Patent Application
20070201918
1. Field of the Invention
The present invention relates to an image copier and an image copying method, and particularly to an image copier and an image copying method, in which an accurate document size can be detected regardless of the kind of document.
2. Related Art
JP-A-61-51447 discloses an image copier in which an infrared ray emitting element is arranged on a document holding cover (platen cover), and document size detection is performed by a light receiving element arranged below a document table glass (platen glass) to be opposite thereto.
Further, JP-A-5-207239 discloses an image copier in which an exposure lamp is used, reflected light of the exposure lamp is received by a CCD sensor, and document size detection is performed.
In the image copier disclosed in JP-A-61-51447, since the infrared ray emitting element is used, in the case where a CCD as a document reading element is used as the light receiving element, there may be a fear that a CCD sensor having high sensitivity to infrared rays is damaged. Accordingly, a dedicated light receiving element is required instead of the CCD. Since the dedicated light receiving element is relatively expensive as compared with the CCD, the cost of the image copier is increased. Further, since it is necessary to arrange the light receiving element inside of a scanner casing, the thickness of the scanner casing is increased.
In the image copier disclosed in JP-A-5-207239, at the time of document size detection, the exposure lamp is caused to emit light in a state where the platen cover is closed to a specified angle, and the document size detection is performed. That is, since the detection operation of the document size is performed before the platen cover is completely closed, there maybe a fear that an erroneous detection occurs by the influence of external light.
Further, since the reflected light of the exposure lamp is used, in the case of a photographic document or the like in which the whole document is printed with a dark color tone or the like, the quantity of reflected light by the document is lowered, and there may be a fear that a size detection error occurs.
Then, an image copier and an image copying method, in which an accurate document size can be detected independently of a document, are desired.
The invention has been made in view of the above circumstances, and has an object to provide an image copier and an image copying method, in which a document size can be accurately detected regardless of the kind of document.
In order to solve the problem, an image copier of the invention includes a scanner configured to read an image and a printer configured to form the image on a sheet. The scanner includes a document table configured to position a document from which the image is read, a light source configured to irradiate a light to the document when the image of the document is read, an image reading light configured to receive element configured to receive reflected light from the document, a document holding cover configured to hold the document on the document table and to include a document size detecting light emitting element to emit light at a time of document size detection and a document size detecting light emitting element controller configured to control the document size detecting light emitting element.
In order to solve the problem, an image copying method of the invention includes: detecting a size of a document as an image read object, reading an image from the document, and forming the image read at the image read step. The document size detection step includes: receiving light irradiated by causing a document size detecting light emitting element to emit light, extracting a specified pixel group including a pixel corresponding to the document size detecting light emitting element, determining whether a CCD output value of the pixel group extracted at the pixel extraction step exceeds a previously set threshold value, and determining the size of the document of the image read object based on a determination result at the threshold value determination step.
In the image copier and the image copying method according to the invention, since the light irradiated from the document size detecting light emitting element is directly used without being reflected in the state where the document holding cover is closed, the high-precision document size detection independent of the influence of external light and the kind of document can be performed.
In the accompanying drawings;
Embodiments of an image copier and an image copying method of the invention will be described with reference to the accompanying drawings.
Incidentally, up, down, right and left directions in the specification are based on a normal device use state except when an explanation is particularly made.
The image copier 1A includes a scanner 2A for reading an image, and a printer 3 for forming the image and printing the formed image on a sheet.
The scanner 2A reads a document 4 positioned to read the image. In the case where the read image is formed, the scanner 2A transmits the information of the read image to the printer 3.
The printer 3 forms the image on a sheet based on the information of the image to be formed, and then prints out the sheet on which the image has been formed to a sheet discharge tray 5.
Incidentally, although the image copier 1A further includes a system controller to perform a control and a control panel as a user interface, they are omitted in
Further, there is also a case where the scanner 2A does not transmit the read image information to the printer 3, but transmits it to a not-shown recording device or the like.
Furthermore, there is also a case where the information of the image to be formed by the printer 3 is received from a not-shown device other than the scanner 2A or is stored in the printer 3.
