JP2010039493A - Image forming device and scanning light control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a scanning light control technique capable of inhibiting variation of density of an image due to reciprocity law failure in an image forming device equipped with so-called multi-beam scanning optical system capable of a plurality of scanning light beams simultaneously scanning to auxiliary scanning direction. <P>SOLUTION: The image forming device includes: a first scanning light which adjoins to another side in either of a plurality of scanning light beams between a plurality of scanning light beams scanning with a first timing and a plurality of scanning light beams scanning with a second timing next to the first timing in a scanning optical system; a second scanning light which adjoins to one side between one side and an another side; a duplicated discrimination part for discriminating a region, where both the sides are illuminated; and an illumination control part for shortening the emission time per dot for one dot regulated by the illumination data corresponding to either of the first and the second scanning light beams between the first and the second scanning light beams in the range of main scanning direction which is determined that both the sides are illuminated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus including a scanning optical system capable of simultaneously scanning a plurality of different positions in the sub-scanning direction on a photosensitive surface of a photoconductor with a plurality of scanning lights based on light emission data corresponding to an image to be formed. The present invention relates to a scanning light control technique.

  Conventionally, in an image forming apparatus having a so-called multi-beam scanning optical system capable of simultaneously scanning a plurality of scanning lights in the sub-scanning direction, a plurality of scans scanned n + 1 times among a plurality of scan lines scanned n times. Light emission data corresponding to a scan line adjacent to the scan line, and light emission data corresponding to a scan line adjacent to the plurality of scan lines scanned n times among the plurality of scan lines scanned n + 1 times, There may be a situation where light is emitted at the same position in the main scanning direction.

  In such a case, there is a problem that “reciprocity failure”, which is a phenomenon in which the density of the dots corresponding to the corresponding positions of the n-th and n + 1-th scanning lines becomes higher than the normal density, occurs. there were.

  In order to solve the problem of the density change of the image due to the reciprocity failure, only when the dot where the reciprocity failure occurs in the two adjacent scanning lines emits full light, it corresponds to the full light emission dot. A technique for stabilizing the density of an image by modulating the pulse width of emitted light data is known.

  However, since the reciprocity failure does not occur only for dots that emit full light, in the above-described prior art, the density change still remains for dots that do not emit full light despite the fact that reciprocity failure occurs. Could not solve the problem.

  The present invention has been made to solve the above-described problems, and is caused by reciprocity failure in an image forming apparatus having a so-called multi-beam scanning optical system capable of simultaneously scanning a plurality of scanning lights in the sub-scanning direction. An object of the present invention is to provide a scanning light control technique capable of suppressing a change in image density.

  In order to solve the above-described problems, according to one embodiment of the present invention, light emission control is independently performed on a plurality of different positions in the sub-scanning direction on the photosensitive surface of a photoconductor based on light emission data corresponding to an image to be formed. An image forming apparatus including a scanning optical system capable of simultaneously scanning with a plurality of scanning lights, wherein the scanning optical system scans a plurality of scanning lights at a first timing and a timing next to the first timing. The first scanning light adjacent to the other one of the plurality of scanning lights scanned at the second timing and the second scanning light adjacent to one of the other scanning lights are in the main scanning direction. An overlap determination unit that determines a range in which both light is emitted, and a small amount of the first and second scanning lights within a range in the main scanning direction in which both are determined to be emitted by the overlap determination unit. And the light emission time per one dot of the even dot corresponding to one, to an image forming apparatus and a light emission control section for less than the time defined by the emission data.

  Further, according to one embodiment of the present invention, a plurality of scans in which light emission is independently controlled at a plurality of different positions in the sub-scanning direction on the photosensitive surface of the photoconductor based on the light emission data corresponding to the image to be formed. A scanning light control method in an image forming apparatus including a scanning optical system that can simultaneously scan with light, the scanning optical system scanning a plurality of scanning light at a first timing, and the next of the first timing The first scanning light adjacent to the other one of the plurality of scanning lights scanned at the second timing and the second scanning light adjacent to one of the other scanning lights are in the main scanning direction. A range in which both emit light is discriminated and corresponds to at least one of the first and second scanning lights within a range in the main scanning direction in which both are determined to emit light. The light emission time per one dot of Tsu bets relates scanning light control method for less than the time defined by the emission data.

