JP3476599B2 - Image reading device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, and more particularly, to an image reading apparatus which can be applied to a facsimile apparatus, a copying apparatus or the like and can read a double-sided original.

[0002]

2. Description of the Related Art Recently, in order to save resources, information is recorded on both sides of a recording paper, and an original having information recorded on such both sides can be read by one reading means. If each side is read, the usability of the image reading device is poor.

Therefore, conventionally, an image reading apparatus having a contact type image sensor on one side of a document conveying path and a reduction optical system CCD linear image sensor on the other side (see Japanese Patent Laid-Open No. 3-240361). ) Is proposed.

In this image reading apparatus, regardless of the original reading mode of reading both sides or one side of the original, the same operation always reads both sides and one side of the original, and the CCD. No mention is made of the processing of signals read by the linear image sensor and the contact image sensor.

According to this image reading apparatus, once the double-sided original is set in the facsimile apparatus, the image information of the double-sided original can be read at one time, the usability of the image reading apparatus can be improved, and the image reading can be performed. The device can be small and inexpensive.

[0006]

However, in such a conventional image reading apparatus, regardless of whether the document is read on both sides of the document or on one side, the same operation always causes both sides of the document to be read. Since the CCD linear image sensor and the contact image sensor read the image information on both sides of the original properly, it is necessary to always match the operation clock of the contact image sensor with a slow operation clock. However, there is a problem that the operation speed of the image reading device is slow and the usability is poor, and when the operation speed is high, image information cannot be read properly and the image quality deteriorates.

Therefore, according to the present invention, the operation clock of the reading means, the document conveying speed, and the signal amplification level are changed according to the double-sided reading mode or the single-sided reading mode.
It is an object of the present invention to provide an image reading apparatus that is small in size and inexpensive, and that can improve image quality while improving processing speed.

[0008]

The image reading apparatus of the present invention comprises:
As described in claim 1, a first reading unit that operates based on a predetermined operation clock to read image information on one side of the document and output an image signal; and based on a predetermined operation clock A second reading unit that operates to read image information on the other side of the document and output an image signal; a selection unit that selects a document reading mode for reading one side or both sides of the document; The frequency of the operation clock supplied by the clock generating means is changed according to the document reading mode selected by the selecting means and the clock generating means for supplying the operation clock to the first reading means and the second reading means. A CCD image sensor using a reduction optical system is used as the first reading means, and the second reading means is a contact-type image using the same magnification optical system. Jisensa are used, the control means operates the supply clock generating means Black
Check that the original scanning mode is double-sided or back-side mode.
In this case, the circumference suitable for the operation of the contact type image sensor
In case of the wave number and the original reading mode is the front mode
Is a frequency suitable for the operation of the CCD image sensor.
To switch to.

[0009]

[0010]

[0011]

[0012]

[0013]

In this way, in the single-sided reading mode, the image information of the original is read at high speed only by the CCD image sensor, and in the double-sided reading mode, the images on both sides of the original are read by the CCD image sensor and the contact image sensor. When reading information, by adjusting the operation clock of the CCD image sensor to the contact type image sensor, in both single-sided reading mode and double-sided reading mode,
The image information of the original can be read appropriately and at high speed, the image quality can be improved, and the processing speed can be increased to improve the usability of the image reading apparatus.

Further, for example, as described in claim 2, the image reading apparatus further comprises an original document conveying means for conveying the original document on a predetermined original document conveyance path at a predetermined speed.
The control means, the conveying speed of the document by the front SL document conveying means, the original reading mode is double-sided or back mode
In the case of, it is suitable for the operation of the contact type image sensor.
Speed, and if the original reading mode is front mode
Is a speed suitable for the operation of the CCD image sensor.
To, or may be varied.

With this arrangement, the document is conveyed at a document conveyance speed suitable for the operating characteristics of the first reading unit and the second reading unit according to the document reading mode, and the first reading unit and the second reading unit are used. The image information of the document can be properly read by the reading means.

As a result, the quality of read images of both double-sided originals and single-sided originals can be improved, and the processing speed can be increased to improve the usability of the image reading apparatus.

Furthermore, for example, as described in claim 3, wherein the first reading hand stage, a signal amplifying means for amplifying the signal level of the output image signal, further wherein the control means, the signal The amplification factor of the amplification means is set to the original reading mode.
Is small in the double-sided mode,
When the mode is the surface mode, it is large and may be changed.

With this arrangement, the signal levels of the output image signals of the first reading means and the second reading means can be kept constant according to the original reading mode, and the image quality can be improved. Therefore, the usability of the image reading device can be improved.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Since the embodiments described below are preferable specific examples of the present invention, various technically preferable limitations are given, but the scope of the present invention is particularly limited in the following description. The present invention is not limited to these embodiments unless there is a statement to limit the invention.

1 to 16 are views showing an embodiment of the image reading apparatus of the present invention.

FIG. 1 is an overall schematic configuration diagram of a facsimile apparatus 1 to which an embodiment of the image reading apparatus of the present invention is applied.

Referring to FIG. 1, the facsimile apparatus 1 has an AD on the upper portion of a main body case 2 which can be opened and closed in a predetermined direction at a predetermined angle.
An F (automatic document feeder) 3 is attached to the book-type facsimile apparatus 1 that can read a so-called book-type document (hereinafter referred to as a book document).

The facsimile apparatus 1 includes a reduction optical system reading unit (first reading unit) 4 and a contact image sensor (second reading unit) 5 which is a unit magnification optical system reading unit. The reading unit 114 is housed in the main body case 2, and the contact image sensor 5 is housed in the ADF 3.

On the upper surface of the main body case 2, a contact glass 6 and a surface shading plate 7 are arranged side by side,
Below the contact glass 6 in the main body case 2, the light source 8, the first mirror 9, and the second mirror 9 which constitute the reduction optical system reading unit 4 are provided.
A mirror 10, a lens 11 and a CCD linear image sensor 12 are housed.

The light source 8 and the first mirror 9 are mounted on the first traveling body 13, and the second mirror 10 is mounted on the second traveling body 14.

The first traveling body 13 and the second traveling body 14 are
The optical path length from the mirror 9 to the CCD linear image sensor 12 is always the same optical path length (see FIG. 1).
The surface of the document 25 set on the contact glass 6 is scanned by relatively moving in the middle left and right directions.

When the document 25 is set on the contact glass 6, the light emitted from the light source 8 to the document 25 is reflected by the first mirror 9 on the surface of the document, and the first mirror 9 reflects the incident light to the second mirror. Reflect to 10. The second mirror 10 reflects the incident light onto the lens 11, and the lens 11 reflects the incident light onto the CC.
An image is formed on the light receiving surface of the D linear image sensor 12.