Next, the structure and operation of the scanner 2A in the image copier 1A will be described.
Note that
In the scanner 2A, a document holding cover 9A is openablely and closablely provided to a casing 8 including a document table glass 7 as a document table.
The document table glass 7 is provided on an upper surface of the casing 8. At the time of image read, the read surface of the document 4 as the image read object points downward, and is positioned on the document table glass 7.
The document holding cover 9A is fixed to the casing 8 at its end so as to be openable and closable, and presses the document 4 positioned on the document table glass 7 onto the document table glass 7 by closing the document holding cover 9A. Besides, a plurality of LEDs (Light Emitting Diodes) 10, which are document size detecting light emitting elements to irradiate light to the document 4 when the size of document 4 is detected, are arranged on the document holding cover 9A. The control of the LEDs 10, for example, switching on and off of the LEDs 10 at the time of document detection, is performed by an LED controller 11A as a document size detecting light emitting element controller provided on the document holding cover 9A.
Besides, a cover opening/closing detection sensor 12 to detect the opening/closing state of the document holding cover 9A is provided in the casing 8.
On the other hand, inside the casing 8, there are provided a light source 13, a first carriage 16 having a reflector 14 and a first mirror 15, a second carriage 20 having a second mirror 18 and a third mirror 19, a collective lens 22, a CCD (Charge Coupled Device) sensor board 23 as an optical/electrical conversion device, and a control board 25A as a scanner controller electrically connected to the CCD sensor board 23 through an electric connecter such as, for example, a harness 24.
Incidentally, there is also a case where the LED controller 11A is mounted on the control board 25, or is mounted at another position in the scanner 2 or the printer 3.
Besides, reference character SP shown in
In the scanner 2A configured as stated above, at the time of image read, first, light from the light source 13 is irradiated to the document 4, and is reflected by the document 4. The reflected light reflected by the document 4 is imaged on a sensor surface of a CCD line sensor 26 as a photoelectric element mounted on the CCD sensor board 23 through the first mirror 15, the second mirror 18, the third mirror 19, and the condenser lens 22.
The first carriage 16 and the second carriage 20 can be moved by the driving of a motor which is not shown in
The CCD line sensor 26 successively reads the document 4 placed on the document table glass 7 line by line, and converts it into an analog electric signal corresponding to the intensity of the light signal as the reflected light. Then, the converted analog electric signal is transmitted to the control board 25A connected to the CCD sensor board 23 through the harness 24.
The control board 25A converts the analog electric signal received from the CCD line sensor 26 into a digital signal. Then, the control board 25A performs a digital signal processing such as a shading (distortion) correction to correct a low frequency distortion due to the condenser lens 22 or a high frequency distortion caused by the fluctuation of sensitivity of the CCD line sensor 26.
When the shading correction is performed, a signal as a reference of black and a signal as a reference of white are required. The signal as the reference of black is an output signal of the CCD line sensor 26 when the light source 13 is placed into a switching-off state and in a state where light is not irradiated to the CCD line sensor 26. The signal as the reference of white is an output signal of the CCD line sensor 26 when the light source 13 is placed into a switching-on state and the reflected light from a white reference plate 27 is read. Further, when the signals as the reference of black and white are generated, in order to reduce an influence due to a singular point or a quantization error, it is generally performed to average signals for plural lines.
Note that the AD conversion processing performed by the control board 25A may be performed in the CCD sensor board 23. The CCD line sensor 26 may be another photoelectric element.
The control board 25A includes a processing IC 29 such as a CPU, a timing generation circuit 30, an analog processing circuit 31, a line memory circuit 32, and an image processing circuit 33A.
The processing IC 29 performs the detection of an opening/closing state of the document holding cover 9A, the control of a signal processing as to a signal transmitted from the CCD line sensor 26, the control of a light source control circuit 37 to perform the control of the light source 13 connected through a bus such as an address bus 35 and a data bus 36, and the control of a drive control circuit 39 for controlling a motor 38 to move the first carriage 16 and the second carriage 20.
