JPS6363146B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image reading device in a facsimile machine or the like.

In conventional image reading devices such as facsimile machines, the scanning method has progressed from an optical scanning method to a solid-state imaging device, but it has always read only information on one side of a document. Therefore, if information to be transmitted by conventional facsimile existed on both sides of a paper, it was necessary to transmit one side, then turn the document over, load it again, and transmit the information on both sides.

The present invention has been made to solve these problems, and provides an image reading device that can simultaneously transmit images on both the front and back sides by loading a document once.

For this purpose, the present invention provides a device for optically reading a document, which includes a means for illuminating both sides of a document, a means for guiding information on the front and back sides of the document to one projection lens, and a device for reading images projected by the projection lens. Provided is an image reading device characterized in that a photoelectric conversion element is provided and one line of information on both sides of a document is aligned substantially in a straight line and simultaneously projected onto the photoelectric conversion element.

The present invention will be described below with reference to the drawings. 1st
The figure shows a conventional reading device. In the figure, 1 is a document, 2 is a feed roller rotating at a constant speed, 3 is a projection lens, and 4 is a reading element. The reading element is a linear array of small photoelectric conversion elements, usually a CCD (charge coupled device).
What is called a line sensor is used.

A document 1 is inserted between a pair of rollers 2. The projection lens 3 projects the image of the original 1 onto the reading element 4 .

Information for one line (scanning) of the original is projected onto the reading element 4, and by inputting an appropriate clock pulse to the reading element, image information for one line of the original is output to the outside. The output information is A/
The signal is converted into a binary signal via a D converter (not shown), subjected to necessary information processing (bandwidth compression, etc.), and then transmitted to a remote location via a telephone line or the like.

Conventionally, such devices have been used to scan originals, so if the necessary information is on both sides of the original, the original must be turned over and reloaded. However, it is inconvenient for the operator.

In order to eliminate the drawbacks of such devices, the second
As shown in the figure, image reading optical systems including projection lenses 3, 3' and reading elements 4, 4' are arranged on the front and back sides of the original 1, respectively, so that images on both the front and back sides can be read by loading the original 1 once. A readable version was proposed. However, in such a case, there are two sets of optical systems, and the control circuit is complicated and expensive.

The present invention provides an apparatus that is inexpensive and capable of simultaneously reading images on the front and back sides.

FIG. 3 is a schematic diagram showing an embodiment of the present invention. The device for photoelectrically reading a document according to the present invention includes means (not shown) for illuminating both sides of the document 1.
It is equipped with a means for guiding information on the front and back sides of the original to one projection lens 3, and a photoelectric conversion element 4 for reading the image projected by this projection lens, so that one line of information on both sides of the original can be read simultaneously in substantially a straight line. configured. In the illustrated embodiment, the original document 1 is fed by a pair of feed rollers 2 . The means for guiding the information on the front and back sides of the document to one projection lens 3 consists of a pair of mirrors 5 and 6 and a mirror 7. Since Figure 3 is drawn on a two-dimensional plane, it may be difficult to understand, but if you look at Figure 3B, the third mirror 7 directs the light in the Z-axis direction (for example, perpendicularly) to the plane of the paper. placed in a reflective manner.

A document 1 is sent by a pair of feed rollers 2. Both sides of the original 1 are illuminated by a light source (not shown),
The light diffusely reflected by the original 1 is reflected by mirrors 5, 6 and 7, and is projected onto the reading element 4 via the projection lens 3. On the reading element 4, the information for one line on the front side of the original 1 is projected on the left half of the reading element 4, and the information for one line on the back side is projected on the right half of the reading element 4, and the information on both lines is projected in a substantially straight line. They are lined up and projected at the same time. Although there is only one reading element 4 in FIG. 3, there is no problem even if physically two elements are used.

