JPH0631978A - Image forming device - Google Patents

Abstract

PURPOSE:To shorten a waiting time at a time when a polygon motor is started and speed is changed. CONSTITUTION:Polygon mirrors 24 are rotated by a polygon motor 25, and laser beams are scanned, thus forming an electrostatic latent image to a photosensitive body 40. A CPU compares a first time when the polygon motor 25 reaches the target speed at the time of start or the time of speed variation of the polygon motor 25 and a second time until the laser beams of image data are projected from a laser diode 20, and an image forming sequence is started when the first and second times are equalized or the first time is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention forms an electrostatic latent image on a photoconductor by rotating a polygon mirror with a polygon motor and scanning with a laser beam as in a digital plain paper copying machine, a facsimile, a printer or the like. Image forming apparatus.

[0002]

2. Description of the Related Art In recent years, noise reduction of OA (office automation) equipment is desired, and in a digital plain paper copying machine (PPC) or the like, a polygon mirror is rotated to scan a laser beam in a main scanning direction. Then, a polygon mirror is used to form an electrostatic latent image, but the noise of this polygon motor is offensive to the ears, and therefore it is desired to reduce the noise. For this reason, the user often starts the power supply of the machine every time it is used, or sets the polygon motor to a standby mode in which it stops. In addition, recently, a device capable of writing at a variable density or changing the linear velocity has appeared, and in this case, the rotation speed of the polygon mirror is changed.

In order to shorten the waiting time of the user as much as possible when the polygon motor is started up from the standby mode or when the speed is switched, a large drive current is applied when increasing the speed or a brake for decelerating. By providing the circuit, the time required to reach the target speed is shortened.

Conventionally, in this type of image forming apparatus, when the polygon motor is started up from the standby mode or when the speed is switched, when the polygon motor is rotated at a constant speed as shown in FIG. The polygon motor drive circuit is configured to output a lock (ready) signal to the main sequence section (steps S21 and S22).

For example, in the case of a copying machine, the main sequence section starts an image forming sequence when the copy button is pressed while the lock (ready) signal is input. Therefore, when the feeding is started and the scanner is started to read the original image, the laser beam of the image data is emitted from the laser diode and scanned by the polygon mirror, and the electrostatic latent image is formed on the photoconductor.

[0006]

However, in the conventional image forming apparatus, the sequence can be started by the detection signal at the time when the polygon motor starts to rotate at the set speed, so that the user can make a copy, for example. The machine has a problem that the waiting time before the copy can be started becomes long.

In view of the above conventional problems, it is an object of the present invention to provide an image forming apparatus capable of shortening the waiting time when starting a polygon motor or changing the speed.

[0008]

In order to achieve the above object, the first means is to form an electrostatic latent image on a photoconductor by rotating a polygon mirror by a polygon motor and scanning a laser beam. In the apparatus, a first time until the polygon motor reaches a target speed and a second time until a laser beam of image data is emitted from a laser diode are provided at the time of starting up the polygon motor or at the time of shifting. In comparison, a control means is provided for setting the image forming sequence to be startable when the first and second times are the same or when the first time is short.

In the second means, the control means of the first means is
It is characterized in that the shift characteristic data of the polygon motor is updated every predetermined time, and the first time is calculated based on this shift characteristic data.

A third means is characterized in that the control means in the first means calculates the first time based on a synchronization signal of the laser beam.

A fourth means is characterized in that the control means in the first means determines the second time period in accordance with the sheet feeding position and the copy mode.

A fifth means is characterized in that the control means in the first means outputs an error message when the first time at which the polygon motor reaches the target speed is equal to or longer than a predetermined time.

[0013]

According to the first means, with the above-described structure, the first time until the polygon motor reaches the target speed and the laser beam of the image data is emitted from the laser diode when the polygon motor is started or when the gear is changed. The image forming sequence is set to be startable at the time when the second time is equal to or when the first time becomes short, so that the first time at which the polygon motor reaches the target speed is predicted and image forming is performed. The sequence is set to startable, thus reducing the waiting time when starting up the polygon motor or changing the speed.

In the second means, the gear shift characteristic data of the polygon motor is updated every predetermined time, and the first time is calculated based on this gear shift characteristic data, so that adverse effects due to aging of the apparatus are prevented. be able to.

In the third means, since the first time is calculated on the basis of the synchronizing signal of the laser beam, the rotation speed of the polygon motor can be detected with high accuracy, and therefore the first time can be increased. It can be calculated with precision. Further, since the synchronization signal of the laser beam is detected by an existing sensor in a normal image forming apparatus, it is not necessary to separately provide a sensor or the like, and the configuration can be inexpensive.

In the fourth means, the second time is determined according to the paper feed position of the paper and the copy mode, so that the waiting time can be shortened in each situation.