The timing generation circuit 30 generates a signal necessary for driving the CCD line sensor 26 and a signal necessary for an analog processing performed in the analog processing circuit 31.
The signal generated by the timing generation circuit 30 and necessary for driving the CCD line sensor 26 is subjected to timing adjustment by a CCD sensor control circuit 41 mounted on the CCD sensor board 23, and is transmitted to a CCD driver 42. Then, after signal amplitude leveling or waveform shaping is performed by the CCD driver 42, an input is made to the CCD line sensor 26.
The signal necessary for the analog processing is inputted to the analog processing circuit 31. The analog processing circuit 31 performs various analog processings, and then transmits the signals performed analog processing to the image processing circuit 33A.
The line memory circuit 32 corrects a position shift generated when each line sensor of the CCD line sensor 26 reads.
The image processing circuit 33A includes a document size detector 43A to detect a document size. The image processing circuit 33A performs, in addition to the document size detection processing performed by the document size detector 43A, the control of the line memory circuit 32, the shading correction performed by using the image signal converted into the digital signal, the enlargement/reduction processing, and the image processing such as LOG conversion.
Incidentally, in
Next, a description will be given to the structure of the document size detector 43A and a document size detection method performed by the document size detector 43A.
The document size detector 43A determines the output levels of the light irradiated from the LEDs 10 arranged at specified positions of the document holding cover 9A as shown in
For example, five LEDs of a first LED 10A to a fifth LED 10E are arranged on the document holding cover 9A shown in
Here, HP1 and HP2 shown in
The second home position is a position where the first carriage 16 at the time of document size detection is moved from the first home position and the light emitted from the fifth LED 10E is received by the CCD line sensor 26.
Hereinafter, for convenience of explanation, it is assumed that the LEDs 10 arranged on the document holding cover 9A are those of the example shown in
The document size detector 43A includes a pixel extraction element 46 to extract pixels and the vicinity corresponding to the arrangement positions of the respective LEDs 10A to 10E, a threshold value determination element 47 to determine the presence/absence of the document 4 based on the result obtained by comparison with a specified threshold value, and a document size determination element 48 to determine the size of the positioned document 4 based on the result determined by the threshold value determination element 47.
CCD output signals obtained when the CCD line sensor 26 receives the light emitted from the respective LEDs 10A to 10E are inputted to the document size detector 43A after various signal processings such as A/D conversion are performed. The CCD output signals after the signal processing are first inputted to the pixel extraction element 46.
In the pixel extraction element 46, pixels corresponding to the previously determined arrangement positions of the respective LEDs 10A to 10E and pixels in the vicinities thereof (hereinafter referred to as pixel groups) are extracted among pixels in a main scanning direction read by the CCD line sensor 26.
In the case where the document 4 is, for example, an A4-size document, the size is 297 mm in a long side direction and 210 mm in a short side direction. In the case where the document read operation is performed while the long side direction is made the main scanning direction and the short side direction is made the sub-scanning direction, it is necessary that the number of effective pixels of the photodiode array of the CCD line sensor 26 is at least 7016 pixels (4677 pixels at the time of 400 dpi). In general, the sensor has 7500 pixels (5000 pixels at the time of 400 dpi).
For example, in the case where the number of effective pixels of the photodiode array of the CCD line sensor 26 is 7016 pixels, and the LEDs 10A to 10E are previously arranged at positions shown in
The pixel extraction element 46 extracts pixels in a specified range including the corresponding pixel, for example, five forward pixels and five backward pixels from each of the corresponding pixels. In the case where the range of pixels to be extracted is made to have five forward pixels and five backward pixels, the output of the first LED 10A is 495th to 505th pixels, the output of the second LED 10B and the fifth LED is 3570th to 3580th pixels, the output of the third LED 10C is 5055th to 5065th pixels, and the output of the fourth LED 10D is 6170th to 6180th pixels.
The pixel positions correspond to the respective document sizes (in the example shown in
When extracting the pixel groups corresponding to the positions of the respective LEDs 10A to 10E, the pixel extraction element 46 transmits CCD output signals (0 to 255) as to the respective pixels of the extracted pixel groups to the threshold value determination element 47.