  As described above in detail, according to the present invention, image density caused by reciprocity failure in an image forming apparatus having a so-called multi-beam scanning optical system capable of simultaneously scanning a plurality of scanning lights in the sub-scanning direction. A scanning light control technique capable of suppressing the change can be provided.

1 is a longitudinal sectional view for explaining a schematic configuration of an image forming apparatus including a scanning light control device according to an embodiment of the present invention. FIG. 3 is a schematic configuration diagram showing a configuration of an optical system unit 13 and a positional relationship between the optical system unit 13 and a photosensitive drum 15 in the embodiment of the present invention. FIG. 3 is a diagram showing a configuration of a control block of the image forming apparatus in the embodiment of the present invention. It is a figure for demonstrating the condition where the reciprocity failure does not generate | occur | produce between adjacent scanning lines. It is a figure for demonstrating the condition where a reciprocity failure is generate | occur | produced between adjacent scanning lines. It is the timing chart and conceptual diagram which show the light emission time of each dot in the line scanned adjacently. It is a figure for demonstrating the example which performed the pulse width modulation process with respect to light emission data, and reduced (it shortens the light emission time per 1 dot) in order to avoid generation | occurrence | production of reciprocity failure. FIG. 5 is a diagram showing a case where light emission data of adjacent rows (corresponding to the relationship between the sixth line and the seventh line shown in FIG. 4) across the scans are not emitting one dot full. It is a figure for demonstrating a mode that pulse width modulation is performed by a fixed ratio and it reduces (it shortens the light emission time per 1 dot). When reducing the pulse width of the light emission data, a state in which the light emission timing and the non-light emission timing in the light emission data are not overlapped as much as possible in the main scanning direction in the adjacent line in the reduced state. FIG. It is a figure for demonstrating a mode that the said reduction process was performed before the alignment process. It is a figure for demonstrating the state which a reduction process does not make a meaning and rather deteriorates an image quality. It is a figure which shows an example of the apparatus structure in the scanning light control method by this Embodiment. It is a figure which shows the other example of the apparatus structure in the scanning light control method by this Embodiment. It is a flowchart for demonstrating one aspect | mode of the process flow of the scanning light control method by embodiment of this invention. It is a flowchart for demonstrating the other aspect of the process flow of the scanning light control method by embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a longitudinal sectional view for explaining a schematic configuration of an image forming apparatus (MFP: Multi Function Peripheral) provided with a scanning light control apparatus according to an embodiment of the present invention. The image forming apparatus according to the present embodiment includes, for example, a scanner unit 1, a printer unit 2, a CPU 801, and a memory 802.

  The scanner unit 1 has a function of reading a document image, and includes, for example, a first carriage 3, a second carriage 4, a condenser lens 5, a photoelectric conversion element 6, a document table glass 7, and the like. The first carriage 3 includes a light source 9 and a mirror 10, and the second carriage 4 includes a mirror 11 and a mirror 12.

  The printer unit 2 has a function of forming an image by electrophotography on paper P that is an image forming medium, and includes an optical system unit 13, an image forming unit 14, a photosensitive drum 15, and a charger 16. , Developing unit 17, transfer charger 18, peeling charger 19, cleaner 20, paper feed cassette 21, paper feed roller 22, separation roller 23, registration roller 24, paper transport mechanism 25, fixing device 26, discharge roller 27, paper discharge tray 28.

  The document O from which an image is read by the scanner unit 1 is first placed on the document table glass 7 with the surface to be read facing down, and the document table glass is provided by a document fixing cover 8 that can be freely opened and closed. 7 is pressed down.

  The document O placed on the document table glass 7 is irradiated by the light source 9, and the reflected light from the document O passes through the mirror 10, the mirror 11, the mirror 12, and the condenser lens 5, and the sensor of the photoelectric conversion element 6. The image is formed on the surface.

