JPH05244345A - Picture reader - Google Patents

Abstract

PURPOSE:To provide the manual scanning type picture reader whose resolution is increased without increasing number of slits of a rotary encoder detecting the scanning speed or increasing its drive speed. CONSTITUTION:A CCD 7 outputs a picture by one line as a picture signal in response to a clock signal fed from a clock generator 85 for a prescribed period. An encoder 2 generates a pulse in response to the scanning speed. The clock period of the clock generator 85 is set to be a sufficiently shorter period than the period of the pulse generated from the encoder 2 at the manual scanning speed and plural picture signals are stored in a memory 83 within one period of pulses generated from the encoder 2. A selection circuit 86 selects at least one (e.g. four) signal among picture signals of plural lines stored in the memory 83 in response to the generating timing of the pulse generated from the encoder 2 and outputs picture signal of lines more than number of pulses generated from the encoder 2 to improve the resolution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device for manually scanning an image of a document or the like to read the image.

[0002]

2. Description of the Related Art A conventional manually operated image reading apparatus (hereinafter referred to as a scanner) includes a light source for irradiating an original with light, an image pickup means including a CCD for picking up an image on the original, and a scanner. It has an encoder that generates a pulse according to the moving speed.

The encoder is provided in FIG. 5 with a roller 1, a rotary encoder 2 rotating in synchronization with the roller 1 and having a number of slits 2a arranged in the circumferential direction, and a position facing the slit 2a of the rotary encoder 2. The photo interrupter 3 outputs a timing pulse according to the presence or absence of the slit 2a.

Therefore, when the scanner moves on the document, the rotary encoder 2 is rotated at a rotational speed corresponding to the moving speed.
, The timing pulse synchronized with this rotation speed is obtained from the photo interrupter 3, and an image for one line is obtained as an image signal from the image pickup means in accordance with the generation timing of each timing pulse.

By the way, in order to improve the resolution in the conventional scanner, it is necessary to shorten the generation period of the timing pulse. For that purpose, the number of slits 2a per one rotation of the rotary encoder 2 is increased, or Alternatively, it is conceivable to use a reduction gear to give the rotary encoder 2 a rotation speed higher than that of the roller 1.

[0006]

However, in order to increase the number of slits 2a per one rotation of the rotary encoder 2, the diameter of the rotary encoder 2 must be increased, and when the reduction gear is used, the reduction ratio is also reduced. In order to improve the above, it is necessary to use a large number of reduction gears or a reduction gear having a large gear ratio, and in any case, it is inevitable that the device becomes large and the assembly becomes complicated.

In the present invention, the number of slits of the rotary encoder 2 is increased, or the rotary encoder 2
It is an object of the present invention to provide an image reading apparatus capable of improving the resolution of a read image without increasing the rotation speed of the.

[0008]

An image reading apparatus of the present invention is an image reading apparatus which scans an image to read the image, and is a clock generator 85 as a clock signal generating means for generating a clock signal of a predetermined cycle. A CCD 7 as an image pickup means for picking up an image of one line according to a clock signal and outputting it as an image signal, a memory 83 as a storage means for storing the image signal over a plurality of lines, and scanning on the image. Rotary encoder 2 as an encoder for generating pulses according to the scanning speed
And a selection circuit 86 as selection means for selecting and outputting at least one of the plurality of image signals stored in the memory 83 in accordance with the pulse generation timing.

[0009]

In the image reading apparatus having the above structure, the CCD 7
Outputs an image of one line as an image signal in accordance with a clock signal supplied from the clock generator 85 in a predetermined cycle, and the image signal of each line is binarized and stored in the memory 8
3 is stored. The encoder 2 generates a pulse according to the scanning speed.

The clock cycle of the clock generator 85 is set to a cycle sufficiently shorter than the cycle of the pulse generated by the encoder 2 at the scanning speed of manual scanning. Therefore, a plurality of image signals are stored in the memory 83 within one cycle of the pulse generated by the encoder 2.

The selection circuit 86 selects at least one (for example, four) of the image signals of a plurality of lines stored in the memory 83 according to the generation timing of the pulse generated by the encoder 2.

As a result, it is possible to output image signals of more lines than the number of pulses generated by the encoder 2, and it is possible to improve the resolution.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the construction of an embodiment of a manually operated scanner, in which a main body 4 is capable of scanning a document surface 10 and a light source 5 such as a lamp and a document are provided inside. A mirror 6 is provided for guiding the light reflected by the surface 10 to a CCD 7 as an image pickup means.

The CCD 7 picks up the level, distribution, etc. of the reflected light to obtain an image signal, and the image signal is supplied to the signal processing circuit 8.

The signal processing circuit 8 processes the read image and then supplies the image signal to an external personal computer or the like via the cable 9.

A roller 1 is provided rotatably on the document surface of the main body 4 at a position facing the document surface, and the rotation amount of the roller 1 is transmitted to the encoder 2 via reduction gears 11a and 11b. Has been done. This reduction gear 11a,
No. 11b has a particularly large reduction gear ratio, or it is not necessary to increase the number thereof, and it has been conventionally used.

The output pulse from the encoder 2 is also supplied to the signal processing circuit 8.

A cable 9 for connecting a signal to an external personal computer or the like is connected to the main body 4.

FIG. 2 is a block diagram showing the configuration of an embodiment of the signal processing circuit 8. The CCD 7 is supplied with a clock ST generated by a clock generator 85 as a clock signal generating means of a predetermined cycle. Outputs an image signal for one line for each clock ST.