In the fifth means, since an error message is output when the first time is longer than the predetermined time, the user is notified of the abnormality of the device when the first time becomes long due to a change with time or the like. be able to.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a side view showing the overall configuration of a digital copying machine which is an embodiment of the image forming apparatus according to the present invention, FIG. 2 is a plan view showing the writing section of FIG. 1, and FIG. 3 is the writing of FIGS. FIG. 4 is a block diagram showing a control unit of the digital copying machine of FIG. 1, FIG. 5 is a block diagram showing an overall configuration of an electrical equipment control unit having the control unit of FIG. 4, and FIG. FIG. 7 is a block diagram showing the detailed configuration of the image scanner unit, FIG. 7 is a block diagram showing the detailed configuration of the image process unit of FIG. 6, FIG. 8 is an explanatory diagram showing the operation of the data depth switching circuit of FIG. 7, and FIG. 4 is a block diagram showing a memory system including the page memory of FIG. 4 and the image processing unit of FIG. 7, FIG. 10 is an explanatory diagram showing a flow of image data in the memory system of FIG. 9, and FIG. 12 is an explanatory diagram showing another flow of the image data, FIG. 12 is a block diagram showing another memory system, FIG. 13 is a block diagram showing a detailed configuration of the memory unit of FIG. 12, and FIG. 14 is a block diagram of the memory unit of FIG. Explanatory diagram showing input data, FIG. 15 is a block diagram showing another memory system, FIG. 16 is a block diagram showing a detailed configuration of the external storage device of FIG. 5, and FIG. 17 is a block diagram showing another memory system. 18 is a flow chart for explaining the operation of the present embodiment, FIG. 19 is an explanatory view showing the relationship between the rotation speed of the polygon motor and the rising time in FIG. 18, and FIG. 20 is for explaining the other operation of the present embodiment. It is a flowchart.

First, the overall structure of a digital copying machine to which the image processing apparatus of this embodiment is applied will be described with reference to FIGS. 1 to 17. This digital copying machine has a copying machine main body (I) and an automatic copying machine. The document feeder (ADH) (II), a sorter (III), and a double-sided reversal unit (IV) are four units. The copying machine main body (I) includes a scanner unit, a writing unit, a photoconductor unit, a developing unit, a paper feeding unit, and the like, which will be described in detail below.

The scanner unit includes a reflecting mirror 1, a light source 3 and a first
The first scanner is attached with the mirror 2 and moves in the sub-scanning direction at a constant speed, and the second mirror 4 and the third mirror 5 are attached and moves in the sub-scanning direction at half the speed of the first scanner. It has a second scanner. A document (not shown) on the contact glass 9 is optically scanned by the first scanner and the second scanner, and the reflected light thereof is transmitted through the color filter 6 and the lens 7 to the light receiving surface of the one-dimensional solid-state image sensor 8. Is imaged.

The resolution of this scanner section is as follows.
For example, it is set to 15.4 dots / mm in the main scanning direction and 15.4 lines / mm (400 dots / inch) in the sub scanning direction. This resolution is 2 in the main scanning direction compared to the standard resolution of the facsimile machine (3.85 dots / mm in the main scanning direction, 7.7 lines / mm in the sub scanning direction).
4 times in the sub-scanning direction, and twice in the main scanning direction and the sub-scanning direction for high resolution.

A fluorescent lamp or a halogen lamp is used as the light source 3, but a fluorescent lamp is generally used because of its stable wavelength and long life. Although the reflecting mirror 1 is used for one light source 3 in this embodiment, two or more light sources 3 may be used. Further, since the solid-state image sensor 8 has a predetermined sampling clock, the fluorescent lamp will adversely affect the image unless it is lit at a frequency higher than this clock.

In general, the solid-state image pickup device 8 is C
CD is used. Since the image signal read by the solid-state image sensor 8 is analog, it is A / D converted, and the processing circuit mounted on the image processing board 10 performs binarization, multi-value gradation processing, scaling processing, editing, etc. Various kinds of processing are performed.
The color filter 6 is arranged so that it can be freely inserted and removed from the optical path to obtain a color signal.
Various types of copying such as double-sided copying are performed. Also, 3
There is a case where a color original is read by simultaneously obtaining three color information of RGB using a line CCD or the like.

As will be described later, image information subjected to image processing is written on the photoconductor 40 in the form of a set of light spots by raster scanning of laser light of a writing section as shown in detail in FIGS. . The laser light emitted from the semiconductor laser 20 is shaped into a parallel light flux by the collimator lens, passes through the aperture, and is shaped into a constant light flux, and then is compressed in the sub-scanning direction by the first cylinder lens 22 to be a polygon mirror. It is incident on the reflecting surface of 24.

