DE19549450C2 - Light scan timing controller for colour laser printers - Google Patents

Abstract

The controller is used in colour laser printers where the scan controller controls the timing of the laser scanners. A number of light scan sections produce a latent image on a photographic leader which is exposed by laser scans. A timing controller generates timing signals from a single clock line supplied by a master oscillator and distributes the timing signal to end of the laser scanning sections. The controller contains a counter and logic circuitry to distributer a lower rate clock derived from the master oscillator.

Description

The present invention relates to a device for Illustration of multi-colored images in which a light scan cone troller is included. The light scan controller controls the Time setting of the light scanning of a scan laser beam, which is irradiated onto a photoconductor, the more map colored images.

From US 48 87 101 an imaging device according to the preamble of claim 1 known. However, there are no constructive measures revealed that this could contribute to a compact design of the whole Device.

Because computer systems have been performing at an ever higher rate in recent years offer, there is a demand for a color printing function Laser printers. A color laser printer is exemplified as follows described laser printer.

For example, if the color laser printer has a polygon mirror for Every primary color used is original image information divided into image information components for each primary color so that each polygon mirror for the primary colors reflects a laser beam, which modulates on the basis of these divided image information components is used to create a laser beam that acts as a scan laser beam for each primary color serves to irradiate on a photosensitive drum. Then one static latent image on a photosensitive drum is imaged and obtained, developed to image a color image. In in such a case, the setup requires that the image positions each primary color match each other, a highly precise control the revolutions of the polygon mirror motor for each primary color and the Printing characters without any color shift.  

Because with single-color laser printers only a polygon mirror such printers do not require highly accurate Control of the revolutions of the polygon mirror motor. With in other words, in such a single color laser an electrical signal called an FG pulse Use to control the revolutions of the polygon mirror motor det. The FG pulse is generated once each time the Polygon mirror makes one revolution. Also be controlled the revolutions of the polygon mirror motor by the electrical signal with the standard pulse of the crystal oscillator is compared. In principle, the speed controlled by the engine.

In contrast, it is required for color laser printers that the image positions of each primary color other agree. In other words, it's color Laser printers need the image positions of everyone Primary color for each scan operation of the laser beam completely agree with each other. When the time of Laser beam scanning is not set to Paper transcribed and synthesized images in her buttocks sition postponed.

Therefore, in the color laser printer using a Variety of polygon mirrors the variety of polygon mirror are rotated at the same rate of rotation while the Rotation phase of which is finely adjusted so that the Posi tion of the image for each primary color is not shifted.

It is also in the related art of the present Invention an image recording device known in the Japanese published unexamined patent application JP 60-48052 (A) describes which device a Variety of image recording parts, a paper feed part with an optional feed channel and a main body controller with a single standard signal generator  part includes; the plurality of image recording parts and the paper feed part of revolution drive sources which corresponding parts are own, have, and a group the rotation drive sources is designed such that the rotation drive sources together with the standard Signal generator part controlled in feedback mode be, making the output of each revolution accurate and with low cost is controlled.

A laser printer as published in Japanese described unexamined patent application JP 62-242909 (A) ben, can be a clear color image with a well balanced Output hue by using a common oscillation source a standard frequency signal is provided which the phase-controlled control loop (PLL) IC chip is supplied.

The Japanese published unexamined patent application JP 62-251714 (A) also describes a laser printer, which allows the phases of each surface the large number of polygon mirrors match each other, while allowing the transmission time setting lungs of the beam detection signal coincide with each other men, whereby a high-quality color image without Farbver shift is mapped.

The japani describes another known device Published unexamined patent application JP 62-287270 (A) a digital color copying machine in which a Si Signal generation time setting for writing images is generated so that the time setting by a Varia tion of the rotational speed of a photoconductor and least affected by a transcription belt is going to get blue, red, yellow and black color images right superimpose.

The japani describes another known device Published unexamined patent application JP 63-73276 (A)  a laser printer in which a variety from recording heads a laser beam on each photo irradiate the conductor to create an image and one high quality color printing without any color shift to be provided by shifting the position of Pressure points when transcribing on the same Transcription paper is eliminated.

Furthermore, the Japanese published unge examined patent application JP 3-271711 (A) as a known device device a surface phase synchronizing circuit Polygon mirror, which the synchronization of scan lines in a variety of exposure devices.

It is a patent published in Japanese Application JP 59-40620 (A) described scanning method be knows, which enables the phases between a Rotate a large number of scan lines through the optical system the polygon mirror match each other, and at which the scope of arrangement of optical systems can be set sufficiently wide and independently.