The CCD linear image sensor 12 photoelectrically converts the light incident through the lens 11 and outputs an image signal.

The ADF 3 includes an original placing table 15, a paper feed roller pair 16, a contact image sensor 5, a back shading plate 17, a guide plate 18, a conveyor belt 19, a conveyor roller pair 20, a guide plate 21, and a discharge roller pair. 22 and a document discharge tray 23, and the like, the paper feed roller pair 16, the guide plate 18, the conveyance belt 19, the guide plate 21, and the discharge roller pair 22 convey the document as a whole on the document conveyance path 2.
4 is forming.

The contact-type image sensor 5 is arranged in the middle of the document transport path 24, reads image information on the back surface of the document 25 being transported through the document transport path 24, and outputs an image signal.

The contact image sensor 5 uses an LED (Light Emitting Diode) array or the like as the light source 26, and the light emitted from the light source 26 to the back surface of the original 25 being conveyed is reflected on the back surface of the original 25. , And is introduced into the CCD image sensor 28 by the SELFOC lens 27.

That is, the contact-type image sensor 5 uses an equal-magnification optical system and is structurally compact and inexpensive in price as compared with the reduction optical system reading unit 4, but the cell Since the depth of focus of the Fock lens 27 is very shallow, if the optical path length from the light receiving surface of the CCD image sensor 28 to the surface of the document 25 such as the binding portion of a book document changes, the image is out of focus and the image is blurred. There is.

However, when the contact type image sensor 5 is used for reading a sheet-like document (hereinafter referred to as a sheet document) 25 conveyed by the ADF 3, as in the present embodiment, the change in the optical path length is small. Therefore, it is possible to obtain a clear image without defocusing.

Further, since the LED 25 is used as the light source, the light amount is smaller than that of the reduction optical system reading section 4,
If the output signal of the CCD image sensor 28 is processed at the same signal level as the output signal of the CCD linear image sensor 12, the image deteriorates.

In general, the CCD linear image sensor 12
The specified value of the pixel clock that specifies the operation of is 3 to 4 times the specified value of the CCD image sensor 28.

Therefore, in the present embodiment, as will be described later, the operation clock (pixel clock) of the CCD linear image sensor 12 of the reduction optical system reading unit 4 and the document conveying speed are closely contacted according to the document reading mode. The CCD linear image sensor 1 is switched to the one suitable for the operation of the CCD image sensor 28 of the mold image sensor 5.
The amplification factor of the image signal output by the output signal 2 is changed.

In the ADF 3, a plurality of sheet originals 25 are set on the original table 13, the set sheet originals 25 are separated one by one by the paper feed roller pair 16, and the original conveying path 2 is provided.
4 and the image information on the back surface of the sheet original 25 conveyed through the original conveying path 24 is read by the contact image sensor 5.

When the sheet original 25 is conveyed to the conveyor belt 19, the conveyor belt 19 conveys it to a predetermined reading position on the contact glass 6 and sets it.

The image information on the surface of the sheet original 25 set on the contact glass 6 is read by the reduction optical system reading unit 4, and the read sheet original 25 is completed.
Is a conveyor belt 19, a guide plate 21, and a pair of discharge rollers 2.
The document is discharged onto the document discharge table 23 by 2.

The front surface shading plate 7 and the back surface shading plate 17 have white surfaces, and are used for shading correction of the reduction optical system reading unit 4 and the contact image sensor 5.

As described above, the ADF 3 is attached to the main body case 2 so as to be openable and closable in a predetermined direction at a predetermined angle. By opening the ADF 3, a book document is set on the contact glass 6.

The image information of the book original set on the contact glass 6 is read by the reduction optical system reading unit 4.

The facsimile machine 1 has a circuit configuration as shown in FIG.

The facsimile apparatus 1 includes a reduction optical system reading unit 4, a clock generator 31, a contact image sensor 5, a plotter 32, an encoding / decoding unit 33, a communication control unit 34, a modem 35, a document conveyance control unit 36, The system control unit 37, the operation unit 38, the display unit 39, the image memory 40, the reading mode selection switch 41, and the like are provided, and the above units are connected by a bus 42.

The reduction optical system reading section 4 includes the reduction optical system and the CCD linear image sensor 12 and also has a signal processing circuit (not shown). The image signal output from the CCD linear image sensor 12 is predetermined by the signal processing circuit. Signal processing is performed and the result is output to the bus 42.

The reduction optical system reading section 4 operates based on the operation clock input from the clock generator 31.

That is, the operation timings of the first traveling body 13, the second traveling body 14, and the CCD linear image sensor 12 operate based on this operation clock, and in particular, C
The CD linear image sensor 12 photoelectrically converts in synchronization with an operation clock (pixel clock) input from the clock generator 31, and outputs an image signal.

The clock generator 31 generates an operation clock for controlling the operation timing of the reduction optical system reading unit 4 and the contact image sensor 5, and in particular, as shown in FIG. A CCD clock generation circuit 50 for generating an operation clock (pixel clock) for controlling the operation timing of the CCD linear image sensor 12 and the CCD image sensor 28 of the contact image sensor 5 is provided.

As shown in FIG. 3, the CCD clock generation circuit 50 is provided with a counter 51, a multiplexer 52 and two drive clock generation circuits 53 and 54. The counter 51 is a 1/2 frequency divider 51a. 1/4 frequency divider 51
.., 1 / n frequency divider 51n.

The basic clock CLK0 having a predetermined frequency is input to each of the frequency dividers 51a to 51n of the counter 51, and the counter 51 divides the basic clock CLK0 into 1/2 by each of the frequency dividers 51a to 51n. 1/4 frequency division ...
., Divided by 1 / n, operating clocks CLK, 2
, NCLK are output to the multiplexer 52.

The multiplexer 52 operates under the control of the system controller 37 shown in FIG.
Operation clocks CLK and 2C input from 1a to 51n
, NCLK among a predetermined number of operation clocks CLK, 2CLK, ..., NCLK designated by a select signal input from the system control unit 37 among LK ,. Output to.

The drive clock generating circuit 53 operates clocks CLK and 2CL input from the multiplexer 52.
Based on K, ..., NCLK, the start pulse ST, the clock pulse PHCCD, PH1 and the reset pulse RS shown in FIG. 4 are generated and output to the CCD image sensor 28 of the contact image sensor 5.