The polygon mirror 24 is formed in an accurate polygon, and is rotated by a polygon motor 25 in a predetermined direction at a constant speed during writing. The rotation speed is determined by the rotation speed of the photoconductor 40, the writing density, and the number of surfaces of the polygon mirror 24. Polygon mirror 2
The laser light incident on the reflecting surface of 4 is deflected at a constant angular velocity,
Then, with the f-θ lenses 26a, 26b, and 26c,
It is corrected so that the photoconductor 40 is scanned at a constant speed and has a minimum light spot. Incidentally, the f-θ lenses 26a, 26
b and 26c also have a function of correcting a tilt.

The laser light corrected by the f-θ lenses 26a, 26b, and 26c is the synchronous detection mirror 2 outside the image area.
The light is guided to the synchronization detection plate 30 by 9 and is guided to the sensor by an optical fiber although not shown. Then, after a predetermined time has elapsed from the cueing signal in the main scanning direction synchronized with this detection signal, one line of image data is output, and thereafter, by repeating this operation, the electrostatic latent image of a two-dimensional image is exposed. Formed on body 40.

On the peripheral surface of the photoconductor 40, a photoconductor layer for forming an electrostatic latent image is formed. Wavelength is 780nm
Organic photoconductors (OPC), α-Si, Se-Te, and the like are known as the photoconductor layer having sensitivity to the semiconductor laser of the present invention, but in the present embodiment, the organic photoconductor (OPC) is used.
Is used. Here, when writing with the semiconductor laser 20, a negative / positive (N /
P) process and positive / positive (P
There are two known types of / P) process, but in this embodiment, writing is performed by the N / P process.

The charging charger 41 shown in FIG. 1 uses a scorotron system having a grid on the side of the photoconductor 40, and uniformly charges the surface of the photoconductor 40 to (-). When the writing section shown in FIGS. 2 and 3 irradiates the image forming area with a laser beam to reduce the potential of the area, the potential of the original background area on the photoconductor 40 becomes -750 to-.
800V, while the potential of the original image area is -500
Since it is about V, an electrostatic latent image is formed on the surface of the photoconductor 40.

The developing units 42a and 42b are connected to the developing roller.
Bias voltage of 500 to -600V is applied, and (-)
The charged toner is attached to the image area of the photoconductor 40 to visualize the electrostatic latent image. The developing unit of this embodiment includes two main developing devices 42a and 42b.
The toner replenishing device 43a corresponding to a is filled with black toner, the toner replenishing device 43b corresponding to the sub-developing device 42b is filled with color toner, and the main pole position of the developing device of another color is developed during development of one color. Can be selectively developed by changing When developing with a single black color, the auxiliary developing device 4
2b and the toner replenishing device 43b are unnecessary.

Further, by using such a developing method, switching the color filter 6 of the scanner to read the information of each color, and combining the multi-transfer and double-sided copying functions of the paper conveyance system, a multifunctional color can be obtained. Although copying and color editing are possible, this type of copying can also be realized by a method of arranging three or more developing devices or a revolver method of rotating and switching three or more developing devices.

The transfer sheet is conveyed to the position of the transfer charger 44 in synchronism with the photoconductor 40, and is transferred to the developing devices 42a and 42b.
The toner image visualized by the
Is transferred to the transfer paper by charging the back surface of the transfer paper to (+). The transfer paper on which the toner image has been transferred is subjected to AC charge removal by the separation charger 45 and separated from the photoconductor 40. The toner remaining on the photoconductor 40 is removed by the cleaning blade 47 and collected in the tank 48.
In addition, the charge remaining on the photoconductor 40 is removed by the charge removal lamp 49 illuminating the photoconductor 40.

A photo sensor 5 for detecting the reflection density on the photoconductor 40 is provided downstream of the developing units 42a and 42b.
0 is provided, and the photosensor 50 reads the density of a pattern such as black or halftone dots formed by the writing unit and developed and the density other than this pattern, and detects the light and shade of the toner image to detect light. Toner supply signal and toner remaining amount shortage signal are output to.

The paper feeding section is composed of a plurality of cassettes 60a, 60.
b, 60c, and is configured to perform double-sided copying and sheet re-feeding by guiding the sheet once transferred to the transfer position via the sheet re-feeding loop 72. When the copy start button is pressed after one of the cassettes 60a to 60c is selected, one of the corresponding paper feed rollers 61a to 61c is rotated, and the transfer paper is conveyed until the leading end contacts the registration roller 62. . Then, the registration roller 62
Starts rotation so that the toner image on the photoconductor 40 and the transfer sheet are synchronized, and the above-described transfer is performed.

The transfer sheet separated from the photoconductor 40 is sucked and conveyed by the separating and conveying section 63, and the fixing roller 6
The toner images are fixed by 4, 65. Then, this transfer sheet is guided to the sheet discharge port on the sorter (III) side in the case of normal one-sided copying, and the switching claws 67, 68, 6 in the case of multiple copy or a message addition mode as described later.
The copy surface is not changed by 9 and returns to the position of the registration roller 62 through the lower re-feeding loop 72. In the case of double-sided copying, the copy surface is reversed by the copying machine body (I) or the double-sided reversing unit (IV). In the former case, the switching claws 68, 69, 71 guide the tray 70 below the refeeding loop 72, and the rollers 71 are reversed to return to the opposite direction. After being reversed, it is returned to the position of the registration roller 62.