In addition, the Japanese published un examined patent application JP 4-195071 (A) as known prior direction an imaging device, which an image without can represent any color shift, even if a more fold transcription for each of a variety of colors is performed, creating a high quality color image without every color shift is provided.

The object of the present invention is to create a picture device for multicolor images of the previously defined type create, which is carried out in a particularly compact design can be.

This object is solved by the features of claim 1.  

An advantageous embodiment of the imaging device according to claim 1 provides sub-claim 2.

The present invention will be described with reference to the enclosed drawings described in detail in which:

Fig. 1 is a view showing the light a basic structure of an embodiment according to the present invention is shown;

Fig. 2 is a view illustrating a basic structure of a color laser printer to which the present invention is applied;

Fig. 3 is a view illustrating a structure of the color laser printer in Fig. 2 in a plan view; and

Fig. 4 is a block diagram showing a structure of a clock controller according to the present invention.

In the present invention, a photoconductor of be of any type as long as he has a latent image can image a received scan laser beam, and a Color image can produce. The latent image is usually uses a static latent image. The photoconductor can from a single photoconductor or a variety of Be formed photoconductors.

If a multicolored image is displayed, it is A large number of photoconductors are provided in a number the number of used to represent the multicolored image corresponding primary colors. Accordingly, the Ab Formation of the multicolor image as a photoconductor preferably three types of photoconductors are used, which are the primary colors Blue, red and yellow correspond, or four types of photo conductors that correspond to the above three primary colors plus black speak. The photoconductors used are surface-coated layers and can have any configuration, like drum-like and belt-like configurations.  

Light scans radiate the scan laser beam onto the Photoconductor. The number of provided in the laser printer Light scan parts correspond to the number of types of images, that are synthesized. Images to be synthesized can have the same color or can be different Have colors. If images to be synthesized differ the colors are usually in a number provided that the number of primary colors corresponds to the representation of multicolored images. Accordingly, the light scans comprise four components, each correspond to the photoconductors. As a light scanning laser beam, the is irradiated onto the photoconductor is usually a laser beam generated by a semiconductor laser ver applies. However, the laser beam is not specific to one limited type.

In the present invention, a clock controller is obtained a single clock signal from a master clock oscillator. The Clock controller can be designed such that it has a Master clock oscillator for outputting the single clock signal contains. Otherwise, the clock controller can be so forms that the controller the single clock from the outside Master clock oscillator receives. Each type of oscillator can be used as Master clock oscillator can be used. Preferably a Crystal oscillator used because of its accuracy.

The clock controller generates a time signal using of the single clock signal. This preferably includes time signal a master clock signal, which by the single clock signal is generated, obtained from the master clock oscillator becomes an original signal by a frequency division of the master clock signal is obtained, and a flan ken- or edge signal to control the phase of the original signal. The clock controller usually includes egg NEN counter and a logic circuit.  

In this way, the phase of the original Si gnals to any position from an edge signal are shifted by the formation of the edge signal.

Each light scanning part preferably contains an optical one Unit comprising a polygon mirror that is ro is tiert, and reflects the scan laser beam. Vorzugswei se each light scanning part is designed such that the on position of the revolutions of the motor controlling the time adjustment of the scan laser beam enables a Shift the position of each light scanning part formed image is set. Such a structure of the light scan components enables the adjustment of the shift Exercise the position of that imaged by each light scanning part Image. A motor can be used as the motor, the one Can output hole signal for rotation control.

Each light scanning part preferably comprises an optical one  Sensor for detecting the reflected from the polygon mirror Scanning laser beam. The Si detected by the optical sensor gnal is preferably used as a write signal on each Photoconductor is formed, and as a signal to control the Time setting of the scan laser beam used.

The optical sensor is conventionally known, and will be commonly used in laser printers. By use tion of this optical sensor as a signal for controlling the The time setting of the scan laser beam is no longer necessary speed of a special device for controlling the time adjustment of the scan laser beam.  

In the present invention, the light scan includes parts components, the number of components of the Number of primary colors corresponds. Preferably, the Photoconductor components, the number of components corresponds to the number of light scanning parts.

According to the present invention, the time setting is generated using the single master clock signal obtained from the master clock oscillator to control the time setting of the scanning laser beam in each light scanning part based on the time signal. Accordingly, the standard for the position of the image imaged by each light scanning part 14 is brought into agreement with the result that the image position can be adjusted in accordance with each light scanning part, thereby enabling the image position to be highly accurately matched.

