JP3939855B2 - Double-sided original reading method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a double-sided document reading apparatus equipped with a color image sensor of a light source sequential lighting system, and particularly has a function of processing image data of three colors of red, green, and blue on each side as a set as an image processing circuit. The present invention relates to a double-sided color original reading method and apparatus capable of configuring a color image scanner with a minimum capacity memory even when necessary.
[0002]
[Prior art]
Due to the low price of high-speed CPUs and large-capacity memories, so-called personal computer digital color images tend to be easily handled.
Accordingly, there is an increasing demand for color support for image input devices.
Specifically, color correspondence is inevitably required for an original reading apparatus (image scanner) which is a component of the image input apparatus.
However, as with all image-related peripheral devices, colorization requires more complex processing than monochrome images, which complicates the mechanism and control, and in the case of color images, Since higher image quality is required than images, the resulting price is high, which is one of the factors that hinder its spread.
[0003]
Color image scanner and scanning method
This also applies to an image scanner that is a color reading device, and it is required to reduce the price without degrading the image quality.
As one conventional countermeasure for solving such a problem, an optical device of a color image reading apparatus can be used with an erecting equal-magnification lens having a short optical path length, thereby enabling downsizing of the apparatus. An optical device has been proposed (Japanese Patent Laid-Open No. 9-261409).
Various types of such small image scanners capable of reading color images have appeared.
On the other hand, it is the reading method of the color image scanner that determines the image quality when the image scanner is compatible with colors.
[0004]
There are several color image scanner reading methods, but a color image is obtained by changing the light source to RGB (Red: Red, Green: Blue, abbreviated as blue, hereinafter simply referred to as RGB). It can be roughly divided into a reading method and a reading method for obtaining a color image separated into RGB by a filter using a white light source.
When these two scanning methods are compared from all viewpoints of speed, image quality, and cost, with the widespread use of high-intensity light-emitting diodes (LEDs), the former method of switching the light source is currently better than the latter method. It can be said that it is excellent.
For example, for a color image reading device, there is also a color image reading device that realizes downsizing of the device by suppressing the loss of the amount of light emitted from the light source to increase the light receiving efficiency of the CCD sensor and speeding up the signal conversion. It has been proposed (Japanese Patent Laid-Open No. 9-247358).
[0005]
The light source used in the former light source switching method is mainly an LED with excellent lighting response due to the necessity of high-speed blinking operation, and the configuration of the image sensor is inevitable due to the limitation of the light amount. However, it is not limited to a reduction optical system such as a CCD, but is limited to a contact-type equal-magnification sensor.
However, recently, by adopting a light guide plate that diffuses and irradiates the light of the LED only in a predetermined direction, a smaller number of LEDs than the conventional method in which LEDs are arranged at equal intervals to obtain a uniform light amount. It became possible to obtain the same amount of light.
For the above technical reasons, the color image sensor can be ideally configured as a computer peripheral device with low cost, low current consumption, and space saving. A light source switching method using a double sensor is becoming mainstream.
[0006]
Light source sequential lighting method
The light source switching method using the same magnification sensor is also called a light source sequential lighting method because the RGB LEDs are sequentially turned on.
In this light source sequential lighting method, when the signal reading method of the image sensor element is the direct reading method, all charges are accumulated during the period in which the light is applied to the light receiving element. There is a problem that color interference occurs unless the LED is turned off.
Here, the direct readout method will be described. This direct readout method is a method of directly extracting charges accumulated by photoelectric conversion to the output stage, and the image signal readout interval of each pixel is directly equal to the photoelectric storage time of the pixel. Therefore, the accumulation timing differs for each pixel.
Therefore, in the light source sequential lighting type color image sensor, the light source is controlled at the timing shown in FIG.
[0007]
FIG. 3 is a diagram for explaining the control timing of the color image sensor of the light source sequential lighting method. In the figure, LED R, LED G, and LED B are red (R) LEDs, green (G) LEDs, blue (B) LEDs (light emitting diodes) on / off timing, and SIG is an RGB image signal. T1 to t3 indicate signal readout periods.