The ADF (II) automatically guides the originals one by one onto the contact glass 9 and automatically ejects the originals after reading them with a scanner. That is, the bundle of originals placed on the original feeding table 100 is aligned in the width direction by the side guides 101, and then separated one by one by the paper feeding roller 104, and taken in by the rotation of the conveyor belt 102. The glass 9 is conveyed to a predetermined reading position and positioned. Then, the originals for which a predetermined number of copies have been completed are rotated by the conveyance belt 102 and the discharge tray 10 is rotated.
3 discharged on top. The document size can be detected from the position of the side guide 101 and the document feed time.

The sorter (III) selectively discharges the transfer paper discharged from the copying machine main body (I) in, for example, page order, page by page, or preset bins 111a to 111x. In this case, the transfer paper is conveyed by a plurality of rollers rotated by the motor 110, and is selectively guided to the bins 111a to 111x by the switching claws arranged near the entrance of each bin.

The double-sided reversing unit (IV) is used for reversing the front and back sides of a plurality of transfer papers for double-sided copying.
In this case, the transfer paper inside the copying machine main body (I) is the discharge roller 6
It is guided downward by 6 and is guided to the double-sided reversing unit (IV) by the next switching claw 68. Then, the discharge roller 1
They are stacked on the tray 123 by 20 and are aligned vertically and horizontally by the feed roller 121 and the side alignment guide 122. The transfer sheets accumulated on the tray 123 are returned to the inside of the copying machine main body (I) by the re-feed roller 124, and are directly guided to the re-feed loop 72 by the switching claw 69. Reference numeral 27 is a mirror, 28 is a dustproof glass, 31 is a lens holding unit, 46 is a separating claw, 80 is a main motor, and 81 is a fan motor.

Next, referring to FIGS. 4 and 5, the control unit of the copying machine main body (I) and the entire circuit configuration will be described. The control unit shown in FIG. 4 is a CP that performs sequence-related control.
U601 and main C that controls operations
It has a PU 602, and the CPUs 601 and 602 are connected by a serial interface (RS232C).
A CPU 601 that performs sequence-related control sets and outputs conditions relating to paper transport timing and image formation. In particular, a paper size sensor, a sensor 603 related to paper transport such as paper discharge detection and resist detection, and a double-sided reversing unit ( IV) and a high voltage power supply unit (not shown), a driver 606 such as a relay, a solenoid and a motor, and a sorter unit (II
I), a laser beam scanner unit 608 for controlling the writing section as shown in FIGS. 2 and 3, an image control circuit 609 and the like are connected. The laser beam scanner unit 608 writes according to the image data from the image control circuit 609.

The sensor 603 is used for the paper feed cassettes 60a-6a.
Detects the size and orientation of the transfer paper attached to 0c. Also, in addition to paper discharge detection and registration, there is a supply of oil end, toner end, etc., and mechanical abnormalities such as door open and fuse blowout. Detect. In addition, the double-sided reversing unit (IV) is equipped with a motor and side fence home position sensor for aligning the paper width, a paper feed clutch, a solenoid for changing the conveyance path, a paper presence detection sensor, and a paper It has a sensor related to the conveyance of.

The high-voltage power supply unit includes a charging charger 41, a transfer charger 44, and a separation charger 4 shown in FIG.
5, P to the bias electrodes of the developing devices 42a and 42b
A predetermined high-voltage power is applied during the duty obtained by the WM control. The driver 606 includes a paper feed clutch, a registration clutch, a counter, a motor, a toner replenishing solenoid, a power relay, a fixing heater, and the like. The sorter unit (III) is connected to the CPU 601 via a serial interface, and
The paper is conveyed at a predetermined timing by the control signal from 1 and is discharged to each bin.

As the analog signal input to the CPU 601, the fixing temperature, the detection signal of the photosensor 50 for density detection, the monitor current of the laser diode 20 and the reference voltage are input. The fixing temperature is the fixing mechanism (rollers 64, 65).
Is detected by the thermistor and the heater is on / off controlled or phase controlled so as to be constant. The detection signal of the photosensor 50 for density detection is detected by reading a pattern formed on the photoconductor 40 with a phototransistor at a predetermined timing, and a toner replenishing clutch is controlled to be turned on and off. The end is detected. The monitor current of the laser diode 20 is controlled so as to match the reference voltage (for example, 3 mW).

