JPH03245662A - Picture reader - Google Patents

Abstract

PURPOSE:To read a picture of an original in the stable state even when the luminous quantity of an external light is changed by specifying the drive condition of a reader reading a data inputted in advance based on the luminous quantity of an incident light so as to drive the reader. CONSTITUTION:When the luminous quantity Li of an external light L received by a photosensor 46 is gradually decreased, the period of the light storage time SH outputted from a 1st program timer 92 is set gradually longer in response to a data from a 1st memory 83. When the luminous quantity Li is gradually increased, the period of the optical storage time SH outputted from the 1st program timer 92 is gradually set shorter in response to the data from the 1st memory 83. Thus, the quantity of integration of the light led to a CCD line sensor 66 is controlled depending on the length of the period of a light signal storage time SH with respect to the fluctuation of the luminous quantity Li of the external light L and an output signal having a nearly constant amplitude is arranged.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention is directed to inputting image information into an image forming apparatus such as a laser printer, or an image processing apparatus connected to a computer, etc. The present invention relates to an image reading device, and particularly relates to a fixed document type image reading device that reads an image while a document is fixed.

(Prior Art) In general, an image reading device that inputs image information to an image processing device connected to a computer, etc. includes a document mounting table on which a document is placed, a lighting device that illuminates the document, and a light source that reflects light from the document. It is equipped with an image reading section that reads light and converts it into an electrical signal. The document placed on the document table is illuminated by an illumination device, and the reflected light from the document passes through a reading optical device (mirror) and an imaging optical device extending in a first direction, that is, the main scanning direction. The image is then imaged onto the image reading section. The reflected light, that is, the image information guided to the image reading section is converted into an electrical signal by a photoelectric conversion element such as a CCD line sensor, so that the image information of the line area of the document along the main scanning direction is read. It will be done. Further, since the illumination device and the reading optical device are moved in the second direction perpendicular to the main scanning direction, that is, the sub-scanning direction, the image information of the line area of the original is sequentially read, and the image information of all the image areas of the original is read. Information is read.

By the way, in this type of image reading device, in order to reduce the overall size of the device, that is, the installation area, two folding mirrors are used in the imaging optical device, thereby reducing the installation area of the device. ing. Incidentally, a lighting device for illuminating the document, a device (or space) for dissipating or cooling heat from the lighting device, a reading optical device, and an imaging optical device including an imaging lens are stacked at the bottom of the document table. Placed.

Furthermore, since the two folding mirrors of the illumination device, reading optical device, and imaging optical device are moved (scanned) in the sub-scanning direction, the illumination device moves in the sub-scanning direction together with the illumination device. A power supply device for the apparatus, and a moving mechanism for moving the illumination device, reading optical device, and folding mirror in the sub-scanning direction are also arranged below the document table.

(Problems to be Solved by the Invention) The above-described image reading device includes an illumination device that illuminates the document;
Since an imaging optical device including a device for dissipating or cooling heat from the illumination device, two folding mirrors, and a condensing lens is disposed below the document table, there is a problem that the height thereof becomes high. Furthermore, since a device for dissipating or cooling the heat from the lighting device is required, there is a problem that the device becomes larger. Furthermore, a power supply device that supplies power to an illumination device that moves in the sub-scanning direction is required to be durable against movement, resulting in a problem that it becomes complicated and large. Moreover, the lighting device is usually a device driven by high voltage and large power such as a fluorescent lamp, and it generates noise to the image reading section formed by a photoelectric conversion element such as a CCD line sensor. Because of the adverse effects, there is a problem in that the power supply device and the lighting device require a shield member to block or reduce noise and the like. In addition, C
Since the detection characteristics of photoelectric conversion elements such as CD line sensors vary considerably depending on the amount of incident light, C
When processing image information output from a CD line sensor (or transferring it to an external device), there is a problem in which the timing must be adjusted accurately.The purpose of the present invention is to eliminate (or simplify) the illumination device in an image reading device. Another object of the present invention is to provide an image reading device that is compact and easy to move by reducing the size of the device.