[0008]
For example, in the case of an R (red) image signal, if an R LED is lit for the time width at the ON timing shown in the uppermost “LED R”, the image of each pixel in that line is displayed on the light receiving element. The signal is accumulated.
Thereafter, when the R LED is turned off and reading is performed within the reading period t1, among the RGB image signals indicated by "SIG" at the bottom of FIG. 3, the image signal for one line of R is read. It is.
The same applies to the G (green) image signal and the B (blue) image signal.
As described above, after the R LED is turned on for a certain period, the signal for one line is read after the LED is turned off, and after the read period t1 is completed, the next G LED is similarly activated for a certain period. Turn on the light and read out the image signal of each color (t2, t3).
[0009]
In this sequential light source lighting method, processing is performed line by line while sequentially turning on / off the RGB LEDs, and therefore, three times of processing is required to read out the RGB color image signals.
If the light source is controlled at the timing shown in FIG. 3, the signal readout period and the LED lighting time can be completely separated.
However, if the control is performed at such timing, there is a drawback that the scanning time is delayed as a result.
Although the direct-reading type 1X color image sensor has such difficulties, it is currently relatively easy as a semiconductor-level configuration and is also inexpensive, so it is useful for reducing the cost of image scanners. It is considered as a unit.
[0010]
Both sides simultaneous reading method
By the way, an original to be input to an image scanner is not only changed due to the progress of colorization, but also has a form of printing / recording on both the front and back sides due to cost reduction and environmental problems in the office.
Therefore, as for image scanners, in order to cope with this change, double-sided image scanners in which image sensors are arranged to face each other so that both sides of a document can be read at once are also appearing.
As a method of reading both sides simultaneously, a method of alternately reading the front and back surfaces is common.
Here, the control timing of the conventional method of switching the front and back for each RGB 1 line will be described with reference to FIG.
[0011]
FIG. 4 is a diagram illustrating an example of the control timing of a color image sensor that switches between front and back for each RGB line. The reference numerals attached to the waveforms in the figure are the same as those in FIG. 3, but the front or back side is added to distinguish the front side from the back side.
[0012]
FIG. 4 shows the timing when the color image is read on both sides in the same manner as when reading a monochrome image, with the front and back lines alternately switched.
Here, the image signal from the red light source of one line with the front surface is represented as front R, and the back surface is represented as back R. Similarly, the green image signal is also represented as G on the front surface and G on the back surface. In the case of the reading method for switching the front and back data in units of one line, the order of the input image signals is as follows: front R → back R → front G → back G → table B → Back B → ...
Therefore, the RGB image signals read by the double-sided reading method shown in FIG. 4 are input to the image processing circuit alternately for each color.
That is, the order of the input signals is as follows: front R → back R → front G → back G → front B → back B →.
[0013]
As shown in FIG. 4, the advantage of adopting the method of switching the front and back for each RGB 1 line is that the front and back image processing can be realized by common hardware (circuit) by switching the input.
Here, the configuration of a double-sided document reading apparatus that lays out the color image sensors that perform the reading operation described in the timing chart of FIG. 4 so as to face each other and can read both sides of the document at once will be described. .
[0014]
FIG. 5 is a functional block diagram showing an example of the configuration of the main part of the double-sided simultaneous reading apparatus. In the figure, 1 is a document, 2 is a front image sensor, 3 is a back image sensor, 4 is an image processing circuit, 5 is a line buffer, 6 is a data bus, SW is a changeover switch, table SIG is a front image read signal, and back SIG indicates a read signal for the back image.
[0015]
The double-sided simultaneous reading apparatus shown in FIG. 5 is a method of switching line by line. The image signal input for each line is switched between the front and back, and the line buffer access area associated with the image processing circuit 4 is different depending on the front and back. By switching the parameters, it has the function of performing the same operation as if the lines on the same side of the document are continuously input / processed.