The drive clock generating circuit 54 operates clocks CLK and 2CL input from the multiplexer 52.
Based on K, ..., NCLK, the shift pulse SH, the clock pulse PH, and the reset pulse RS shown in FIG. 5 are generated and output to the CCD linear image sensor 12 of the reduction optical system reading unit 4, which will be described later. 5 according to the frequency of the operation clock selected by the multiplexer 52.
The high frequency pulses SH, PH, and RS shown in FIG. Pulse ST, PHCC for contact image sensor 5
Pulses SH, PH of the same low frequency as D, PH1, RS,
RS is generated and output to the CCD linear image sensor 12 of the reduction optical system reading unit 4.

The start pulse SH and the shift pulse ST are pulses for driving the shift electrodes that pass through when the signal charges accumulated in the photosensitive portions of the CCD image sensor 28 and the CCD linear image sensor 12 are transferred to the transfer portion. Yes, it occurs for each line. Clock pulse PH,
PHCCD and PH1 are pulses for driving a transfer unit that transfers the signal charges generated in the photosensitive units of the CCD image sensor 28 and the CCD linear image sensor 12 to the output unit, and the reset pulse RS is the CCD image sensor 28.
And a drive pulse for returning the output part for converting the signal charge transferred from the transfer part of the CCD linear image sensor 12 to a voltage to the initial state for detecting the signal charge.

The CCD linear image sensor 12 of the reduction optical system reading unit 4 operates based on each pulse SH, PH, RS which is an operation clock input from the clock generator 31, photoelectrically converts incident light, and an image is obtained. Output a signal.

Further, the reduction optical system reading section 4 has an amplifier circuit 60 as shown in FIG. 6 in its signal processing circuit,
An amplifier gain variable circuit 61 that changes the gain (amplification factor) is connected to the amplifier circuit 60.

The amplifier circuit 60 is a video amplifier (AMP).
A resistor R1 and a capacitor C1 for removing noise are connected to an input portion of 62, and the video amplifier 62 receives the sensor output OS of the CCD linear image sensor 12 to be input.
The input image signal of 1 (see FIG. 5) is amplified according to the set gain of the amplifier gain variable circuit 61 and output as an output image signal.

The amplifier gain variable circuit 61 is composed of a multiplexer (MUL) 63 and three resistors R2, R3 and R4. The multiplexer 63 operates according to a select signal from the system control section 37 to turn on the resistor R2. The resistors R3 and R4 are alternatively connected.

In the amplifier gain variable circuit 61, the resistance value changes depending on whether the resistor R2 is connected to the resistor R3 or the resistor R4 by the multiplexer 63, and the gain of the video amplifier 62 becomes 1 of the gain A0 and the gain A0. The gain A0 / 4, which is / 4, is selectively switched.

The contact type image sensor 5 includes the light source 2
6, including the Selfoc lens 27 and the CCD image sensor 28, and having a signal processing circuit (not shown),
The image signal output from the CCD image sensor 28 is subjected to predetermined signal processing by a signal processing circuit and output to the bus 42.

The contact image sensor 5 operates on the basis of the respective pulses ST, PHCCD, PH1 and RS which are operation clocks input from the clock generator 31, photoelectrically converts incident light, and an image signal is not shown. The signal is processed by the signal processing circuit and then output to the bus 42.

The signal processing circuit includes an amplifier circuit for amplifying the image signal output from the CCD image sensor 28. As will be described later, this amplifier circuit operates the CCD image sensor 28 at the constant frequency. Each pulse S
Since it is performed in synchronization with T, PHCCD, PH1, and RS, it is fixedly adjusted in advance according to the characteristics of the CCD image sensor 28.

Referring again to FIG. 2, as the plotter 32, for example, a thermal recording device using a thermal element or an electrophotographic recording device is used, and the plotter 32 is
When the thermal recording device is used, the received image information or the image read by the reduction optical system reading unit 4 or the contact image sensor 5 is directly applied to the thermal recording paper or indirectly to the ordinary recording paper via an ink sheet. Record the information.

The encoding / decoding unit 33 is intended to shorten the transmission time of the image information and improve the efficiency, and the efficiency of storing the image information in the image memory 40. The image information is encoded by a predetermined encoding method. The encoded image information is decoded according to the following.

The communication control section 34 exchanges a facsimile control signal with the facsimile apparatus of the other party and executes a facsimile communication procedure.

The communication controller 34 has a built-in network controller and automatically receives a call from the line L via the modem 35 and performs an automatic call processing to the line L.

The communication control section 34 is connected to a modem 35, and a line L, for example, a telephone line is connected to the modem 35.

The modem 35 modulates the transmission signal and demodulates the reception signal.

The original document conveyance control unit 36 controls the conveyance of the original document by the ADF 3, and the stepping motor 7 shown in FIG.
1, a driver circuit 72, a motor drive control circuit 73 shown in FIG. 8, and the like.

The stepping motor 71 includes a pair of feed rollers 16 of the ADF 3, a pair of feed rollers 20, and a pair of discharge rollers 22.
Is controlled by controlling the rotation speed of the stepping motor 71 so that the conveyance speed of the sheet original 25 conveyed by the ADF 3 is controlled.

The stepping motor 71 is driven by the 2-phase drive current or 1-2 phase drive current input from the driver circuit 72, and the driver circuit 72 is input from the motor drive control circuit 73 shown in FIG. A drive current corresponding to the phase excitation signals A, −A, B, and −B of a predetermined frequency (− indicates the opposite phase of the corresponding A and B, respectively) is generated and output to the stepping motor 71. To do.

The motor drive control circuit 73 uses the counter 7
4, multiplexer 75 and phase excitation pattern generation circuit 7
6 and the like, and the counter 74 is a 1/2 frequency divider 74.
a, 1/4 frequency divider 74b, 1/8 frequency divider 74c, ...
., 1 / n frequency divider 74n.

The basic clock CLK0 having a predetermined frequency is input to each of the frequency dividers 74a to 74n of the counter 74, and the counter 51 divides the basic clock CLK0 into 1/2 by each of the frequency dividers 74a to 74n. 1/4 frequency division, 1/8
.., 1 / n, and output to the multiplexer 75 as operation clocks CLK, 2CLK, 4CLK ,.

The multiplexer 75 operates under the control of the system controller 37 shown in FIG.
Operation clocks CLK and 2C input from 4a to 74n
, NCLK among the LK, 4CLK, ..., NCLK selected by the select signal input from the system control unit 37, and output to the phase excitation pattern generating circuit 76. To do.

The phase excitation pattern generating circuit 76 operates with the operation clocks CLK and 2CL input from the multiplexer 75.
.., nCLK are used to generate phase excitation signals A, -A, B, and -B, which are phase excitation patterns corresponding to the frequency of the operation clock, and the driver circuit 72 shown in FIG. Output to.