[Structure of the Invention] (Means for Solving the Problems) The present invention has been made based on the above-mentioned problems, and includes a condensing means for converging external light onto an object to be read, and a condensing means for converging light from the outside onto an object to be read. a light amount detection means for detecting the amount of incident light; an imaging means for forming an image of the reflected light from the object to be read; a reading means for reading information on the object formed by the imaging means; The processing means includes a processing means for processing a signal output from the reading means, and a storage means into which data for driving the reading means is input in advance, and the processing means is configured to store the data corresponding to the amount of light detected by the light amount detection means. There is provided an image reading device characterized in that a signal outputted from the reading means is processed within one period of a driving time of the reading means defined by output data from the reading means.

(Function) According to the present invention, a plate-shaped condensing device that condenses light from the outside is used as an illumination device. By using this plate-shaped light condensing device, it is possible to eliminate the illumination device and its peripheral members that make the image reading device larger. Further, the amount of external light incident on this condensing device is detected by the light amount detection means, and pre-input data corresponding to the detected amount of light is called to define the driving conditions of the reading device, and the reading device is activated. Driven.

At the same time, images read within one cycle of the time when this reading device is driven are processed (or output).

Therefore, even if the amount of light from the outside changes, the processing of image information output from the CCD line sensor (
or transfer to an external device) are always kept aligned.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a cross section of an image reading apparatus according to an embodiment of the present invention, with the drive mechanism omitted.

FIG. 2 shows the main body of the image reading device shown in FIG.
The outline of the state in which the housing) is omitted is shown.

The image reading device 2 has a reading window 1 whose bottom surface is placed on a document.
6, and a housing 10 having a lighting window 14 disposed opposite to the reading window 16 and admitting light from the outside.
It is equipped with This housing IO includes a first carriage 40 which has a reading optical device or mirror formed long in a first direction, that is, a main scanning direction, for scanning an original at a predetermined speed, and a first carriage 40 that transmits light from this carriage 40. 2
The second carriage 5 is guided to the image reading section by total reflection of the second carriage 5.
0. The housing 10 also drives a carriage support mechanism 20.22 that supports the first and second carriages movably independently of each other and drives the first and second carriages 40.50, which are detailed in FIG. It is equipped with a drive mechanism to

The housing 10 further includes an imaging section 60 that forms an image of image information from a document, an image reading section B4 that reads the image information formed by this imaging section 60, and a signal from this image reading section 64. Signal processing unit 68 that processes and outputs
It is equipped with

Next, each unit forming an image reading apparatus which is an embodiment of the present invention will be described in detail with reference to FIGS. 1 and 2.

The image reading device 2 has a lighting window 14 and a reading window 16.
A reading window 1 is placed on the document surface of the document G that supplies information to be read.
B is placed so that they are in close contact with each other. The lighting window 14 and the reading window 16 are transparent plates made of polycarbonate or acrylonitrile, for example. The lower part of this transparent plate is pressed from the outside by bending due to force.
/X-Using internal first or second carriage 40.5
22 dia. parallel to the main reading direction to avoid contact with 0 etc.
Metal lines of tn are embedded at intervals of 1t+a.

The first carriage 40 is movable at both ends in the second direction, that is, the sub-scanning direction, by the carriage support member 20.
and is supported parallel to the reading window 1G, that is, the document surface of the document,
It is scanned at a predetermined speed in the sub-scanning direction by a drive mechanism to be described later. The carriage 40 has a plate-like light condensing member, ie, a Fresnel lens 42, which is disposed almost parallel to the reading window 1B, that is, the original surface of the original, and near the lighting window 14, and a part of the reflected light from the original is returned to the optical path. The first one is for guiding the image to the image reading unit via the corner cube prism 52 which is a device.
a mirror 44, a photosensor 4B that is arranged approximately parallel to the lighting window 14 and approximately at the center in the main scanning direction and detects the amount of light Li from the outside, and a third photo sensor that is driven by a drive motor (not shown). It is provided with a connecting member 25 detailed in the figure.