For this purpose, the double-sided simultaneous reading apparatus is provided with a front image sensor 2 and a back image sensor 3 as image sensors on both sides of the document 1.
Output signals from the front image sensor 2 and the back image sensor 3 are alternately input to the image processing circuit 4 line by line through the changeover switch SW.
[0016]
In this case, in the line memory 5 associated with the image processing circuit 4, the buffer data storage areas on the front and back surfaces are separated so that the data corresponding to the surface on which the image signal is selected can be accessed by the changeover switch SW. The address is controlled.
Note that, in the image processing circuit 4, it is also necessary to configure so that the processing using the parameter related to the line input immediately before can be switched in units of lines as in the line memory. .
According to the double-sided simultaneous reading apparatus of FIG. 5, even if image signals of different planes are input in line units by the operation as described above, processing can be performed in the same manner as continuous lines.
[0017]
[Problems to be solved by the invention]
As described in the prior art, a light source switching method for sequentially turning on RGB LEDs corresponding to colorization, a so-called light source sequential lighting method, is the mainstream, and in this method, an equal magnification sensor is used.
In addition, due to cost reductions in the office and environmental problems, the number of forms to be printed / recorded on both the front and back sides is increasing, and a double-sided simultaneous reading device capable of reading both sides of a document at once is used.
This double-sided simultaneous reading apparatus employs a method of switching between front and back image signals in line units.
In the case of a monochrome image, the method of switching the front and back image signals for each line unit is information of only the light and shade, so the information of one main scanning line is completed with one signal line from the image sensor. There is no problem in sorting and processing the front and back data by alternately switching in units of one line.
[0018]
However, in the case of a color image, since the image information is the density of each color of RGB, a signal of 3 lines (1 line for each RGB) is required in order to obtain the information for one main scanning line completely.
For this reason, when a method of alternately switching in units of one line, such as a monochrome image, is employed, there are cases where the advantages of the switching method are impaired.
Specifically, such a case may occur in processing that cannot be executed unless all the RGB3 lines are prepared. One example is arithmetic processing associated with color conversion such as complementary colors.
[0019]
Normally, color conversion is performed by calculation of each RGB color data. Therefore, when all the RGB data of the line is used for the calculation, it is desirable that the RGB data of a certain main scanning line is continuously input.
However, as for the color image, when the front and back data is switched in units of lines as in the double-sided reading of the monochrome image, the RGB data of the other side alternately interrupts while the RGB data for one line on one side is prepared. Unless there is a memory area for storing the RGB data for both sides, the color conversion operation for each of the front and back sides cannot be executed.
[0020]
In addition, when performing an arithmetic process such as a complementary color for the color conversion, data for one line of RGB is necessary as information for one main scanning line, so the first table R is input as the image signal of the table. Until the final table B is input, data for a total of four lines of the table R, the table G, the back R, and the back G must be stored.
In other words, a memory capacity for four lines is required to store the data for these four lines.
As described above, this is a big problem for a color image scanner in which low cost is an issue, and the burden of costs associated with an increase in memory capacity cannot be ignored.
The first object of the present invention is to realize a color image scanner with a memory configuration having a small capacity even when a function for processing RGB data on each of the front and back surfaces as a set is required as an image processing circuit.
[0021]
Here, the characteristics in the case of taking out signals of each color of RGB by sequential lighting in a method of switching the front and back for each RGB 1 line shown in FIG. 4, that is, in a direct reading type image sensor will be briefly described.
When the front and back sides are switched in units of one line by the switching method shown in FIG. 4, it is possible to read the signal on the other side during the light source lighting period on one side.
Therefore, as in the case of single-sided reading, double-sided reading can be performed without changing the reading time.
[0022]
FIG. 6 is a diagram for explaining the second control timing of a color image sensor that switches between front and back for each line of RGB. The reference numerals attached to the waveforms in the figure are the same as those in FIG.
[0023]
In FIG. 6, the front and back are switched for each RGB 1 line at the same control timing as in FIG. 4 except that the signal read rate is increased.
