JPH01268344A - Image reader - Google Patents

Abstract

PURPOSE:To immediately stop a read scan in accordance with a temporary stop request from an external device by providing a judging means for judging whether the external device can execute a transfer or not, and a document read stopping means. CONSTITUTION:A CPU 208 is provided with a ROM 208A in which a processing procedure, etc., have been stored and a work use RAM 208B, and executes a control of each part in accordance with the procedure stored in the ROM 208A. When document image information is being transferred, an input permitting signal of image information outputted from an external device 250 is monitored by the CPU 208 and whether the external device is in a state that the image information can be transmitted or not is judged. As a result of judgement, in case the transfer is impossible, a CCD driving circuit 203 is driven by the CPU 208, and by this CCD driving circuit 203, document read of a CCD 22 is stopped immediately. In such a way, a read scan can be stopped immediately in accordance with a temporary stop request from the external device.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an image reading device.

(Prior Art) A conventional image reading device scans a document by moving a CCD, a photoelectric conversion element, etc. relative to the document.
The document image information and print information obtained by this scanning are subjected to binarization processing or multi-value processing, and the binary image information or multi-value image information obtained by these processes is transferred to an external device such as a host computer. What has been done is known.

Transfer in the opposite direction to the above-mentioned transfer direction is performed after a transfer direction switching signal is supplied from the external device to the interface to switch the transfer direction and enable reception of a control command from the external device.

The interface for transferring binary image information or multi-value image information from the image reading device to an external device such as a host computer, or for receiving control commands from an external device, is an R5-232C compliant serial interface. , or bidirectional parallel interfaces are known.

When data is transferred serially via a serial interface, there is a problem in that the transfer takes a long time.

As a method for solving this problem, there is a method of compressing the image signal, but the compression device used for signal compression has a complicated structure and is expensive.

On the other hand, when data is transferred via a bidirectional parallel interface, image signals can be transferred at high speed and economically, but control signals such as ACK signals are required for handshaking with the host computer. (
acknowledge signal), BUSY signal (busy signal),
Since STB signals (strobe signals) and the like are required, the interface control means, particularly the control means for synchronizing with the host computer during image signal transfer, are complicated.

[Problems to be Solved by the Invention (2)] In conventional image reading devices, when document reading scanning is paused for reasons on the host computer side during image information transfer, the host computer first issues a pause F command to read the image. Since the contents of the command are not sent to the CP II on the reading device side, but the contents of the command are analyzed and processed by the CPU, there is a time delay before the document reading scan is actually stopped.

As a result, the actual scanning stop position on the image reading device J side deviates from the document reading position at which a temporary stop is requested on the host computer side, and an extra image signal is transferred to account for the deviation. There was a point.

The present invention has been made to solve the above-mentioned problems, and its purpose is to provide an image reading device that can immediately stop reading and scanning in response to a temporary stop request from an external device. It is about providing.

[Means to solve the problem]

In order to achieve such an object, the present invention provides an image reading device having a reading means for reading a document image, and a transfer means for transferring information of the read document image to an external device, the image reading device comprising: The apparatus further comprises a determination means for determining whether or not the external device can transfer the document image information during the transfer, and a document reading stop means for immediately stopping the document reading if the determination results that the transfer is not possible. It is characterized by

(Function) In the present invention, while the document image information is being transferred to the external device by the transfer device, the determining device determines whether or not the external device can transfer the information, and as a result of the determination, if the transfer is not possible, the document reading is stopped. Immediately stop reading the original by the means.

〔Example〕

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

1 to 3(B) show an embodiment of the present invention.

In FIG. 1, reference numeral 1 has an original image reading device that reads an original image, and 15 has a lighting device (lamp) FL that illuminates the surface of the original for reading. ), 16 is a reflection mirror for regulating the optical path of the reflected light from the document surface, 14 is a lens for focusing the reflected light, and 12 is arranged in an array corresponding to one line in the main scanning direction of the document. A CCD 13 that photoelectrically converts the focused reflected light is a CCD driver that drives this CCD 12. Reference numeral 11 represents a control unit for controlling each part, and reference numeral 17 represents a platen glass for regulating the surface of the document to be read flat.

