JPH01293361A - Driving system for laser printer - Google Patents

Abstract

PURPOSE:To easily adjust the length of print by controlling the rotating speed of a stepping motor for driving a photosensitive body by switching the interval of two-phase exciting pulses adjusted with an analog input. CONSTITUTION:A variable resistor 14 inputs the analog input value to the motor adjusting register of a control circuit 9 so as to adjust the rotating speed of the stepping motor 12 for driving the photosensitive body. The excitation phase of the stepping motor 12 is switched by setting the value obtained by adding the analog value to the timer value of a timer which switches the excitation phase as the time of the timer. Consequently, the length of print is finely adjustable and a paper conveyance driving system by a main motor is separated, so variance due to gears is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a driving method for a laser printer, and particularly to control of the rotational speed of a step motor for driving a photoreceptor.

(Prior Art) As shown in FIG. 5, the drive system of a conventional laser printer operates by driving the gears of each unit with the power of one main motor (DC servo motor) 1.

That is, from the main motor drive transmission gear 2 to the paper feed roller drive gear 3, the conveyance roller drive gear 4, the development unit drive gear 5, the photoconductor (OPC) magazine drive gear 6, the hot roller drive gear 7, and the paper discharge unit drive gear 8. transmitted to.

Since the photoconductor and the paper are conveyed by a common drive system, the printing length, or writing length, may vary depending on the individual laser printers due to overall variations in gears, etc. (Problem M to be solved by the invention) In a laser printer, the above-mentioned photoconductor and paper are transported by the main motor of the same drive system, and the rotation of the polygon mirror of the laser optical system is driven separately by a scanner motor. However, these rotational controls are all performed by a control circuit.

In the above configuration, since the main motor and the scanner motor use DC motors, it is necessary to finely adjust the rotational speed of the DC motor in order to adjust the print length. However, DC motors have a large starting torque, have large speed fluctuations depending on the load, and can reach dangerously high speeds under light or no load conditions, making fine adjustment quite difficult.

In particular, the paper conveyance speed by the main motor varies greatly depending on each laser printer due to variations in the drive gear.

The present invention solves these conventional problems by separating the paper conveyance and photoreceptor drive systems, allowing fine adjustment of the photoreceptor drive using analog input, and increasing the print length. The purpose of this is to eliminate variations in performance between laser printers.

(Structure and Operation) In order to achieve the above object, the present invention is provided with a main motor that drives a paper conveyance mechanism, a step motor that drives a photoreceptor, and a scanner motor that drives a polygon mirror. The present invention is characterized in that the rotational speed of the drive step motor is controlled by switching the interval between two-phase excitation pulses adjusted by analog input.

In the present invention, in order to adjust the rotational speed of a step motor for driving a photoreceptor, an analog input value is inputted to a motor adjustment register of a control circuit using a variable resistor.

The value obtained by adding this analog value to the timer value of a timer for switching the excitation phase of the step motor is set as the timer time, thereby switching the excitation phase.

As a result, the print length can be finely adjusted, and since the paper transport drive system using the main motor is separated, variations due to gears are eliminated.

(Embodiment) FIG. 1 shows a block diagram showing the configuration of an apparatus according to an embodiment of the present invention, and 9 is a control circuit (CPU) of a laser printer.
, 10 is a polygon mirror scanner motor (DC motor) for optical writing, and 11 is a main motor for transporting paper (
DC motor), 12 is a step motor for driving the photoreceptor (
(2-phase excitation force type), 13 is a driver for driving this step motor 12, 14 is a slide volume whose resistance change is analog, and is input to the control circuit 9.

The two-phase excitation of the step motor 12 is supplied from the control circuit 9 to the drive driver 13 via excitation control lines A, B, C, and D, and the phase relationship (90
This is done using pulses with a phase delay of 100°.

Next, the operation of this embodiment will be explained using the main routine shown in FIG. 3 and the interrupt routine shown in FIG. 4.

(a) First, the driving power (not shown) of the laser printer is turned on, the resistance value is adjusted with the slide volume 14, and the analog input value is input to the control circuit 9. The analog value is now input to the adjustment register of the step motor 12. (FIG. 3(A)) (B) Next, when a print start command is input, the control circuit 9 starts the paper conveyance main motor 11. In addition, a step motor 12 for driving the photoreceptor
A timer value for starting a timer (located in the control circuit 9) for switching the excitation phase of the controller is set.

Here, the minimum speed of the step motor 12 is set to (a) above.
Add the analog value imported into the register to the timer value, set the timer time, and start.

(FIG. 3(A)) (1) An interrupt shown in FIG. 4 is applied at regular time intervals set in (A) above to switch the excitation phase of the step motor for driving the photoreceptor. As a result, the photoreceptor continues to be driven according to the time adjusted by the slide volume 14 in (a). (Figure 3) In this way, during the print processing process, it is possible to adjust the length of the print by adjusting the slide volume 14 while looking at the print output for each laser printer. be.

(Effects of the Invention) As described above, in the present invention, the photoreceptor and the motor for transporting the paper are separated, thereby making it easier to adjust the length of printing.

The motor for driving the photoreceptor does not use a DC motor whose rotational speed is difficult to fine-tune, but instead uses a step motor, and the excitation phase can be easily switched by adjusting the resistance value of an external slide volume and setting the timer. I decided to do it.

Therefore, even if there are variations in the length of individual prints on a laser printer, it can be adjusted, and even if there is some variation in the drive system (gear), it is possible to eliminate variations in the length of the prints as a whole. can.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an apparatus according to an embodiment of the present invention, Fig. 2 is a two-phase excitation waveform diagram of a step motor for driving a photoreceptor, Fig. 3 is a main routine of the apparatus according to the embodiment, and Fig. 4 is an interrupt routine, and FIG. 5 is a diagram showing a conventional main motor drive system of a laser printer. 9...Control circuit, 10...Scanner motor for optical writing, 11...Main motor for paper conveyance, 12...
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Claims (1)

[Claims] A main motor for driving a paper conveyance mechanism, a step motor for driving a photoreceptor, and a scanner motor for driving a polygon mirror are each independently provided, and the rotational speed of the step motor for driving the photoreceptor is adjusted by analog input. A laser printer drive system characterized by controlling the interval of phase excitation pulses by switching them.