JPH11122483A - Picture processing device and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply a conversion reference voltage for an A/D converter in a simple constitution even when plural A/D converts are present. SOLUTION: An original picture is scanned, and the picture signal from a CCD 3 is converted into a corresponding analog electric signal by a reading circuit 4, and outputted. This device is provided with A/D converters 5 and 6 for converting the analog signal from the reading circuit 4 into digital signals, reference signal controlling means 8 and 13 for controlling a conversion reference signal value at the time of conversion by the A/D converters 5 and 6, and picture forming device 200 for forming a picture corresponding to the digital signal on a recording medium. Then, the reference voltage controlling means 8 and 13 control the conversion reference signal value according to the output signal of the A/D converter 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and method capable of scanning and reading an original image and copying and recording the image on a recording medium.

[0002]

2. Description of the Related Art Conventionally, this type of apparatus includes a linear CCD for reading a document image and an analog-digital converter (A / D converter) for converting an analog signal from the linear CCD into a corresponding digital signal. ) And a digital copying machine having an image reading unit composed of a drive motor as a reading position moving means and a movable mirror base.

In such a copying machine, an automatic density adjusting means (hereinafter referred to as "AE") is used to improve the reproducibility of image information.
Called. ) Is common. The AE is generally configured to perform preliminary scanning (pre-scanning) of a document by a reading unit before recording an image, and to determine a recording information correction value by detecting density information of the entire image.

However, in recent digital copiers,
To avoid an increase in the required time due to the pre-scanning described above in order to improve productivity, a circuit for feeding back the output of the A / D converter to control the conversion reference voltage of the A / D converter and improving the density information (hereinafter referred to as " The density is adjusted using an “ABC circuit”).

In this conventional ABC circuit, when output data has a high density, the reference voltage is changed in a direction of decreasing the density,
When the output data has a low density, the reference voltage is changed in a direction to increase the density. In addition, feedback is performed with a constant time constant so that a majority value of a plurality of output data is reflected. By taking such control, there is an effect of improving the contrast with information such as characters recorded especially when the background color of the document has an intermediate density.

[0006]

However, recently, in order to improve the speed, many devices have come to appear in which the output of the CCD is output as a plurality of parallel signals of, for example, odd pixels and even pixels. In this type of apparatus, a plurality of A / D converters are often used for odd-numbered pixel signals and for even-numbered pixel signals. Therefore, if an ABC circuit is to be implemented with this kind of device, a plurality of conversion reference voltages for the A / D converter and a plurality of voltage control means are required, and the circuit configuration becomes complicated.

[0007] In addition, if the odd and even pixels are controlled independently of each other, it may cause unevenness of each adjacent pixel.

[0008]

SUMMARY OF THE INVENTION The present invention has been made for the purpose of solving the above-mentioned problem, and for example, A / A
An object of the present invention is to provide a conversion reference voltage for an A / D converter with a simple configuration even when a plurality of D converters are present. .

A scanning means for scanning a document image and outputting a corresponding analog electric signal; a plurality of analog-digital converting means for converting an analog signal from the reading means into a corresponding digital signal; -A reference signal control means for controlling a conversion reference signal value at the time of conversion of the digital conversion means, and an image forming means for forming an image corresponding to the digital signal on a recording medium, the reference voltage control means, The conversion reference signal value is controlled by an output signal of one of the plurality of analog-to-digital converters.

A reading means for scanning a document image and outputting a corresponding analog electric signal; a plurality of analog-digital converting means for converting an analog signal from the reading means into a corresponding digital signal; -A reference signal control means for controlling a conversion reference signal value at the time of conversion of the digital conversion means, and an image forming means for forming an image corresponding to the digital signal on a recording medium, the reference voltage control means, The conversion reference signal value at the time of the conversion is controlled by a logical operation signal of each digital signal of the plurality of analog-digital conversion means.