  The first carriage 3 and the second carriage 4 are synchronized with the reading timing signal by a carriage driving motor (not shown) so that the optical path length until the reflected light from the document O reaches the photoelectric conversion element 6 is always constant. Then, it moves from the right side to the left side in FIG. As a result, the irradiation light from the light source 9 is scanned on the document O.

  In this manner, the image of the document O placed on the document table glass 7 is sequentially read for each line, and is converted into an analog electric signal corresponding to the intensity of the optical signal which is reflected light by the photoelectric conversion element 6. The The analog electric signal converted in the photoelectric conversion element 6 is converted into a digital signal indicating the density of the image by the CPU 801 having an image processing function, and is output to the laser optical system unit 13 in the printer unit 2.

  A plurality of semiconductor laser oscillation units provided in the optical system unit 13 (details will be described later) perform a light emission operation according to a laser modulation signal output from the CPU 801, and generate a plurality of light beams having different irradiation positions in the sub-scanning direction. To do. The plurality of light beams are reflected and deflected by the rotating polygon mirror 35 to become scanning light and are emitted to the outside of the optical system unit 13.

  The plurality of light beams emitted from the optical system unit 13 are imaged as spot light having a necessary resolution at the position of the exposure position X on the photosensitive drum 15 as an image carrier, and the photosensitive drum 15 is exposed to light. The surface is scanned in the main scanning direction (rotational axis direction of the photosensitive drum). Further, when the photosensitive drum 15 rotates, an electrostatic latent image corresponding to the image signal is formed on the photosensitive drum 15.

  Around the photosensitive surface of the photosensitive drum 15, a charger 16, a developing device 17, a transfer charger 18, a peeling charger 19, and a cleaner 20 are arranged along the circumferential direction. The photosensitive drum 15 is rotationally driven at a predetermined outer peripheral speed by a drive motor (not shown), and is charged by a charger 16 provided facing the surface thereof. A plurality of light beams are spot-imaged side by side in the sub-scanning direction (the direction in which the surface of the photosensitive drum moves) at the exposure position X on the photosensitive surface of the charged photosensitive drum 15.

  When the exposure position X on the photosensitive surface of the charged photosensitive drum 15 is irradiated with light, the potential of that portion decreases, and the reduced potential forms an electrostatic latent image. The electrostatic latent image formed on the photosensitive surface in this way is visualized (developed) by the toner supplied by the developing device 17.

  The toner image formed on the photosensitive surface of the photosensitive drum 15 by development is transferred by the transfer charger 18 onto the paper P supplied at a timing from the paper feeding system at the transfer position.

  The paper P stored in the paper feed cassette 21 is separated one by one by the paper feed roller 22 and the separation roller 23. Thereafter, the paper P is sent to the registration roller 24 and supplied to the transfer position at a predetermined timing. On the downstream side of the transfer charger 18, a paper transport mechanism 25, a fixing device 26, and a discharge roller 27 that discharges the image-formed paper P are disposed. As a result, the paper P on which the toner image has been transferred is heated and fixed by the fixing device 26, and is discharged to the external discharge tray 28 via the discharge roller 27.

  After the transfer of the toner image onto the paper P is completed, the toner remaining on the photosensitive surface 15 is removed by the cleaner 20 to return to the initial state, and enters a standby state for the next image forming process.

  By repeating the above process operation, it is possible to continuously perform image forming operations on a plurality of sheets P.

  The CPU 801 has a role of performing various processes in the scanning light control device and the image forming apparatus having the same, and also has a role of realizing various functions by executing programs stored in the MEMORY 802. Yes. The MEMORY 802 can be composed of, for example, RAM (Random Access Memory), ROM (Read Only Memory), DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), VRAM (Video RAM), etc. It has a role of storing various information and programs used in the light control device and the image forming apparatus including the light control device.

  Next, details of the optical system unit 13 will be described.

  FIG. 2 is a schematic configuration diagram showing the configuration of the optical system unit 13 and the positional relationship between the optical system unit 13 and the photosensitive drum 15 in the embodiment of the present invention. The optical system unit 13 includes, for example, a two-channel semiconductor laser oscillator 31 capable of controlling the emission of two light beams individually (so-called multi-beam scanning optical system). With such a configuration, each laser beam whose emission is controlled individually performs an image forming operation for each scanning line at the same time, thereby realizing high-speed image forming processing without increasing the number of rotations of the polygon mirror 35. Yes.