Thus, one of the advantages of the method of switching the front and back for each RGB 1 line shown in FIG. 4 is that the LED on the other side can be lit during the signal readout period on one side, and the signal readout rate It is possible to raise.
The present invention pays attention to the reading method having such advantages, that is, the double-sided reading method for switching the front and back for each RGB line shown in FIG. 6, and in the color image scanner, the RGB data on each side as the image processing circuit. When the function of processing the image as a set is not required, a second problem is to enable the use of a document reading method that can increase the signal reading rate.
[0024]
[Means for Solving the Problems]
  Document reading according to claim 1apparatusThen, a light source sequential lighting type color image sensor unit that sequentially turns on light sources of three colors of red, green, and blue to obtain color signals of each color for each line is arranged facing each other, and both sides of a document are read simultaneously. In a double-sided color original reading device having a configuration capable ofIt has a front and back shared memory that stores only two lines on one side that do not separate the front and back access areas,One line for each surface of the image sensor unit obtained by sequentially lighting each light source with respect to the image processing apparatusOne by oneFront and back as a set of three color signalsSignalBy alternately switching and inputting, both sides of the original are read simultaneously.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
  Double-sided document reading of this inventionDressingThis is a double-sided color original reading device described in the prior art, that is, a color image of a light source sequential lighting system in which light sources of three colors of red, green, and blue are sequentially turned on to obtain color signals of each color for one line. A two-sided color original reading apparatus having a configuration in which sensor units are arranged to face each other and both sides of an original can be read simultaneously is a prerequisite technology. This apparatus is realized by the configuration shown in FIG. The double-sided color original reading apparatus shown in FIG. 5 is a method in which reading of the front and back sides of the original is switched on a line-by-line basis for each RGB line, in order to read out each RGB image signal without color interference (to perform normal color separation). In addition, the light source can be controlled at the timing shown in FIG.
[0029]
Therefore, the apparatus of FIG. 5 is a color image sensor using a sequential lighting method, and the light source irradiation time (accumulation time) and the signal readout period overlap in order to perform color separation by sequentially lighting different color light sources. It is the structure which can be controlled so that it may not.
The reason for this has already been described. In the light source sequential lighting method shown in FIG. 3, the color image sensor assumes a type called a direct readout method as a charge readout method. Therefore, the accumulation timing is controlled differently for each pixel.
In other words, if the other color LEDs are lit during the period when the image signal is being read out, the charge will be re-accumulated from the pixel that has been read out, and mixed with the accumulated charge of the next lit color. Therefore, there is a problem that normal color separation cannot be performed. In order to avoid this problem and perform normal color separation, the light source is controlled at the timing shown in FIG.
However, the method shown in FIG. 3 is a one-sided document reading method.
[0030]
On the other hand, in the double-sided original reading method, for example, the image processing circuit 4 in FIG. 5 is required to have a function of processing the RGB data of the front and back surfaces as a set, as in the case of performing arithmetic processing associated with color conversion. In order to hold the image data of one side of the document, for example, the surface until the image data for a total of 3 lines of 1 line for each RGB is completed, it is necessary to add a line memory for 4 lines. is there.
The direct-reading type 1x color image sensor is relatively easy as a semiconductor level configuration and is inexpensive, so it is currently a unit useful for reducing the price of image scanners. Cost increase is unavoidable in that line memory for 4 lines is required.
In the present invention, in the double-sided document reading method, the reason why the memory for four lines is required is because a method of switching one line for each RGB line by line as shown in FIG. Focusing on the fact that the front and back image data are alternately input as shown in Table R → Back R → Front G → Back G → Front B → Back B →... If the front and back signals are switched in units of one cycle, it is possible to input the front and back image data continuously as if reading a single-sided document, so only the line memory for two lines can be used. This is based on the idea that a function for processing RGB data of each surface as a set can be realized.