The threshold value determination element 47 calculates the maximum value from the data of 11 pixels extracted for each of the LEDs 10A to 10E. The maximum value is calculated at each of the arrangement positions of the respective LEDs 10A to 10E. The presence/absence of the document 4 is determined by comparing the calculated maximum value with a specified threshold value.
At this time, the LED 10 is adjusted so that the level of the CCD output signal (hereinafter referred to as the CCD output value) in the state where there is no document 4 becomes saturated (255). The threshold value based on which the presence/absence of the document 4 is determined is a CCD output value at the time when transmission is performed through a sheet having a basis weight of 45 g/m2, which is thinnest among generally used sheets.
For example, in the case where the LEDs 10A to 10E are arranged as shown in
On the other hand, since the third LED 10C and the fourth LED 10D are not shaded from the light, the CCD output values as to the third LED 10C and the fourth LED 10D are output values close to 255. By performing the determination as stated above, the shaded LEDs 10 can be detected.
The threshold value determination element 47 determines whether each of the LEDs 10A to 10E is shaded from the light, and transmits the determination result to the document size determination element 48.
The document size determination element 48 performs a document size determination based on the received LED shading determination result and information indicated in the following Table 1.
The word “ON” in each LED item indicated in Table 1 denotes a state (there is document) in which shading is performed by the document 4, and “OFF” indicates there is no document. Besides, “-” denotes neglect (Don't Care).
As stated above, the document size determination element 48 can make the determination on the document size based on the received LED shading determination result and the information indicated in the following Table 1.
After making the determination on the document size, the document size determination element 48 transmits the information of the determination result to the processing IC 29 shown in
Next, the structure and operation of the printer 3 in the image copier 1A will be described.
The printer 3 includes an image processing board 50 as an image processing unit, a laser optical system unit 52 and an image formation unit 53. The image processing board 50 performs a processing which is necessary for generating an image, for example, a processing of converting information read by the CCD line sensor 26 into a control signal of a not-shown light emitting element such as a semiconductor laser. The laser optical system unit 52 includes the light emitting element, such as the semiconductor laser to form a latent image on a photoreceptor drum 51.
The image formation unit 53 includes the photoreceptor drum 51 necessary for generating an image by an electrophotographic process, a charger 55, a developer 56, a transfer charger 57, a peeling charger 58, a cleaner 59, a sheet transport mechanism 60 to transport a sheet P, and a fuser 61. The sheet P on which an image is formed by the image formation unit 53 is outputted to the sheet discharge tray 5 through a discharge roller 62 to discharge the sheet P to the outside of the machine body.
For example, as shown in
Further, as shown in
Next, an image copying method of the first embodiment of the invention will be described.
The image copying method of the first embodiment of the invention includes a document size detection step of detecting a size of the document 4, an image read step of reading an image from the document 4, and an image formation step of forming the image read at the image read step. The image copying method of the invention is characterized in a method of detecting the size of the document 4, that is, the document size detection step.
The first document size detection step is performed in the case where a mode of automatically detecting the size of the document 4 is selected.
The first document size detection step includes a document holding cover closing confirmation step of detecting whether the document holding cover 9A is closed and confirming that the document holding cover 9A is closed (step S1), a document size detecting light emitting element step of causing the LEDs 10A to 10E as document size detecting light emitting elements to emit light (step S2, step S4), an irradiation light receiving step of receiving the irradiation light from the LEDs 10A to 10E (step S3, step S5), a pixel group extraction step of extracting specified pixel groups including pixels corresponding to the respective LEDs 10A to 10E (step S6), a threshold value determination step of determining whether CCD output values of the pixel groups extracted at the pixel extraction step exceed a previously set threshold value (step S7), a document size determination step of determining a size of a document as an image read object based on a determination result at the threshold value determination step (step S8), and a document size designation request step of requesting designation of a document size (step S9) in a case where the size of the document 4 can not be determined at the document size determination step (NO at step S8).