For example, the reading means projects an original image onto an image reading position by an optical means, and sequentially converts the projected image into an electric signal by a synchronization signal.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. [First Embodiment] FIG. 1 is a block diagram of a copying apparatus according to an embodiment of the present invention. In FIG.
100 reads a document image and performs predetermined image processing;
A reading apparatus 100 that outputs to the image forming apparatus 200 is an image forming apparatus that receives a digital signal from the reading apparatus 100, and is driven in accordance with the received digital signal to copy and record a document image on a recording medium. Image forming apparatus 200
Is composed of, for example, a laser beam printer.

In the reading apparatus 100, reference numeral 1 denotes a fluorescent lamp as an original irradiating means, 2 denotes a moving mirror for guiding reflected light from the original irradiated from the fluorescent lamp 1 to the original to the CCD 3,
Reference numeral 3 denotes a CCD as photoelectric conversion means, and reference numeral 4 denotes a reading circuit which drives the CCD 3 and processes an output signal from the CCD 3.

Reference numeral 5 denotes a first A / D converter as an odd-numbered pixel signal digital converter, 6 denotes a second A / D converter as an even-numbered pixel signal digital converter, and 7 processes a digitally converted image signal. An image signal processing circuit. Reference numeral 8 denotes an ABC circuit that variably outputs an analog signal according to the output of the A / D converter 5, 9 denotes a capacitor, 10 denotes a resistor for controlling a charging time constant, 11 denotes a resistor for controlling a discharging time constant, and 12 denotes resistors 10 and 11. This is a switch circuit for selectively connecting the capacitor 9.

The switch circuit 12 includes an A / D converter 5
When the value of the converted signal 101 is the maximum, the charge resistance 1
0 is selected, and when it is equal to or less than the maximum value, the discharge resistor 11 is selected. A switch circuit 13 switches between the output Vs of the ABC circuit 8 and the fixed voltage Vrt to input the reference voltage Vt of the A / D converters 5 and 6, which can be arbitrarily switched by a control signal 103 from the image signal processing circuit 7.

Reference numeral 14 denotes an automatic document feeder (SDF)
Reference numeral 15 denotes a document transport sensor that detects the transport of the document by the automatic document feeder (SDF) 14.

FIG. 2 is a graph showing the output of the A / D converter 5 shown in FIG. 1 and the change over time of the reference voltage Vt which fluctuates depending on the output of the A / D converter 5. Va is analog data of odd-numbered pixels sampled and held by the processing circuit 4 from output data of the CCD 3 at the time of document scanning, that is, A / D
This is the input voltage of the converter 5.

The operation of the embodiment of the present invention having the above configuration will be described with reference to FIGS.

It is assumed that the switch circuit 11 has been switched to the Vs side by the control signal 103, that is, the side that makes the ABC circuit 8 valid. Next, when the original is on the original platen D1, the movable mirror base 2 scans in the F direction, so that the CCD 3
The document image is projected onto the document. The CCD 3 is driven by a drive signal from the reading circuit 4, and the image signals which are sequentially photoelectrically converted are taken into the reading circuit 4 and processed by the reading circuit 4.

Accordingly, the input to the A / D converters 5 and 6 fluctuates, for example, as shown by Va in FIG. Here, the higher the voltage value, the higher the brightness (low density), and the lower the voltage value, the lower the brightness (high density). In the embodiment of the present invention, the outputs of the A / D converters 5 and 6 are closer to the maximum value as the voltage value is higher, and are closer to the minimum value as the voltage value is lower.

For example, as shown in FIG. 2, since Vs> Va in the region 201, the output 10 of the A / D converter 5
1 is 101 <maximum value, and the switch circuit 12 connects the discharge resistor 10 to the capacitor 9 (discharge). Accordingly, the voltage Vs decreases with a constant time constant, whereby the output value of the A / D converter 5 approaches the maximum value and is improved from high density to low density.

Next, since Va> Vs in the region 202, 101 = maximum value, and the switch circuit 12 connects the charging resistor 10 to the capacitor 9 (charging).

In the region 203, Va ≒ Vs is stabilized, and the switch circuit 12 repeats the charging / discharging little by little. At this time, it is the maximum value of 101 ° (charge / discharge).

In the region 204, Vs> Va again holds, so that the discharge resistor 11 is selected, and Vs is reduced (discharged) until the temperature reaches the maximum value of 101 ° and becomes stable.