Further, the second carriage 50 follows the movement of the corner cube prism 52 that guides the reflected light from the document, that is, image information, to the image reading unit by two reflections, and the movement of the first carriage at approximately 1/2 the speed. It is provided with connecting members 26 and 27, which will be described later.

The corner cube prism 52 is fixed to the carriage 50 so as to be perpendicular to the optical axis of the first mirror 44 in the main scanning direction and parallel to it in the sub-scanning direction.

The imaging section 60 includes an imaging lens 62 that is a lens unit that is a combination of a plurality of lenses that guides light from the second carriage 50 to an image reading section 64 .

The lens 62 is disposed outside the sub-scanning area for the purpose of reducing the thickness (ie, height) of the housing 10, and has a relatively long front focal length.

The imaging lens 6z forms an image of the reflected light from the document guided through the first mirror and the corner cube prism on the reading surface 66 of the image reading section 64.

The image reading section 64 includes a reading surface or CCD line sensor 86 for reading the imaged light beam or image information.

This image reading section B4 is formed on the electrical equipment board 96 together with a signal processing section 68, which will be described later. This electrical equipment board 96 includes the optical axis of the light reflected from the original document and is disposed at a predetermined position parallel to the main scanning direction of the light beam.

Next, a process in which image information on the document surface is guided to the image reading section will be described. External light incident through the lighting window 14 is focused by the Fresnel lens 42 onto the document surface of the document G held by the reading window 16. In this example,
Light from the outside is focused by the Fresnel lens 42 to five times the brightness. At the same time, light from the outside
The light is guided to a light amount sensor 4B disposed near the Fresnel lens 42 of the first carriage 40, the amount of light Li is measured, and the light is led to a memory device to be described later.

The surface of the document G is illuminated by this focused light, and reflected light is generated in an unspecified direction. A portion LF of the reflected light from the original G is reflected by a first mirror 44 fixed to the first carriage 40 and is incident on the first surface of a corner cube prism 52 fixed to the second carriage 50. Ru. This light is reflected at right angles from the first surface of the prism 52 and is incident on the second surface. The light incident on the second surface is reflected at right angles again and guided to the imaging lens 62 of the imaging section 60. That is, the direction of the light LP from the original is changed by 180@ by total reflection at the corner cube prism 52 twice. Further, the optical path (course) of the light LP from the document whose direction has been changed by the corner cube prism 52 is a part of the reflected light L that is illuminated by the condensed light from the Fresnel lens 42.
Intersect with P itself.

The light LP guided to the imaging lens 62 is converted into convergent light Ls. This light LS is converted by the CCD line sensor 6B into an image (voltage) signal corresponding to line image information of the document along the main scanning direction (for example, the short side direction of the document). Here, the above-mentioned clause and the second carriage 40.
50 is moved in the second direction perpendicular to the main scanning direction, that is, the sub-scanning direction, so that the line areas of the original are read sequentially, and for example, all image areas of the original of A4, 85, etc. are read. The image information is converted into an image signal corresponding to the image information. This image signal is processed by a signal processing unit, which will be described later, and input to an output device (not shown), such as an image forming device, to print a reproduced image, or reproduced (displayed) on an image display device such as a monitor.

FIG. 3 schematically shows a driving device in the sub-scanning direction of the image reading device shown in FIGS. 1 and 2, with the main body of the device omitted.