  That is, the laser oscillator 31 controls light emission of each channel independently by the laser driver 32a and the laser driver 32b based on the data for two channels modulated by the pulse width modulation method. The beam light output from the laser oscillator 31 passes through a half mirror 34 after passing through a collimator lens (not shown), and enters a polygon mirror 35 as a rotating polygon mirror.

  The polygon mirror 35 is rotated at a constant speed by a polygon motor 36 driven by a polygon motor driver 37. As a result, the reflected light from the polygon mirror 35 becomes scanning light that scans in a constant direction at an angular velocity determined by the number of revolutions of the polygon motor 36, passes through the fθ lens 60b and the fθ lens 60a, and detects the light beam passage position at a constant velocity. And the light receiving surface of the light beam detection sensor 38 as the beam light amount detecting means and the photosensitive drum 15 are scanned.

  The laser driver 32a has an auto power control (APC) function of each channel, and each channel in the two-channel laser oscillator 31a maintains a light emission power level set by a main control unit (CPU) 801 described later. Is activated.

  The light beam detection sensor 38 detects the passage timing of the two light beams. The beam light detection sensor 38 is disposed in the vicinity of the end of the photosensitive drum 15 so that the light receiving surface is equivalent (same position) as the surface of the photosensitive drum 15. The beam light detection sensor 38 reflects the beam light scanned by the polygon mirror 35 using a folding mirror (not shown), and the light receiving surface is on the extension line of the beam light reflected by the folding mirror (not shown). There is no problem even if it is arranged so as to be equivalent to the surface of 15.

  The laser driver 32a performs light emission timing control (image formation position control in the sub-scanning direction) based on the detection signal from the beam light detection sensor 38. In order to generate signals for performing these controls, a beam light detection device output processing circuit 40 is connected to the beam light detection sensor 38.

  Next, a scanning light control apparatus according to an embodiment of the present invention and a control system in the image forming apparatus including the same will be described.

  FIG. 3 is a diagram showing the configuration of the control block of the image forming apparatus in the embodiment of the present invention. The main control unit (CPU) 801 has a role of controlling the whole. The main control unit 801 includes, for example, a memory 802, a control panel 53, an external communication interface (I / F) 54, a laser driver 32a, a laser driver 32b, a polygon motor driver 37, a beam light detector output processing circuit 40, a synchronization A circuit 55 (timing adjustment circuit) and an image data interface (I / F) 56 are connected.

  An image data interface (I / F) 56 is connected to the synchronization circuit 55, and an image processing unit 57 and a page memory 58 are connected to the image data I / F 56. The scanner unit 1 is connected to the image processing unit 57, and an external interface (I / F) 59 is connected to the page memory 58.

  Next, the data flow during the image forming operation in the present embodiment will be described.

  In the case of the copy operation, as described above, the image of the document O set on the document table glass 7 is read by the scanner unit 1 and sent to the image processing unit 57. The image processing unit 57 performs shading correction processing, various filtering processes, gradation processing, gamma correction processing, and the like on the image signal from the scanner unit 1.

  The image data processed by the image processing unit 57 is sent to the image data I / F 56. The image data I / F 56 serves to distribute the image data to the laser driver 32a and the laser driver 32b.

  The synchronization circuit 55 generates a clock that is synchronized with the timing at which each light beam passes through the light beam detection sensor 38, and in synchronization with this clock, the image data is transmitted from the image data I / F 56 to the laser driver 32a and the laser driver 32b. Output as a laser modulation signal. Further, the synchronizing circuit 55 forcibly causes the laser oscillator 31 to emit light in the image formation region and controls the output power of each light beam, and when each light beam scans on the light beam detection sensor 38. A logic circuit for detecting the position of each beam light in the sub-scanning direction by emitting each beam of the laser oscillator 31 is provided. Here, the synchronization circuit 55 and the CPU 801 correspond to a scanning position correction unit.