In the first document size detection step, first, it is detected at step S1 whether the document holding cover 9A is in a completely closed state. When the document holding cover 9A is in the completely closed state (in the case of YES at step S1), next, at step S2, the first LED 10A to the fourth LED 10D arranged at the positions corresponding to the first home position are caused to emit light.
The light emitted from the first LED 10A through the fourth LED 10D is received by the CCD line sensor 26 through the first carriage 16 standing by at the first home position, the second carriage 20 and the condenser lens 22 (step S3). At step S3, the fifth LED 10E and the light source 13 are switched off.
Next, when the first carriage 16 is moved to the second home position and the movement is completed, the fifth LED 10E arranged at the position corresponding to the second home position emits light (step S4). The light emitted from the fifth LED 10E is received by the CCD line sensor 26 through the first carriage 16 standing by at the second home position, the second carriage 20, and the condenser lens 22 (step S5). At step S5, the first LED 10A to the fourth LED 10D and the light source 13 are switched off.
When the irradiation light receiving step (step S3 and step 5) is completed, the pixel extraction element 46 extracts the specified pixel groups including the pixels corresponding to the LEDs 10 (step S6), the threshold value determination element 47 determines whether the respective LEDs 10A to 10E are shaded based on the extracted CCD output values of the pixel groups (step S7), and the document size determination element 48 makes a document size determination based on the LED shading determination result and the information indicated in Table 1 (step S8).
In the case where the determination of the document size can be made (in the case of YES at step S8), the first document size detection step is ended (END).
On the other hand, in the case where the document holding cover 9A is not in the completely closed state (in the case of NO at step S1), the processing step at step S1 is repeated until the document holding cover 9A becomes the completely closed state and standby is performed.
In the case where the determination of the document size has not been made (in the case of NO at step S8), the designation of the document size is requested to the user (step S9), and the first document size detection step is ended (END).
According to the image copier and the image copying method of the first embodiment of the invention, the light irradiated from the LED 10s in the state where the document holding cover 9A is closed is not reflected but is directly used. Then, the size of the document 4 can be detected.
Further, since the irradiation light from the LED 10s are directly used, it becomes possible to perform high-precision document size detection independent of the influence of external light and the kind of document.
Furthermore, in the image copier 1A, since the CCD line sensor 26 as the image reading light receiving element is used also as the document size detecting light receiving element, a new light receiving element for document size detection is unnecessary, and costs can be reduced.
Incidentally, in the image copier 1A, although the description has been given to the case where the LED 10 is used as the document size detecting light emitting element, an organic EL (Electro Luminescence) or another light emitting element to emit a visible light may be used instead of the LED 10.
Further, although the description has been given to the case where the CCD line sensor 26 is used as the image reading light receiving element, a CIS (Contact Image Sensor) may be used instead of the CCD line sensor 26.
Furthermore, although the size of the document 4 in the long-side direction is detected by using the fifth LED 10E, in order to improve the performance, the image copier 1A may be constructed such that the fifth LED 10E is eliminated, a conventional document size detection sensor having light emitting/receiving elements is arranged in the scanner 2A, and the document size detection is performed based on the detection result.
An image copier 1B as an example of an image copier of a second embodiment of the invention is different from the image copier 1A shown in
Next, the structure and operation of the scanner 2B in the image copier 1B will be described.
As shown in
In the document holding cover 9B, instead of the document size detecting light emitting element (LED 10) arranged in the document holding cover 9A, document size detecting light receiving elements are arranged. As the document size detecting light receiving element, for example, a photodiode (hereinafter referred to as a PD) 70 is adopted.
Besides, the control of the PD 70 and a necessary signal processing such as A/D conversion are performed by a PD controller 71 provided in the document holding cover 9B.
On the other hand,
As shown in
Next, the structure of the document size detector 43B and a document size detection method performed by the document size detector 43B will be described.
As shown in
In the document holding cover 9B shown in
Hereinafter, for convenience of explanation, a description will be made while it is assumed that the PDs 70 arranged in the document holding cover 9B are those of the example in
The document size detector 43B includes a threshold value determination element 47 to determine the presence/absence of the document 4 based on the result of comparison with a specified threshold value, and a document size determination element 48 to determine the size of the positioned document 4 based on the result of the determination of the threshold value determination element 47.
