JP3663316B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that moves an optical scanning system to read an original to form an image.
[0002]
[Prior art]
As a conventional example (1) of this type, Japanese Patent No. 2656171 discloses that when continuous copying is performed at a magnification larger than a predetermined first magnification in order to shorten the copying time in the continuous copying mode at the time of enlargement, 2 A method has been proposed in which the scanning start position of the optical system traveling body after the first sheet is brought closer to the original scanning start position (lead edge) than the scanning start position when copying at the first magnification.
[0003]
As another conventional example (2), Japanese Patent Laid-Open No. 5-14609 discloses an imaging unit (optical system traveling body) according to a reading magnification in order to shorten the copying time in the continuous copying mode at the time of enlargement. There has been proposed a method of scanning by changing the home position according to the reading magnification, and having a driving means that drives by creating a trapezoidal profile that performs regular acceleration / deceleration in a staircase pattern.
[0004]
[Problems to be solved by the invention]
By the way, in a copying machine that forms a full color by positioning and superimposing toner images of respective colors on an intermediate transfer belt, a belt mark frame gate signal MFGATE issued by detecting a belt mark provided on the intermediate transfer belt is output. The optical scanning system moves to achieve high-speed continuous copying when aligning the toner images of each color on the intermediate transfer belt by issuing a scanner motor start or image capture frame gate signal IFGATE as a reference. It is important to shorten the time LE until the image reading tip (lead edge) is reached at the target speed after starting the operation, and to shorten the “return time” until the optical scanning system returns to the home position. .
[0005]
In particular, since the scanning speed of the optical scanning system is low at the time of enlargement than at the time of enlargement, this time LE becomes longer, so that it is more important to shorten the return time. Further, at the time of reduction, since the return time becomes long because the scanning distance of the optical scanning system becomes large, it is also important to shorten the return time. For this reason, it is not preferable to increase the speed of the motor due to problems such as an increase in cost and noise accompanying an increase in torque. Therefore, it is desired to shorten the time LE and the return time by shortening the distance until the lead edge is reached at the target speed and the return distance after the optical scanning system starts moving.
[0006]
However, in the above conventional examples (1) and (2), the home position is changed only at the time of continuous reading at the time of enlargement.
[0007]
SUMMARY OF THE INVENTION In view of the above-described problems of the conventional example, the present invention provides an image forming apparatus capable of speeding up both at the same magnification and at the time of enlargement / reduction scaling when a document is read a plurality of times to form a full color image. Objective.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the first means, in an image forming apparatus that reads a document a plurality of times to form a full-color image, moves in the sub-scanning direction of the document and scans the document, and 1 of the document Read the data necessary for reading the document including at least one of variable magnification and document size before the second reading, and calculate the motor profile pattern for each time for performing the plurality of reading operations by the scanning optical system, and an arithmetic means for storing said calculation means, from the first of the movement of the optical system starts from the home position at the time of reading, the movement of the scanning optical system when the second and subsequent read before Kiho over home position of the original calculating the motor profile pattern to start et placed position have close to document, and to store.
[0009]
The second means is characterized in that in the first means, switching means for switching to the stored motor profile pattern of the next reading operation at the end of the return operation of the scanning optical system is provided .
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a color copier as an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a block diagram showing the color copier of FIG. 1, and FIG. 3 is a full color for one sheet on an intermediate transfer belt. FIG. 4 is a timing chart showing main signals when two full-color images are formed on the intermediate transfer belt. FIG. 5 is a timing chart showing motor profiles. 6 is a timing chart for explaining a communication sequence and a motor profile switching timing in the color copying machine.
[0012]
In FIG. 1, a document (not shown) on the contact glass 101 is scanned by the optical scanning system 102 and read by the image sensor 103. The optical scanning system 102 can move in the sub-scanning direction (left and right direction in the drawing). The image signal read by the image sensor 103 is subjected to image processing, and is optically modulated by the laser writing unit 104 and applied to the photosensitive drum 105. Thus, each time the photosensitive drum 105 rotates, the charger 106 One latent image of black (K), cyan (C), magenta (M), and yellow (Y) is selectively formed on the surface of the photosensitive drum 105 that is uniformly charged in advance.
[0013]
The latent images of the respective colors on the photosensitive drum 105 are developed with toner by the developing unit 107, and then are aligned and superimposed on the intermediate transfer belt 108, thereby forming a full color image. The full color image on the intermediate transfer belt 108 is transferred to the paper P, and the full color image on the paper P is fixed by the fixing device 109. Here, the intermediate transfer belt 108 is provided with a belt mark (not shown) for aligning the toner images of the respective colors. In addition, the length of the intermediate transfer belt 108 is, for example, two letter lateral sizes plus an image forming margin.
