JPH02114761A - Original read circuit - Google Patents

Abstract

PURPOSE:To attain independent setting while a carrier speed of an original in the subscanning direction and a scanning speed of an image sensor in the main scanning direction are synchronized with each other by frequency-dividing an output of a variable frequency divider at the 2nd frequency divider, giving the result to a motor driver, frequency-dividing the output of the variable frequency divider at the 3rd frequency divider, and giving the result to a sensor driver as a clock pulse. CONSTITUTION:A clock pulse from an oscillator 1 is frequency-divided by a frequency divider 1 into 1/N1 frequency and the result is given to a variable frequency divider 3. A control circuit 12 controls the frequency division ratio of the variable frequency divider 3 to control the speed of a stepping motor 8. Every time an output of a frequency divider 4 is outputted by NF pulse, the stepping motor 8 carries the original by one line in the subscanning direction. A sensor driver 7 drives an image sensor 9 at each output of one pulse of the frequency divider 5 to scan the image by one line in the main scanning direction. Let the frequency division ratio of a frequency divider 4 be 1/N4 and let the frequency division ratio of a frequency divider 5 be 1/N5, then the image sensor reads scanning lines of N4XNF when the read original 10 is carried by N5 lines.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applied to a document reading circuit of a facsimile machine. In particular, the present invention relates to a timing generation circuit for a document reading circuit used in a high-speed facsimile machine.

〗〗〗〗〕

The present invention, in a document reading circuit, separates the output of a variable frequency divider into two systems, divides the frequency of each at an appropriate frequency division ratio, and applies the frequency to the motor dry nose and image sensor driver as clock pulses, thereby reading the document. The conveying speed in the sub-scanning direction and the scanning speed of the image sensor in the main scanning direction can be set independently in a synchronized state, and the resolution setting can be changed.

[Conventional technology]

FIG. 2 is a block diagram of a conventional document reading circuit.

Conventionally, a document reading circuit having a configuration as shown in FIG. 2 has been used. That is, the output of the oscillator 1 is given to the frequency divider 2, and the output of the frequency divider 2 is given to the variable frequency divider 3. The output of the variable frequency divider 3 is given to a motor driver 6 and a sensor driver 7. The output of the motor driver 6 is given to the stepping motor 8, and the output of the sensor driver 7 is given to the image sensor 9. The output of the control circuit 12 is given to the variable frequency divider 3 to control the frequency division ratio.

The stepping motor 9 mechanically drives a transport roller (not shown) to transport the original document 10 to be read. The image on the original document 10 to be read is transmitted to the image sensor 9 by the lens 11.
An image is formed on the imaging surface of the image sensor 9, and converted into an electrical signal by the image sensor 9. The control circuit 12 controls the conveyance speed of the stepping motor 9 by controlling the frequency division ratio of the variable frequency divider 3. Every time the variable frequency divider 3 outputs one pulse, the stepping motor 8 transfers the document to the facsimile I.
It is conveyed by an amount equivalent to one line in the sub-scanning direction at the J i position. The sensor driver 7 drives the image sensor 9 every time one pulse of the output from the variable frequency divider 3 is output, and scans one line of image in the main scanning direction.

Since the sensor driver 7 receives the output of the variable frequency divider 3 similarly to the motor driver 6, the image sensor 9 scans the image every time the original to be read 10 moves one line in the sub-scanning direction.

[Problem that the invention seeks to solve]

However, in such conventional document reading circuits, the image sensor is mechanically driven for each line in the sub-scanning direction to scan the image of the document, so there is less freedom in setting the resolution in the sub-scanning direction. There were no drawbacks.

The present invention solves the above-mentioned drawbacks, and allows the speed at which the document is conveyed in the sub-scanning direction and the speed at which the image sensor scans in the main-scanning direction to be set independently while being synchronized, thereby increasing the degree of freedom in setting the resolution. The purpose of the present invention is to provide a document reading circuit with improved functionality.

[Means for solving problems]

In the document reading circuit, the present invention includes a second frequency divider that divides the output of the variable frequency divider and supplies the clock pulse to the motor driver, and a second frequency divider that divides the output of the variable frequency divider and supplies the clock pulse to the motor driver. The present invention is characterized in that it is equipped with a 30 frequency divider that provides the clock pulse.