Respective PD output signals (a first PD output signal to a fifth PD output signal) obtained as a result that the respective PDs 70A to 70E receive the light irradiated from the light source 13 are inputted to the document size detector 43B after various signal processings such as A/D conversion are performed. The PD output signals after the signal processings are first inputted to the threshold value determination element 47.
In the threshold value determination element 47, the respective inputted PD output signals (PD output signal values) and a specified threshold value are compared with each other. The PD output signal value is adjusted so that it becomes saturated (255) in a state where there is no document 4. Accordingly, in the case where the PD output signal value is larger than the specified threshold value, the threshold value determination element 47 determines that there is no document 4, and in the case where it is smaller, a determination is made that the document 4 exists. Then, the document presence/absence determination result (shading determination result) is inputted from the threshold value determination element 47 to the document size determination element 48.
The document size determination element 48 makes a document size determination based on the shading determination result and information indicated in the following Table 2. Then, the information of the determination result is transmitted to a processing IC 29 shown in
Incidentally, the word “ON” in each PD item shown in Table 2 indicates a state (there is a document) where shading is performed by the document 4, and “OFF” indicates there is no document. Besides, “-” indicates neglect (Don't Care)
Similarly to the image copier 1A, the image copier 1B constructed as stated above can be used as shown in
Next, an image copying method of the second embodiment of the invention will be described.
The image copying method of the second embodiment of the invention is different from the image copying method of the first embodiment of the invention in a partial processing step of a document size detection step of detecting the size of the document 4, however, they are substantially the same in an image read step and an image formation step. Then, the document size detection step (hereinafter referred to as a second document size detection step) in the image copying method of the second embodiment of the invention will be described.
Incidentally, in the second document detection step, processing steps which are substantially the same as those of the first document detection step are denoted by the same step numbers and their description will be omitted.
The second document size detection step is performed in the case where a mode of automatically detecting the size of the document 4 is selected.
The second document size detection step includes a document holding cover closing confirmation step (step S1), an image reading light emitting element step of causing the light source 13 as the image reading light emitting element, which is used also as the document size detecting light emitting element, to emit light (step S12, step S14), an irradiation light receiving step of receiving the light irradiated from the light source 13 (step S13, step S15), a threshold value determination step of determining whether PD signal output values of the respective PDs 70A to 70E received at the irradiation light receiving step exceed a previously set threshold value (step S16), a document size determination step (step S8), and a document size designation request step of requesting the designation of a document size (step S9) in a case where the size of the document 4 can not be determined at the document size determination step (in the case of NO at step S8).
In the second document size detection step, first, when the document holding cover 9B is in a completely closed state (in the case of YES at step S1), next, the light source 13 standing by at the first home position at step S12 is caused to emit light. The light emitted from the light source 13 is received by each of the first PD 70A to the fourth PD 70D arranged at the positions corresponding to the first home position (step S13).
Subsequently, when the first carriage 16 moves to the second home position and the movement is completed, the light source 13 emits light (step S14), and the light irradiated from the light source 13 is received by the fifth PD 70E arranged at the position corresponding to the second home position (step S15).
When the irradiation light receiving step (step S13 and step S15) is completed, based on the PD signal output values of the respective PDs 70A to 70E received by the threshold value determination element 47, it is determined whether the light from the light source 13 is shaded (step S16), and the document size determination element 48 makes a document size determination based on the shading determination result and the information indicated in Table 2 (step S8). In the case where the determination of the document size can be made (in the case of YES at step S8), the second document size detection step is ended (END).
Note that processing steps performed in the case of NO at step S1 and in the case of NO at step S8 are similar to those of the first document size detection step.
According to the image copier and the image copying method of the second embodiment of the invention, the light irradiated from the light source 13 in the state where the document holding cover 9B is closed is not reflected but is directly used, and the size of the document 4 can be detected.
Further, since the irradiation light from the light source 13 is directly used, it becomes possible to perform the high-precision document size detection independent of the influence of external light and the kind of document.
