaged with each other by a spring member 54 having two stability, the action of the spring member 54 causes the stop collar 52 provided on the shutter means 50 to rotate. The light-emitting device 33 and the light-receiving device 34 release the light-emitting element 33 and the light-receiving element 34 from blocking the optical axis, and the frame is returned to the standby position. Paper feeding is performed by a paper feeding mechanism after printing. B of arrow 18 on axis 31
When the rotation in the direction causes power to be transmitted to the type ring spring 39 of the type ring 9 and returns to the standby position, the protrusion 56 on the shaft 31
The stopper 57 fixed to the frame or the like may collide and bounce. Due to this bounce phenomenon, the reference signal S disappears, and the print signal T is generated. In order to prevent this from occurring, the print signal T is sent from the standby position. The width of the slit 36-s is set large to prevent noise generation. The present invention eliminates the need for a conventional detector consisting of a reed switch and a permanent magnet, and uses a timing signal that also serves as a stop command. An embodiment of the present invention is shown in the time chart shown in Fig. 5 and the circuit diagram shown in Fig. 6. show.

In FIG. 6, a shows the creation of a stop command and the detection of the end of one print cycle, and b shows an embodiment of synchronizing the timing signal with the type on the type wheel. The timing signal is a print signal T from the slit 36 corresponding to the print character.
. -Tl2, and a standby signal (reference signal) S corresponding to the slit 36-s generated during the return stroke (after the selection stroke). In this embodiment, in which the type wheel 9 reciprocates, the return signal R generated during the return stroke is canceled by the shutter section 51 of the shutter means 50 used as a type position detector. Shutter means 50 rotatable in directions A and B of arrow 55
In the standby state and in the selection process, the shutter section 51 provided at the shutter section 51 moves away from the optical axis of the light emitting element 33 and the light receiving element 34, and receives the print signal T. -Tl2, the projection 36-1 is aligned with the optical axis while the return signal R is being generated, and is again deviated from the optical axis when the type wheel 9 returns to alignment, where the slit 36-s corresponding to the reference signal S arrives. comes into contact with the protrusion 53-a or 53-b, obtains movement in the directions A and B of the arrow 55, and generates the reference signal S. FIG. 6a shows that the valley width from Tl2 to S of the timing signal is larger than the normal valley width σ and has more than γ time.
When it is detected that the time has elapsed, the power supply to the drive motor is cut off due to the generation of the reference signal S, and an electric grapple is applied to bring the motor to a sudden stop. One print cycle ends with the motor remaining stopped. When the next printing cycle continues, as shown by the two-dot chain line, the next printing command is applied at the same time as the reference signal S is generated, and the motor also rotates continuously. b is to synchronize the print and print signals using the output COut of the γ time counter, so even if the printer is stopped at an arbitrary position,
When the power of a calculator or the like is turned on, the motor is rotated to detect the reference signal S at point a, and synchronization is obtained at point b to perform a normal printing operation.
Since the end of the print cycle is detected without loss time due to control circuits such as clock variations, there is an advantage that the printing speed of the printer is not impaired.

Moreover, in the case of continuous printing, since the motor start-up time is reduced, further improvement in printing speed is expected. In FIG. 7, the recess 31-1 (FIG. 4) in which the type ring spring 39 engages with the shaft 31 is removed, and the rotational force of the shaft 31 is transferred to the type ring 9 through friction with the type ring spring 39. It is intended to be communicated to the public. In this case, it is necessary to rotate the type wheel shaft 31 twice in one printing cycle. This is type ring spring 39
A plate spring is used to reduce the cost, and the coil spring 10 is removed to eliminate the energy loss of winding up the coil spring. Since the type wheel shaft 31 rotates twice, the shutter means 5
1 is necessary to erase the return signal. Briefly explaining the operation below, the intermittent gear 8 rotates twice while the intermittent 1 drive gear 7 rotates once. The shutter means 51 supported by the shaft 56 of the intermittent drive gear 7 is off from the optical axis of the light emitting element 33 and the light receiving element 34 in the standby state (the figure shows the standby state), and the shutter means 51 is supported by the detection plate 35 and the shutter means 51. Due to the engagement between the intermittent 1 drive gear 7 and the intermittent gear 8, the detection plate 35 rotates in the direction of arrow A and the shutter means rotates in the direction of arrow B. A slit 36 provided on the detection plate 35 corresponding to each type position detects each type position, and a type wheel selection claw 37 is activated by energizing a trigger electromagnet (not shown) corresponding to a desired character position. The type ring 9 is selected by engaging with the type ring locking pawl 38. When character selection on the type wheel 9 is completed, the printing roller 14 presses the recording paper 15 to print. During printing, the intermittent drive gear 7 rotates while sliding on the uncut portion (not shown) of the intermittent gear 8. When printing is completed, the shutter means 51 supported by the shaft 56 of the intermittent drive gear 7 is activated by the wide slit 36-s of the detection plate 35 before the light receiving element 34 receives the light from the light emitting element 33. The end 51-a of the light emitting element 33
Then, the signals of the slits 36 corresponding to the respective character positions are blocked. Thereafter, the last slit of the slits 36 corresponding to the type position passes through the optical axis, and the end 51-b of the shutter means 51 is removed from the optical axis of the light emitting element 33 and the light receiving element 34, and the wide slit 36 passes again.
-s, the light receiving element 34 receives the light from the light emitting element 33, thereby generating the reference signal S, and one printing cycle is completed. Repeat the same operation below. As described in detail above, there is a type signal during the selection process obtained from the part corresponding to the type, and a standby signal obtained from the part corresponding to the vicinity of the standby position of the type wheel, and redundant signals are eliminated at the time of resetting. Detection can be mechanically prevented by a combination of shutter means with a simple structure, and there is no need for signal erasure processing, which was conventionally performed using a complicated electric circuit. It can provide a high character position detection mechanism,
The effect is huge.

[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 of a conventional printer. FIG. 3 is a circuit diagram, in which a shows a motor drive signal, b shows a motor control circuit, and c shows a circuit for synchronizing printed characters and timing signals. FIG. 4 shows an embodiment of the printer according to the present invention.
35 is a detection plate, and 36-s is a reference signal slit. FIG. 5 is a time chart of the printer according to the present invention.

Claims (1)

[Claims] 1. In a printer that achieves a type selection process, a printing process, and a return process of aligning and returning the type wheel to a waiting position by rotating the type wheel shaft that supports the type wheel and rotates in the forward and reverse directions or in the same direction. A detection plate having slits respectively corresponding to the position of the type and a wide slit unrelated to the position of the type corresponding to the vicinity of the standby position, facing each other with the detection plate in between, and receiving a type signal and a reference signal through the slit A light-emitting/light-receiving element that emits a timing signal including the above, and in the selection process and the standby position, the light-emitting/light-receiving element is electrically connected through the slit and the wide slit to obtain the printed character signal and the reference signal; A small printer comprising: shutter means that acts to cut off conduction of the light emitting/light receiving element so as to cut off generation of the print signal through the slit in the return process.