  The image data corresponding to each scanning line is transferred while synchronizing with the scanning timing of each light beam scanned in this way, so that the image formation synchronized (in the correct position) in the sub-scanning direction is performed. Is called.

  The control panel 53 is a man-machine interface for starting a copying operation and specifying the number of sheets.

  Of course, the image forming apparatus according to the present embodiment can perform not only a copying operation but also an image forming process based on image data input from the outside via the external I / F 59 connected to the page memory 58. ing. Note that image data input from the external I / F 59 is temporarily stored in the page memory 58 and then sent to the synchronization circuit 55 via the image data I / F 56.

  When the image forming apparatus according to the present embodiment is controlled from the outside via, for example, a network, the external communication I / F 54 serves as the control panel 53.

  The polygon motor driver 37 is a driver that drives the polygon mirror motor 36 for rotating the polygon mirror 35 that scans the four light beams described above. The main control unit 801 can instruct the polygon motor driver 37 to start rotation, stop rotation, and change the number of rotations. The rotation speed is switched when the light beam detection sensor 38 confirms the passage position of the light beam when it is lower than a predetermined rotation speed as necessary.

  As described above, the laser driver 32a and the laser driver 32b emit the beam light based on the image data, and the forced laser oscillator 31 uses a forced light emission signal from the main control unit 801 regardless of the image data. Has a function of controlling the light emission operation. The main control unit 801 sets the power of each light beam emitted from each laser oscillator 31 using the laser driver 32a and the laser driver 32b. The setting of the light emission power is changed according to a change in the latent image forming condition of the photosensitive drum 15 and a detection result of the beam light passing position.

  Specifically, the memory 802 has a role of storing information necessary for control, for example. For example, by storing the circuit characteristics (amplifier offset amount) for detecting the light beam passage position and the order of arrival of the light beams, the optical system unit 13 is made ready for image formation immediately after the power is turned on. Can do.

  Hereinafter, a scanning light control method according to an embodiment of the present invention will be described in detail.

  When the photosensitive surface of the photoconductor 15 is scanned with a plurality of laser beams, for example, when an image is formed using a two-beam laser array, as shown in FIG. As shown in FIG. 5, the density of the second line dots, the density of the sixth line dots formed in the third scan and the density of the seventh line dots formed in the fourth scan are different as shown in FIG. Despite recording with the same light amount (light emission time) on the image surface (on the photosensitive drum), the surface potential of the photosensitive member when the two adjacent dots are scanned simultaneously is −257 V, and the image density is 0. 40, and the surface potential of the photosensitive member is −249 V and the image density is 0.47 when two adjacent dots are scanned by different scanning, and the density increases when an image is formed by different scanning ( Reciprocity ) Is generated.

  FIG. 6 is a timing chart and a conceptual diagram showing the light emission time of each dot in adjacent lines that are simultaneously scanned.

  FIG. 7 shows that the adjacent lines across the scans (the sixth line and the seventh line shown in FIG. 4) have the same density as when the scanning light of two lines is scanned simultaneously (FIG. 6). The emission data of the row to be scanned later (first beam in FIG. 7) is the same as the density under the situation shown in FIG. An example is given in which pulse width modulation processing is performed so as to obtain a density, and the width is reduced (the light emission time per dot is shortened).

  Here, in the scanning light control method according to the present embodiment, the light emission data of adjacent rows (corresponding to the relationship between the sixth line and the seventh line shown in FIG. 4) across the scans are emitted with one dot full. Even if not (see FIG. 8), the light emission data of the row to be scanned later is the density in the case where the non-full emission dots are adjacent on the line to be scanned simultaneously (see FIG. 8). The pulse width modulation is performed at a constant rate so as to obtain the same density as the reference (see FIG. 9), and the width is reduced (the emission time per dot is shortened) (see FIG. 9).

  Specifically, as can be seen from FIGS. 8 and 9, the light emission data of the dot whose pulse width is “64/256” in FIG. 8 is reduced to “61/256” in FIG.