When the stepping motor 71 is driven by two-phase excitation, the phase excitation pattern generating circuit 76 generates the excitation patterns of the phase excitation signals A, -A, B, -B as shown in FIG. Motor 71 1-
When driven by two-phase excitation, excitation patterns of the phase excitation signals A, -A, B, -B as shown in FIG. 10 are generated.

Further, when the stepping motor 71 is rotated counterclockwise, the phase excitation pattern generating circuit 76 causes the phase excitation signals A, -A, B, of the excitation patterns in the directions in which the steps in FIGS. 9 and 10 increase. When -B is generated and the stepping motor 71 is rotated clockwise,
The phase excitation signals A, -A, B, and -B of the excitation pattern in the direction in which the steps of FIGS. 9 and 10 decrease are generated.

The system control unit 37 includes the multiplexer 7
By outputting the select signal to 5, the counter 74
Operation clock CLK, 2CLK, 4CL input from
.., nCLK, the image reading of the original 25 is performed by the reduction optical system reading unit 4 or the contact type depending on whether the original reading mode is the front side reading mode, the back side reading mode or the double side reading mode. An operation clock CLK having a frequency that is a conveyance speed of the document 25 suitable for being read by the image sensor 5,
2CLK, 4CLK, ..., nCLK are selected, and the operation clocks CLK, 2CLK, and
The phase excitation pattern generation circuit 76 generates the phase excitation signals A, -A, B, and -B based on 4CLK, ..., NCLK, and outputs them to the driver circuit 72.

For example, stepping motor 7 with two-phase excitation
1 is driven, the system control unit 37 reads the back surface of the original 25 by the contact image sensor 5 in the back side reading mode and the double side reading mode. Therefore, as shown in FIG. The multiplexer 75 is caused to select the operation clock CLK at which the document conveyance speed Vo is suitable for the sensor 5 to read the image information on the back surface of the document 25, and the phase excitation signals A, -A, B, having the frequencies corresponding to the operation clock CLK are selected. -B is the phase excitation pattern generation circuit 7
6 to generate.

Further, since the system control section 37 reads the image information of the original 25 only by the reduction optical system reading section 4 in the front side reading mode, as shown in FIG. 12, the original conveyance speed is reduced by the reduction optical system reading section. 4 is an operation clock 4CLK that is an original conveyance speed suitable for reading image information on the surface of the original 25, for example, an original conveyance speed 4Vo that is four times the original conveyance speed Vo when the contact type image sensor 5 is used for reading. , And the phase excitation signals A, −A of the excitation pattern of the frequency corresponding to the operation clock 4CLK,
B and -B are generated by the phase excitation pattern generation circuit 76.

The driver circuit 72 generates a drive current by the phase excitation signals A, -A, B, -B input from the phase excitation pattern generation circuit 76 of the motor drive control circuit 73,
The stepping motor 71 is driven by the phase excitation signals A, -A, B,-.
It is driven at a speed corresponding to the frequency of B, and the document conveying speeds Vo and 4V corresponding to the frequency of the operation clock CLK or the operation clock 4CLK selected by the multiplexer 75.
The document 25 is conveyed at o.

The system control unit 37 has a CPU (Central
Processing unit), ROM (Read Only Memory), RAM (Random Access Memory), etc., and various processing programs such as a basic processing program as the facsimile apparatus 1 and a double-sided / single-sided original reading control processing program are stored in the ROM. In addition, system data and the like necessary for executing the basic processing program, the double-sided / single-sided original reading control processing program, and the like are stored.

In the system controller 37, the CPU is RO
While using the RAM as a work memory based on the program in M, it controls each part of the facsimile apparatus 1,
In addition to performing the process as the facsimile apparatus 1, the double-sided / single-sided document reading control process, particularly a CCD clock control process, a document conveyance speed control process, and an image signal amplification control process, which will be described later, are executed.

The operation unit 38 includes various operation keys necessary for operating the facsimile apparatus 1, for example, ten keys, function keys, start key, stop key, and FIGS.
A reading mode selection switch 41 shown in is provided.

The reading mode selection switch 41 is used for the document 25.
It is used to select a document reading mode of whether to read the front side of the document, the back side of the document 25, or the front and back sides of the double-sided document 25, and is provided in the operation unit 38, for example.

In the vicinity of the reading mode selection switch 41, as shown in FIG. 13, the reading mode selection switch 4 is provided.
Lamps 81, 82, and 83 for lighting and displaying the original reading mode selected by 1 are provided.

The lamps 81, 82, 83 are, for example, LE
The lamp 81 is composed of a D (Light Emitting Diode).
13 shows a front side reading mode for reading the front side of the original 25, a lamp 82 for a rear side reading mode for reading the back side of the original 25, and a lamp 83 for a double side reading mode for reading the front and back sides of the double sided original 25. Are shown respectively.

Note that FIG. 13 shows a state in which the lamp 83 shown in black is turned on and the double-sided reading mode for reading the front and back surfaces of the double-sided original 25 is selected as the original reading mode.

Again, in FIG. 2, the display unit 39 is, for example, an LCD (liquid crystal display), and various commands input from the operation unit 38 and transmitted from the facsimile machine 1 to the operator are displayed on the display unit 39. Various information to be displayed is displayed.

The image memory 40 is composed of, for example, a RAM, and the reduction optical system reading section 4 and the contact image sensor 5 are provided.
The image information for transmission, the image information for reception, and the like read in step 1 are temporarily stored.

Next, the operation will be described.

In this embodiment, the reading operation of the reduction optical system reading section 4 and the document conveying speed are changed depending on whether the document reading mode is the front side reading mode, the back side reading mode or the double side reading mode. The feature is that the image information of the document 25 is appropriately read by the reduction optical system reading unit 4 and the contact image sensor 5, and the read image signal is processed appropriately and at high speed to obtain a good image. is there.

The double-sided / single-sided original reading control process will be described below.

First, the CCD clock control processing for adjusting the operation clock (pixel clock) of the CCD linear image sensor 12 of the reduction optical system reading unit 4 to read the original 25 appropriately will be described with reference to the flowchart shown in FIG. Will be described below.

When reading the original 25, the system control section 37 first checks whether the double-sided reading mode is selected by the reading mode selection switch 41 as shown in FIG. 14 (step S1). When selected, the image information of the document 25 is read by both the reduction optical system reading unit 4 and the contact image sensor 5.

