JPH0125265B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image reading device used for reading originals in electronic files, facsimiles, and the like.

Configuration of Conventional Example and Its Problems FIG. 1 shows a schematic configuration of a conventional image reading device. A document 3 held between a feed roller 1 and a pinch roller 2 travels between guide plates 4 as the feed roller 1 rotates. A notch 5 is provided in a part of the guide plate 4, and the document 3 exposed through the notch 5 is irradiated with light from a fluorescent lamp 6, and the reflected light enters an image sensor 8 via a condenser lens 7. Light is emitted and photoelectric conversion is performed. When reading of one page per line is completed in this manner, the original 3 is ejected from the apparatus while being held between the ejecting roller 9 and the pinch roller 10.

By the way, in such conventional devices,
When setting original 3 in the device, either the front or back side must be specified, and if it is set incorrectly, the receiving side will receive a blank received image. .

Purpose of the Invention The present invention has been made in view of the above-mentioned problems in the prior art, and provides an image that does not require specifying the loading side when setting an original, and can also read an original that has been copied on both sides. A reading device is provided.

Structure of the Invention The present invention provides two reading devices so that both sides of a document can be read, and counts the number of black pixels out of the image signals for one page of the document obtained by these two reading devices. However, if this count value exceeds a predetermined number, it is determined that there is information on the surface that was read, and conversely, if it is less than the predetermined number, there is no information. The aim is to achieve the above objectives.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a schematic configuration of an image reading device according to an embodiment of the present invention. Reference numeral 11 designates a document having information to be read on both sides, and reference numeral 12 designates a feed roller 13 as a pinch roller.The document 11 is held between the feed roller 12 and the pinch roller 13 and travels between the guide plates 14. The guide plate 14 has a notch 1
5 and a notch 16 are provided, each of which serves as a reading point for reading the front and back sides of the document 11.
Fluorescent lamps 17 and 18 illuminate the front and back surfaces of the document 11 exposed through the cutouts 15 and 16, respectively. 19 and 20 are fluorescent lamps 1 that illuminate the original 11;
a condensing lens that condenses the reflected light of lights 7 and 18;
Reference numerals 1 and 22 denote image sensors 2 that receive light collected by condensing lenses 19 and 20 and convert it into electricity.
3 and 24 are analog-to-digital converters that convert the outputs of the image sensors 21 and 22 into digital signals;
25 and 26 are analog-to-digital converters 23 and 24
This is a page memory that inputs and stores the output of 27 is a gate circuit that selectively outputs the outputs of the page memories 25 and 26, and 28 is an output terminal. A detector 29 detects the entry of a document, and is composed of a light emitting element 29a and a light receiving element 29b, and a detection signal is input to the control circuit 30.
The control circuit 30 activates the page memory 25 t ₁ second after the detection signal from the light receiving element 29 b is input, and further activates the page memory 26 t ₂ seconds after the detection signal from the light receiving element 29 b ends. The operation of the page memory 25 is terminated after t ₁ second, and the operation of the page memory 26 is terminated after ₂ seconds t. Control is performed to retrieve the information stored in the .

The operation of this embodiment configured as described above will be explained in the third section.
The following description will be made using the main part signal waveform diagram of this embodiment shown in FIG.

The originals 11, which have been placed in page order in advance, are fed into the apparatus one by one by an automatic paper feeder or the like (not shown). At this time, when the leading edge of the original 11 reaches the detector 29, light is emitted from the light emitting element 29a. The light entering the light receiving element 29b is blocked and the signal a rises and the control circuit 3
0 detects the entry of the original 11. Control circuit 30
After t ₁ second, page memory 2 is activated by signal b.
5 is in a writing state and the black pixel counter 31 is in a countable state. During this time corresponding to t ₁ second, the original 11 is moved between the roller 12 and the pinch roller 13.
While being held between the two, the tip travels at a constant speed until the tip reaches the notch 15. Document 1 exposed through notch 15
The surface of the sensor 1 is illuminated with light from a fluorescent lamp 17, and this reflected light is collected by a condenser lens 19 and accumulated in an image sensor 21. Information photoelectrically converted by the image sensor 21 is stored in the black pixel counter 31 and page memory 25 via the analog-to-digital converter 23.

Further, at t ₂ seconds after the rise of the control signal b of the page memory 25, the control circuit 30 uses the signal c to set the page memory 26 in a writing state and to enable the black pixel counter 32 to count _.
The leading edge of the document 11 reaches the notch 16 at a time corresponding to seconds, and the back surface of the document 11 exposed from the notch 16 is illuminated with light from the fluorescent lamp 18, and the reflected light is focused by the condenser lens 20. and enters the image sensor 22. The image sensor 22 photoelectrically converts incident light and outputs a signal to an analog-to-digital converter 24, and the digital signal is input to a black pixel counter 32 and a page memory 26.

