JPS6247662A - Density control system - Google Patents

Abstract

PURPOSE:To form an optimum image by controlling the driving current for the laser light of a device which has two groups of driving parts, laser optical system, and developing parts from an external operation part, and controlling the image density on a photosensitive body. CONSTITUTION:A laser driving part 5, a laser optical system 7, and a developing part 8 performs development of colors other than black and a driving part 9, a laser optical system 10, and a developing part 11 performs development of black. A printing control part 2 generates signals 3 and 4 with the printing signal of a CPU 1 and laser light outputs modulated by the driving parts 5 and 9 form a latent image on the photosensitive body 16 by the optical systems 7 and 10. Color density is adjusted by the driving part 5, so the signal of an operation part 6 is inputted to the driving part 5 to vary the driving current of the optical system 7. consequently, the quantity of light of a laser is controlled to control the image density on the photosensitive body, thereby forming an optimum image.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrophotographic two-color printer, and particularly to a method for adjusting density by adjusting the output of a semiconductor laser.

[Conventional technology]

Conventionally, this type of non-innocuous printer has adjusted the density by changing the bias power supply included in the developing section or by increasing or decreasing the amount of toner supplied.

[Problem that the invention seeks to solve]

In the conventional system, so-called "coverage" is likely to occur, and since the output of the high-voltage power supply is changed, the power supply becomes expensive. Furthermore, devices that do not adjust the concentration have problems such as not being able to respond to user preferences and having poor marketability.

The present invention provides a density control method for controlling the density of a printed image by controlling the irradiation energy onto the surface of a photoreceptor.

[Means for solving problems]

The present invention provides an electrophotographic system capable of two-color printing, which includes a printing control section that controls two-color printing, two developing sections, an optical system having two semiconductor lasers, and a drive circuit for these semiconductor lasers. Noninno? This is a density control method in which a drive current is controlled by an external operation unit in a print printer to change the density printed on paper.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, a first developing section 8 develops toner other than black, for example, red, and a second developing section 11 develops black toner. According to the print information π from the host CPU 1, the print control unit 2 generates a signal 3 for printing the first color, and a signal for printing the second color. 4 is generated from the signal line. and,
According to these signals, the semiconductor laser is driven in the loop drive section 5. The laser light output modulated by this drive signal passes through the second laser optical system 7 and forms a first latent image on the photoreceptor surface.

On the other hand, the second printing signal 4 is supplied to the second laser driving section 9, passes through the second laser optical system 10, and passes through the photoreceptor 1.
A second latent image is formed on the 6th surface. Then, a red image, for example, is formed in the first developing section 8, and a red image is formed in the second developing section 11.
For example, a black image is formed. Generally, each user has different preferences regarding color density, so the density adjustment is performed by the first laser driving unit 5. A signal from the operation unit 6 is supplied to the second laser drive unit 5, the output of the semiconductor laser changes, the irradiation energy to the photoreceptor surface changes, and as a result, the density of the image changes. The image formed on the photoreceptor 16 is transferred onto a sheet of paper in the transfer section 12, and then fixed in the fixing section 14, completing image formation. 13 is a paper running section, and 15 is a printing paper.

FIG. 2 shows detailed electrical circuits of the semiconductor laser drive section and the operating section. The variable resistor 21 and the pace resistor 22 of the transistor 24 are connected in parallel to each other, and this value and the bias resistor 23 determine the pace voltage of the transistor 24. , emitter voltage VD is determined. On the other hand, VD2, which defines the bias current of the laser diode 33, is determined by the bias resistor 35, 36 and the operational amplifier 34.

Normally, when there is no drive signal, the transistor 32 is in an off state, and a constant bias current □ flows through the radar diodes vD1-vD2 33.

Here, when the drive signal is input (high level), the transistor 32 turns on, and therefore the transistor 30 also becomes conductive. At this time, the pace voltage of the transistor 3o is determined by the voltage division between the current control resistors 28 and 31, and a constant current is applied to the laser diode 3 through the current control resistor 27.
It will be supplied to 3. 25 is a capacitor, 26
is a current control resistor. Here, the variable resistance 2 of the operation part
As a result, the value of VD changes, resulting in a change in the drive current to the laser diode 33 and a change in the light emission output level. In this way, by fully adjusting the variable resistor 21 of the operating section 6, the amount of light from the laser diode 33 changes, and it
6. Finally, due to the change in energy and the change in image density, it is possible to supply an optimal image.

〔Effect of the invention〕

As explained above, the present invention includes a control unit that performs printing control, and two
In an apparatus having one developing section, an optical system having two semiconductor lasers, and a drive circuit for these semiconductor lasers, the drive current is controlled by an external operation section to control the irradiation energy onto the surface of the photoreceptor. In particular, controlling the density of the printed image has the effect of making it possible to supply an optimal image.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a detailed electrical circuit diagram of a semiconductor laser driving section. 1... host) CPU, 2... print control section, 3...
First print signal, 4... Second print signal, 5... Second laser drive unit, 6... Operation unit, 7... Second laser optical system, 8... First developing unit, 9... Second laser drive unit, 10... Second laser optical system, 11... Second
Developing section, 12... Transfer section, 13... Paper running section, 1
4... Fixing unit, 15... Printing paper, 21... Variable resistor, 22... Bias resistor. 23...Bias resistor, 24...Transistor,
25... Capacitor, 26... Current control resistor,
27... Resistor for current control, 28... Resistor for current control, 29... Trannostar, 30... Transistor, 31... Resistor for current control, 32... Transistor, 33... - Laser diode, 34... operational amplifier, 35... bias resistor, 36... bias resistor. Figure 2

Claims (1)

[Claims] (1) An electrophotographic non-electrophotographic device capable of two-color printing that has a control unit that controls two-color printing, two developing units, an optical system that has two semiconductor lasers, and a drive circuit for these semiconductor lasers. In an impact printer, a density control method is characterized in that the drive current is controlled from an external operation unit to change the density printed on paper.