[Effect]

The 20th frequency divider divides the output of the variable frequency divider and gives it to the motor driver as the clock pulse, and the 30th frequency divider divides the output of the variable frequency divider and supplies the clock pulse to the sensor driver. Give as a pulse.

The frequency division ratio of the 20th frequency divider and the 30th frequency divider is set according to the resolution. By the above-described operation, the conveying speed of the document in the sub-scanning direction and the scanning speed of the image sensor in the main-scanning direction can be set independently in a synchronized state, and the resolution can be changed.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings. 1st
The figure is a block diagram of a document reading circuit according to an embodiment of the present invention. In FIG. 1, the document reading circuit includes an oscillator 1 that oscillates a clock pulse, a frequency divider 2 as a 10 frequency divider that divides the output of the oscillator 1, and a frequency divider 2 that divides the output of the frequency divider 2. A variable frequency divider 3 with a variable frequency division ratio, a control circuit 12 that controls the variable frequency divider 3 and the entire device, a stepping motor 8 that transports the original to be read 10 in the sub-scanning direction, and drives the stepping motor 8. and an image sensor 9 that converts the image on the document 10 to be read into an electrical signal.
, a sensor driver 7 that scans the image sensor 9 in the main scanning direction, and a lens 11 that forms an image of the read document 10 on the imaging surface of the image sensor 9.

Here, the feature of the present invention is that a frequency divider 4 is used as a second frequency divider which divides the output of the variable frequency divider 3 and supplies the clock pulse to the motor driver 6; A frequency divider 5 is provided as a 30 frequency divider which divides the frequency of the output of and supplies it to the sensor driver 7 as a clock pulse.

The operation of the document reading circuit having such a configuration will be explained. In FIG. 1, a clock pulse from an oscillator 1 is divided into a frequency of 1/N1 by a frequency divider 1, and is applied to a variable frequency divider 3. The frequency division ratio of the variable frequency divider 3 is controlled by the control circuit 12. The output of variable frequency divider 3 is given to frequency divider 4 and frequency divider 5. Therefore, the outputs of frequency divider 4 and frequency divider 5 are indirectly controlled by control circuit 12.

The control circuit 12 controls the speed of the stepping motor 8 by controlling the frequency division ratio of the variable frequency divider 3. Every time the frequency divider 4 outputs N pulses, the stepping motor 8 conveys the document in the sub-scanning direction by an amount corresponding to one line. The value of this NF is usually set to 2-4. The sensor driver 7 drives the image sensor 9 every time one pulse of the output from the frequency divider 5 is output, and scans one line of image in the main scanning direction.

The frequency division ratio of frequency divider 4 is 1/N4, and the frequency division ratio of frequency divider 5 is 1/N4.
If it is N5, the image sensor will read N4 XNF scanning lines when the document 10 to be read is conveyed N5 lines.

〔Effect of the invention〕

As described above, the present invention has the excellent effect that the conveying speed of the document in the sub-scanning direction and the scanning speed of the image sensor in the main scanning direction can be set independently, and that the resolution setting can be changed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a document reading circuit according to an embodiment of the present invention. FIG. 2 is a block diagram of a conventional document reading circuit. DESCRIPTION OF SYMBOLS 1... Oscillator, 2.4.5... Frequency divider, 3... Variable frequency divider, 6... Motor driver, 7... Sensor driver 8... Stepping motor, 9... Image sensor, 10... Original to be read, 11... Lens, 12...
・Control circuit. Patent applicant: NEC Corporation, 6 Agent: Patent attorney Naotaka Ide t゛Conventional example diagram

Claims (1)

[Claims] 1. An oscillator that oscillates a clock pulse, a first frequency divider that divides the output of this oscillator, and a frequency division ratio that divides the output of this first frequency divider is variable. a variable frequency divider, a stepping motor that transports the original to be read in the sub-scanning direction, a motor driver that drives this stepping motor, an image sensor that converts the image of the original to be read into an electrical signal, and a main component that uses this image sensor. A document reading circuit including a sensor driver that scans in a scanning direction, a second frequency divider that divides the output of the variable frequency divider and supplies the frequency to the motor driver as a clock pulse, and the variable frequency divider and a third frequency divider that frequency-divides the output of the circuit and supplies the frequency-divided signal to the sensor driver as a clock pulse.