JPH06987A - Printing density determination device - Google Patents

Abstract

PURPOSE:To ensure that an appropriate density adjustment value is meticulously set in compliance with the image density and color of printed matter and thereby a sharp printed image is obtained always. CONSTITUTION:A CPU 21 calculates the image color, minimum value of a bright part and output difference between the minimum value of a bright part and the maximum value of a dark part of a copy, based on the detected data of CCD line sensors 7 to 10. The CPU 21 sets an appropriate threshold value in accordance with a fuzzy rule and a membership function which are previously stored in ROM 22, based on the color of an image, the minimum value of a bright part and an output difference between the minimum value and the maximum value of a dark part. Further, CPU 21 binarizes output data from the CCD line sensor 10 using the set threshold value, and supplies the binary coded data to a thermal head driver 34 as print data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing apparatus such as a facsimile apparatus for printing an image on a thermal recording paper or the like, and more particularly to a printing density determining apparatus for determining the printing density in the printing apparatus by using fuzzy inference.

[0002]

2. Description of the Related Art In a device such as a facsimile machine for reading an image of an original and converting it into print data, an image of the original is read by a reading section constituted by a CCD line sensor or the like, and a bright portion and a dark portion of the original are predetermined. Create print data by dividing by the threshold value of. That is, in the output signal of the CCD line sensor, the portion exceeding the threshold value is the bright portion, and the portion below the threshold value is the dark portion, and bit data for each printing element is created. In a fax machine,
The print data created in this manner is transmitted to the facsimile machine of the communication destination via the telephone line.

[0003]

However, in a conventional printing apparatus such as a facsimile apparatus which prints an original image, when the image of a handwritten original is printed, the density of the printed image is determined exclusively by the image density of the original. However, there is a problem in that the density of the original varies depending on the difference in writing pressure, and when printing an original composed of characters with weak writing pressure, the density of the printed image becomes thin, making it difficult to read. Further, the reading density of the image is influenced not only by the writing pressure but also by the color of the original document, and the color close to the light source color of the reading light is read thinly, so that the density of the printed image becomes thin. further,
Even in printing devices that use electrophotography, such as copiers,
The density of the entire document is detected and the light amount of the light source that exposes the document is changed based on this detection result.However, there is one that detects the density and color of the characters and line drawings themselves on the document. In addition, the density of the copied image cannot be finely adjusted according to the image density of the original due to the difference in writing pressure and color.

An object of the present invention is to adjust the print density by fuzzy reasoning based on the state of a single factor or a plurality of factors that may affect the print concentration, so that the state of characters and line drawings constituting a document can be adjusted. Accordingly, it is an object of the present invention to provide a print density determination device that can finely determine the print density and can always obtain a clear print image.

[0005]

According to a first aspect of the present invention, there is provided state detecting means for detecting the state of a single factor or a plurality of factors relating to an image on a printing medium which affects the print density,
Fuzzy inference means for inferring a density adjustment value to be supplied to a print density adjusting device for adjusting print density according to a fuzzy rule, using a detection result of the state detecting means as an input.

According to a second aspect of the present invention, the state detecting means includes a color detecting means for detecting the color of the image of the printed material.

[0007]

According to the first aspect of the present invention, the state detecting means detects the state of a single factor or a plurality of factors relating to the image of the printed matter which may affect the print density, and the detection result of the state detecting means. Is input, the density adjustment value supplied to the print density adjusting device for adjusting the print density in the printing device is inferred by the fuzzy inference means according to a predetermined fuzzy rule. As a result, the print density in the printing apparatus is finely adjusted based on the state of factors relating to the image of the printing material.

According to the second aspect of the invention, since the color of the image of the printed material is one of the inputs of the fuzzy inference, the print density can be finely adjusted according to the color of the image of the printed material. it can.

[0009]

1 is a schematic side sectional view showing the construction of a camera copying apparatus which is a printing apparatus to which a printing density determining apparatus according to an embodiment of the present invention is applied. The camera copying apparatus 1 takes in the image of the original 11 via the lens 2 into the apparatus and reads the image of the original image 12 by the reading unit 3. The reading unit 3 moves downward from the top at a predetermined speed.
During this time, light incident from a slit formed on the front surface of the reading unit 3 is read by a CCD line sensor (not shown) provided inside the reading unit 3. The detection output of the CCD line sensor provided in the reading unit 3 is input to the control unit 4, converted into print data in the control unit 4 and supplied to the thermal head 5. The thermal head 5 heats the image portion on the thermal recording paper 6 to form a print image corresponding to the original image.