Next, the main CPU 602 for controlling the operation will be described.
The U602 controls a plurality of serial ports (SCI), the calendar IC 610, the image processing unit 621, and the like,
In addition to the CPU 601, the serial ports include
An operation unit 611, a scanner control circuit 612,
Application unit 613 and editor unit 614
Etc. are connected. The operation unit 611 includes a touch panel having a key input device for an operator and a display for displaying the status of the copying machine, and notifies the main CPU 602 of key input information by serial communication. Main CPU6
02 uses the key input information to operate the operation unit 611.
It is determined whether the indicator of (1) is on or off, and the display command is notified to the operation unit 611 by serial communication. The operation unit 611 turns on, blinks, or turns off the display according to this display command. The scanner control circuit 612 notifies the main CPU 602 of information regarding drive control of the scanner servo motor, image processing, and image reading by serial communication, and performs interface processing between the ADF (II) and the main CPU 602.

Next, the flow of the image data in FIG. 4 will be described. The image data read under the control of the scanner control circuit 612 is the gate array 6 as it is.
15 and the case of flowing to the gate array 615 after being processed on the page memory 620,
The image data stored in the page memory 620 is subjected to various image processes according to an instruction from the image processing unit 621.

The gate array 615 is the main CPU 60.
Image data from the scanner control circuit 612 (or page memory 620) to the image control circuit 609, from the scanner control circuit 612 (or page memory 620) to the application unit 613, or from the application unit 613 to the image control circuit. It is selectively output to 609. When the image data is output from the scanner control circuit 612 or the page memory 620 to the image control circuit 609, the image data of 8-bit data (4 bits or 1 bit in some cases) from the scanner is synchronized with the laser beam scanner unit 608. It is transmitted in synchronization with the signal PMSYNC.

When output from the scanner control circuit 612 or page memory 620 to the application unit 613, a parallel signal of image data of 8-bit data (4 bits or 1 bit in some cases) from the scanner is output. When the image data is output from the application unit 613 to the image control circuit 609, 8-bit data (4
Image data of 1 bit or 1 bit) is a synchronization signal PMSY from the laser beam scanner unit 608.
It is transmitted in synchronization with NC. When the external data is 1 bit or 4 bits, it is converted to 8 bits and output to the image control circuit 609.

Next, the detailed structure of the image scanner unit will be described with reference to FIGS. An analog image signal output from the CCD image sensor 8 is amplified and light amount corrected by a signal processing circuit 451 in an image preprocessor (IPP) 451, 452, 453,
It is converted into a digital multi-valued signal by the A / D converter 452, is subjected to shading correction by the shading correction circuit 453, and is applied to the image processing unit (IPU) 454 as shown in detail in FIG.

In the IPU 454, as shown in FIG. 7, the image data is first emphasized in the high frequency range by the MTF circuit 501, electrically scaled by the scaling circuit 502, and then gamma-converted by the gamma conversion circuit 503 in accordance with the input characteristics. Is corrected. The image data corrected by the γ conversion circuit 503 includes the switches SW1 and SW2, the circuits 504, 505, and 5.
In accordance with the desired data depth, the data is selectively output at four quantization levels (output data DATA0 to D0).
ATA7).

The 4-bit conversion circuit 504 outputs the 8-bit data as shown in FIG. 8A as the upper 4-bit data as shown in FIG. 8B, and the binarization circuit 505 outputs the 8-bit data as shown in FIG.
By comparing the 8-bit data as shown in FIG. 8A with the threshold value, 1-bit data as shown in FIG. 8C is output. The dither circuit 506 performs area gradation processing with 1-bit data, and the data from the binarization circuit 505 or the dither circuit 506 is output via the switches SW2 and SW1.

Returning to FIG. 6, the scanner control circuit 612 has a lamp control circuit 458 for stabilizing the light quantity of the fluorescent lamp 3 under the control of the main CPU 602, a timing control circuit 459, and an electric scaling circuit 5 in the IPU 454.
02 and the scanner drive motor (M) 465 are controlled. The lamp control circuit 458 turns on and off the fluorescent lamp 3 and controls the light amount under the control of the scanner control circuit 612.
A rotary encoder 466 is connected to the drive shaft of the scanner drive motor 465, and the position sensor 462 detects the reference position of the scanner in the sub-scanning direction. The electric scaling circuit 502 scales the image in the main scanning direction according to the magnification set by the scanner control circuit 612.

The timing control circuit 459 outputs various signals according to instructions from the scanner control circuit 612,
For example, when the scanner starts reading, a transfer signal for transferring data for one line to the shift register and a shift clock pulse for outputting the data in the shift register bit by bit are output to the CCD image sensor 8. In this embodiment, the CCD image sensor 8 outputs 4800 bits of effective data per line. The timing control circuit 459 also outputs a pixel synchronizing clock pulse CLK, a main scanning synchronizing pulse LSYNC, and a main scanning effective period signal LGATE to the image reproducing system.