18 is a document placed on the platen glass 17, and 19 is a platen cover. Reference numeral 20 denotes a stepping motor as a driving source for bidirectionally moving the document illumination unit.

(CCD Driver 13) In FIG. 2, 201 is an amplifier that amplifies the output of the CCD 12, 202 is an A/D converter that performs A/D conversion of the amplified output to obtain, for example, a 6-bit digital output;
03 is a CCO drive circuit that drives the CCD 12 as a reading means in accordance with a timing signal supplied from the control unit 11 to regulate the reading timing.

(Control unit 11) 207 is an interface circuit, which receives control signals and outputs image signals with an external device 250 that serves as a host device of the image reading device according to this embodiment, such as a digital printer or a personal computer. , 208 is a CPt1 in the form of a microcomputer, for example, and has a ROM 208A that stores the processing procedures shown in FIGS. 4(^) and 4(B), and a working RAM 208B. Controls each part.

The CPO 208 serves as a determining means and determines whether or not the external device 250 can transfer document image information while transferring the original image information. C.P.
O208, selector 206 and interface circuit 2
A transfer unit is configured to transfer the document image information read by 07 to the external device 250.

If transfer is not possible by the CPU 208 and CCD drive circuit 203, an original reading stop means is configured to immediately stop reading the original IN.

A background density detection circuit 204 detects the maximum density value (brightest point) for every l line in the width direction of the document corresponding to the main scanning direction, that is, the direction in which the CCDs 12 are arranged. A binarization circuit 205 binarizes the image signal, and a threshold value for the binarization is set by the CPO 208 in accordance with a detection value of the detection circuit 204 or a designation from an external device 250. 206 is a selector, CPO208
A multi-value mode in which the image signal is multi-valued (for example, 4 bits) and sent to the interface circuit 207, and a binary mode in which the binarized image signal is supplied to the interface circuit 207 in response to a command from the interface circuit 207. It can be switched to either one.

210 is, for example, a crystal oscillator, and 209 is a timing signal generation circuit that frequency-divides the output of the oscillator 210 according to the settings of the CPU 208 to generate various timing signals that serve as operating standards.

(Interface Circuit 207) The interface circuit 207 receives a control signal VDLTCH for backing the binary or multi-value, for example, 4-bit image signal selected by the selector 206, and a control signal for outputting the image signal to the external device 250. This is a circuit that generates a signal plane.

In FIG. 3(A), a binary counter 4011 such as LSI 61 and gates 402 and 403 are connected to C
According to the selection signal 2V/16V indicating the selection of binary or multi-value, for example 4 bits, from the Pt1208, a carry is output once every 8 clocks or 2 clocks using the image signal sampling clock [■] obtained from the timing generation circuit 209. It is something to do. The carry is latched by the D flip-flop 405 at the rising edge of the signal [H, and the gate 406, 407° 408 latches the signal VD.
LTCH and signal VSTB are output.

D flip-flops 409, 410 and gate 411
°412 is C obtained from the timing generation circuit 209
A signal surface for controlling a strobe signal when outputting an image signal to the external device 250 is generated using the CO image signal section signal) IENB and the image signal output signal VTRN5 from the CPO 20B.

For example, during image signal transfer, a signal AC is sent from the external device 250.
If the signal 11 is not supplied, the CPU 208
By deactivating the signal VTRN5 at the falling edge of END, the transfer of the image signal is stopped, and the scanning system drive stepping motor 20 is stopped.
Enables pausing of document reading sequence.

(Bidirectional Interface Circuit) In FIG. 3B, a tristate D flip-flop 501 such as LS374 latches a command from an external device 250 at the rising edge of the signal.