However, since the light source 27 of the contact-type image sensor 5 uses an LED or the like as described above, the accumulation time is lengthened in order to obtain an output signal of a certain amount with a small amount of light. In addition, since the CCD image sensor 28 of the contact image sensor 5 has one CCD image sensor 28 formed from a plurality of elements, there is variation in sensitivity between elements and AC / DC component, and accumulation. If the time is short, the variation with respect to the output image signal becomes large, and therefore the accumulation time needs to be lengthened. In particular, when the pixels of the CCD image sensor 28 are arranged in a staggered pattern, the transfer time of the line memory for correcting the spatial deviation of the reading position due to the chip arrangement is necessary.

Therefore, the system controller 37 causes the multiplexer 52 of the CCD clock generation circuit 50 of the clock generator 31 to use, for example, as a pixel clock of a frequency at which the contact image sensor 5 can appropriately read the image information of the original 25. An operation clock CLK (hereinafter, referred to as a pixel clock fo) is selected, and the drive clock generation circuit 53 uses the pixel clock fo to generate the contact image sensor 5 corresponding to the frequency of the pixel clock fo shown in FIG. Operation pulse ST, PHCCD, PH1,
A drive clock generation circuit 54 for generating RS
Based on the pixel clock fo, the operation pulse S for the reduction optical system reading unit 4 corresponding to the frequency of the pixel clock fo
H, PH, and RS are generated (step S2).

The system control section 37 operates the contact type image sensor 5 for the double-sided original 25 conveyed through the original conveying path 24 by the operation pulses ST, PHCCD, PH1 and RS based on the pixel clock fo, thereby causing the double-sided original. When the image information on the back surface of 25 is read and the double-sided document 25 is conveyed to a predetermined reading position on the contact glass 6 and set, operation pulses SH, P based on the pixel clock fo.
The reduction optical system reading unit 4 is operated by H and RS to read the image information on the front surface of the double-sided document 25 (step S
3).

When the double-sided reading mode is not selected in step S1, it is checked whether the front-side reading mode is selected (step S4). When the front-side reading mode is selected, the reduction optical system reading unit 4 determines Since only the image information on the surface of the original 25 is read, the system control unit 37 uses, for example, the operation clock CLK as a pixel clock having a frequency suitable for the operation of the reduction optical system reading unit 4.
The operating clock 4CLK (hereinafter, referred to as pixel clock 4fo) having a frequency four times higher than that of the pixel clock 4fo is selected by the multiplexer 52, and the driving clock generation circuit 54 is operated based on the pixel clock 4fo as shown in FIG. Four
The operation pulses SH, PH, and RS for the reduction optical system reading unit 4 corresponding to the frequency fo are generated (step S5).

The system control unit 37 operates the reduction optical system reading unit 4 by the operation pulses SH, PH, RS based on the pixel clock 4fo to read the image information on the surface of the document 25 (step S6).

In step S4, when the front side reading mode is not selected, it is checked whether the back side reading mode is selected (step S7). When the back side reading mode is selected, only the contact image sensor 5 is used. Since the image information on the back surface of the original 25 is read, the system control unit 37 selects, for example, the pixel clock fo as the pixel clock having a frequency suitable for the operation of the contact image sensor 5, and the drive clock generation circuit 53.
Based on this pixel clock fo, as shown in FIG. 4, operation pulses ST, PHCCD, PH1 for the contact image sensor 5 corresponding to the frequency of the pixel clock fo,
RS is generated (step S8).

The system controller 37 operates the operation pulses ST, PHCCD, PH1, R based on the pixel clock fo.
By S, the contact image sensor 5 is operated to read the image information on the back surface of the document 25 (step S9).

When the back side reading mode is not selected in step S7, it is determined that the original reading mode is not set, and the process returns to step S1.
The same process is performed from the beginning.

Therefore, when the image information on the front surface of the original 25 is read only by the reduction optical system reading unit 4, the reading speed is suitable for the operation of the reduction optical system reading unit 4 and quickly and
The image information can be read properly, and the reduction optical system reading unit 4 and the contact-type image sensor 5 allow the double-sided document 25 to be read.
When the image information on both sides of the document 25 is read or when the image information on the back side of the document 25 is read only by the contact image sensor 5,
The image information can be read at a reading speed suitable for the operation of the contact image sensor 5, and the image information of the document 25 can be read appropriately.

Next, the operation clock of the document transport control section 36 is switched to control the document transport speed of the ADF 13, and the document transport speed control process for appropriately reading the document 25 will be described with reference to the flowchart shown in FIG. This will be described below.

Prior to starting the conveyance of the document 25, the system control section 37 first checks whether the double-sided reading mode is selected by the reading mode selection switch 41 as shown in FIG. 15 (step S11). When the double-sided reading mode is selected, the reduction optical system reading unit 4
The image information of the double-sided document 25 is read by both the contact type image sensor 5 and the contact type image sensor 5.

However, as described above, the contact type image sensor 5 needs to lengthen the accumulation time for one line in the main scanning direction in order to perform appropriate reading, and this time in the main scanning direction is lengthened. In order to do so, it is necessary to lengthen the time in the sub-scanning direction, that is, the document conveyance speed, in accordance with the time in the main scanning direction.

Therefore, the system control unit 37 uses, for example, as an operation clock for the contact type image sensor 5 to properly read the image information of the double-sided original 25 in the multiplexer 75 of the motor drive control circuit 73 shown in FIG. The operation clock CLK is selected, and the phase excitation pattern generation circuit 76 is caused to generate the phase excitation signals A, -A for the contact image sensor 5 corresponding to the frequency of the operation clock CLK shown in FIG. 11 based on the operation clock CLK. B and -B are generated and output to the driver circuit 72 shown in FIG.

The driver circuit 72 receives the phase excitation signal A,
A driving current corresponding to the frequencies of the phase excitation signals A, -A, B, and -B is output from -A, B, and -B to the stepping motor 71, and the stepping motor 71 is operated by the operation clock CLK.
The A / D conversion unit 13 is driven at the document transport speed Vo corresponding to the frequency of to transport the document 25 (step S1).
2).

The system control section 37 conveys the double-sided original document 25 through the original document conveyance path 24 at the original document conveyance speed Vo, and the operation pulse S based on the pixel clock fo.
The contact type image sensor 5 is operated by T, PHCCD, PH1 and RS to cause the contact type image sensor 5 to read the image information on the back surface of the double-sided document 25 conveyed at the document conveying speed Vo. When it is conveyed and set at a predetermined reading position on 6, the reduction optical system reading unit 4 is operated by the operation pulses SH, PH, RS based on the pixel clock fo, and the double-sided original 25
The image information on the surface of is read (step S13).