[0031]
  ThisBothArea document scanningThe deviceAccording to this, even when a function for processing RGB data on each of the front and back surfaces as a set is required as an image processing circuit, such as color conversion, a color image sensor can be obtained with the same small-capacity memory configuration as that for single-side reading. Reading speed may be slightly reduced. Therefore, in the case of a processing mode in which RGB data is output as it is without color conversion, it is possible to select a double-sided original reading method that can increase the signal reading rate, and the operation mode and connection environment of the original reading apparatus. By switching to the most suitable reading method, the advantage of a color image sensor with a small-capacity memory configuration and the advantage of performing double-sided reading at the same speed as single-sided scanning can be obtained as appropriate.The
[0032]
  First embodiment
  ThisIn the first embodiment of the present invention, by performing front / back switching with one line for each of RGB (3 lines in total) as one unit, it is possible to perform operations such as color conversion only by using a memory having the same capacity as that for single-sided reading. Double-sided scanning that enables scanning with processingDressingIt has a feature in realizing the position.
[0033]
  FIG. 1 shows a double-sided original reading according to the present invention.LilyIt is a figure explaining the switching timing of the front and back screen by this, and is a time chart which shows an example of the embodiment. The reference numerals attached to the waveforms in the figure are the same as those in FIG.
[0034]
FIG. 1 shows a case where the front and back of a document are switched in units of one color signal cycle of three colors for each RGB line obtained by sequentially turning on each RGB light source.
In this case as well, the double-sided simultaneous reading device shown in FIG. 5 is used, but the switching timing of the changeover switch SW is different from that of the double-sided reading method shown in FIG.
That is, as is apparent from the comparison between FIG. 1 and FIG. 4, in the case of FIG. 4 where the front and back are switched for each line, the input signal is front R → back R → front G → back. G → front B → back B →... The front image signal and the back image signal are alternately mixed.
On the other hand, in the case of FIG. 1, the front and back sides are switched by setting each line of RGB as a set, and the input signals are front R → front G → front B → back R → back G → back B → Are inputted to the image processing circuit 4 in FIG.
An image processing circuit when signals are input in this order will be described.
[0035]
  FIG. 2 shows a double-sided original reading according to the present invention.TheIt is a functional block diagram which shows an example of embodiment of the principal part structure about the image processing circuit for implementing. In the figure, 11 is an A / D conversion unit, 12 is a dark correction unit, 13 is a light correction unit (shading correction unit), 14 is a color conversion unit, 15 is a line memory, 15a is a memory area for surface image data, 15b Is a memory area for back side image data, 15c is a memory area for each color of RGB, 15d is an R line memory for both front and back, and 15e is a G line memory for both front and back.
[0036]
The image processing circuit shown in FIG. 2 corresponds to the image processing circuit 4 provided in the double-sided simultaneous reading apparatus shown in FIG. 5 as a conventional example, and other configurations are basically the same as those in FIG. is there.
As the line memory 15, a front image data memory area 15 a and a back image data memory area 15 b are added to the dark correction unit 12 for dark correction, and each line of RGB colors for six lines is used for light correction. Each memory area 15 c is added to the bright correction unit 13.
Further, in order to perform color conversion, two lines of memory, an R line memory 15 d common to the front and back and a G line memory 15 e common to the front and back, are provided on the input side of the color conversion unit 14. The feature of the image processing circuit of FIG. 2 is that only two lines of the front / back shared R line memory 15d and the front / back shared G line memory 15e are used as the line memory 15.
[0037]
The A / D conversion unit 11 has a function of converting an analog signal into digital data.
The offset is removed from the image data converted into digital data in the dark correction unit 12.
Here, the offset component is an image sensor output signal in a dark state where the light source is not turned on, and the information (dark correction data) is stored in advance in the memory area 15a of the front image data and the back image data of the line memory 15. Assume that the data is stored in the memory area 15b.
Since this offset greatly contributes to the characteristics of the image sensor itself, the correction data is managed separately for each image sensor. As described above, the offset component is an output signal in a state in which the light source is not turned on, and the characteristics thereof are not different for each color signal, and therefore are not distinguished for each color.