[0014]
FIG. 2 functionally shows the copying machine shown in FIG. The intermediate transfer unit 2 transfers toner images of a plurality of colors (here, four colors) onto the intermediate transfer belt 108, and the intermediate transfer belt 108 transfers a plurality of toner images (here, two letters in a horizontal size) in the length direction. It has a length that can be transcribed and transferred. The rotational position detection signal generating means 5 detects a belt mark on the intermediate transfer belt 108 and generates a rotational position detection signal 4 to detect the position of the intermediate transfer belt 108 in the rotational direction, and this is used as an image forming reference signal. Apply to generating means 7. When the rotational position detection signal 4 is inputted to the image forming reference signal generating means 7, the image forming reference signal MFGATE is generated after a predetermined time for adjusting the scan timing, and this is generated as the exposure scanning control means 12 and the gate signal generating means. 18 is applied.
[0015]
The exposure scanning control means 12 starts the exposure scanning of the image reading means 11 with a predetermined operation (motor profile) after a predetermined time has elapsed with reference to the image forming reference signal MFGATE. The gate signal generation means 18 uses the image forming reference signal MFGATE as a reference, and after an elapse of a predetermined time until the optical scanning system 102 reaches the document leading edge (lead edge) from the reference start position (home position), the effective scanning of the document is performed. A writing reference gate signal OFGATE and an image reading gate signal IFGATE that are valid for a predetermined time corresponding to the area are applied to the writing means 22 and the image processing means 27, respectively.
[0016]
The image reading means 11 has means for detecting that the optical scanning system 102 is located at the home position, and starts scanning the document on the contact glass 101 by the optical scanning system 102 and photoelectrically converts it by the image sensor 103. The read image signal is sent to the image processing means 27. The image processing means 27 converts this read image signal into an image forming color image signal and sends it to the writing means 22 while the image reading gate signal IFGATE is valid. The writing means 22 performs image formation by controlling the laser writing unit 104 while the write reference gate signal OFGATE is valid based on the image forming color image signal. The image forming sequence control means 29 controls these image forming sequences.
[0017]
The reading sequence control means 26 includes an exposure scanning control calculation setting means 14, a gate signal generation control calculation setting means 19 and an image reading means communication means 23 for managing and controlling the reading sequence. The exposure scanning control calculation setting means 14 calculates the exposure scanning start time and operation, and the gate signal generation control calculation setting means 19 calculates the start time and width of the image reading gate signal IFGATE. The image reading means communication means 23 communicates various conditions for image reading with the system control means 24 via the main communication means 21.
[0018]
The operation unit control means 20 and the main communication means 21 are the reading document size, the image forming magnification, and the full color necessary for the exposure scanning control calculation setting means 14 and the gate signal generation control calculation setting means 19 to perform each calculation. / Communicate various conditions such as single color mode according to the setting conditions of the operation unit by the user The system control means 24 manages and controls the above means in an integrated manner.
[0019]
FIG. 3 shows the transfer of four colors (KCMY) for only one sheet at the same magnification onto the intermediate transfer belt 108 having a length that can be transferred by arranging toner images of two letters in the horizontal size in the length direction. It shows the operation when doing. In FIG. 3, the image forming reference signal MFGATE is generated once with reference to the rotational position detection signal 4 generated every time the intermediate transfer belt 108 makes one rotation, and the optical scanning system 102 is operated with reference to the image forming reference signal MFGATE. After the elapse of a predetermined time for reaching the lead edge from the home position, the write reference gate signal OFGATE (and the image read gate signal IFGATE) is generated once for a predetermined time corresponding to the effective scanning area of the document, and four times. Four colors (KCMY) for one sheet are developed on the basis of the write reference gate signal OFGATE, and are aligned and superimposed on the intermediate transfer belt 108.
[0020]
FIG. 4 shows the operation when transferring four colors (KCMY) for two sheets to the intermediate transfer belt 108 at the same magnification. In FIG. 4, the image forming reference signal MFGATE is generated twice with reference to the rotation position detection signal 4 generated every time the intermediate transfer belt 108 makes one rotation, and the optical scanning system 102 uses the image forming reference signal MFGATE as a reference. After the elapse of a predetermined time for reaching the lead edge from the home position, the writing reference gate signal OFGATE (and the image reading gate signal IFGATE) is generated twice for a predetermined time corresponding to the effective scanning area of the original, and 2 × 4 = 4 colors (KCMY) for two sheets are developed on the basis of the write reference gate signal OFGATE for eight times, and are aligned and superimposed on the intermediate transfer belt 108. In the case of two or more repeat copies, this is repeated for the number of repeat copies.