When the double-sided reading mode is not selected in step S11, it is checked whether the front-side reading mode is selected (step S14). When the front-side reading mode is selected, the reduction optical system reading unit 4 determines Since only the image information on the surface of the original 25 is read, the system controller 37 can quickly and appropriately convey the original 25 to quickly convey the original 25 to the predetermined reading position on the contact glass 6. As an operating clock,
For example, the multiplexer 75 is caused to select the operation clock 4CLK having a frequency four times the operation clock CLK (step S15).

Based on this pixel clock 4fo, the system control section 37 causes the drive clock generation circuit 54 to operate as shown in FIG.
2, the phase excitation signals A, -A, B, -B corresponding to the document transport speed 4Vo which is four times the document transport speed Vo.
Is generated and the document 25 is transported at a document transport speed of 4 Vo.

The system control section 37 controls the document transport speed of 4V.
The original 25 is placed at a predetermined reading position on the contact glass 6 with o.
Is conveyed, the reduction optical system reading unit 4 is operated by the operation pulses SH, PH, and RS based on the pixel clock 4fo to read the image information on the surface of the document 25 (step S16).

In step S14, when the front side reading mode is not selected, it is checked whether or not the back side reading mode is selected (step S17). When the back side reading mode is selected, the contact image sensor 5 is selected.
Since the image information on the back side of the document 25 is read only by
The system controller 37 causes the multiplexer 75 to select the operation clock CLK as an operation clock having a frequency suitable for the operation of the contact image sensor 5, and causes the phase excitation pattern generation circuit 76 to perform the operation based on the operation clock CLK. , Phase excitation signals A, −A, B, and −B for the contact image sensor 5 shown in FIG. 11 are generated.

The system control section 37 has a driver circuit 72.
Then, the drive current corresponding to the frequency of the phase excitation signals A, -A, B, and -B is output to the stepping motor 71, and the stepping motor 71 drives the ADF 13 at the document conveyance speed Vo corresponding to the frequency of the operation clock CLK. Then, the document 25 is conveyed (step S18).

The system control section 37 operates the operation pulses ST, PHCCD, PH1, R based on the pixel clock fo.
By S, the contact image sensor 5 is operated to read the image information on the back surface of the document 25 transported through the document transport path 24 at the document transport speed Vo (step S19).

When the back side reading mode is not selected in step S17, it is determined that the document reading mode is not set, the process returns to step S11, and the same process is performed from the beginning.

Therefore, when the image information on the surface of the original 25 is read only by the reduction optical system reading unit 4, promptly,
In addition, the document 25 can be properly conveyed at a document conveyance speed of 4 Vo
Can be conveyed to a predetermined reading position on the contact glass 6, and when the image information on both sides of the double-sided original 25 is read by the reduction optical system reading unit 4 and the contact type image sensor 5, or only the contact type image sensor 5. When the image information on the back surface of the original document 25 is read by, the image information of the original document 25 can be read appropriately by carrying the image information of the original document 25 at the original document transport speed Vo suitable for the operation of the contact image sensor 5.

Next, the amplifier circuit 6 for amplifying the image signal.
The signal amplification control processing for switching the gain of 0 and performing the appropriate signal amplification will be described below with reference to the flowchart shown in FIG.

That is, generally, the image signal output from the CCD is proportional to the illuminance on the light receiving surface and the main scanning time, that is, the accumulation time.
By switching the pixel clock to the pixel clock fo and the pixel clock 4fo having a frequency four times as high as the pixel clock fo in order to perform more appropriate reading, the CCD linear image sensor of the reduction optical system reading unit 4 responds to the change of the pixel clock. The signal level of the output image signal 12 changes.

Therefore, in the present embodiment, the amplification factor (gain) of the amplification circuit 60 for amplifying the output image signal of the CCD linear image sensor 12 is changed by the amplifier gain variable circuit 61 according to the original reading mode. There is.

That is, the system control unit 37 determines that the document 2
Prior to the start of conveyance of No. 5, first, as shown in FIG. 16, it is checked whether the double-sided reading mode is selected by the reading mode selection switch 41 (step S2).
1) When the double-sided reading mode is selected, the image information of the document 25 is read by both the reduction optical system reading unit 4 and the contact image sensor 5, so the system control unit 37, as described above, According to the characteristics of the contact image sensor 5, the reduction optical system reading unit 4 and the contact image sensor 5 are operated at the pixel clock fo, and the document 25 is transported at the document transport speed Vo.

Therefore, the system control unit 37 causes the multiplexer 63 of the amplifier gain variable circuit 61 shown in FIG. 6 to make a selection for reducing the gain of the amplification circuit 60 of the reduction optical system reading unit 4 to set the amplifier gain. Original transport speed V
An amplifier gain Ao having a small amplification factor that provides an appropriate signal level when the document 25 conveyed at 0 is read at the pixel clock fo is set (step S22).

After that, the system control section 37 operates the contact image sensor 5 on the basis of the pixel clock fo to operate the double-sided original document 25 conveyed on the original document conveyance path 24 at the original document conveyance speed Vo, thereby causing the double-sided original document 25 to move. When the double-sided document 25 is conveyed to a predetermined reading position on the contact glass 6 and set, the reduction optical system reading unit 4 is operated based on the pixel clock fo, and the double-sided document 25 is read on both sides. The image information on the front surface of the document 25 is read (step S23).

The output image signal of the CCD linear image sensor 12 of the reduction optical system reading unit 4 is amplified by the amplifier circuit 60 with the amplifier gain Ao set by the amplifier gain variable circuit 61, and then subjected to predetermined signal processing.

In step S21, when the double-sided reading mode is not selected, it is checked whether or not the front side reading mode is selected (step S24). When the front side reading mode is selected, the reduction optical system reading unit 4 determines Since only the image information on the surface of the original 25 is read, the reduction optical system reading unit 4 is operated at the pixel clock 4fo having a frequency four times the pixel clock fo, as described above.

Therefore, the system control unit 37 causes the amplifier gain variable circuit 61 as the amplifier gain to have a larger amplification factor than the amplifier gain Ao, for example, the amplifier gain Ao.
The amplifier gain 4Ao having an amplification factor of 4 times is set (step S25).

After that, when the document 25 is set at a predetermined reading position on the contact lens 6, the system control unit 37 operates the reduction optical system reading unit 4 based on the pixel clock 4fo to operate the document 25. After the image information on the surface is read and the output image signal of the CCD linear image sensor 12 of the reduction optical system reading unit 4 is amplified by the amplifier circuit 60 with the amplifier gain 4Ao set by the amplifier gain variable circuit 61, a predetermined signal is obtained. Perform processing (step S2)
6).