[0038]
The image data subjected to the dark correction is corrected for waveform distortion due to output variation for each pixel by the light correction unit 13 (shading correction unit).
In the bright correction unit 13, the data for bright correction (bright correction data) is an output signal obtained by reading a reference white plate in a state where the light source is turned on. The data is stored in the memory area 15c for each of RGB colors in the line memory 15.
Since the bright correction data is contributed by various factors such as a light source and an image sensor, it is necessary to set the front and back and the color signal independently.
That is, a memory area for 6 lines is required for the bright correction data.
[0039]
The image data from which distortion has been removed by the light correction unit 13 is output as RGB data (R / G / B output) as it is, and the color conversion unit 14 performs color conversion according to the output once. , And the path sent to the R line memory 15d for both front and back and the G line memory 15e for both front and back.
The color conversion unit 14 performs color conversion by calculating the complementary colors A, B, and C using all three primary colors of RGB, and the calculated three complementary colors are line periods in which data of the three primary colors of RGB are arranged. To output simultaneously.
In this case, the line memory for supplying input data to the color converter 14, that is, the front and back shared R line memory 15d and the G line memory 15e are only for two lines on one side that do not separate the front and back access areas. Is different from the conventional one.
[0040]
  Double-sided document reading according to the first embodimentRideWhen the signal output from the image sensor is input to the image processing circuit of FIG. 2, the image data is as follows: front R → front G → front B → back R → back G → back B →. The RGB data of each surface is continuous. As described above, when the color data follows the order of R → G → B, the image data that needs to be stored until the last B image signal is input is the one side of R and G on that side. Only two lines of image data are required. With respect to this reading method, the order of the input signals is expressed by the same notation as above: Table R → Table G → Table B → Back R → Back G → Back B →. According to the method of the first embodiment, it is possible to align the RGB color data at a time only by storing the data of two lines of the table R and the table G until the table B is input. It is.
[0041]
The same applies to the back side, and it is possible to align each color data of RGB at once by only storing data for two lines.
Therefore, according to the first embodiment, it is possible to share the area of the line memory for the R line memory 15d and the G line memory 15e shared between the front and back sides.
On the other hand, as shown in FIG. 4, in the case of a switching method in which data is input alternately between the front and back sides, the image data must be saved for the R and G image data on the front and back sides. In other words, the line memory required for color correction requires four lines.
[0042]
In the embodiment described above, the case where three systems of complementary colors are performed as converted data has been described. However, it is not always necessary that there are three systems, and the type and number of data after conversion are as follows: The present invention is not limited to the above embodiment.
In addition, although the configuration in which the complementary color data calculated in the color conversion unit 14 is output at the same time is shown, a configuration in which the complementary color data is output sequentially is also possible. Note that, in the case of this sequential output configuration, it is necessary to add to the color conversion unit 14 a memory for holding data during that time.
As described above, in the first embodiment, the image signals input on the front and back sides are switched in units of one cycle of the RGB three primary color signals obtained by sequentially turning on the RGB light sources.
Therefore, for example, when a function for processing RGB data on each side of the front and back sides as a set is required as an image processing circuit, such as color conversion, it can be realized with a memory configuration with the same small capacity as when reading on one side, Cost reduction of the color image sensor is achieved.
[0043]
  Second embodiment
  This second embodiment is, ContractClaim1'sIt also relates to the invention. In the previous first embodiment, the front and back are switched by using three colors of one line for each RGB as one unit, thereby performing a reading operation accompanied by arithmetic processing such as color conversion in a line memory having the same capacity as that for single-sided reading. A possible duplex reading method and apparatus has been described. However, in the case of the double-sided reading method described in the first embodiment, as shown in FIG. 6, the control method for increasing the reading rate by turning on the light source on the back surface during the signal reading period on the front surface. Can not be adopted. That is, in the document reading method in which the front and back are switched with the three colors of each RGB line described in FIG. 1 as one unit, while the LED of the image sensor on one side is lit or data is being read, The image sensor on the other side is not operating at all. As a result, the reading time is twice as long as that for single-sided reading.