The light scan controller is preferably present the invention for practical use in a Vorrich for multi-color images. One of the like device for imaging multi-colored images can in a color copier, color fax machine or color laser printer can be used.

This device for imaging multicolored images preferably contains photoconductors in a number that the Corresponds to the number of light scanning parts, and a development part that is read in correspondence with each photoconductor hen, to develop a latent mapped on it Image. Furthermore, each light scanning part is in this device for imaging multicolored images preferably in this way forms a variety of primary color information data is divided into image information data, which is each primary color correspond, whereby the information thus shared in About be delayed in accordance with the transcription period, a laser beam in accordance with the transcription period is modulated, and the modulated laser beam through the polygon mirror is reflected to act as a scanning laser beam to be spent. In this case, the paper is in front preferably transported along the photoconductors. One of the like construction enables multi-colored imaging Pictures.

It includes the multicolor imaging device Pictures an approximately L-shaped or upside down L-för  mige optical unit, the optical unit a Has frame that has a recessed part is so that the optical units are arranged telescopically are not. This enables the process to be reduced distance from a photo at the time of paper transport is generated to the subsequent photoconductor in which Size to an extent that is smaller than a process module in the optical unit.

When the wave of the polygon mirror is roughly parallel is arranged relative to the direction in which the paper is also transported, the process module in the Size can be reduced to an extent that is smaller than the process distance that is generated when paper from one Photoconductor transported to the subsequent photoconductor becomes.

The present invention is in connection with the attached drawings explained in detail, this however, are not intended to limit the scope of the present invention limit.

Fig. 1 is an explanatory diagram showing a basic structure of an embodiment of the present invention, the view showing an example in which the light scanning controller of the present invention is used in a color laser printer.

Referring to Fig. 1, reference numeral 12 denotes a photosensitive drum (photoconductor) which is formed in a cylindrical configuration and the surface of which is coated with the photoconductive material. A static latent image can be imaged when the laser beam is irradiated onto the cylindrical surface. The photosensitive drum unit comprises N photosensitive drums 12 which have a drum 1 , a drum 2 ,. , ., include a drum N (N is an arbitrary finite number).

In normal color printing, the photosensitive drum unit contains four photosensitive drum components for three primary colors, such as blue, red and yellow, plus black, the drum components being arranged in the order of transcription. However, since it is possible to arrange the photosensitive drum components in any number, in the present invention, the number is denoted by the character N. In the preceding paragraph, N denotes an arbitrary number of colors that can be arranged according to the number N of photosensitive drums 12 .

Each component 1 , 2 , 3 or N of the photosensitive drums 12 provides development parts 13 which comprise development parts with the numbers 1 , 2 , 3 or to N. When printing images in a variety of colors, the paper is transported in the direction indicated by an arrow in Fig. 1.

Reference numeral 14 denotes a light scanning part for irradiating the scanning laser beam 15 on each of the N light sensitive drums 12 . The light scanning part 14 comprises N components, which range from the light scanning part component 1 to the light scanning part component N. The light scanning part controls the timing of the scanning laser beam 15 based on the timing signal received by the clock controller as described below.

Fig. 2 is an explanatory view showing a structure of a color laser printer in which the present invention is used.

Referring to Fig. 2, reference numeral 101 denotes a polygon mirror formed in an octagonal configuration with a mirror on each surface thereof, 102 an optical frame, 103 a GS motor for rotating the polygon mirror, 104 an fθ lens, 105 a laser diode and a collimator lens, 106 and 107 a reflection mirror, 108 a cleaner, and 109 a charger. With reference to FIG. 2, an arrow denotes an irradiation direction of the laser beam. The motor 103 can output a hole signal (FG signal) for revolution control once per revolution.

The imaging part, which includes a pair of light scanning parts 14 and the photosensitive drum 12 , is formed in the same manner as the conventional laser printer. In the color laser printer of the present invention, four sets of imaging parts are provided for three primary colors; Blue, red and yellow, plus black. These four parts of the illustration are arranged in the order of transcription from the right side.

Fig. 3 is an explanatory view illustrating a structure veran the color laser printer in Fig. 2 in a plan view.

With reference to FIG. 3, reference numeral 105 denotes a laser diode, a collimator lens 105b, the lens 111 a Zylin, 112 and 113, reflecting mirror 114 and a photo diode, which is used as an optical sensor. With reference to Fig. 3, an arrow denotes an irradiation direction of the laser beam.

