JPH03287177A - Image forming device - Google Patents

Abstract

PURPOSE:To accurately adjusting an image density without having dispersion by changing the developing bias of an electrophotographic processing part by an image density varying means with an instruction from a host computer. CONSTITUTION:A controller part 1 sends a command to set a value to the D/A 72 inside an engine driver part 2, thereto, according to the command sent from a host machine 56 to the controller part 1 setting the developing bias of the electrophotographic processing part. A CPU 59 inside the engine driver part 2 is set to data the D/A 72 based on the command, and changes the value of a reference voltage VrefB. Thus, the image density varying means 72 changes the reference value of the developing bias with the instruction from the host computer 56, so that the image density of the electrophotogrphic process part is accurately adjusted without having the dispersion.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a laser printer, an LE printer, which is connected to a host computer and forms an image by an electrophotographic process.
The present invention relates to an image forming apparatus such as a D (light emitting diode) printer.

(Prior Art) In conventional image forming apparatuses, a method of adjusting the developing bias voltage of the electrophotographic process is used as a means to change the image density. Image density was adjusted by adjusting the volume.

(Problems to be Solved by the Invention) In the above-mentioned conventional technology, since the volume itself has relatively large variations, the bias voltage also has variations accordingly. Therefore, even if the rotational position of the volume is the same, the bias output voltage differs depending on the image forming apparatus, resulting in a problem that the image density varies.

In addition, 1. If a volume with a negative tolerance is set to cover the desired bias voltage output range in consideration of volume variations, if a volume with a positive tolerance is installed, the bias voltage output range will become larger. There was a problem that fine adjustment of the output voltage became difficult.

An object of the present invention is to provide an image forming apparatus in which image density can be adjusted accurately.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an image forming apparatus that includes an electrophotographic process section and is connected to a host computer. , characterized in that it includes an image density variable means for changing the developing bias of the electrophotographic processing section.

(Function) Since the above means is employed, the image density variable means changes the reference value of the developing bias in response to instructions from the host computer, thereby accurately adjusting the image density of the electrophotographic process section without variation.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 2 is a diagram showing the internal structure of a laser printer according to an embodiment of the present invention. In the figure, the reference numeral 10 indicates the main body of the apparatus. The main body 10 of the apparatus is composed of an earth structure 10a and a lower structure 10b, and the earth structure 10a is connected to the lower structure 10b by a shaft 11 so that it can be opened and closed. installed.

Furthermore, a photoreceptor 12 is provided approximately in the center of the apparatus main body (20). Around this photoreceptor 12, charging means 13, developing means 14, . Transfer means 1
5. It consists of a cleaning means (6), and an electrophotographic processing section excluding the optical writing means is arranged. A paper feed cassette 19 is arranged above this electrophotographic processing section, and an optical writing means 8 is arranged below.

Then, the paper fed by the paper feed roller 20 from the paper feed cassette 19 is conveyed to the upper side of the photoreceptor 12 at a timing determined by a pair of registration rollers 21 . The photoreceptor 12 is driven to rotate counterclockwise as shown by the arrow, and at this time, the surface is uniformly charged by the charging means 13 and is irradiated with laser light from the optical writing means 18 to form an electrostatic latent image. It is formed. This latent image is visualized by toner when passing through the developing means (4). Then, this visible image is transferred by the transfer means 15 to the lower surface of the paper that has been conveyed above the photoreceptor 12. The transferred paper is guided by the conveyance guide 23 and then fixed by the fixing roller 17a of the fixing means 17.
and the pressure roller 17b, and the visible image is fixed thereon. The paper that has left the fixing means 17 is further conveyed to a paper discharge section 25 by a paper discharge roller 24, guided by a paper discharge guide 26, and stacked on a paper discharge tray 27.

By the way, in this embodiment, the optical writing means 18 is arranged below the base cover 29 of the main body 10 of the apparatus. This base cover 29 directly or indirectly supports most of the components mentioned above. Furthermore, base cover 2
9 is made of a heat insulating thermosetting resin or the like, and leg portions 30 and 30 are provided in parallel on both sides. This leg 30.30
The flat plate part 31 that connects the
is provided, and within the bulge 32 is a space 3 that opens downward.
3 is provided.

Further, a long slit-shaped window hole 34 is formed in the bulging portion 32 in the direction of the leg portions 30 and 30, and a part of the space 33 is opened.

Then, in the space 33 of the base cover 29, the optical writing means 1
Eight different components are attached directly to the base cover 29 itself. That is, in the figure, 36 is a scanner motor, 37 is a polygon mirror, 38 is an fθ lens, 39 is a second mirror, and 40 is a cylinder lens attached to the main body of the developing means 14.

Light that flashes in response to an image information signal emitted from a laser unit (not shown) enters a polygon mirror 37 that is integrally attached to the shaft of a scanner motor 36, and is polygonally deflected repeatedly over a certain angular range.

