JPH01223876A - Picture reader - Google Patents

Abstract

PURPOSE:To attain picture reading utilizing sufficiently the read function by differentiating the read magnification possible for setting according to the set read picture element density. CONSTITUTION:The magnification enable range is obtained in response to the designated resolution from an external device and the internal resolution and the internal magnification are decided in response to the designated magnification from the external device. Then in response to the internal resolution and the internal magnification, the clock interleave rate of control circuits 213, 214 is set to apply picture reading by the designated resolution and designated magnification from the external device. Thus, when a read magnification is designated externally and even if the magnification is at the outside of the range, the reading is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device, and particularly to an image reading device in which pixel density and reading magnification are variable when reading an original.

[Prior Art] Conventionally, an image reading device is known in which a reading severity is specified from outside the reading device, and a read image is transmitted to the outside with the specified reading and pixel density. Further, similar devices with respect to reading magnification are also known.

[Problem to be solved by the invention] However, in conventional image reading devices, the reading magnification and the reading pixel density are related, and there is a predetermined magnification range regardless of the reading magnification or the designated pixel density. It was configured so that it could only be specified. That is, when a certain reading magnification is externally designated and the magnification is outside the above-mentioned range, no reading is performed.

[Means for Solving the Problems] The present invention has been made by focusing on the problems of the conventional example as described above, and is an image reading system that scans an original image and transmits it to the outside as an image signal. The apparatus includes a first setting means for setting the reading pixel density and a second setting means for setting the reading magnification.
The present invention provides an image reading apparatus in which a magnification range that can be set by the second setting means is varied according to the reading pixel density set by the setting means and the first setting means.

[Example] The present invention will be explained below based on preferred embodiments.

FIG. 1 shows an external perspective view of an embodiment of an image reading apparatus to which the present invention is applied, and FIG. 2 shows an explanatory diagram of its internal configuration. The pixel density of the image reading device of this embodiment is 75 and 150.
, 300 P P I (Pixelpeninch)
The magnification ratio is 50 to 200%.

In FIG. 1, 1 is a document image reading device (hereinafter referred to as a leak), 2 is a leak main body, and 3 is an automatic document feeder that conveys the document to a reading position. In FIG. 2, the document is placed on a platen glass 27 with the image side to be read facing downward, and a Heroken lamp 2 in the document illumination unit 24 is placed on the platen glass 27.
4a is irradiated. The reflected light from the original is passed through a lens 26 to a C, which has a plurality of light receiving elements arranged in a line.
It is configured to be imaged onto a CD (charge coupled device) 22.

23 is a COD driver that drives the CCD 22, and 25 is a reflection mirror that guides reflected light from the original to a lens 26. 21 is a control unit that controls leakage operation.

The original illumination unit 24 and the mirror 25 are reciprocated in the direction of the arrow shown in the figure by a stepping motor.

FIG. 3 shows a block diagram for electrical control of the image reading device shown in FIG. If you explain that you want this diagram, 2
2 is a CCD sensor that reads images, 203 is a CCD 22
201 is an amplifier that amplifies the image analog signal from the CCD 22, 202 is an amplifier 2
This is an A/D converter that converts the analog signal from 01 into a predetermined signal for each pixel.

209 is a timing generation circuit for timing operation of the CCD 22 and other circuits; 213 and 214 are rate multi-prior circuits for thinning out the clock from the timing signal generation circuit 209 in order to use the signal from the microprocessor 208; and a control circuit for converting the pixel density in the main scanning direction and converting the image magnification, respectively.

212 is a binarization circuit for binarizing the image signal,
It is configured to perform binarization using a dither matrix, binarization using a fixed threshold, etc. 205 is a parakink circuit having a serial-parallel converter function for converting the image signal binarized by the binarization circuit 212 into an 8-bit parallel signal; 206 is an 8-bit parallel binarized image signal; A buffer memory is used to match the output of the image signal to the speed of the external device receiving and receiving the image information.

These image signals are once transmitted to the external device 250 through the I/F circuit 207. Reference numeral 249 is a control signal line for giving instructions from the external device 250 to the image reading device, and information including the image signal from the image reading device to the external device 250 is also transmitted through this signal line 249. That is, this signal line 249 is bidirectional, and its direction is determined based on an instruction from an external device 250 (host). Further, 215 and 216 are circuits that control read/write of the motor to the buffer memory 206. Note that the external device 250 is provided with a pixel density and magnification setting section 251 consisting of a keyboard or the like.

The microprocessor 208 includes a memory ROM 208A.
, a memory RAM 208B is attached, and controls the sequence inside the leak.

