JPS58193534A - Scanning system driving method of slit exposure type copying machine - Google Patents

Abstract

PURPOSE:To speed up the reverse driving of a scanning system, by supplying pulses of higher frequency than the command pulse frequency of a scanning stroke during the reverse driving of the scanning system a specific time after the frequency of command pulses supplied to a motor is set to zero, and then supplying pulses of specific frequency a specific time later. CONSTITUTION:A platen 2 is provided on the top surface of a copying machine casing 1 in a free reciprocating state and driven by the DC motor 8 of a semiconductor driving device 7. The CPU 12 of a computer 11 sends out setting pulses of frequency corresponding to a necessary speed to control the motor 8. The setting pulses for the scanning stroke has a frequency Ns and braking pulses after the completion of scanning has a frequency Nb twice as high as the frequency Ns. The motor 8 is powered off when a return sensor 17 operates in the ending of a return stroke, and pulses of frequency Nb are supplied to the motor 8 by a normal stroke signal time t0 later; and pulses Ns for a scanning stroke are supplied further time t1 later. Consequently, the scanning system is reversed speedily without being applied with large impulsive force.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning system driving method for a slit exposure type copying machine that returns the scanning system at a high speed.

For example, in a conventional slit exposure type copying machine with a movable document table, the document table (mirror in the case of a movable mirror type) is driven at a constant scanning speed by a t-conductor drive device.

In order to increase the copying capacity, the return speed of the document table is set to twice the scanning speed (for example, 14/sθC) (for example, 2
The operation of the return sensor detects just before the end of the return stroke (from this, when the command pulse frequency corresponding to the return speed is switched to the command pulse frequency corresponding to the scan speed), both semiconductor drive Although the device was being reversed, the inertia of the document table caused the document table to overrun by more than F〕■, and the movement range of the document table expanded.

In order to reduce this overrun during direction change, there is a semiconductor drive device in which a command pulse frequency corresponding to twice the scanning speed is applied to the semiconductor drive device when switching from the return stroke to the scanning stroke. , Overrun Co., Ltd. has 10 rhymes or less. As a result, the amount of change in the fingertip noculus frequency becomes significantly large, causing a large speed change on the document table, generating shock and vibration, and the speed becoming constant after entering the scanning process. It took a long time to stabilize, and good quality copies could not be obtained.

The present invention relates to an improvement of a scanning system drive method for a slit exposure type copying machine that overcomes the above-mentioned difficulties, and its purpose is to drive the scanning system drive motor in two stages when switching from the return stroke to the scanning stroke. An object of the present invention is to provide a driving method that can immediately and stably drive a scanning system in reverse by performing switching control over the entire range.

Hereinafter, a illustrated embodiment in which the present invention is applied to a seven-step variable magnification slit exposure type copying machine with moving original table (hereinafter simply referred to as a copying machine) will be described.

Reference numeral 1 denotes a copying machine casing, in which a document table 2 is placed on the L side of the case song 1 so as to be able to reciprocate from side to side, and a cover 3 is provided on the document table 2 so as to be openable and closable. A rack 4 is integrally provided in the rack 4, and a pinion 5 that meshes with the rack 4 is connected to a semiconductor drive device 7 via a reduction gear mechanism 6.
The rotating shaft of the DC motor 8 is connected to the rotating shaft of the DC motor 8.

Furthermore, the semiconductor drive device 7 includes a motor drive circuit 9 that controls the rotational speed of the DC motor 8 and a tacho generator 1o that detects the rotational speed of the motor 8 and provides a feedback signal. There is.