  Further, in the case of reducing the pulse width of the light emission data as shown in FIG. 9, the adjacent line in the reduced state (corresponding to the relationship between the sixth line and the seventh line shown in FIG. 4). In FIG. 10, it is desirable that the light emission time and the non-light emission time in the light emission data are not overlapped as much as possible in the main scanning direction (see FIG. 10). As a result, it is possible to avoid the phenomenon that the non-light-emitting region generated by the reduction becomes conspicuous due to the continuous positioning in the sub-scanning direction.

  In order to adjust the positional relationship between the position of the electrostatic latent image formed on the photosensitive surface of the photosensitive drum 15 and the position of the sheet on which the toner image obtained by visualizing the electrostatic latent image is transferred, for example, a resist Positioning processing in the sub-scanning direction, such as adjustment, is performed. When such alignment is performed, the boundary position between a line scanned at a certain timing and an adjacent line scanned next to the timing is shifted in the sub-scanning direction depending on the content of the alignment. Therefore, even if the above reduction processing is performed before the alignment processing (see FIG. 11), the position that becomes the boundary of scanning may be shifted by the subsequent alignment processing. Rather, the image quality may be deteriorated (see FIG. 12).

  Therefore, in the scanning light control method according to the present embodiment, by adopting the configuration as shown in FIG. 13 or FIG. 14, light emission data (image data) serving as a reference when generating scanning light is reduced as described above. Before being processed, it is temporarily stored in the page memory (FIG. 13) 58 or the line memory (FIG. 14). Then, the stored light emission data is shifted in the sub-scanning direction by an amount that the light emission data is predicted to be shifted in the sub-scanning direction by the alignment process (see FIG. 12). Thus, by performing the above-described reduction processing on the light emission data whose position in the sub-scanning direction is adjusted, it is possible to avoid a situation in which the reduction processing becomes meaningless due to the above-described alignment.

  FIG. 15 is a flowchart for explaining the processing flow of the scanning light control method according to the embodiment of the present invention.

  Based on information obtained from the registration sensor 701 (for example, an optical sensor arranged in the vicinity of the registration roller upstream in the paper conveyance direction), the registration control unit 702 controls the writing position in the main scanning direction and the sub-scanning direction. (Act 101).

  Data subjected to image processing read into the page memory 58 based on the information from the writing position information (n-th line) in the sub-scanning direction is stored for n-1 lines by the sub-scanning writing position control unit (implemented by the CPU 801). Is added to the upper side in the sub-scanning direction (Act 102).

  Based on the image data, the CPU 801 (corresponding to the overlap determination processing unit) scans adjacent light lines in the light emission data scanned at an arbitrary timing and the light emission data scanned next to the timing (for example, shown in FIG. 4). (Corresponding to the relationship between the sixth line and the seventh line), it is determined whether there is data (dots) that emit light at the same position in the main scanning direction (overlap determination process) (Act 103).

  When there is no overlapping data (dot) at the same position in the main scanning direction (Act 103, No), the image data of the two scanning lines compared are transferred to the synchronization circuit and the main scanning control unit (Act 105).

  When there is overlapping data at the same position in the main scanning direction (Act 103, Yes), the CPU 801 (light emission control unit) only scans later or in the sub-scanning direction of the adjacent row to be scanned before and after. The pulse width of the overlapped light emission data is reduced at a certain rate, and the converted image data is transferred to the CPU 801 (synchronization circuit and main scanning control unit), and “registration control unit alignment in sub-scanning direction” and “horizontal” Based on the synchronization signal from the “synchronization sensor”, the writing position in the sub-scanning direction is controlled (scanning position correction processing) and transferred to PWM (light emission control processing).

  As for the emission data, the ratio (predetermined ratio) when shortening the emission time per dot with respect to the original emission data (a reduction process) is the two adjacent scans to be subjected to the reduction process. It is determined by the ratio between the density when the lines are scanned simultaneously and the density when these two scan lines are separately scanned at different timings.

  FIG. 16 is a flowchart for explaining another aspect of the processing flow of the scanning light control method according to the embodiment of the present invention. The process shown in FIG. 16 is a modification of the process shown in FIG. Specifically, the process shown in FIG. 16 differs from the process shown in FIG. 15 only in that a line memory is used instead of the page memory.