The CPU 208 receives command data when the signal FDIR is active, makes its output high impedance when the signal FDIR is inactive, and enables the output of a status yes signal from the CI'' 11208. The CPU 208 generates a control signal for transferring an image signal or a status signal, and when transferring an image signal, the CPU 208 activates the signal FDI port to enable the output of status data. V[l/ST
By setting "H", the output of the tri-state output buffer 503 such as LS242 becomes high impedance, and the 8-bit image signal latched by the rising edge of the signal VDLTCI+ is output from the tri-state output D flip-flop 502 such as LS374. When outputting the status signal, the output of the image signal is made high impedance by setting the signal VD/Blue to "off", thereby enabling the status data to be output from the CPU 28.

J- to flip-flops 508, 509 and gate 5
06, 507, and 510 generate control signals BIJSY, ACK, and ■ for the interface circuit.

The oven collector (O, C,) output gate 511 of the LS38 etc. controls the data output of the interface, and by setting the level of the signal DIR from the external device 250 to "Yes", the gate 511 outputs the data from the document image reading device. enables the transfer of

FIG. 4(8) and FIG. 4(B) are flowcharts showing an example of an image reading processing procedure by the CPU 208.

First, when control data such as designation of pixel density, designation of binary mode and multi-value mode, etc. is received from the external device 250 in a manner described later with reference to FIG. is developed, for example, in the work area of the RAM 208B.

Next, in step S3, the specified pixel density, for example, 400 dpi, 300 dpi, 200 dpi, or 100 dpi, is determined, and various timing signals generated in the timing signal generation circuit 209 are set according to the determination result.

In step S9, it is determined whether the reading mode specified by the external device 250 is multilevel mode or binary mode. As a result of the determination, if it is the binarization mode, the selector 206 is set to that effect, and
Proceeding to step 511, it is determined whether or not there is an instruction for setting contents in the binarization mode, that is, a threshold value for binarization is specified.As a result of the judgment, if there is a specification, the process proceeds to step 513. The specified threshold value is set in the binarization circuit 205, and the process advances to step S15. Also, step Sl
If the binarization threshold is not specified in step 1, the process advances to step 515. Furthermore, if it is determined in step S9 that the mode is multilevel mode, the process proceeds to step 515 after setting the selector 206 to that effect.

In step 51.5, it is determined whether or not there is a command to start reading from the external device 250. If the result of the determination is that there is a command, the process moves to the reading process shown in FIG. 4(B).

Prior to reading, first place the original 18 on the platen glass 17.
Place the document on top so that the left edge in Figure 1 is the leading edge of the document. The left end of the optical original illumination unit 15 in FIG. 1 is the scanning start position (initial position), and the position is confirmed by an optical position sensor disposed near the left end.

When a manual reading start command is input from the external device 250, in step SBI, the CPU 28 moves the original illumination unit 15, which is at the stop position during non-reading, for example, the position shown in the first figure, to the initial position during reading. Thereafter, a lamp control signal is output to turn on the lamp FL in step SB3. Even if the lamp FL is turned on, scanning for reading the document is not started immediately, and in step SB4, the scanning is continued for example from 300 m5ec to 300 m5ec until the light amount of the lamp PL becomes stable.
Waits for 50011 seconds. During this time, an image signal is input to the interface circuit 207, but since this image signal is not regular image information related to reading, the CPU 208
According to the control signal, no output is made from the interface circuit 207 to the external device 250.

Then, when the waiting time has elapsed, in step SB5,
A drive signal is sent to the motor 20, and the document illumination unit 15 starts scanning in the direction of the arrow layer shown in FIG. 1 due to the stiffness. The scanning speed of the optical system by the motor is approximately 2 to 3 IllI from the initial position of the original illumination unit 15 to the position where the leading edge of the original placed on the platen glass 27 is aligned.
It is controlled to be stable during I+.

Then, when the original illumination unit 15 reaches the leading edge position of the original, the CPO 20B outputs a control signal to enable image signal output via the interface circuit 207, and thereby,
In step SB7, each line is read, and the image signal, which has been binarized based on the pixel density and the binarization threshold in binary mode, is sequentially sent to the external device 250 line by line. will be sent to. In addition, in connection with the reading of this one line, the presence or absence of human power on the signal ACH from the external device 250 is monitored, and if there is no human power on the signal CH for that signal, the transmission of the image signal is immediately stopped, and the motor 20
Stops driving.

