JPH0736235A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce copying time by minimizing the decrease of copying speed in the case of automatically adjusting density in an image forming device such as an electrophotographic copying machine which is provided with an original feeder for automatically feeding an original from a tray to an original platen. CONSTITUTION:A reading sensor 5 such as a CCD capable of reading the gradation of the original 1 is provided on the front side of an original carrying path of the original feeder 3 which feeds the original 1 to an original platen glass 2. The image density of the original is detected by the read sensor 5, and prescan for automatic density correction is finished until the time the original 1 is carried to the original platen glass 2. A read sensor 6 which is the same as the reading sensor 5 is also provided on the rear side of the original carrying path to automatically detect that whether or not the original has images on both sides, and the input of double-side copying direction is omitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer having a document feeder.

[0002]

2. Description of the Related Art FIG. 6 is a diagram showing the structure of a document feeding device of a conventional electrophotographic copying machine. In the figure, 1 is a document, 2 is a document platen glass, 3 is a document feeder for conveying the document 1 to the document platen glass 2, and 4 is a conveyance path used when performing double-sided copying of the document 1.

In a copying machine having the above-mentioned document feeder 3, the document 1 to be copied is set in a predetermined place (tray) at the position shown in the figure, and the copy start key on the operation panel is pressed. As a result, the original 1 is automatically sent to the original glass 2 and the image of the original 1 is read. Then, an original image is formed by an image processing unit (not shown), and the copy sheet onto which the image is transferred is ejected. When this copying is completed, the document 1 is returned to the document feeder 3 again.

When copying both sides of the original 1,
Specify the double-sided copy operation on the operation panel. As a result, when the copying of the first side is completed, the document 1 is reversed via the conveyance path 4 of the document feeding device 3 and is fed again to the platen glass 2. Then, when the copying of the second side is completed, the document 1 is returned to a predetermined position on the document feeding device 3 again.

[0005]

However, in the conventional image forming apparatus as described above, when performing the automatic density correction (AE), the original is fed from the predetermined position of the original feeding device to the original platen glass. Since the document is pre-scanned after that, there is a problem that the copy speed is reduced.

Further, in the case of double-sided copying, the document feeder does not perform double-sided feeding unless the designation of double-sided copying is input on the input section of the apparatus main body, that is, the operation pulse, and therefore, double-sided copying is designated. There was a problem that it took time to input.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an image forming apparatus which minimizes a decrease in copy speed when performing automatic density correction and shortens the copy time. Has an aim.

Another object of the present invention is to provide an image forming apparatus capable of saving the trouble of inputting double-sided designation at the time of double-sided copying.

[0009]

The image forming apparatus of the present invention is configured as follows.

(1) A reading sensor for reading the image information of the original is provided on the original feeding path of the original feeding device for feeding the original to the original table, and the reading sensor can read the gradation of the original.

(2) In the image forming apparatus of the above (1), the reading sensors are provided on the front side and the back side of the document conveying path, respectively.

(3) In the image forming apparatus of the above (1) or (2), the image density of the original is detected by the reading sensor, and the density correction on the image output side is performed based on the detected data. .

(4) In the image forming apparatus of the above (1) or (2), the reading sensor detects the histogram of the image density of the document, and the gradation correction is performed on the image output side based on the detected data. I chose

(5) In the image forming apparatus according to (1) or (2) above, the reading sensor is capable of determining whether or not the original is colored.

(6) In the image forming apparatus of (5), when the chromatic color of the original is determined by the reading sensor, the color image output mode is automatically entered.

(7) In the image forming apparatus according to any one of (2) to (6), the reading sensor determines whether the image of the original is single-sided or double-sided.

[0017]

In the image forming apparatus of the present invention, since the original image reading sensor is provided in the original feeding device, it is possible to make a determination such as density correction while the original is being sent to the original table. The prescan on the platen can be omitted, and the decrease in copy speed can be minimized.

Further, by providing a reading sensor at a position where the back side of the document of the document feeding device can be read, it can be determined whether the document is double-sided, and the operation for double-sided copying can be automatically performed.

[0019]

1 is a diagram showing the construction of an embodiment of the present invention, in which the same reference numerals as those in FIG. 6 designate the same components. In the figure, 1 is a document, 2 is a platen glass, and 3 is a document feeding device for feeding the document 1 to the platen glass 2. ing.

CCs 5 and 6 read the image information of the original 1.
A reading sensor such as D is a sensor that can read the gradation of the document 1 and is provided on the front side and the back side of the document feeding path of the document feeding device 3, respectively.

FIG. 2 is a block diagram showing a main part of a control system of the image forming apparatus. In the figure, 7 is a control device using a CPU, 8 is an operation control section for controlling the operation of the document feeding device 3, and 9 is an image for performing processing such as scanning of the document 1, formation of an electrostatic latent image, development and transfer. It is a processing unit.

The control unit 7 is designed to perform density correction on the printer side (image output side) based on the image density data detected by the reading sensors 5 and 6, but the reading sensors 5 and 6 It is also possible to detect a histogram of image density (density-number of pixels) and perform gradation correction (character mode, photo mode) on the printer side based on the detected data.