The cycle of the clock ST generated by the clock generator 85 is set to be sufficiently shorter than the cycle of the pulse KS generated by the rotary encoder 2 at the scanning speed of general manual scanning.

The image signal read by the CCD 7 is amplified by an amplifier 81 and then binarized circuit 84 such as an A / D converter.
Is converted into a binary signal VD according to the luminance level and the color signal and stored in the memory 83.

The clock ST generated by the clock generator 85 is also supplied to the selection circuit 86 as the selection means and the timing matching circuit 87, and the timing matching circuit 87 is further supplied with the pulse KS generated by the rotary encoder 2. ing.

The timing matching circuit 87 is for matching the timings of both pulses ST and KS to be inputted, and for example, as shown in FIG.
Is set by the pulse KS generated by the clock ST
RS flip-flop 20 reset by
The delay circuit 21 delays the Q output of the S flip-flop 21 by a predetermined time d, and the AND gate 22 that obtains the logical product of the output of the delay circuit 21 and the clock ST. The output of the AND gate 22 becomes the timing signal YS. .. The timing signal YS is supplied to the selection circuit 86.

The selection circuit 86 has a built-in counter that is reset when the timing signal YS is generated and counts up with the clock ST.
The number of lines stored in the memory 83 can be monitored in one cycle of, and, for example, four lines among a plurality of lines stored in the memory 83 are selected in response to the generation of the timing signal YS. This is read out and supplied to the interface 84.

The interface 84 is for matching data with an external personal computer or the like connected via the cable 9.

Next, the operation of the signal processing circuit of FIG. 2 will be described with reference to the timing chart of FIG.

The clock ST is generated in a predetermined cycle, and the CCD 7 outputs the image signal VD for one line in accordance with the generation timing of the clock ST. Image signal V of each line
D is stored in the memory 83.

The pulse KS generated from the encoder 2 at an arbitrary timing is RS in the timing matching circuit 87.
Since it is supplied to the set input terminal of the flip-flop 20, the high-level signal Q1 from the Q output terminal of the RS flip-flop 20 is synchronized with the rising edge of the pulse KS.
Is output.

The signal Q1 is delayed by the delay circuit 21 for a predetermined time d to obtain the signal Q2.

First clock S immediately after generation of pulse KS
RS flip-flop 20 is reset by T,
The Q output goes low.

Therefore, the output of the AND gate 22 becomes the timing signal YS which coincides with the generation timing of the first clock ST immediately after the generation of the pulse KS, which in other words has the action of matching the timing of the pulse KS with the clock ST. ..

The selection circuit 86 selects and reads, for example, four lines of the image signals of a plurality of lines stored in the memory 83 until then according to the generation timing of the timing signal YS.

In FIG. 4, at time B, since the image signal VD for 5 lines is stored in the memory 83 after the timing signal YS immediately before, the selection circuit 86 selects the image signal VD for 4 lines from this. select.

The image signal VD selected by the selection circuit 86 is
The latest image signal VD may be selected, but the number of lines of the image signal VD stored in the period of one cycle of the timing signal YS is monitored. It is preferable to select the image signals VD of lines with equal intervals. That is, when the image signals VD of 7 lines are stored during one cycle of the timing signal YS, the image signals VD of 1, 3, 5, 7 lines are selected.

Therefore, in contrast to the conventional case where the image signal for one line is read every time the pulse KS is generated,
Double resolution can be obtained.

Although the number of lines selected by the selection circuit 86 is four in the above embodiment, the number of lines is not limited to this, and the necessary resolution, the frequency of the clock ST, the capacity of the memory 83, etc. are taken into consideration. Therefore, it is possible to set an appropriate number of lines such as 2 lines and 8 lines.

[0038]

As described above, according to the image reading apparatus of the present invention, the image pickup means for outputting the image signal of one line in response to the clock ST generated by the clock generation means and the image signals of a plurality of lines are stored. Since the storage means, the encoder that generates a pulse according to the scanning speed, and the selection means that selects at least one of the plurality of image signals stored in the memory according to the pulse are provided, the conventional encoder is used. Even when used, the resolution of the read image can be improved. It is also possible to reduce the number of reduction gears or reduce the diameter of the rotary encoder.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an embodiment of an image reading apparatus of the present invention.

FIG. 2 is a block diagram showing the configuration of an embodiment of the signal processing circuit 8 of FIG.

FIG. 3 is a block diagram showing the configuration of an embodiment of the timing matching circuit of FIG.

4 is a timing chart showing signal waveforms of various parts of the signal processing circuit 8 of FIG.

FIG. 5 is a block diagram showing a configuration of an example of a conventional encoder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 roller 2 rotary encoder (encoder) 3 photo interrupter 4 main body 5 light source 6 mirror 7 CCD (imaging means) 8 signal processing circuit 81 amplifier 82 binarization circuit 83 memory (storing means) 84 interface 85 clock generator (clock signal generating means) ) 86 selection circuit (selection means) 87 timing coincidence circuit

Claims (1)

[Claims] 1. An image reading apparatus for scanning an image to read the image, comprising: a clock signal generating means for generating a clock signal having a predetermined cycle; and an image for one line is picked up according to the clock signal.
An image pickup unit that outputs the image signal as an image signal, a storage unit that stores the image signal over a plurality of lines, an encoder that generates a pulse according to a scanning speed for scanning the image, and a generation timing of the pulse. An image reading apparatus comprising: a selection unit that selects and outputs at least one of a plurality of image signals stored in the storage unit.