  In order to realize the processing shown in FIG. 16, the capacity of the line memory must be secured for at least two scans. This is because a line for at least two scans is used to determine whether there is a position that overlaps in the sub-scanning direction (the same position emits light in the main scanning direction) between the scanning at a certain timing and the next scanning at the timing. This is because memory is required.

  Further, in consideration of the amount of light emission data shifted in the sub-scanning direction for alignment (n−1 rows), the line memory includes a line memory for two scans + a line memory for a shift (n−1 rows). Is required.

  The CPU 801 (sub-scan writing position control unit) adds non-light emission data (blank data) for n-1 rows to the image data (light emission data) read into the line memory for 2 scans + shift (n-1 rows). ) To the upper side in the sub-scanning direction (the side to be scanned first), and based on the image data to which the non-emission data is added, a plurality of scanning light and the first scanning light scanned at the first timing by the scanning optical system A first scanning light adjacent to the other one of the plurality of scanning lights scanned at a second timing next to one timing, and a second scanning light adjacent to one of the other scanning lights; However, it determines the range in which both emit light in the main scanning direction.

  Each operation in the processing in the scanning light control apparatus described above is realized by causing the CPU 801 to execute a scanning light control program stored in the memory 802.

  Furthermore, it is possible to provide a program for causing the above-described operations to be executed in a computer constituting the scanning light control device and the image forming apparatus including the scanning light control program. In the present embodiment, the case where the program for realizing the function for carrying out the invention is recorded in advance in a storage area provided inside the apparatus is exemplified. The program may be downloaded to the apparatus, or a similar program stored in a computer-readable recording medium may be installed in the apparatus. The recording medium may be in any form as long as it can store a program and can be read by a computer. Specifically, as a recording medium, for example, an internal storage device such as a ROM or a RAM, a portable storage medium such as a CD-ROM, a flexible disk, a DVD disk, a magneto-optical disk, or an IC card, a computer Examples include a database holding a program, another computer, its database, and a transmission medium on a line. Further, the function obtained by installing or downloading in advance may be realized in cooperation with an OS (operating system) or the like inside the apparatus.

  Note that a part or all of the program may be an execution module that is dynamically generated.

  In the above-described embodiment, the image forming apparatus configured to scan the photosensitive member using two laser beams is described as an example. However, the image forming apparatus is not necessarily limited to this. Needless to say, a configuration in which eight laser beams are simultaneously scanned is employed.

  Moreover, in the above-described embodiment, as an example, a configuration in which only one reduced emission data is included per dot when the emission processing per dot is subjected to the reduction process is illustrated. However, the present invention is not necessarily limited to this. As a result, if the light emission time based on the light emission data per dot can be reduced, it is possible to avoid the influence of reciprocity failure. Therefore, for example, it is needless to say that a reduction process that distributes the reduced emission data in a state of being divided into a plurality of sections in one dot can be performed.

  Further, in the above-described embodiment, as a countermeasure against reciprocity failure, a reduction process is performed only on light emission data corresponding to a dot belonging to one of two adjacent scanning lines that may cause reciprocity failure. However, the present invention is not necessarily limited to this, and depending on the situation of other scan lines surrounding these two scan lines, the first scan in the main scan direction in which a reciprocity failure may occur. For the range, the first scanning light is reduced, and for the second range in the main scanning direction where reciprocity failure may occur, the second scanning light is reduced. It is also possible to adopt a configuration such as. That is, it is only necessary to realize density adjustment as a result of each dot in two scanning lines in a relationship that may cause reciprocity failure.

  The present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is indicated by the scope of claims, and is not restricted by the text of the specification. Further, all modifications, various improvements, alternatives and modifications belonging to the equivalent scope of the claims are all within the scope of the present invention.

Main controller 801, memory 802, control panel 53, external communication interface (I / F) 54, laser driver 32a, laser driver 32b, polygon motor driver 37, beam light detector output processing circuit 40, synchronization circuit 55, image data Interface (I / F) 56.