That is, whether the original 1 is a photograph or a character is discriminated from the data read by the sensor 5, and the image processing is changed according to the discrimination result to perform gradation correction in the photograph mode or the character mode. be able to.

Next, the operation will be described. On the document feeding path of the document feeding device 3, CCDs are provided on both front and back sides.
And the like, and read sensors 5 and 6 for reading the AE and AC from the read sensor 5 on the first surface side (front side) of the sent document 1.
Image information for S or the like is read, and whether or not there is a second side is read by the reading sensor 6 on the second side (back side). FIG. 3 is a flowchart showing the operation.

First, after copying is started, the original 1 is sent to the original platen glass 2. At that time, the document image is read by the sensor 5 on the front side in the middle of the conveyance path of the document 1, and the control device 7 determines (detects) AE (ACS) (step S1). Subsequently, it is judged whether or not the copy is the first screen (step S2), and if so, the original image is read by the sensor 6 on the back side, and both sides of the original 1 are detected (step S3).

Next, it is determined whether or not the original 1 has a second side by the above-mentioned double-sided detection (step S4). At this time, if there is no second side, the operation of the original feeding device 3 for single-sided copying is performed (step S5), the image of the first side of the original 1 is copied, and the copy ends.

However, if there is the second side in step S4, the operation of the original feeding device 3 for the second side copying is performed (step S6), and the process returns to step S1. Then, the same operation as described above is performed, but at this time, since it is determined in step S2 that the copy is the second side, step S2 is performed as is
In step 5, the image on the second side of the original 1 is copied.

As described above, since the original image reading sensors 5 and 6 are provided in the original feeding device 3 to determine the density correction while the original 1 is being conveyed, the prescan on the original table glass 2 is performed. It can be omitted. Therefore, it is possible to minimize the decrease in copy speed when performing automatic density correction,
The copy time can be shortened.

Further, since the reading sensors 5 and 6 are provided on the front side and the back side of the original 1 to detect both sides of the original 1, it is possible to save the trouble of inputting both sides when performing double-sided copying.

FIG. 4 is an enlarged view of the reading sensors 5 and 6. The document 1 is conveyed to the front side of the drawing, and the lengths of these sensors 5 and 6 are the width of the maximum size document that the document feeder 3 can convey. .

FIG. 5 is an enlarged view of the reading sensors 5 and 6 according to another embodiment of the present invention. This uses a CCD sensor having a length that allows a part of the original 1 to be read. Even with such reading sensors 5 and 6, the original table glass 2 is used.
The prescan is completed before the original 1 arrives at the sheet, and the same effect as that of the above embodiment can be obtained.

If the reading sensors 5 and 6 are capable of discriminating the presence / absence of the color of the original 1, and if the reading sensors 5 and 6 discriminate the chromatic color of the original 1, white / black is automatically detected. A copying mode other than copying (color image output mode) may be entered.

Further, the sensor 6 is a photo sensor, and the presence / absence of an image of the document 1 can be detected by this photo sensor by transmitting / receiving light to determine whether the image of the document 1 is single-sided or double-sided. In this case, if the brightness of the white paper is 100%, it is judged that an image having a reflected light of 50% or less has an image.

[0034]

As described above, according to the present invention, since the reading sensor capable of reading the gradation of the original image is provided in the original feeding device, the original reaches the original table when the automatic density correction is performed. Since the prescan is completed before, the reduction of the copy speed can be minimized, and the copy time can be shortened.

Further, by providing a reading sensor also on the back side of the document feeding path, it is possible to automatically determine whether the document is double-sided, and it is possible to save the labor of inputting double-sided designation in double-sided copying.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a control system according to an embodiment.

FIG. 3 is a flowchart showing the operation of one embodiment.

4 is an enlarged view of the reading sensor of FIG.

FIG. 5 is an enlarged view of a reading sensor according to another embodiment of the present invention.

FIG. 6 is a configuration diagram showing a conventional example.

[Explanation of symbols]

 1 Document 2 Document Platen Glass 3 Document Feeding Device 5 Reading Sensor 6 Reading Sensor 7 Control Device

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area H04N 1/19 // B65H 7/14 9037-3F

Claims (7)

[Claims] 1. A reading sensor for reading image information of an original is provided on an original feeding path of an original feeding device for feeding an original to an original table, and the reading sensor can read the gradation of the original. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the reading sensor is provided on each of a front side and a back side of the document conveying path. 3. The image forming apparatus according to claim 1, wherein the image density of the original is detected by the reading sensor, and the density is corrected on the image output side based on the detected data. 4. The image forming apparatus according to claim 1, wherein the reading sensor detects a histogram of the image density of the document, and gradation correction is performed on the image output side based on the detected data. 5. The image forming apparatus according to claim 1, wherein the reading sensor can determine the presence or absence of coloring of the document. 6. The image forming apparatus according to claim 5, wherein when the chromatic color of the document is determined by the reading sensor, the color image output mode is automatically entered. 7. The image forming apparatus according to claim 2, wherein the reading sensor determines whether the image of the original is single-sided or double-sided.