When the front side reading mode is not selected in step S24, it is checked whether the back side reading mode is selected (step S27). When the back side reading mode is selected, the contact type image sensor 5 is selected.
Since the image information on the back side of the document 25 is read only by
The system control unit 37 operates the contact image sensor 5 based on the pixel clock fo without adjusting the amplifier gain of the amplifier circuit 60, and the document is conveyed through the document conveyance path 24 at the document conveyance speed Vo. The image information on the back surface of the original 25 is read by the contact image sensor 5 (step S28).

When the back side reading mode is not selected in step S27, it is determined that the original reading mode is not set, the process returns to step S21, and the same processing is performed from the beginning.

Therefore, the amplifier gain of the amplification circuit 60 of the reduction optical system reading unit 4 can be adjusted according to the reading speed of the image signal of the reduction optical system reading unit 4, and the signal level of the image signal is always constant. Can be

As a result, the subsequent signal processing circuit can appropriately perform signal processing without performing complicated signal processing, and image quality can be improved.

As described above, according to the present embodiment, the CC of the clock generator 31 is changed according to the original reading mode.
CC of the reduction optical system reading unit 4 is added to the D clock generation circuit 50.
D linear image sensor 12 and contact type image sensor 5
The pixel clock supplied to the CCD image sensor 28 is changed to the pixel clocks fo and 4fo suitable for the operations of the CCD linear image sensor 12 and the CCD image sensor 28.
The CCD image sensor 28 and the CCD image sensor 28 can be operated by an operation clock (pixel clock fo, 4fo) suitable for each operation characteristic according to the original reading mode, and the reduction optical system reading unit 4 can be operated according to the original reading mode. And the contact type image sensor 5 appropriately and at high speed
The image information of 5 can be read.

As a result, the quality of the read images of both double-sided and single-sided originals can be improved, and the processing speed can be increased to improve the usability of the image reading apparatus 1.

Further, according to the present embodiment, according to the document reading mode, the document feeding speed by the ADF 3 is set to the document feeding speed Vo suitable for the operation characteristic of the CCD image sensor 28 of the contact image sensor 5. 25, the image information of the document 25 can be read properly,
It is possible to improve the quality of the read images of both the double-sided and single-sided originals 25, and increase the processing speed to improve the usability of the image reading apparatus 1.

Further, according to the present embodiment, since the amplification factor of the amplification circuit 60 of the reduction optical system reading unit 4 is changed according to the original reading mode, the CCD linear image of the reduction optical system reading unit 40 is changed. The signal level of the output image signal of the sensor 12 can always be made constant, and the image quality can be improved.

Although the invention made by the present inventor has been specifically described based on the preferred embodiments, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the scope of the invention. It goes without saying that it can be changed.

For example, in the above-described embodiment, the case where the present invention is applied to the book type facsimile apparatus 1 has been described, but the present invention is not limited to the book type facsimile apparatus.
As shown in FIG. 17, the present invention can be similarly applied to a so-called sheet type facsimile apparatus 100 that reads only a sheet original.

In the facsimile apparatus 100, a document placing table 101 is formed on an upper part of its main body case 100a, and a pair of paper feed rollers 102, a contact glass 103, a conveying roller pair 104, and a back shading plate 105 are arranged side by side on the document placing table 101. A pair of guide plates 106 and a pair of document discharge rollers 107 are sequentially arranged.

A front surface shading plate 108 is provided at a position facing the contact glass 103, and a contact image sensor 109 is provided at a position facing the back surface shading plate 106.

These paper feed roller pair 102, contact glass 103, conveyance roller pair 104, back shading plate 105, guide plate pair 106, document discharge roller pair 10
7, the surface shading plate 108 and the contact-type image sensor 109 form a document conveyance path 110, and the cover 1
It is covered by 11.

The contact-type image sensor 109 has the same structure as the contact-type image sensor 5 and includes a light source 112,
Selfoc lens 113 and CCD image sensor 1
14 are provided.

The reduction optical system reading unit 115 is housed in the main body case 100a, and the reduction optical system reading unit 115 is included.
Is a light source 116, a mirror 117, a lens 118 and a CC
The D linear image sensor 119 is used.

The reduction optical system reading unit 115 includes the sheet original 1 conveyed on the contact glass 103 from the light source 116.
20 is irradiated with light, the reflected light reflected by the sheet original 120 is introduced into the CCD linear image sensor 119 by the mirror 117 and the lens 118, and photoelectrically converted by the CCD linear image sensor 119.
The image information of 0 is read.

The contact-type image sensor 109 and the reduction optical system reading unit 115 have basically the same characteristics as the contact-type image sensor 5 and the reduction optical system reading unit 4, and are conveyed through the document conveyance path 110. Sheet manuscript 120
The image information on the back side and the image information on the front side are read.

That is, a plurality of sheets of sheet originals 120 are placed on the original placing table 101 with their front surfaces facing down,
The sheet originals 120 placed on the original placing table 101 are separated one by one by the paper feed roller pair 102 and sent to the original conveying path 110.

The sheet original 120 delivered to the original conveying path 110 is conveyed through the original conveying path 110 by the conveying roller pair 104 and the original discharge roller pair 107, and finally,
Paper ejection tray 1 attached to the side of the main body case 102
21 is discharged onto.

Facsimile apparatus 100 uses sheet original 1
When 20 is passing over the contact glass 103, the reduction optical system reading unit 115 reads the image information on the surface of the sheet original 120, and the contact image sensor 109
Image sensor 1 when it is passing below
At 09, the image information on the back surface of the sheet original 120 is read.

At this time, the facsimile apparatus 100 controls the pixel clock and the document conveying speed and the amplifier gain in accordance with the document reading mode, as in the above embodiment.

Therefore, the present invention can be similarly applied to the sheet type facsimile apparatus 100.

In addition, in the above embodiment, FIG.
As shown in FIG.
A reading mode selection switch 41 capable of selecting three types of original reading modes of a front side reading mode, a back side reading mode, and a double side reading mode is provided, and based on these three types of original reading modes, shown in FIGS. As described above, the pixel clock, the document conveyance speed, and the amplification factor of the image signal are changed, but the present invention is not limited to this, and for example, FIG.
As shown in FIG. 3, a reading mode selection switch 131 for selecting two types of original reading modes, a single-sided reading mode and a double-sided reading mode, is provided in, for example, the operation unit 38, and the original selected by the original reading mode changeover switch 131 is selected. You may make it provide the lamps 132 and 133 which light up and display a reading mode.

Note that, in FIG. 18, the lamp 132 shown in black is lit to indicate that the single-sided reading mode is selected.