FIG. 4A is a diagram of the apparatus shown in FIG. 3 viewed from the original surface. It can be clearly understood that the mirror 6 is a mirror tilted at 45 degrees with respect to the original (paper surface), and information for one line of the original is projected onto the image reading element via the mirror 7 by a projection lens. FIG. 4B is a view of the apparatus shown in FIG. 3, viewed from the original direction. The reason why the optical system is formed by the mirror 5 or 6, 7 and two mirrors is to avoid a so-called mirror image. In order to avoid mirror images, it is sufficient to insert an even number of mirrors into the optical path, but if there is a problem such as a decrease in the amount of light, the scanning direction of the reading device and the device that restores the image signal output from this device should be adjusted. This can be avoided by reversing the output scanning direction left and right. That is, in a normal facsimile or other receiver, the receiving scanning direction is fixed, so in the case of this apparatus, reverse scanning can be performed on the transmitting side. i.e. reading element (CCD line sensor)
It is sufficient to scan the output from the opposite direction.

However, if the document feed speed is normal, the information will be reduced to 1/4, so the document feed speed,
In other words, if you reduce the sub-scanning speed to 1/2, the amount of information decreases by 1/2.
It is possible to do so.

FIG. 5 shows the reception state when a normal receiver receives the results of image reading according to the above-described embodiment with the original feeding speed set at 1/2 of the normal speed. It is true that the front and back sides of the document can be received at the same time, but since the width is halved, it looks unsightly, but it is acceptable for practical use. To avoid this unsightly appearance, when transmitting to a normal receiver, set the sub-scanning speed on the transmitting side to the normal speed to obtain an image with a correct vertical-to-horizontal ratio and 1/2 the size. This method is effective because it can reduce the transmission time to 1/2 without causing any practical problems.

FIG. 6 is a block diagram showing the control system. The line sensor drive circuit 16 sequentially reads the outputs of the individual photoelectric conversion elements of the line sensor. The read analog signal is sent to A/D converter 1
“0” due to the threshold value set in advance in 9.
Or it is converted into a digital signal of "1". Although there is a method of directly transmitting this signal to the outside via a modem or the like on a telephone line, since the amount of data becomes large, normally it is stored once in the line buffer 20 for band compression processing. The signal stored in the line buffer 20 is converted into a run length by a code converter 21, and then encoded using a conventional compression method such as a modified Huffman or modified read method. This coded signal is converted into a serial signal by a parallel-to-serial converter 22 and transmitted from a modem 23 to the outside. When the processing for one line is completed, a signal is sent to the motor drive unit 15 to feed the original for one line.After that, the signal from the line sensor is read again and the same process is performed to create one original. Transmitted externally. The block diagram shown in FIG. 5 is conceptual, and in reality multiple processing is performed. For example, when one line of information is transferred to a line buffer, the motor is driven to prepare for reading the next line, and at the same time the current line is processed and transmitted to the outside.

As described above, the present invention makes it possible to simultaneously transmit images on both the front and back sides by loading a document once.
Further, an image reading device is provided which can be controlled by a relatively inexpensive and simple control circuit.

[Brief explanation of drawings]

1 and 2 are schematic diagrams of a conventional image reading device, FIG. 3A is a sectional view showing an embodiment of the present invention, FIG. 3B is an explanatory diagram explaining its operation, and FIGS.
B is a diagram of the device shown in FIG. 3 viewed from another direction, and FIG. 5 is a diagram showing the reception state when the result of image reading according to the embodiment of the present invention is received by a normal receiver. , FIG. 6 is a block diagram showing a control system used in the present invention. 1...Document, 2...Feed roller, 3, 3'...
Projection lens, 4, 4'...reading element, 5, 6,
7...Mirror.

Claims (1)

[Claims] 1 In a device that photoelectrically reads a document, a means for illuminating both sides of the document and information on the front and back sides of the document is provided.
An image reading device characterized in that it is provided with a means for guiding the information to two projection lenses, and a line image sensor for reading images projected by the projection lens, and the information of one line on both sides of a document is arranged substantially in a straight line and simultaneously projected onto the line image sensor. .