FIG. 2 is a block diagram showing the configuration of the control unit of the camera copying apparatus. The control unit 4 has a ROM 22.
And a CPU 21 having a RAM 23. A / D converters 30 to 33 and a thermal head driver 3 are provided to the CPU 21 via interfaces 24 to 29.
4 and the motor driver 35 are connected. A / D
CCD line sensors 7 to 10 provided in the reading unit 3 are connected to the converters 30 to 33, respectively.
Each of the CCD line sensors 7 to 9 detects the light amount of each of the three primary colors of light from the document 11. CCD
The line sensor 10 detects the total amount of light from the document 11. Each detection signal of the CCD line sensors 7 to 10 is A
It is converted into digital data in the D / D converters 30 to 33 and is transmitted to the CPU 2 via the interface circuit 24/27.
Input to 1. The CPU 21 uses the interface circuit 24 according to a program previously written in the ROM 22.
Print data is created by processing the detection data input from .about.27. This print data is the interface circuit 28.
Is input to the thermal head driver 34 via. The thermal head driver 34 drives the thermal head 5 according to this print data. Further, the motor drive data is output to the motor driver 35 to the interface circuit 29. A motor for moving the reading unit 3 is connected to the motor driver 35, and the motor driver 35 reciprocates the reading unit 3 according to drive data.

FIG. 3 is a flowchart showing the processing procedure of the control unit of the camera copying apparatus. The CPU 21 waits until the start switch is turned on (n1), and when the start switch is turned on, it outputs drive data to the motor driver 35 to move the reading unit 3 downward (n).
2). After that, the output data of the CCD line sensors 7 to 9 is read at a predetermined timing (n3), and the color of the image color of the document is determined from the output ratio of this output data (n).
4). Further, the detection data of the CCD line sensor 10 is read (n5), and out of the detection data of one line,
Calculate the output difference between the minimum value in the bright area and the maximum value in the dark area (n
6). The CPU 21 infers an appropriate threshold value by fuzzy inference using the color of the original image image determined in n4 and the output difference between the bright portion and the dark portion calculated in n6 as input variables (n7).

The fuzzy rule used in the fuzzy inference for inferring the appropriate threshold is, for example, a slightly higher threshold when the minimum value of the bright part is high and the output difference from the maximum value of the dark part is large. To do.

When the minimum value in the bright part is high and the output difference from the maximum value in the dark part is small, the threshold value is set to be considerably high.

If the color of the image is blue, the threshold value is lowered a little.

These are represented by, for example, and are preset in the ROM 22. The membership function shown in FIG. 4 is also stored in the ROM 22, and the minimum value of the bright portion, the output difference between the minimum value of the bright portion and the maximum value of the dark portion, and the color of the image are respectively shown in FIGS. The horizontal axis of the membership function shown in C) is taken, and the label including each input value and the degree of belonging are obtained.

Based on this label and the degree of affiliation, the function of the label corresponding to the fuzzy rule in the consequent part membership function shown in FIG. 6D is truncated, and the centroids of the truncated values for a plurality of fuzzy rules are truncated. The value is set as an appropriate threshold which is the result of inference.

The CPU 21 determines C by this proper threshold value.
The output data of the CD line sensor 10 is binarized (n
8) The thermal head is driven by the obtained binary data (n9). The above processing of n2 to n9 is continuously performed until the image reading unit 3 reaches the downward limit position (n10).

As described above, in this embodiment,
Of the output signals of the CCD line sensor 10, the minimum value of the bright portion is set as the background density, and the maximum value of the dark portion is determined as the density of the character or line drawing drawn on the background. By creating the binarized data to be supplied to the driver 34, even when the density of the character or the line drawing is not sufficient, these can be printed clearly in the printed image. Further, since the image color of the document is taken into consideration when setting the threshold value, it is possible to finely set the density of the print image based on the document density and color.

In the present embodiment, the camera copy device for printing the image of the original on the thermal recording paper by the thermal head 5 has been described as an example, but a facsimile device adopting the same printing method or copying by the electrophotographic method is performed. It can be similarly applied to a copying machine that creates an image. In this case, the density adjustment value is changed to an appropriate threshold value for the binarization processing of this embodiment, and the light quantity of the exposure light source is determined by fuzzy reasoning.

[0020]

According to the present invention, since the print density can be finely set based on the state of a single factor or a plurality of factors related to the image of the printed material, the density or color of the image on the printed material changes. Also, there is an advantage that a clear printed image can be obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a schematic configuration of a camera copying apparatus to which a printing density determining apparatus of the present invention is applied.

FIG. 2 is a block diagram showing a configuration of a control unit of the camera copying apparatus.

FIG. 3 is a flowchart showing a processing procedure of the control unit.

FIG. 4 is a diagram showing a membership function used for fuzzy inference executed in the print density determining apparatus.

[Explanation of symbols]

 1-Camera Copy Device 3-Image Reading Unit 4-Control Unit (Fuzzy Inference Means) 5-Thermal Head (Printing Density Adjusting Device) 7-10-CCD Line Sensor (State Detection Means) 34-Thermal Head Driver (Printing Density Adjusting) apparatus)

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H04N 1/23 102 A 9186-5C 8907-2C B41J 3/20 109 Z

Claims (2)

[Claims] 1. A state detecting means for detecting a state of a single or a plurality of factors relating to an image of a printing medium which influences a print density, and a print density is adjusted in accordance with a fuzzy rule using a detection result of the state detecting means as an input. A fuzzy inference means for inferring a density adjustment value supplied to a print density adjusting device,
A print density determining apparatus, characterized by being provided with. 2. The print density determining apparatus according to claim 1, wherein the state detecting means includes a color detecting means for detecting a color of an image of a printed material.