The housing IO includes a carriage support member 20 that movably supports the first carriage 40, a carriage support member 22 that movably supports the second carriage 50, and a drive member, that is, a timing belt 24 that drives each carriage 40, 50. We are prepared. This carriage support member 20.22 vibrates between the lighting window 14 and the reading window 16 (that is, in the vertical direction in the image reading device 2) when the first and second carriages 40.50 move in the sub-scanning direction. The first and second carriages 40.50 are supported from below, or are arranged so as to sandwich the first and second carriages 40.50 from above and below, so that the first and second carriages 40.50 are not damaged. This housing 10 also includes a drive pulley 2 that drives a timing belt.
8, a switch 80 for detecting the operation of the first and second carriages 40.50, a roller 36 for supporting the timing belt, a spring 38 for applying a predetermined tension to the timing belt, and a drive motor (not shown). . On the other hand, the first carriage 40 connects the connecting member 25 to be used for connecting with the timing belt 24 to the second carriage 5.
0 is a pulley 2B for receiving drive from the timing belt 24 at a moving speed of 1/2 of the first carriage 40;
It is equipped with 27.

The carriage 40 having the Fresnel lens 42 and the first mirror 44 is moved or scanned at a predetermined height by the first support member 20 and the second carriage 50 having the corner cube prism 52 is moved by the second support member 22, respectively. Possibly supported. One end of the timing belt 24 is fixed to a predetermined position on the nozzing 10. This timing belt 24 is attached to the second carriage 5
Its direction is reversed via the pulley 26 of 0, and at the same time,
It is converted to the same height as the connecting portion of the first carriage 40. The first carriage 40 is directly fixed at a predetermined position via a connecting member 25 to the belt 24 whose height has been changed to the connecting portion with the first carriage 40 . The belt 24 is again changed in height and direction via the drive pulley 28, and is guided below the fixed position where one end of the belt 24 is fixed. The belt 28 whose direction has been reversed by the drive pulley 28 is
The height and direction are further changed via the rollers 36 and guided to the pulley 27 of the second carriage 50 which is disposed close to the pulley 26 . Belt 2 guided to pulley 27
4 is further connected to a spring 38 which is transformed in height and direction and applies a predetermined tension to the belt 24.

The first carriage 40 is directly connected to the timing belt 24 and is moved at a predetermined speed V via a drive pulley 28 that transmits drive from a drive motor (not shown). Further, as is clear from FIG. 3, the second carriage 50 follows the movement of the first carriage 40, that is, when the first carriage 40 is moved at a speed of 2, the belt 24 is folded back by the pulley 27. Therefore, the belt 24 moves a distance that is 1/2 of the moving speed of the belt 24 at a speed of V/2. That is, the ratio of the moving speeds of the first carriage 40 and the second carriage 50 is 2:1. In addition, the first carriage 4
Since the switches 30, 32, and 84 are arranged at the home position, the reading start position, and the reversing position, respectively, the movement of the first and second carriages 40, 50 is detected.

FIG. 4 shows a block diagram of a signal processing section that is incorporated into the image reading apparatus shown in FIGS. 1 and 2 and drives the image reading apparatus.

The photosensor 46 detects the amount of light Li from the outside and generates a signal corresponding to this amount of light Li. This signal is amplified by an amplifier circuit 81, input to an A/D converter 82, and converted into a digital signal. The digital signal from this A/D converter 82 is
It is supplied as an address to the first memory 83 and the second memory 84, and this first memory 83 and the second memory 84
Desired data is retrieved from. (In this embodiment, the first and second memories 83 and 84 contain predetermined numerical values, that is, numerical values related to changes in the amount of light Li from the outside obtained from experiments or experiences, as data. Also, in FIG. 4, the first memory 8
Although the third and second memories 84 are arranged independently, they may be formed as one memory by devising the addresses. ) The data read from the first memory 83 is output to the first program timer 92, and is clocked by a clock φR from a CCD line sensor drive circuit 91, which will be described later.
8 and is used to set the cycle of the optical signal accumulation time SR of the CCD line sensor 66. The optical signal accumulation time SH whose period is set by the first program timer 92 is the period of the optical signal accumulation time SH set by the first program timer 92.
supplied to Similarly, the data read from the second memory 84 is output to the second program timer 93 and used together with the clock φR8 to set the period of the sub-scanning drive signal MT. The sub-scanning drive signal MT whose cycle is set by the second program timer 93 is transmitted to the sub-scanning drive circuit 94 which controls the speed of the drive motor that drives the first and second carriages shown in FIGS. 1 and 2. supplied to