The pixel synchronizing clock pulse CLK is the CCD
The signal is almost the same as the shift clock pulse applied to the image sensor 8, and the main scanning synchronization pulse LSYNC
Is almost the same signal as the main scanning synchronization signal PMSYNC output from the beam sensor of the image writing unit described above, but is output in synchronization with the pixel synchronization clock pulse CLK. The main scanning effective period signal LGATE is the image data DA.
It becomes high level at the timing when TA0 to DATA7 are regarded as valid data.

Further, the scanner control circuit 612 is a main C
When receiving the reading start instruction from the PU 602, the fluorescent lamp 8 is turned on, the scanner drive motor 465 is started to be driven, and the CCD image sensor 8 is started by driving the timing control circuit 459. In this case, the sub-scanning effective period signal FGATE is set to the high level. Then, the sub-scanning effective period signal FG
The ATE becomes low level when the time for scanning the maximum reading length of the scanner in the sub-scanning direction (for example, the dimension in the A size longitudinal direction) elapses.

FIG. 9 shows a memory system including the IPU 454 shown in detail in FIG. 8 and the page memory (MEM) 620 shown in FIG. The image signal read by the CCD image sensor 8 has the IPP 4 having the functions of shading correction, black level correction and light amount correction as described above.
After being processed by 51 to 453, it is inputted to this memory system as 8-bit data. This data is normally selected by the multiplexer MUX1 and has the spatial frequency high-frequency emphasis (MTF correction), the speed conversion (magnification) function, the γ conversion function, and the data depth conversion function as described above. After being processed by the IPU 454, it is selected by the multiplexer MUX3 and output to the writing unit (printer unit PR).

On the other hand, when performing image processing on the page memory 620, the image data processed by the IPU 454 is selected by the multiplexer MUX2 and stored in the page memory 620 as shown in FIG. It is recognized, processed, and edited by 621, read when necessary, selected by the multiplexer MUX3, and output to the writing unit. In this configuration, when a plurality of copies of one original is made, the original can be read once and stored in the memory system to make a plurality of copies in one read.

Further, in this memory system, the flow of image data as shown in FIG. 11 can be realized by the multiplexers MUX1 to MUX3. That is, for example, in the case of changing and outputting the parameters of a plurality of copies in one scan of the scanner, first, the input terminal A of the multiplexer MUX1, the input terminal B of the multiplexer MUX2, and the input terminal A of the multiplexer MUX3 are selected to make one sheet. The image data is output to the writing unit, and the raw data not processed by the IPU 454 is stored in the page memory 620.

When outputting the second and subsequent sheets,
The input terminal B of the multiplexer MUX1 is selected, the raw data stored in the page memory 620 is read, and the IPU is read.
Processing is performed by the 454, the parameters of the IPU 454 are changed for each copy, and the image data processed by the IPU 454 is output to the writing unit.

Further, when holding compact data such as 1-bit data, the multiplexer MUX2 is used.
The image data processed by the IPU 454 can be stored in the page memory 620. When holding and outputting data from the outside, the input terminal C of the multiplexer MUX2 and the input terminal B of the multiplexer MUX3 are selected, respectively.

In FIG. 12, a compressor (COMP) 701 and an expander (EXP) 702 are provided before and after the memory unit 700 shown in detail in FIG. 13, and a multiplexer MU is provided.
The case where compressed data other than actual data is stored by X4 and MUX5 is shown. Note that in this configuration, the compressor 701 matches the speed of the scanner and the expander 7
02 must operate according to the speed of the printer PR.

In the memory unit 700, as shown in detail in FIG. 13, data width converters 711 and 712 for processing three types of data as shown in FIG. They are provided on the input and output sides of the memory block 710, respectively. And a direct memory access controller (DM
C) 713 and 714 respectively write and read data in a predetermined address of the memory block 710 according to the number of packed data and the data width of the memory block 710.

Here, the speed of image data from a normal scanner and the speed of image data to a printer are
It is constant regardless of 8-bit data, 4-bit data, and 1-bit data, and the period of 1 pixel is fixed in the device. In the example shown in FIGS. 12 to 14, 8
The data width converter 711 defines the most significant bit MSB justification such as 1-bit data, 4-bit data, and 8-bit data from the most significant bit MSB side of the book data line.
The data width of the memory block 710 is respectively packed and unpacked by 712. Therefore, in this memory system, by packing the data, the memory block 710 can be effectively used according to the data depth.

FIG. 15 shows the compressor 701 and the expander 702.
Instead of the pixel process unit (PPU) 72
An example in which 0 is provided outside the memory unit 700 is shown. P
The PU 720 is a logical operation (for example, AND, OR, EXO) between input data and output data of the memory unit 700.
R, NOT) and output to the printer,
This switching is performed by multiplexers MUX6 and MUX7. This function is generally used for image composition, and can be composed, for example, by storing the overlay data in the memory unit 700 in advance and overlaying the overlay data on the data read by the scanner.