The operation when the signal ACH is not input will be explained in detail when FIG. 6 is explained.

Then, at the same time as the motor 20 stops, the CP 112
08 starts an internal timer (not shown) and measures the time until the next ACK signal is input from the external device 250 in step 5B18, and only when the measured time exceeds 10 seconds, proceeds to step 5B19 and ramps F1.
．． is turned off, and the supply of electric power to the motor 20 is stopped. In step 5820, the GK signal from the external device 250 is monitored, and when the signal is input manually, the lamp FL is turned on again in step SB21, and the power supply to the motor 20 is restarted, and in step 5B22. The time it takes for the light source to stabilize, e.g. 300m5ec~500a
After waiting +sec, the optical system is restarted in step 5823, and the process proceeds to step SB9.

In step 589, the scanning length of the optical system can be uniquely determined by the number of pulses used to drive the stepping motor used in this embodiment. It is determined that reading of the original page has been completed.If the reading of the original is completed as a result of the judgment, the lamp FL is turned off in step SBI l, an image signal output disable command is sent, and step 5B
At step 12, the motor is reversed and a document reading end signal is output to the external device 250.

By this motor reversal control of the CPU 208, the optical system including the original illumination unit 15 is moved in the direction of the arrow in FIG. 2, and is stopped when the optical position sensor detects that it has reached the initial position. In step 5B13,
Until this optical system returns to its initial position, the external device 25
If the start command is not supplied as a result of the diagnosis, the document illumination unit 15 is moved to the non-reading stop position in step 5B17. to end the operation.

During the transfer of the above-mentioned document image information, the manual permission signal of the image information output from the external device 250 is transmitted to the CPt1208.
The external device 250 monitors and determines whether or not it is possible to transfer image information. As a result of the judgment, if transfer is not possible, the CPO 20B transfers the CG [+ drive circuit 203
is driven, and this CCD drive circuit 203 drives the CCD2.
Reading of the second document is immediately stopped.

Next, the operation of the circuit shown in the second diagram during the image reading operation of step SB7 mentioned above will be explained.

11: cD22 receives the timing signals φl, φ2 . φB and φS
When driven by the CCD drive circuit 203 in synchronization with ++, an analog image signal is output from the CCD 22, this image signal is amplified by the amplifier 201, and after amplification,
The amplified signal VIDEOA is input to the A/D converter 202 . In the A/D converter 202, the timing signal φ generated by the timing signal generation circuit 209 is converted into, for example, a 6-bit digital signal VIDEOD, and this signal is supplied to the control unit 11.

This digital signal VIDEOD is outputted by the control unit 11 to the external device 250 in either the binary mode or the multilevel mode described above. The binary mode and the multilevel mode are set by the external device 250, and the CPO 20B outputs a mode selection control t311 (No.

In the case of multi-value mode, 4 bits of a 6-bit image signal per pixel, for example, the upper 4 bits, are received and supplied to the interface circuit 207. The interface circuit 207 backs up two pixels and outputs it as an 8-bit signal 17 to the external device 250.

On the other hand, in the binarization mode, the 6-bit image signal per pixel is converted into 1-bit 48-bit image signal by the binarization circuit 205 according to the binarization threshold set by the PII 208.
It is converted into a code and supplied to the selector 206.

Here, the threshold value for binarization is set using the two methods described above.

One method is to set the binarization threshold specified by the external device 250 in the binarization circuit 205 by the CPU 208, as described in step S1.3 of FIG. 4(^). be.

Another method is to calculate the maximum density value detected by the background density detection circuit 204 for each line in the main scanning direction of the image, as described in step SB7 of FIG.
This is a method in which a binarization threshold is calculated on average using the PII 208 and the calculated binarization threshold is set in the binarization circuit 205.