On the other hand, the image information of the original G read by the CCD line sensor 66, that is, the analog image signal data Gi, is amplified by the amplifier circuit 71, and then by the correction circuit 72, the image information of the original G read by the CCD line sensor 66 is amplified by the correction circuit 72. frequency distortion,
Furthermore, the influence of high frequency distortion caused by variations in elements of the CCD line sensor 6B is removed (shaped). The analog image signal data Gi corrected by the correction circuit 72 is supplied to the binarization circuit 73 and the third memory 85. (Here, the data supplied to the third memory 85 for identification is analog image signal data Gis, and the data transferred to the binarization circuit 73 without passing through the third memory 85 is analog image signal data Gie. ) The analog image signal data Gis is converted to an A/D converter (not shown).
(which may be incorporated into a part of the correction circuit 72)
The data is supplied as an address to the memory 85 and the desired data is retrieved. (In this embodiment, the third memory 85 includes
Data regarding the background of the document read by the CCD line sensor 6B, that is, the optical density minus the base density of the paper on which the document is written, is input in advance. ) Third memory 85
The data called from is analog image signal data O1
The threshold level (“1”,
It is supplied to the binarization circuit 73 as a reference for determining "0". The analog image signal data Gie is binarized based on the data from the third memory 85, and is outputted to an external device (not shown), such as an image processing device or a computer, via an interface or an output section 98 including an interface. Ru.

FIG. 5 shows a timing chart showing the relationship between the operations of the electric circuit shown in FIG.

The operation of the entire electric circuit shown in FIG. 4 will be explained with reference to FIG.

As shown in FIG. 5, when the amount of light Li from the outside that the photosensor 46 receives gradually decreases, the current output from the photosensor 46 decreases in proportion to the amount of light LL. However, the output voltage from the amplifier circuit 81 gradually decreases. As the output voltage from the amplifier circuit 81 decreases, the output of the digital signal output from the A/D converter 82 fluctuates.
And data corresponding to each address is output from the second memory 84. Here, CCD line sensor 6
Since it is necessary to increase the integral amount of light guided to the first program timer 6, the period of the light accumulation time SH output from the first program timer 92 is gradually set to be longer in accordance with the data from the first memory 83. In this case, the period of the sub-scanning drive signal MT output from the second program timer 93 is
The period of the excitation signal that excites the drive motors that drive the first and second carriages 40, 50 in the sub-scanning direction is gradually set to be longer in accordance with the data from the memory 84, - and second carriage 40
．． The scanning speed of 50 may be reduced. Similarly, when the amount of external light Li received by the photosensor 4B gradually increases, it is necessary to reduce the integrated amount of light guided to the CCD line sensor 66, so the first program timer 92 The light accumulation time SH output from
The period is gradually set shorter according to the data from the first memory 83. In this case, the second program timer 93
The period of the sub-scanning drive signal MT outputted from the second memory 84 is gradually set to be shorter in accordance with the data from the second memory 84. The period of the excitation signal to be excited is gradually set to be longer, and the second and second carriages 40.50
The scanning speed of may be increased.

In this way, the integrated amount of light guided to the CCD line sensor 6B is controlled by the length of the period of the optical signal accumulation time SH with respect to fluctuations in the external light lLi, and an output having a generally constant amplitude is produced. The analog image signal data Gi arranged into a signal is a CC that drives a CCDC line sensor.
It is output in synchronization with the basic clock φR9 generated from the D line sensor drive circuit 91.