[0044]
Therefore, from the viewpoint of reading time, the method described in FIG. 4 and FIG. 6, that is, the front / back switching method in units of one line is superior to the method of switching front / back in RGB 1 cycle units in FIG. It can be said that.
In the color double-sided original reading method, it is not always necessary to perform arithmetic processing associated with color conversion.
Therefore, in the second embodiment, in the processing mode in which RGB data is output as it is without color conversion, the timing shown in FIG. 6 is switched by switching the front and back for each RGB line. By performing double-sided scanning under the control of, the scanning operation can be performed in a time that is not much different from that for single-sided scanning to improve scanning speed, and in the processing mode that performs color conversion, As described in the first embodiment, the double-sided reading method using the line memory having the same small capacity as that of the single-sided reading can be selected by performing double-sided reading by the double-sided reading method shown in FIG. It has the characteristics.
[0045]
For this purpose, a document reading unit (first document reading unit) that executes a method for simultaneously reading a two-sided document that switches between front and back in units of one cycle of RGB color signals described in the first embodiment. ) And a simultaneous reading means (second original reading means) for double-sided originals for switching the front and back for each RGB 1 line shown in FIG. 6, for example, each color of RGB is 1 as main scanning 1 line information like color conversion. Since the data for the line is required, the first processing mode in which the R and G image data on the front and back sides need to be stored for a certain period of time, and the second processing mode in which the RGB data is output as it is without color conversion, Depending on the situation, two reading means can be selected.
As described above, in the second embodiment, two-sided document reading method described in the first embodiment and a two-sided document reading method capable of increasing the signal reading rate in duplex color reading are provided. An original reading method and apparatus capable of arbitrarily switching the method (method) are realized.
Therefore, it is possible to switch to the most suitable reading method (or reading means) according to the operation mode of the document reading device and the connection environment, and to perform a double-sided document reading operation, which compensates for the disadvantages of each reading method and its advantages. It is possible to select a reading operation utilizing the above.
[0046]
【The invention's effect】
  Double-sided original reading according to claim 1apparatusIn this case, the front and back signals are switched in units of one color signal cycle obtained by sequentially turning on each of the RGB light sources. Therefore, even when the image processing circuit needs a function for processing RGB data on each side of the front and back surfaces as a set, the color image sensor can be realized with a memory configuration with the same small capacity as that for single-side reading.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining switching timing of front and back screens according to a double-sided document reading method of the present invention.
FIG. 2 is a functional block diagram showing an example of an embodiment of the main configuration of an image processing circuit for carrying out the double-sided document reading method of the present invention.
FIG. 3 is a diagram for explaining the control timing of a color image sensor of a light source sequential lighting method.
FIG. 4 is a diagram illustrating an example of the control timing of a color image sensor that switches front and back for each line of RGB.
FIG. 5 is a functional block diagram illustrating an example of a configuration of a main part of a double-sided simultaneous reading device.
FIG. 6 is a diagram for explaining a second control timing of a color image sensor that switches front and back for each line of RGB1.
[Explanation of symbols]
11: A / D conversion unit, 12: Dark correction unit, 13: Bright correction unit, 14: Color conversion unit, 15: Line memory

Claims (1)

A color image sensor unit of the light source sequential lighting system that obtains the color signal of each color by turning on the light sources of three colors of red, green, and blue one by one is arranged facing each other, and both sides of the document can be read simultaneously. In the double-sided color original reading apparatus having the following configuration:
It has a front and back shared memory that stores only two lines on one side that do not separate the front and back access areas,
By inputting by switching the front and back signal alternately as a set color signals each surface 1 by line at three colors of the image sensor unit in which each light source is obtained by sequentially lighting the image processing apparatus, simultaneous Duplex A double-sided color original reading apparatus characterized by performing reading .

Images