FIG. 16 shows an example of storing image data using an external storage device. Image data (illustrated EXT
OUT) is stored in the floppy disk 721, the interface (I / F) 722, the floppy disk controller (FDC) 723, and the floppy disk drive device (FDD) 724 are stored in the floppy disk 721. The disk controller (FDC) 723 is controlled by the file controller 725. The file controller 725 can also store image data in the hard disk by controlling the hard disk controller (HDC) 726 and the hard disk drive device (HDD) 727. It should be noted that format data and overlay data that are frequently used can be stored in the hard disk in advance and can be read out as needed. FIG. 17 shows an example of recovery when the processing speeds of the compressor 701 and the expander 702 are not in time. Compressed data and raw data are input to the memory unit 700 simultaneously with scanning by the scanner.
The compressed data and the raw data are stored in different areas of the memory unit 700, and the compressed data is decompressed by the decompressor 702 and output as it is. By the time all the data of one page is input to the memory unit 700, if the processing of the compressor 701 and the decompressor 702 ends normally in time, only the compressed data remains in the memory unit 700, and the raw data is Erased. On the other hand, when the processing of the compressor 701 or the decompressor 702 is not in time, it is detected by the error detector 731, the compressed data is immediately canceled, and the raw data is adopted. Memory management unit (M
The MU) 730 controls the memory unit 700 so that two input data and one output data are simultaneously input and output. Therefore, in this example, by monitoring the compression and decompression, high speed and certainty of the data can be secured, and the area of the memory unit 700 can be effectively used. In this example, the memory management unit (MMU) 730 dynamically allocates the area of one memory unit 700. However, two memory units 7 for compressed data and raw data are used.
00 may be used. This memory system is suitable for applications such as electronic sorting in which a plurality of stored pages must be compatible with the printing speed when a plurality of page data are stored and output to a printer in real time.

Next, the operation of the image forming apparatus of this embodiment will be described with reference to FIGS. Polygon motor 2
When the 5 starts rotating or the rotation speed is changed, as shown in FIG.
In step S1 shown in FIG. 8, the rotation speed of the polygon motor 25 is calculated in real time on the basis of the synchronization detection signal in the main scanning direction detected via the synchronization detection plate 30 and the internal timer. Based on the rotation speed of _No. 25, the shift characteristic data of the polygon motor 25 as shown in FIG. 19, and the set speed, the time t ₁ until the set speed is reached is calculated (step S3).

Here, the shift characteristic data of the polygon motor 25 may be set in advance as a constant, but instead, it is individually set at the time of shipment in consideration of the variation of each machine, and a predetermined rotation using a synchronization signal is performed. A more accurate time t ₁ can be obtained by automatically updating every number x and by the internal timer T (steps S8 and S9). Further, in consideration of the change of the shifting characteristic of the polygon motor 25 due to the installation place and the change over time, the internal clock (calendar IC shown in FIG. 4), the setting can be variably set at every predetermined time, or the sheet passing counter can be used. An accurate time t ₁ is obtained by counting the number of times a predetermined number of sheets have passed and the number of times the polygon motor 25 has been turned on and off, monitoring the number of revolutions of the polygon motor 25 at each predetermined number of times, and updating this shift characteristic data. be able to.

In step S5, the time t ₂ from the start of the operation of the copying machine to the emission of the image data beam from the laser diode 20 is set to the paper feeding position and various image processing modes such as zooming. It is calculated based on the state. Then, in step S6, the times t ₁ and t ₂ are compared, and t ₁ ≤t ₂
In this case, a series of operations such as paper feeding is started (step S
7). It should be noted that the time t ₂ until the beam is emitted may be configured to be compared with the time t ₁ as the time t ₂ −α by slightly estimating the margin α.

Therefore, according to the above-described embodiment, when the polygon motor 25 starts to rotate or the rotation speed is changed, the time t ₁ required to reach the set speed and the beam of the image data from the laser diode 20 is generated. The time t ₂ until emission is compared, and when t ₁ ≦ t ₂ , the operation such as paper feeding is started, so that the waiting time of the user can be shortened.

FIG. 20 shows the operation when the time t ₁ until the polygon motor 25 reaches the set target speed is delayed for some reason. In step S11, it is determined whether or not the lock signal of the polygon motor 25 is obtained, thereby determining whether or not the polygon motor 25 has reached the set target speed, and the polygon motor 25 has reached the set target speed. If not, since the digital PPC has a memory for image data, the image data is written in this memory (step S13) and waits until the set target speed is reached (steps S13 → S14 → S).
11).

When the polygon motor 25 reaches the set target speed, the laser diode 20 is controlled to emit a beam of image data by reading the image data written in the memory in step S12.