Fig. 4 is a block diagram showing a structure of the clock controller 16 . The clock controller 16 is a controller in which a light scan control signal is output to each light scan part 14 , which serves as a time signal for controlling the timing of the scanning laser beam. As shown in Fig. 4, the clock controller 16 has a master clock oscillator 17th The master clock oscillator 17 contains a crystal oscillator, and outputs a master clock signal that is generated from a single clock signal obtained from this crystal oscillator.

The clock controller 16 receives an original signal and a described edge signal by frequency division and edge detection of the master clock signal output from the master clock oscillator 17 , the frequency division and edge detection circuit 18 three signals, the master clock signal, the original signal and the edge signal, each light scanning part 14 as a light scan - Feeds timing signals.

In addition, the clock controller 16 can be designed such that the clock controller 16 does not contain the master clock oscillator 17 and receives the master clock signal from outside.

The color laser printer is designed as shown in FIGS. 2 and 3. In other words, the optical unit is formed in an inverted L-shaped configuration. Furthermore, a recessed part is formed on the optical frame 102 which houses an optical unit. In addition, since part of the remaining optical unit is telescoped in the recessed part, the process distance which is generated when the paper is transported from the photosensitive drum 12 to the subsequent photosensitive drum 12 can be reduced in size to an extent which is smaller is as a process module 122 of the optical unit.

Furthermore, in this particular embodiment, the  optical unit in an approximately wrong L-shaped cone figuration can be formed, but the optical unit can also formed in an approximately L-shaped configuration his.

According to the present invention, a time signal is generated using a single master clock signal obtained by the master clock oscillator to control the timing of the scanning laser beam in each light scanning part. If the standards for the position of images imaged by each light scanning part 14 are brought into agreement with one another, the image position can be precisely adjusted. Therefore, when the apparatus of the present invention is incorporated in a color laser printer, the rotation of the polygon mirror can be controlled with high precision, thereby realizing clear color printing without printing pattern and color shift.

Claims (2)

1. An image forming apparatus having a plurality of image forming units, comprising:
a clock controller ( 16 ) for generating and outputting a timing signal; and
a plurality of image forming units ( 122 ) each receiving the timing signal from the timing controller ( 16 ) to form a multicolor image based on the timing signal,
each imaging unit ( 122 ) including:
a photoconductor ( 12 );
a light scanning part ( 14 ) for controlling the scanning position of a scanning laser beam ( 15 ) based on the timing signal received by the clock controller ( 16 ) to receive a latent image on the photoconductor ( 12 ) by irradiating the same with the scanning laser beam ( 15 ) to create; and
a developing part ( 13 ) for developing the latent image formed on the photoconductor ( 12 ),
wherein the original multicolor image information is divided into image information components corresponding to each of the primary colors, and the image information components thus divided into each of the light sensing parts ( 14 ) with a delay in accordance with the start of transmission of the latent image of the respective primary color from that of the photoconductors ( 12 ) are input, each of the light scanning parts ( 14 ) modulates a laser beam in accordance with the divided image information components to output a modulated laser beam as a scanning laser beam ( 15 ) by reflecting the modulated laser beam with a polygon mirror ( 101 ), and a paper is conveyed along the photoconductors ( 12 ) in such a way that multicolor images are transferred onto the paper with the photoconductors ( 12 ),
characterized in that the clock controller ( 16 ) generates the timing signal using a single clock signal obtained from a main clock oscillator ( 17 ), each light sensing part ( 14 ) has an optical unit together with a laser beam transmission device ( 106 , 107 ), the optical unit is surrounded by a frame ( 102 ), the frame ( 102 ) is formed in an approximately L-shaped or vice versa L-shaped configuration in its side view, the frame ( 102 ) of each of the optical units is one has the recessed part in its plan view, the recessed part accommodates a part of an adjacent optical unit in plan view, and in that the optical units are arranged tele head-shaped in plan view, so that each of the optical units is in contact with the photoconductor ( 12 ) of a neighboring imaging unit ( 122 ) overlaps, causing the process distance ( 121 ) between adjacent photoconductors rn ( 12 ) is made smaller than the length of each image generating unit (122) in the paper feed direction and because it is reduced by the size of the image forming device. 2. Apparatus according to claim 1, wherein the plurality of image forming units ( 122 ) comprises four image forming units ( 122 ) for cyan or magenta or yellow or black.