By the way, regarding the structure of the notches 15 and 16 described above, there is a guide plate 14 on the back side of the notch 15 provided on the front side of the original 11, and a guide plate 14 is provided on the back side of the notch 16 provided on the back side of the original 11. Similarly, there is a guide plate 14. That is, the reading points on the front and back sides of the document set in the notches 15 and 16 are at mutually shifted positions, and as a result, the guide plate 14
blocks the light from the fluorescent lamp 17 located on the front side of the original 11 from the image sensor 22 that reads the back side of the original 11;
It functions to block the light from the image sensor 21 that reads the surface of the document 11, and improves the S/N ratio.

In this state, the front and back sides of the document 11 are read simultaneously, and as the feed roller 12 rotates, the document 11 gradually advances and reaches the paper ejection roller 33.The paper ejection roller 33 moves at the same speed as the feed roller. It rotates, and pinches the original 11 with a pinch roller 34 to run the original 11 at a constant speed. feed roller 1
The reason why the rotational speeds of the paper ejection roller 2 and the paper ejection roller are the same and constant is that both sides are read simultaneously. That is, when reading only one side, the time required for encoding differs depending on the density of information on the document, so it is possible to change the document traveling speed, but in this embodiment, this is done at a constant speed. The structure of the document transport system is simplified by running the document at the same time.

Now, as the document 11 gradually travels, its rear end passes through the detector 29, and as a result, the light receiving element 29b
When the light from the light emitting element 29a enters, the signal a falls, and the control circuit 30 detects the completion of the document.

By the way, the black pixel counters 31 and 32 start counting the number of black pixels of the image signals input to the page memories 25 and 26 in synchronization with the rise of the signals b and c from the control circuit, and notify the completion of reading the original 11. Counting ends in synchronization with the fall of signals b and c and is cleared. Further, when this count value exceeds a predetermined number, carry signals d and e are inputted to the control circuit 30. Based on the carry signals d and e, the control circuit 30 determines whether there is information on both sides of the document, or whether it is on either the front or back side, and sends a gate control signal f.
is output to the gate circuit 27.

That is, when the carry signals d and e are output from both the black pixel counters 31 and 32 as shown in FIG. 3, the page memory 25 is read out in synchronization with the fall of the control signals b and c. , 26 passes through the gate circuit 27 and is output from the output terminal 28, so that the gate circuit 27 is controlled by the gate control signal f.

However, as shown in FIG. 4, when the front side of the document 11 is blank and there is information on the back side, the black pixel counter 31 does not output the carry signal d, and only the black pixel counter 32 outputs the carry signal c. be done.

At this time, the control circuit 30 closes the gate circuit 27 using the gate control signal f when reading the image signal stored in the page memory 25.
Thereafter, the image signal stored in the page memory 26 is read out in synchronization with the fall of the signal c, but at this time the gate circuit 27 is opened and outputted from the output terminal 28.

In the embodiment, there is information on the back side of the document 11 and the front side is blank, but in the opposite case, that is, when there is information on the front side and the back side is blank, only the black pixel counter 32 The carry signal d is output to the control circuit 30 and the page memory 2
It is easy to understand that only the image signal stored in 6 is output from the output terminal 28.

By the way, the predetermined numbers for the black pixel counters 31 and 32 are 0 (that is, a completely blank state).
However, even if there is no information, there is usually dust, pre-printed characters, etc., so it is only necessary to take these into consideration when deciding.

Although the front and back sides of a single document are read through the series of operations described above, if an automatic paper feeder is provided in the paper feed section, both sides of a considerable number of documents can be automatically read.

Effects of the Invention As is clear from the above description, according to the present invention, it is possible to automatically detect the presence or absence of information on a document (both sides or one of the front and back sides). This has the effect of eliminating the need to specify the set plane.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a conventional image reading device;
This figure is a block diagram of an image reading apparatus according to an embodiment of the present invention, and FIGS. 3 and 4 are signal waveform diagrams of the same essential parts, respectively. 12... Feed roller, 21, 22... Image sensor, 23... Paper discharge roller, 25, 26... Page memory, 27... Gate circuit, 29... Detector, 30... Control circuit, 31, 32 ...Black pixel counter.

Claims (1)

[Claims] 1. A sub-scanning unit that feeds the document in the sub-scanning direction, a first image sensor that optically reads the front side of the document, and a reading scanning position of the first image sensor that reads the back side of the document at a position that is different in the sub-scanning direction. a second image sensor for optically reading the image, a first storage means for storing the image signal read by the first image sensor, and a second storage means for storing the image signal read by the second image sensor. a control circuit that controls input and output of the first and second storage means according to the sub-scanning state of the document;
a first counter that counts the number of black pixels among the image signals input to the storage means; and a second counter that counts the number of black pixels among the image signals input to the second storage means. An image reading device comprising: when the count values of the two counters exceed a predetermined number, an image signal stored in the storage means corresponding to the counter is output.