Since Vs controlled by A / converter D5 is input to A / D converter 6, A / D converter 6 receives As.
The output 102 of the / D converter 6 has almost the same output result as the output 101 of the A / D converter 5.

As described above, according to this embodiment, even when there are a plurality of A / D converters,
The conversion reference voltage for the A / D converter can be supplied with a simple configuration, and the optimum density correction can be performed even in a high-speed image forming apparatus. [Second Embodiment] Hereinafter,
An embodiment of the second invention according to the present invention will be described in detail. FIG. 3 shows a configuration of a copying apparatus according to an embodiment of the second invention.
Shown in In FIG. 3, the same components as those in the embodiment of the first invention shown in FIG. 1 described above are denoted by the same reference numerals, and detailed description will be omitted.

In FIG. 3, reference numeral 301 denotes a logical product circuit for calculating the logical product of the output signal 101 from the A / D converter 5 and the output signal 102 from the A / D converter 6, and both the signal 101 and the signal 102 are used. If the maximum value is "1"
(True) ";otherwise," 0 (false) "is output.

The switch circuit 302 includes a logical product circuit 301
When the output is true, the charge resistor 10 is selected, and when the output is false, the discharge resistor 11 is selected.

The operation of the embodiment of the second invention having the above configuration will be described with reference to FIGS.

It is assumed that the switch circuit 11 has been switched to the Vs side by the control signal 103, that is, to the side that makes the ABC circuit 8 valid. Next, when the original is on the original platen D1, the movable mirror base 2 scans in the F direction, so that the CCD 3
The document image is projected onto the document. The CCD 3 is driven by a drive signal from the reading circuit 4, and the image signal that is sequentially photoelectrically converted is read and processed by the reading circuit 4.

Therefore, the A / D converter 5 and the Vo, Vae in FIG.
The input to 6 fluctuates. Here, the higher the voltage value, the higher the brightness (low density), and the lower the voltage value, the lower the brightness (high density). The outputs of the A / D converters 5 and 6 are closer to the maximum value as the voltage value is higher, and are closer to the minimum value as the voltage value is lower.

In the area 401, since Vs> Vao and Vae, both the output 101 of the A / D converter 5 and the output 102 of the A / D converter 6 become (101, 102 <maximum value), and the output of the AND circuit 301 is false (see FIG. 4 and L)
The switch circuit 302 connects the discharge resistor 11 to the capacitor 9 (discharge). Therefore, the voltage Vs decreases with a constant time constant, whereby the output values of the A / D converters 5 and 6 approach the maximum value, and are improved from high density to low density.

Next, in the area 402, since Vao> Vs, 101 = the maximum value, but since Vs> Vae, 102 <the maximum value. Therefore, the output of the AND circuit 301 is still false, and the switching circuit 302
Remains connected to the capacitor 9 (discharge).

In the region 403, the voltage value of Vae increases (the luminance of the pixel increases), Vao, and Vae> Vs, so that the outputs 101 and 102 both have the maximum values. Therefore 3
Since the 01 output becomes true (H in FIG. 4), the switch circuit 30
2 connects the charging resistor 10 to the capacitor 9 (charging).

In the region 404, Va ≒ Vs is stabilized, and the output of the AND circuit 301 repeats H⇔L, so that the switch circuit 302 repeats the charging / discharging little by little. Output 10
1,102 ≒ The maximum value (charge / discharge).

In the area 405, the output 102 is established when Vae> Vs.
= Maximum value, output 101 <maximum value when Vs> Vao, the output of the AND circuit 301 becomes false again, the discharge resistor 11 is selected, and Vs continues to decrease until Vs ≤ Vao (discharge) .

In the area 406, Vae is also Vs> Vae.
Therefore, Vs is reduced (discharged) until the temperature reaches the maximum value of 101, 102 ≒ and stabilizes.

In the second embodiment described above, even when there are a plurality of A / D converters,
The conversion reference voltage for the A / D converter can be supplied with a simple configuration, and the optimum density correction can be performed even in a high-speed image forming apparatus. (Other Embodiments) Even if the present invention is applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), a device including one device (for example, , A copying machine, a facsimile machine, etc.).