Furthermore, in the image copier 1B, since the light source 13 as the image reading light emitting element is used also as the document size detecting light emitting element, a new light emitting element for document size detection is unnecessary, and costs can be reduced.
An image copier 1C as an example of an image copier of a third embodiment of the invention is different from the image copier 1A shown in
Next, the structure and operation of the scanner 2C in the image copier 1C will be described.
As shown in
In the document holding cover 9C, as compared with the document holding cover 9A, an LED controller 11C is provided instead of the LED controller 11A. The LED controller 11C is different from the LED controller 11A in that the LEDs 10 are controlled to emit light not only at the time of document detection but also at the time of image detection. That is, the document holding cover 9C is such that the document holding cover 9A is further improved.
A conventional document holding cover including the document holding cover 9A is generally configured by a white material so that a see-through copying of the bottom side of the document 4 does not occur. However, since the LEDs 10A to 10E are arranged in the document holding cover 9A, the document holding cover 9A has such a structure that holes (hereinafter referred to as LED arrangement holes) for arrangement of the LEDs 10A to 10E are opened. The LED arrangement holes become shadows at the time of document read, and cause image noise.
Therefore, in the document holding cover 9C, in order to prevent the image noise, that is, the occurrence of the shadow, the LEDs 10 are caused to emit light also at the time of document read, so that the white degree almost equivalent to the white of the document holding cover is realized and the see-through copying of the bottom side of the document is suppressed.
Generally used sheets include sheets from a thin paper having a basis weight of 45 g/m2 to a thick paper having a basis weight of 150 g/m2. With respect to these sheets, the output value of the CCD line sensor 26 at the LED arrangement position (LED is switched off) has a relation indicated by a solid line of
The light emission quantity of the respective LEDs 10 is controlled by the LED controller 11C so that the output value of the CCD line sensor 26 at the arrangement position of the LEDs 10 are almost equal to the output value of the CCD line sensor 26 in the white member area (area other than the arrangement position of the LEDs 10) of the document holding cover 9C.
Besides, as shown in
Since the light emission quantity of the LED 10 at the time of image read has only to compensate the quantity of light absorbed by the LED arrangement hole, it may be smaller than the light emission quantity at the time of document size detection. That is, as shown in
Next, an image copying method of a third embodiment of the invention will be described.
The image copying method of the third embodiment of the invention is different from the image copying method of the first embodiment of the invention in that the LEDs 10 as the document size detecting light emitting element emits light also at the image read step, however, they are substantially the same in other points.
According to the image copier and the image copying method of the third embodiment of the invention, in addition to the effects of the image copier and the image copying method of the first embodiment of the invention, the see-through copying of the bottom side of the document 4 at the time of image read can be suppressed by causing the LEDs 10 as the document size detecting light emitting element to emit light also at the time of image read.
As stated above, according to the invention, it is possible to perform the high-precision document size detection independent of the influence of external light and the kind of document. Besides, since the document size detecting light receiving element is used also as the CCD line sensor 26 as the image reading light receiving element, or the document size detecting light emitting element is used also as the light source 13 as the image reading light emitting element, costs can be reduced. Further, the see-through copying of the bottom side of the document can be suppressed by causing the LEDs 10 as the document size detecting light emitting element to emit light also at the time of image read.
Note that the invention is not directly limited to the above embodiments, and at the stage of practice, structural elements are modified and can be embodied within the range not departing from the gist of the invention. Besides, various inventions can be formed by suitable combination of plural structural elements disclosed in the embodiments. For example, some structural elements may be deleted from all structural elements disclosed in an embodiment. Further, structural elements of different embodiments may be suitably combined.
For example, in the present specification, although the description has been made on the assumption that the apparatus of the invention is the image copiers 1A to 1C, the invention can be applied to only the scanners 2A to 2C as an image read apparatus, or applied also to a document size detection apparatus which does not perform the image read of the document 4 but performs only the size detection.
Similarly, although the description has been made on the assumption that the method of the invention is the image copying method, an image read step including the document size detection step described in the specification can be applied as the image read method, or the document size detection step described in the specification can be applied as the document size detection method.