Reference numeral 230 denotes, for example, a stepping motor, which is used to control the positions of the original illumination unit 24 and mirror 25 in the sub-scanning direction when reading an original image. A circuit 211 generates a motor trites signal for driving the stepping motor 230, and operates according to a driving clock generated by an internal timer (not shown) of the CPU 208.

FIG. 4 shows an example of the operation of the density control circuit 213 in the main scanning direction. The main scanning direction density control circuit 213 is configured, for example, by a rate multiplier that thins out the input clock at a rate according to an external instruction and outputs the thinned out clock. In FIG. 4, (1) shows the control circuit 213 at 300 PPI.
There is an output clock for the main scanning direction density control circuit 213.
The base clock input to the base clock is output as is.

(2) is the base clock divided by 1/2, which is 1
This is the clock at 50 PPI. Also, (3) is 75P
There is an output clock for PI. These density switches are performed by a density instruction signal from the CPU 208.

FIG. 5 shows an example of the operation of the main scanning direction magnification control circuit 214. The main scanning direction magnification control circuit 214 is constituted by a rate multiplier based on a decimal counter, for example, and the input clock of the rate multiplier is given by the main scanning direction density control circuit 213.

Figure 5 (1), (2), (3) and (4) are all
Main scanning direction magnification control circuit 214 at 300 PPI
shows the status of the output clock. In this diagram,
(1) is at 200%, (2) is at 150%, (3) is l
'00% time', (4) shows the state at 50% time. These are performed according to instructions from the CPU 208.

The output clock generated by the main scanning direction magnification control circuit 214 is transmitted to the para-kink circuit 205 and the write control circuit 215.
given to. In the case of a binary mote, the para-kink circuit 205 is configured to output packing data when eight clocks are counted. The write control circuit 215 generates address information and write information to be given to the buffer memory 206 based on the clock given from the main scanning direction magnification control circuit 214. Similar to the para-kink circuit 205, these address information and write information are binary-valued. In the case of a mote, valid information is output when eight clocks are calculated.

The read control circuit 216 controls the transmission of the image information stored in the buffer memory 206 to the external device 250 via the interface circuit 207. That is, the read control circuit 216 sequentially outputs address information and read information to the buffer memory 206 based on a preset transfer rate, and sequentially reads the image data.

FIG. 6 shows the optical system (original illumination unit 24) in the sub-scanning direction.
．． This figure shows the mode of an input clock given to the motor trites signal generation circuit 211 in order to move the mirror 25). In this figure, H3YNC of (1)
The signal shows a one-line periodic signal. (2) is 50
This is an example of a clock when reading ~100%, and in this example, 4 pulses are applied to drive one line. (2) is 10
There is an example of the clock when reading 1 to 200%, and (1) is 1/
The frequency is divided into two. These clocks are CPU2
Generated by the 08 internal timer.

FIG. 7 shows an example of an operation in which the write permission signal is controlled when an image take is written to the buffer memory 206, and the image signal is thinned out line by line. (2) is the output state of the write permission signal when thinning out to 1/2, (3) is thinning out to 1/3, and (4) is thinning out to 1/4.

Pixel density control and reading magnification control in the sub-scanning direction are performed by a combination of operations shown in FIGS. 6 and 7. That is,
The pixel density and reading magnification are controlled by controlling the moving speed of the optical system in the sub-scanning direction and by controlling the splitter for thinning out the image signal in line units.

Under each of the heartware mentioned above, it will be explained how the reading magnification and the reading pixel density are related.

FIGS. 8A and 8B show an example of a procedure for determining the range of variable magnification for image reading according to this embodiment. First, the pixel density, reading magnification, and several other parameters are specified from the external device 2φ0. These data are stored, for example, in the RAM 208 in step S1.
Expanded to B's work area.

In step S2, the range of magnification is calculated according to the pixel density specified by the external device 250. A detailed explanation of this step S2 will be given using FIG. 8(B).

First, in step S21, it is checked whether the pixel density specified by the external device 250 is 300 PPI. If it is 300 PPI, step S22 is processed.

In this step S22, the maximum magnification ratio is first calculated. That is, in this example, the maximum pixel density is 300
PPI, and the maximum probability is 200%, so as shown in the calculation formula, the maximum magnification when reading 300 PPI is 200%. In step S23, the minimum magnification ratio is calculated. In this example, the minimum pixel density is 7
5 PPI, and the minimum magnification is 50%. Therefore, as shown in the formula, when reading 300 PPI, 12
．． The minimum magnification is 5%. When performing this 12.5% magnification, the CPU 208 controls the density control circuit 2 in the main scanning direction.
13, and issues a 50% instruction to the main scanning direction magnification control circuit 214. The meaning of the expression is as follows. 300PP like this
When instructed to read I, the image reading device reads 12.5%.
This means that a magnification ratio of up to 200% can be obtained.