Further, in the second embodiment, the explanation has been made using the AND circuit. However, the present invention is not limited to this as long as the relationship between the input and the output is equivalent.

Further, according to the present invention, a storage medium storing software program codes for realizing the functions of the above-described embodiments is supplied to a system or an apparatus, and the computer (or CPU or MP) of the system or the apparatus is provided.
It goes without saying that U) can also be achieved by reading and executing the program code stored in the storage medium.

In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiment, and the storage medium storing the program code constitutes the present invention.

As a storage medium for supplying the program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD
-R, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the readout program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer based on the instruction of the program code. ) May perform some or all of the actual processing, and the processing may realize the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the program code is read based on the instruction of the program code. It goes without saying that the CPU included in the function expansion board or the function expansion unit performs part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0045]

As described above, according to the present invention, A
Even when there are a plurality of / D converters, it is possible to supply a conversion reference voltage for the A / D converter with a simple configuration, and optimal density correction can be performed even with a high-speed image forming apparatus.

[0046]

[Brief description of the drawings]

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

FIG. 2 is an operation explanatory diagram of the embodiment of the present invention.

FIG. 3 is a configuration diagram of an embodiment of the second invention according to the present invention.

FIG. 4 is an operation explanatory diagram of the embodiment of the second invention.

[Explanation of symbols]

 Reference Signs List 3 CCD 4 reading circuit 5, 6 A / D converter 7 image signal processing circuit 8 ABC circuit 12, 302 charge / discharge switching switch circuit 13 reference voltage switching switch circuit 14 automatic document feeder (SDF) 100 reading device 200 image forming device 301 AND circuit 302 Charge / discharge select switch circuit

Claims (5)

[Claims] A scanning unit that scans a document image and outputs a corresponding analog electric signal; a plurality of analog-to-digital conversion units that converts an analog signal from the reading unit into a corresponding digital signal; -Reference signal control means for controlling a conversion reference signal value at the time of conversion of the digital conversion means, and image forming means for forming an image corresponding to the digital signal on a recording medium, the reference voltage control means, An image processing apparatus, wherein the conversion reference signal value is controlled by an output signal of one of a plurality of analog-digital conversion means. 2. A reading means for scanning a document image and outputting a corresponding analog electric signal, a plurality of analog-digital converting means for converting an analog signal from the reading means into a corresponding digital signal, and -Reference signal control means for controlling a conversion reference signal value at the time of conversion of the digital conversion means, and image forming means for forming an image corresponding to the digital signal on a recording medium, the reference voltage control means, An image processing apparatus, wherein a conversion reference signal value at the time of the conversion is controlled by a logical operation signal of each digital signal of a plurality of analog-digital conversion means. 3. The reading device according to claim 1, wherein the reading device projects the document image onto an image reading position by an optical device, and sequentially converts the projected image into an electric signal using a synchronization signal. An image processing device according to any one of the above. 4. A reading step of scanning a document image and outputting a corresponding analog electric signal, a plurality of analog-to-digital conversion steps of converting the analog signal from the reading step into a corresponding digital signal, -A reference signal control step of controlling a conversion reference signal value at the time of conversion in the digital conversion step; and an image forming step of forming an image corresponding to the digital signal on a recording medium, wherein in the reference voltage control step, Any one of the plurality of analog-to-digital conversion steps
An image processing method, wherein the conversion reference signal value is controlled by an output signal of a digital conversion step. 5. A reading step of scanning a document image and outputting a corresponding analog electric signal, a plurality of analog-to-digital conversion steps of converting an analog signal from the reading step into a corresponding digital signal, -A reference signal control step of controlling a conversion reference signal value at the time of conversion in the digital conversion step; and an image forming step of forming an image corresponding to the digital signal on a recording medium, wherein in the reference voltage control step, An image processing method, wherein a conversion reference signal value at the time of the conversion is controlled by a logical operation signal of each digital signal in the plurality of analog-digital conversion steps.