Further, in step S14, the time t ₁ required for the polygon motor 25 to reach the set speed is, for example, 5
If it is longer than the predetermined time such as seconds, the process branches to step S15 and an error message is displayed. Therefore, it is possible to notify the user of the abnormality of the device when the time t ₁ becomes long due to, for example, a change with time.

[0070]

As described above, according to the first aspect of the invention, an image is formed in which an electrostatic latent image is formed on a photoconductor by rotating a polygon mirror using a polygon motor as a drive source and scanning a laser beam. In the apparatus, a first time until the polygon motor reaches a target speed and a second time until a laser beam of image data is emitted from a laser diode are provided at the time of starting up the polygon motor or at the time of shifting. By comparison, the control means for setting the image forming sequence to be startable when the first and second times are equal or when the first time is short is provided, so that the polygon motor reaches the target speed. When the image forming sequence is set to be startable by predicting the first time, and therefore when waiting for starting the polygon motor or changing the speed. It is possible to shorten the.

According to a second aspect of the present invention, the control means according to the first aspect updates the shift characteristic data of the polygon motor at predetermined time intervals, and based on the shift characteristic data, the first shift characteristic data is updated.
Since the time is calculated, it is possible to prevent a bad influence due to a change with time of the apparatus.

According to a third aspect of the present invention, the control means according to the first aspect calculates the first time based on the laser beam synchronizing signal, so that the rotational speed of the polygon motor can be detected with high accuracy. Therefore, the first time can be calculated with high accuracy. Further, since the synchronization signal of the laser beam is detected by an existing sensor in a normal image forming apparatus, it is not necessary to separately provide a sensor or the like, and the configuration can be inexpensive.

According to a fourth aspect of the invention, the control means according to the first aspect determines the second time in accordance with the sheet feeding position and the copy mode, so that the waiting time is shortened in each situation. You can

According to a fifth aspect of the present invention, the control means according to the first aspect outputs an error message when the first time at which the polygon motor reaches the target speed is equal to or longer than a predetermined time. With this, it is possible to notify the user of the abnormality of the device when the first time period becomes long.

[Brief description of drawings]

FIG. 1 is a side view showing an overall configuration of a digital copying machine which is an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a plan view showing a writing unit of FIG.

FIG. 3 is a diagram illustrating a schematic configuration of a writing unit in FIGS. 1 and 2.

4 is a block diagram showing a control unit of the digital copying machine of FIG.

5 is a block diagram showing an overall configuration of an electrical equipment control section having the control unit of FIG.

6 is a block diagram showing a detailed configuration of an image scanner unit in FIG. 1. FIG.

7 is a block diagram showing a detailed configuration of the image process unit of FIG.

8 is an explanatory diagram showing an operation of the data depth switching circuit of FIG. 7. FIG.

9 is a block diagram showing a memory system including the page memory of FIG. 4 and the image processing unit of FIG. 7.

10 is an explanatory diagram showing a flow of image data in the memory system of FIG.

11 is an explanatory diagram showing another flow of image data in the memory system of FIG.

FIG. 12 is a block diagram showing another memory system.

13 is a block diagram showing a detailed configuration of the memory unit of FIG.

FIG. 14 is an explanatory diagram showing input data of the memory unit of FIG.

FIG. 15 is a block diagram showing another memory system.

16 is a block diagram showing a detailed configuration of the external storage device of FIG.

FIG. 17 is a block diagram showing another memory system.

FIG. 18 is a flow chart for explaining the operation of this embodiment.

FIG. 19 is an explanatory diagram showing the relationship between the rotation speed and the rising time of the polygon motor in FIG.

FIG. 20 is a flowchart for explaining another operation of this embodiment.

FIG. 21 is a flowchart for explaining the operation of the conventional example.

[Explanation of symbols]

 20 Laser diode (LD) 24 Polygon mirror 25 Polygon motor 30 Synchronous detection plate 40 Photosensitive drum 601 and 602 CPU

Claims (5)

[Claims] 1. An image forming apparatus for forming an electrostatic latent image on a photoconductor by scanning a laser beam by rotating a polygon mirror using a polygon motor as a driving source, wherein when the polygon motor is started up or when gear shifting is performed. The first time until the polygon motor reaches the target speed and the second time until the laser beam of the image data is emitted from the laser diode are compared, and the first and second times are compared.
The image forming apparatus is provided with a control means for setting the image forming sequence to be startable when the time is equal to or when the first time becomes short. 2. The control means updates the gear shift characteristic data of the polygon motor every predetermined time, and calculates the first time based on the gear shift characteristic data. Image forming apparatus. 3. The image forming apparatus according to claim 1, wherein the control unit calculates the first time based on a synchronization signal of a laser beam. 4. The image forming apparatus according to claim 1, wherein the control unit determines the second time period according to a sheet feeding position and a copy mode. 5. The control means outputs an error message when the first time at which the polygon motor reaches a target speed is a predetermined time or more.
The image forming apparatus described.