Further, a microcomputer 11 that controls the semiconductor drive device 7 includes a CPU 12, a ROM 13, and a RAM.
14, I/015, and preset counter I6, ROM 13 records information necessary for 7-step magnification, and RAM +4 records information such as the number of copies set and the number of copies ejected. Output terminals such as a return sensor I7, a registration sensor 18, and a copy number setting switch (not shown) are connected to the I/O 1015, and an output terminal 15as15b of the I/O 15 is connected to the motor drive circuit 9. Output terminal 15
An on/off control signal is sent to the electric motor 8 from the output terminal P15b, and a forward/reverse rotation control signal is sent to the electric motor 8 from the same output terminal P15b.

The preset counter 16 is controlled by the OPU 12 to send a setting pulse with a frequency corresponding to the required speed to the motor drive circuit 9. The electric motor 8 is controlled by a control signal from the electric motor drive circuit 9 so that the detected speeds detected by the two coincide with each other.

Furthermore, a projecting piece 19 is provided on the document table 2 so as to protrude from the document table 2.
When the return sensor I7 is installed so that it faces the position of the protrusion 19 when the document reaches the end of the return stroke side, the document table 2 is scanned and stabilized in the scanning stroke 21. The same displacement sensor 18 is installed so that the registration sensor 18 faces the position of the protrusion 19 when the scanning speed is reached.

Then, in the preset counter 16, cPU1
In the scanning process 21, the scanning frequency Ns corresponding to the scanning speed v8 adapted to the seven levels of copying magnification is determined by the control signal from 2.
), and on the return stroke side, as shown in FIG. It has become.

Further, in the I/O 15, when the return sensor 17 is activated, a turn-off signal is sent to the motor drive circuit 9 so as not to supply power to the motor 8 for a predetermined period of time.

Further, in the preset counter 16, the predetermined time t
After o has elapsed, a pulse with a braking frequency Nb, which is twice the scanning frequency N8, is transmitted to the motor drive circuit 9 for a predetermined time t1.

The operation of the F example will now be explained with reference to the flowchart in FIG.

When the copying machine is set to a desired copying magnification (not shown) and started, the DC motor 8 is started by the output of the machine 1015, and the DC motor 8 rotates at a speed corresponding to the set copying magnification. .

In this case, in the scanning process 21, the frequency of the pulse emitted from the preset counter 16 is Ns,
The feedback signal from the tacho generator 1o is compared with the set pulse signal, and the pulse width applied to the base of the DC motor drive transistor in the motor drive circuit 9 is adjusted so that both signals become zero. is moved forward at a predetermined scanning speed VB.

When the scanning process 21 is completed, a reversal signal is sent from the motor 1015 to the motor drive circuit 9 by a sensor or the like (not shown).
At the same time, a pulse with a return frequency Nr, which is twice the scanning frequency N8, is sent from the preset counter 16 to the drive circuit 9, and the document table 2 is decelerated to a stop and then accelerated in the return direction, increasing the scanning speed. The return movement is made at a return speed Vr that is twice as high as v8.

Furthermore, at the final stage of the return stroke, when the return sensor 17 is activated due to the approach of the protrusion 18, the I
/ A power cutoff signal is sent from the O15 to the motor drive circuit 9, and the drive circuit 9 cuts off the power supply circuit to the motor 8. This t. After a period of time has elapsed, when a forward rotation signal is sent from the 1/O 15 to the motor drive circuit 9, a pulse with a braking frequency Nb, which is the same as the return frequency Nr, is sent from the preset counter 16 to the drive circuit 9. 2
is decelerated to −k1. After stopping, it is accelerated in the scanning direction. Furthermore, after a period of time t2 has elapsed after the transmission of the forward rotation signal, a pulse with a scanning frequency N8, which is half the braking frequency Nb, is transmitted from the preset counter 16 to the drive circuit 9, and the document table 2 is moved forward at a predetermined scanning speed v8. Ru.

By repeating this process, the required copying is performed repeatedly.

In the embodiment described above, when switching from the return stroke 4) to the scanning stroke 21, the pulse applied to the motor drive circuit 9 is set to the braking frequency Nb, which is twice the scanning frequency Ne, so that the protrusion I9 acts as a return sensor. The distance l (see Fig. 3) from passing through point 17 to reversing can be greatly shortened.