The deflected light is imaged on a straight line by the fθ lens 38 at the optical writing position on the photoreceptor 12, corrected so that the projection point moves at a constant speed, and then the second mirror 39. cylinder lens 4
0 to the photoreceptor 12.

Then, main scanning is performed by deflecting the incident light, and sub-scanning is performed by rotating the photoreceptor 12, thereby writing an image according to the image information signal and forming the electrostatic latent image.

The second engineering drawing is a block diagram showing a schematic configuration of the control system of this embodiment, and the control system includes a controller part 1, an engine driver part 2. Print engine section 3, power supply section 4. It is composed of an operation panel section 5.

The controller part 1 has a host interface (I
/F) 71, host computer (machine) 5
6, and receives print data and print control commands from the host machine 56. In addition, a CPU (central processing unit) 52 is located above the controller 5-6-roller. Memory ROM50. RAM51.110 port 53. Video I
/F54, host I/F71, CPU5
2 is a host I/F 71. The print data sent from the host machine 56 via the I/O boat 53 is converted into video data, stored in the RAM 51, and the video data is sent from the engine driver section 2 via the video I/F 54. The output signal is output to the engine driver section 2 in synchronization with the signal coming from the engine. The ROM 50 stores a program for controlling the controller 1 to the controller part 1 and font data. The video/F 54 is composed of an image signal part including a video data signal and a communication control signal part for communicating between the controller part 1 and the engine driver part 2.

The operation panel unit 5 is connected to the controller unit 0 and sends commands to the controller unit 1 to control the printer.

Engine driver section 2 is CPU59.110 boat 6
0. ROM57. RAM58. It is composed of a D/A (digital/analog converter) 72 which is an image density variable means. The CPU 59 controls the printer engine section 3 during warm-up and during print operation according to the program stored in the ROM 57.

Communicate with controller 0. RAM5g is
Used as working memory. D/A 72 is a reference voltage (2) for controlling the developing bias voltage. 4B is generated based on data from the CPU 59.

The printer engine section 3 includes a writing device 61. Sequence equipment group 62. It is composed of sensors 63.

The writing device 61 includes the optical writing means 18. of FIG. The scuna motor 369 consists of a laser unit (not shown) and a synchronization detection section, and turns on/off a semiconductor laser (LD) in response to a video signal from the engine driver section 2. The sequence equipment group 62 is composed of a driving conveyance section, an electrophotographic processing section shown in FIG. 2, and a fixing means 17. The engine driver section 2 controls the main motor and clutch of the laser printer in the drive conveyance section, and the charging means 13 in the electrophotographic processing section. Transfer means 15. Developing means 14
In the development bias fixing means 17, a heater is controlled on/off in order to keep the temperature of the fixing roller 17a constant.

The power supply section 4 includes an AC plug 64 and a switch (SW) 65.

AC input section consisting of a noise filter 66, a fuse 67, a heater control circuit 69, an engine driver section 2, a constant voltage circuit 68 for generating +5V used in the controller part l, and +24V for driving the motor and clutch.
It is comprised of a high voltage generation circuit 70 that generates high voltage used in the electrophotographic process section.

The sensors 63 detect the presence or absence of paper during paper conveyance.
It consists of a paper feed sensor, manual feed sensor, registration sensor, paper ejection sensor, and an ultrasonic sensor to detect the amount of toner remaining in the developing section.

In the control system having the above configuration, the controller section 1 sends a value to the D/A 72 in the engine driver section 2 in accordance with a command sent from the host machine 56 to the controller section 1 to set the developing bias of the electrophotographic process section. A command to be set is sent to the engine driver section 2. The CPU 59 in the engine driver section 2 sets data to the D/A 72 based on this command, and sets the reference voltage (2).

Change the value of 4B. The power supply section 4 outputs a developing bias voltage according to the value of v0□.

When the power is turned on, a default value stored in advance in the ROM 57 is set in the D/A 72.

When an 8-bit D/A 72 is used, up to 256 levels of adjustment, that is, fine adjustment of the image density according to the resolution of the D/A 72, is possible, and the central value is set as the default value.

(Effects of the Invention) According to the present invention, the developing bias of the electrophotographic processing section can be changed by the image density variable means in accordance with instructions from the host computer, and image formation is performed in which image density is accurately adjusted without variation. equipment can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a control system of an embodiment of an image forming apparatus of the present invention, and FIG. 2 is a configuration diagram showing an internal mechanism of this embodiment. -〇- 10- 12, 13.14.15.16.18... Electrophotographic process department, 56... Host computer, 72...
Image density variable means.

Claims (1)

[Claims] An image forming apparatus including an electrophotographic processing section and connected to a host computer, characterized in that the image forming apparatus includes an image density variable means for changing the developing bias of the electrophotographic processing section according to instructions from the host computer. Forming device.