Similarly, the magnification range when specifying 150 PPI and 75 PPI is calculated in steps 324 to S29. These results are expanded to the RAM 208B and used during subsequent transmission with an external device (step S4). In addition, the specified pixel density is 300. ．． If there is neither 150 nor 75 PPI, an error signal is generated in step S30.

Through the above procedure, after the external device 250 is notified of the specified magnification range corresponding to the specified pixel density, the external device 250
50 instructs to start reading together with the necessary magnification for leakage (step S3).

The procedure for determining the actual internal resolution and the actual internal magnification ratio ISR from the leakage magnification ratio instructed from the external device 250 will be explained using FIGS. 9(A) to 9(D). In this figure, SMAX and SMIN are the maximum and minimum values of the variable magnification range determined in step S2 of FIG. 8(A). Also, R3F is RequesteclSca
It is an abbreviation of ling factor, and is a parameter of a magnification change instruction sent from an external device. Also, RR is R
It is an abbreviation for "quested resolution" and is a parameter of a pixel density instruction sent from an external device.

Step S501. At step S, 601, the contents of RR are checked, and if it is desired to set each value, step 550
Branches to processing routines 2,5602° and 5701.

If the specified resolution expressed in RR is 300 PPI,
The process is executed from step 5502, and in step S503, it is checked whether there is a variable magnification range determined according to the designated magnification ratio represented by R3F or the designated resolution.

If 200% or more exceeds SMAX, step 5
In 504, an error is notified to the external device 250, and the process ends.

When R3F is from 50% to 200%, R3F is used with l5R1, that is, the internal magnification ratio unchanged. If R and SF are less than 50%, first, in step 5506, the internal reading resolution is changed to 75 PPI. Thereafter, in step 5507, the value of X shown in the equation is determined. Then, in step 8508, X is determined as the internal magnification factor ISF. For example, when R3F is 40%, X is 1
60% and is determined as 160% or ISF.

Below 5602, 5701 <150PPI and 75P
Each process when specifying PI is almost the same as in the case of 300 PPI, so a brief explanation will be given below.

That is, in steps 5603 and 5702, it is determined whether the specified magnification ratio R3F represented by R3F is within the variable magnification range determined according to the respective designated resolutions;
If it is outside the range, the external device 250 is notified as an error in steps 5604 and 5703. On the other hand, if it is within the range, in steps 5605 and 5704 the specified magnification ratio R
Perform the 3F classification, and according to the classification, step 56
06-612 and 5705-711, the internal resolution is changed and the internal magnification ratio IRF is determined as necessary.

As described above, the variable magnification range is determined according to the specified resolution from the external device, and the internal resolution and internal magnification are determined according to the specified magnification from the external device. Then, the control circuits 213 and 214
By setting the thinning rate of the clock, images can be read from an external device at a specified resolution and a specified magnification ratio.

In this embodiment, the image magnification/density conversion in the main scanning direction has been explained in detail, and that in the sub-scanning direction has also been explained using FIGS. 6 and 7 based on each of the similarly determined values. This is done by executing line-by-line thinning control of the image signal of the cityscape image signal of the moving optical system.

Although the present invention has been described above using the preferred embodiment configuration, the present invention is not limited to this configuration. For example, the reading density may be other than 300, 150° 75 PPI, and the magnification ratio may also be changed to The same goes for things other than . Furthermore, pixel signal thinning may be performed by a para-kink operation or by changing the input clock to the buffer memory, or may be performed, for example, when reading from the buffer memory.

Further, as the output light of the image signal, it is possible to use not only an external device such as a host computer but also a printer or a display.

[Effects of the Invention] As described above, according to the present invention, the read magnification that can be set is varied according to the set reading pixel density, so it is possible to read images by fully utilizing the reading function.

[Brief explanation of the drawing]

FIG. 1 is an external view of an image reading device according to the present invention, FIG. 2 is a diagram showing the internal configuration, FIG. 3 is a block diagram of the circuit configuration of the main part of FIG. 1, and FIGS. Each signal timing chart in FIG. 3, FIGS. 8(A) and (B) are flowcharts showing the procedure for determining the reading magnification range, and FIG.
Figures (A) to (D) are flowcharts showing the procedure for determining the internal reading resolution and internal magnification based on the requested magnification. 2--Image reading device (LEAKU) 21...Control unit 22...CCD 24...Original illumination unit 208...CPU

Claims (1)

[Claims] An image reading device configured to scan a document image and transmit it to the outside as an image signal, comprising: a first setting means for setting a reading pixel density; a second setting means for setting a reading magnification;
An image reading apparatus characterized in that a magnification range that can be set by the second setting means is varied according to the reading pixel density set by the first setting means.