By the way, it goes without saying that each of the above-mentioned methods may be used alone or at the same time.

The image information read by the CCD line sensor 6B, that is, the analog image signal data Gi, is amplified by the amplifier circuit 71, corrected by the correction circuit 72 (that is, as analog image signal data O1e), and sent to the binarization circuit 73. be transferred. In this binarization circuit 73, the third memory 85
When the base density of the document is light, the threshold level is shifted to a positive level compared to the reference value, and when the base density of the document is high, the threshold level is shifted to a positive level, for example, from the reference value. Since a threshold level shifted to a more negative level than Gie is defined, the analog image signal data Gie transferred to this binarization circuit 73 is accurately binarized.

Next, the optical signal accumulation time SH, the basic clock φRS, and the timing of image processing will be explained.

The CCD line sensor 66 receives the basic clocks φR3, φ1°φ2 and the first clock from the CCD line sensor drive circuit 91.
It is driven by the optical signal accumulation time SH from the program timer 92. For example, set the maximum scan size to an A4 document (
effective reading (216 sum), resolution 8 dots/11
Assuming a CCD line sensor with 1728 pixels per reading, after the optical signal accumulation time SH is input, 1728
By inputting the φR3 lock twice, a voltage signal for one line (one scan), that is, image information is transferred (read).

In the embodiment of this invention, as shown in FIG.
RS clock input time, that is, image information transfer time (A),
The image data processing time (B) for converting the image signal data Gi into 2Vi by the binarization circuit is the optical signal accumulation time SR.
It is arranged during one period of . That is, since the period of the optical signal accumulation time SR is changed, the optical signal accumulation time SH
By feeding back the cycle of Gie to the CCD drive circuit 91, the image information is transferred and the binarization circuit executes the binarization of the image signal data Gie in synchronization with the cycle of the optical signal storage time SH. The CCD line sensor 66 reads the next line upon completion of the transfer of the image information and the binarization of the image signal data Gie. According to this method, for example, image information transfer in which the cycle of the optical signal accumulation time SH, which changes according to a change in the amount of light i from the outside, is synchronized with the φRS clock, and image processing by a binarization circuit. Even if there is a case where the specified time is shorter than the specified time, image transfer and binarization processing are reliably executed.

(Effects) As explained above, according to the present invention, the amount of light incident on the plate-shaped light collecting device that collects light from the outside is detected,
Based on this amount of light, data input in advance is retrieved, driving conditions for the reading device are defined, and the reading device is driven. At the same time, images read within one cycle of the time when this reading device is driven are processed (or output). Therefore, even if the amount of light from the outside changes, it is possible to read the image of the document (or transfer it to an external device) in a stable state. Furthermore, since there is no bulky lighting device, the size (height) of the device is reduced, and a compact image reading device is provided. In addition, because the number of parts is reduced, the cost of parts and assembly of the device are reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an image reading device according to an embodiment of the present invention, FIG. 2 is a schematic view of the image reading device shown in FIG. 1 with the main body omitted, and FIG. , a schematic diagram showing a method of driving the image reading device shown in FIGS. 1 and 2 in the sub-scanning direction, and FIG. 4 shows the signal processing unit and control of the image reading device shown in FIGS. FIG. 5 is a timing chart showing the operation of the electric circuit that controls the image reading device shown in FIG. 3. FIG.

Claims (1)

[Claims] a light condensing means for converging external light onto an object to be read; a light amount detection means for detecting the amount of light incident on the condensing means;
An imaging means for forming an image of reflected light from the object to be read, a reading means for reading information on the object imaged by the imaging means, and processing for processing a signal output from the reading means. and a storage means into which data for driving the reading means is input in advance, and the processing means is configured to perform the reading defined by the output data from the storage means corresponding to the amount of light detected by the light amount detection means. An image reading device characterized in that a signal output from the reading means is processed within one cycle of the time when the means is driven.