In this case, the original 25 or the sheet original 1
When the document 20 is set on the document table 15 or the document table 101, the orientations of the documents 25 and 120 are always set in a fixed direction, for example, in the single-sided reading mode, the descriptive surface of the image information is the reduction optical system reading unit 4 or Reduction optical system reading unit 11
If you set it in the direction that can be read by 5,
In the single-sided reading mode, the reduction optical system reading units 4 and 115 are always provided.
The image information of the originals 25, 120 is read by the originals 25, 120 by the reduction optical system reading units 4, 115 and the contact image sensors 5, 109 only in the double-sided reading mode.
The image information of can be read.

By doing so, the above-mentioned FIG. 14 to FIG.
The pixel clock, the document conveying speed, and the amplification factor shown in (4) can be controlled more easily.

Further, in the above embodiment, the case where the invention is applied to the facsimile machine 1 has been described, but the invention is not limited to the facsimile machine 1 and can be applied to an image reading apparatus such as a copying machine which generally reads a double-sided original.

[0158]

[0159]

[0160]

[0161]

[0162]

According to the image reading apparatus of the present invention, in any of the single face reading mode and the double-sided reading mode, appropriately and high speed can read image information of the original, to improve the image quality In addition, the processing speed can be increased and the usability of the image reading apparatus can be improved.

[0163] Further, in accordance with the originals reading mode, and conveys the document by the document conveying speed suitable for operation characteristics of the first reading means and the second reading means, to read image information of a suitable sincerely document You can

As a result, the quality of the read images of both double-sided and single-sided originals can be improved, and the processing speed can be increased to improve the usability of the image reading apparatus.

[0165] Further, in accordance with the originals reading mode, Runode can be always constant signal level of the output image signal of the first reading hand stage, Ru can improve the image quality.

[Brief description of drawings]

FIG. 1 is an overall schematic configuration diagram of a book-type facsimile apparatus to which an embodiment of an image reading apparatus of the present invention is applied.

FIG. 2 is a circuit block diagram of the facsimile apparatus shown in FIG.

3 is a circuit block diagram of a CCD clock generation circuit housed in the clock generator of FIG.

FIG. 4 is a timing chart of operation pulses for the reduction optical system reading unit, which are generated by the CCD clock generation circuit of FIG.

5 is a timing diagram of operation pulses for the contact image sensor generated by the CCD clock generation circuit of FIG.

6 is a circuit diagram of an image signal amplification circuit and an amplifier gain variable circuit thereof housed in the reduction optical system reading unit of FIG. 2;

FIG. 7 is a circuit diagram of a stepping motor and its driver circuit incorporated in the document conveyance control unit of FIG.

8 is a circuit diagram of a motor drive control circuit that is generated by changing a phase excitation signal output to the driver circuit of FIG. 7 according to a document reading mode.

FIG. 9 is a pattern diagram of a phase excitation signal when the stepping motor is driven by two-phase excitation.

FIG. 10 is a pattern diagram of a phase excitation signal when the stepping motor is driven by 1-2 phase excitation.

FIG. 11 is a timing chart of a phase excitation signal of a stepping motor when a document is transported at a document transport speed Vo in the back surface and double-sided reading mode.

FIG. 12 is a document conveyance speed of 4 Vo in the front surface reading mode.
Diagram of the phase excitation signal of the stepping motor when the document is conveyed in the.

FIG. 13 is a diagram showing an example of a reading mode selection switch of FIG. 2 and a lamp for displaying a selection state of a document reading mode.

FIG. 14 is a flowchart showing a CCD clock control process for controlling the reading operation of the reduction optical system reading unit and the contact image sensor by changing the pixel clock according to the original reading mode.

FIG. 15 is a flowchart showing a document transportation speed control process for controlling a document transportation speed by changing an operation clock according to a document reading mode.

FIG. 16 is a flowchart showing a signal amplification control process for controlling an amplification factor of an image signal amplification circuit of a reduction optical system reading unit by changing an amplifier gain according to a document reading mode.

FIG. 17 is an overall schematic configuration diagram of a sheet type facsimile apparatus to which an embodiment of the image reading apparatus of the present invention is applied.

FIG. 18 is a diagram showing another example of a reading mode selection switch and a lamp for displaying a selection state of a document reading mode.

[Explanation of symbols]

1,100 facsimile machine 2,100a body case 3 ADF 4,115 Reduction optical system reading unit 5,109 Contact image sensor 6 Contact glass 12,119 CCD linear image sensor 24,110 Original transport path 25,120 manuscripts 28 CCD image sensor 31 clock generator 36 Document driver 37 System control unit 38 Operation part 41, 131 Read mode selection switch 50 CCD clock generation circuit 51 counter 52 multiplexer 53, 54 drive clock generation circuit 60 amplifier circuit 61 Amplifier gain variable circuit 62 video amplifier 63 multiplexer 71 Stepping motor 72 Driver circuit 73 Motor drive control circuit 74 counter 75 multiplexer 76-phase excitation pattern generation circuit 81-83, 132, 133 lamps R1 to R4 resistance C1 capacitor

Claims (3)

(57) [Claims] 1. Operating based on a predetermined operating clock,
First reading means for reading image information on one side of the document and outputting an image signal, and operating based on a predetermined operation clock to read image information on the other side of the document and output an image signal Second reading means, selection means for selecting a document reading mode for reading one side or both sides of a document, and a clock for supplying the operation clock to the first reading means and the second reading means. The first reading unit includes a generation unit and a control unit that changes the frequency of the operation clock supplied by the clock generation unit according to the document reading mode selected by the selection unit. A CCD image sensor using a CCD is used, the second reading unit is a contact image sensor using an equal-magnification optical system, and the control unit is a clock generator. Operation provided by raw means
Set the clock to the double-sided or
In the case of a cable, it is suitable for the operation of the contact image sensor.
Frequency and the original reading mode is the front mode.
In this case, the circumference suitable for the operation of the CCD image sensor
An image reading device characterized by switching to a wave number . Wherein said image reading apparatus, a document conveying means for conveying the original predetermined document transport path at a predetermined speed, further wherein the control means, the conveying speed of the document by the front SL document conveying means , The original reading mode is double-sided or back-sided mode
In the case of, it is suitable for the operation of the contact type image sensor.
In addition to the speed, the original reading mode is set to the surface mode.
In this case, the speed suitable for the operation of the CCD image sensor
The image reading apparatus according to claim 1, wherein the image reading apparatus is changed every time . Wherein the first reading hand stage, a signal amplifying means for amplifying the signal level of the output image signal, further wherein the control means, the amplification factor of the signal amplification means, the original reading mode Is small in double-sided mode,
The image reading apparatus according to claim 1 or 2 , wherein the document reading mode is changed when the original reading mode is a front mode .