Claims (12)

A scanning optical system capable of simultaneously scanning a plurality of different positions in the sub-scanning direction on the photosensitive surface of the photoconductor with a plurality of scanning lights each independently controlled to emit light based on light emission data corresponding to an image to be formed An image forming apparatus comprising:
Adjacent to the other of the plurality of scanning lights scanned at the first timing by the scanning optical system and the plurality of scanning lights scanned at the second timing next to the first timing. An overlap determining unit for determining a range in which the first scanning light and the second scanning light adjacent to one of the other are both emitted in the main scanning direction;
A light emission time per dot of dots corresponding to at least one of the first and second scanning lights within a range in the main scanning direction in which both are determined to be emitted by the overlap determination unit. A light emission control unit for making the time shorter than the time defined by the light emission data;
An image forming apparatus comprising: The image forming apparatus according to claim 1.
The light emission control unit outputs light emission data defining at least one of the first and second scanning lights within a range in the main scanning direction in which it is determined that both are emitted by the overlap determination unit. An image forming apparatus that reduces the pulse width at a predetermined rate. The image forming apparatus according to claim 2.
The light emission control unit has a predetermined ratio of light emission data that defines both the first and second scanning lights within a range in the main scanning direction in which both are determined to be emitted by the overlap determination unit. In the main scanning direction, when the pulse width is reduced, the range in which the emission data defining the first scanning light is reduced, and the range in which the emission data defining the second scanning light is reduced. Is an image forming apparatus that prevents overlapping. The image forming apparatus according to any one of claims 1 to 3,
A scanning position correction unit that corrects a positional deviation of the scanning light with respect to the photosensitive surface by shifting a scanning start position in the light emission data in the sub-scanning direction;
The overlap determination unit emits both the first scanning light and the second scanning light in the main scanning direction based on light emission data in a state where the scanning start position is shifted by the scanning position correction unit. An image forming apparatus for determining a range to be performed. The image forming apparatus according to claim 4.
A storage unit for temporarily storing the light emission data;
The scanning position correction unit corrects a positional deviation of scanning light with respect to the photosensitive surface by adding data to the light emission data stored in the storage unit. The image forming apparatus according to claim 5.
The image forming apparatus, wherein the storage unit is one of a page memory and a line memory. A scanning optical system capable of simultaneously scanning a plurality of different positions in the sub-scanning direction on the photosensitive surface of the photoconductor with a plurality of scanning lights each independently controlled to emit light based on light emission data corresponding to an image to be formed A scanning light control method in an image forming apparatus comprising:
Adjacent to the other of the plurality of scanning lights scanned at the first timing by the scanning optical system and the plurality of scanning lights scanned at the second timing next to the first timing. Determining a range in which the first scanning light and the second scanning light adjacent to one of the other are both emitted in the main scanning direction;
The light emission time per dot of the dot corresponding to at least one of the first and second scanning lights within the range in the main scanning direction in which both are determined to emit light is determined by the light emission data. A method for controlling scanning light that is shorter than a prescribed time. In the scanning light control method according to claim 7,
The pulse width of the light emission data defining at least one of the first and second scanning lights within the range in the main scanning direction determined to emit both is reduced by a predetermined ratio. Scanning light control method. The scanning light control method according to claim 8,
When light emission data defining both the first and second scanning lights within a range in the main scanning direction in which both are determined to emit light is reduced in pulse width by a predetermined ratio, A scanning light control method for preventing a range in which light emission data defining the first scanning light is reduced from a range in which light emission data defining the second scanning light is reduced in the scanning direction. . The scanning light control method according to any one of claims 7 to 9,
By shifting the scanning start position in the light emission data in the sub-scanning direction, the positional deviation of the scanning light with respect to the photosensitive surface is corrected,
A scanning light control method for determining a range in which both the first scanning light and the second scanning light are emitted in the main scanning direction based on light emission data in a state where the scanning start position is shifted. The scanning light control method according to claim 10,
Temporarily storing the emission data;
A scanning light control method for correcting a positional deviation of scanning light with respect to the photosensitive surface by adding data to the stored light emission data. The scanning light control method according to claim 11,
A scanning light control method for storing the light emission data in one of a page memory and a line memory.

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