[0021]
FIG. 5 shows in more detail the operation when transferring only one color (KCMY) to the intermediate transfer belt 108. FIG. 5 shows that the original is scanned four times (Ptn1, Ptn2, Ptn3, Ptn4) in order to form a full-color image. Each symbol in FIG. 5 is shown below.
[0022]
T_LE: driving time of the optical scanning system 102 from the normal home position until reaching the lead edge t_SCN: driving time of the optical scanning system 102 from the leading edge (lead edge) to the trailing edge of the document t_RTN: trailing edge of the document Drive time of the optical scanning system 102 until the return to the normal home position is completed. T_WAIT: waiting time until the optical scanning system 102 starts after the image forming reference signal MFGATE is asserted. Also, the drive time t_LE ′ is The driving time of the optical scanning system 102 from the home position to the lead edge at the second to fourth reading (Ptn2 to Ptn4) is shown. The driving time t_RTN ′ is the first to third reading (Ptn1 to Ptn3). ) Shows the return time. As shown in FIG. 5, at the time of return at the time of the first to third readings (Ptn1 to Ptn3), the return is finished before the normal home position (between the normal home position and the lead edge).
[0023]
Further, during this return, the image formation reference signal MFGATE for forming the next color is asserted (issued), and the image reading gate signal IFGATE is asserted after elapse of time t_LE from the image formation reference signal MFGATE. . Further, the optical scanning system 102 starts after the elapse of the waiting time t_WAIT from the assertion time of the image forming reference signal MFGATE so that the optical scanning system 102 reaches the lead edge when the image reading gate signal IFGATE is asserted. .
[0024]
FIG. 6 shows a communication sequence of the system control means 24 and the reading sequence control means 26 for performing the above processing. First, before the first reading (Ptn1), the system control unit 24 sends process data necessary for reading a document such as variable magnification, document size, full color / single color, to the reading sequence control unit 26, and the reading sequence control unit 26 Calculates the motor profile for four times (Ptn1, Ptn2, Ptn3, Ptn4) based on this process data, and sets this in the internal memory. Next, when the system controller 24 instructs the reading sequence controller 26 to select the first (Ptn1) motor profile, the reading sequence controller 26 selects the first Ptn1 motor profile based on this selection instruction. Based on this, the image forming reference signal MFGATE is asserted and the scanner motor is driven.
[0025]
When the reading sequence control means 26 negates the first (Ptn1) image reading gate signal IFGATE, the system control means 24 sends "image reading end" to the system control means 24. In response to this, the system control means 24 responds to the motor profile of the second Ptn2. Is instructed to the reading sequence control means 26. In this case, even if the reading sequence control means 26 receives this selection instruction, the scanner motor is still operating, so that the motor profile is not switched immediately but the motor profile is switched at the end of the return. In FIG. 6, since the image forming reference signal MFGATE has already been asserted, the operation of the motor profile of the second Ptn2 is started after the standby time t-WAIT has elapsed.
[0026]
【The invention's effect】
As described above, according to the present invention, by operating based on the motor profile pattern, it is possible to increase the speed both at the same magnification and at the time of enlargement / reduction scaling.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a color copying machine as an embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a block diagram showing the color copier of FIG.
FIG. 3 is a timing chart showing main signals when a full color image for one sheet is formed on an intermediate transfer belt.
FIG. 4 is a timing chart showing main signals when two full-color images are formed on an intermediate transfer belt.
FIG. 5 is a timing chart showing a motor profile.
FIG. 6 is a timing chart for explaining a communication sequence and a motor profile switching timing in the color copying machine.
[Explanation of symbols]
21 Reading means 24 System control means 26 Reading sequence control means 102 Scanning optical system

Claims (2)

In an image forming apparatus that reads a document multiple times to form a full-color image,
A scanning optical system that moves in the sub-scanning direction of the document and scans the document;
Before the first reading of the document, data necessary for reading the document including at least one of the scaling factor and the document size is read, and each time the motor profile pattern for performing the plurality of reading operations by the scanning optical system is obtained. Computing means for computing and storing;
With
The calculating means, the movement of the optical system when reading the first original starts from the home position, near have position located et started from movement of the scanning optical system when the second and subsequent read before Kiho over home position to the original An image forming apparatus that calculates and stores the motor profile pattern as described above . The image forming apparatus according to claim 1, further comprising a switching unit that switches to a stored motor profile pattern for a next reading operation when a return operation of the scanning optical system ends .

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