Also, when switching from the return stroke addition to the scanning stroke 21, -1
After the power to the electric motor 8 is cut off, the electric motor 8 is braked and the speed is changed in two steps. Therefore, the impact generated during speed change can be halved, and a stable scanning stroke can be achieved immediately after reversal. 21.

In the embodiment described above, the power to the electric motor 8 is cut off by the operation of the return sensor 17 at the end of the return process 2(), but instead of this, the pulse of the preset counter I6 may be set to zero. .

Furthermore, the present invention can of course be applied to a moving mirror type copying machine instead of a moving document table type copying machine.

In the present invention, the scanning system is driven faster in the return stroke than in the scanning stroke by an electric motor whose speed is changed in proportion to the command pulse frequency and can be rotated in forward and reverse directions, and the return sensor detects the period just before the end of the return stroke. In a method for driving a scanning system of a slit exposure type copying machine in which the scanning system is driven in reverse to the scanning stroke, when the scanning system is driven in reverse by the operation of the return sensor, a predetermined period of time after the power to the motor is cut off or the command pulse frequency is set to zero. After the elapse of time, the command pulse frequency is increased to a frequency higher than the command pulse frequency of the scanning stroke, and after a predetermined period of time has elapsed, the scanning system is driven at the command pulse frequency of the scanning stroke. Even if the inertia of the scanning system is large, the scanning system can be reversed from the return stroke to the scanning stroke within a relatively short time and over a short distance.

Further, in the present invention, since the moving speed is changed in two steps from the return stroke to the scanning stroke, even if the moving speed in both strokes is high, a large impact force is not applied to the scanning system. do not have.

Furthermore, in the present invention, when changing from the return stroke to the scanning stroke, the movement characteristics of the scanning system are increased by increasing the command pulse frequency to an appropriate command pulse frequency higher than the command pulse frequency of the scanning stroke before transitioning to the scanning stroke. can be set to the optimum value.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of a copying machine to which an embodiment of the scanning system driving method for a slit exposure type copying machine according to the present invention is applied;
Fig. 2 is a block diagram thereof, Fig. 3 is an explanatory diagram illustrating the operating state of the copying machine, Fig. 4 is a characteristic diagram of the command pulse frequency of the above embodiment, and Fig. 5 is an illustration of the operation of the above embodiment. The edge that was created is G. ■...Copy machine casing, 2...Document table, 3...Cover, 4...Rack, 5...Binion, 6...Reduction gear mechanism, 7...Semiconductor drive device, 8... DC motor, 9...-Electric motor 4 [dynamic circuit, lO... tacho generator, ll... microcomputer,] 2...OP
U, , 13...ROM, l.1...RAM, +
5...I/O, 16...Preset counter,
17...Return sensor, 18...-Registration lane sensor, 19...Protrusion piece, 20...Return process, 2
1...Scanning process. Agent Patent attorney Nozomi Ehara (1 person) Figure 1 63 Figure 2 Figure 3 -t (+h-

Claims (1)

[Claims] The scanning system is driven at a higher speed in the return stroke than in the scanning stroke by an electric motor that changes speed in proportion to the command pulse frequency and can be reversed by d', and the above-mentioned scanning is performed by the operation of a return sensor that detects just before the end of the return stroke. In a method for driving a scanning system of a slit exposure type copying machine that performs reversal drive to a wandering scan stroke,
When the scanning system is reversely driven by the operation of the return sensor, after a predetermined period of time has elapsed after the power to the motor is cut off or the command pulse frequency is set to zero, the command pulse frequency is increased to a frequency higher than the command pulse frequency of the scanning stroke. 2. A method for driving a scanning system of a slit exposure type copying machine, characterized in that (2) the scanning system is driven at the command pulse frequency of the scanning stroke after a predetermined period of time has elapsed.