Image information that has been binarized using a binarization threshold set by one of these methods is input to the selector 206, which selects it and sends it to the interface circuit 207.
is man-powered. In the case of the binarization mode, the interface circuit 207 generates an 8-bit signal for 8 pixels and outputs it to the external device 250.

FIG. 6 is a time chart of the signals shown in the second diagram during the image reading process according to this embodiment.

RESET is an initialization request signal given from the external device 250, and the document reading device 1 is initialized by the rise of this signal. DIR is a signal from the external device 250, which controls the outputs of the bidirectional data lines DATA1 to DATA8. That is, when the level of this signal is "L", the signal flow is from the reading device 1 to the external device 250, and when it is "H", the signal flow is from the external device 250 to the reading device l, etc. ■.

BUSY and violet are signals for performing handshake control with the external device 250. 11εNB and VTn
NS is No. 48 from the timing signal generation circuit 209 and CPU 208, respectively, as described above.

Prior to starting the document reading process, the external device 250 initializes the reading device 1 with a signal DIR, and then raises the signal DIR to set a parameter for determining the reading operation mode, such as read image density. , data PI indicating binarization mode or multi-value mode, area designation, etc.
- P3 is transmitted (step Sl in FIG. 4(A)). Thereafter, when the reading device receives the reading command C1 from the external device 250 (step 515 in FIG. 4(A)), the reading device receives the reading command C1 from the external device 250 (step 515 in FIG. 4(A)). is turned on, and waits for a period of time, for example, 300 m5 ec to 500 m5 ec, until the light amount of the lamp FL is saturated. After the waiting time has elapsed (step 5 in Fig. 4 (B))
B4), send CK to the signal.

After receiving the signal =, the external device 250 raises the signal DIR, so the CPU 208 drives the scanning system drive stepping motor 20 at that point. In step 5B5) of FIG. After passing through the signal +(E N B, the signal VT
Activate Rll5 and start transferring the image signal. Transfer of one line is based on data D regardless of signal BUSY.
Performed by ATA1-08TA8 and °STB. Further, after one line of image signals is transferred, the reading device 1 transmits an EOL (end of line) code for line synchronization. After detecting the EOL code, the external device 250 returns a signal to the AC as a signal indicating that one line has been manually operated or that transfer of the next line is permitted. Thereafter, reading up to the final line is performed according to the above-described sequence (steps SB7 and 5B9 in FIG. 4(B)).

When giving a pause command to the reading device 1 during document reading scanning, after detecting the EOL code, do not send the signal before, but raise the signal DIR to change the direction of transfer to the external device 250.
- Just switch to the reading device 1 and then give a new command C2. However, as described above, since it takes time for the reading device 1 to receive the pause command and for the CPO 28 to process the contents of the command and stop the reading scan, unnecessary image signals may be transferred. is possible.

In this embodiment, the reading device 1 monitors the presence or absence of human power from the external device 250 at the falling edge of the signal 11EN[l, and if the signal car is not human powered, the reading device 1 immediately scans the unit 15. and stop the signal V.
TRN5 is deenergized and image signal transfer is interrupted. Therefore, during image signal transfer, the CP 11208 simply monitors the signal m from the external device 250 and monitors the signal m from the external device 250.
It becomes possible to synchronize with 50, and it becomes possible to immediately respond to a request for stopping at -' on a line-by-line basis.

That is, the interface 207 according to the present embodiment only needs to monitor the response of the signal l from the external device 250 in order to synchronize with the external device 250 in the main scanning direction during image signal transfer. Therefore, the interface control method becomes simple, and it becomes possible to immediately respond to a reading pause request on a line-by-line basis, making it possible to transfer accurate image signals at higher speeds. .

In this embodiment, the reading of the original image is stopped for 10 seconds.
If c continues, the lamp FL is turned off and the power supply to the motor 20 is stopped. This prevents damage to the original glass due to the heat of the lamp FL and damage to the windings of the motor 20 due to the power supply. There is no burnout and it can stand by for a long time.

In this embodiment, an example has been described in which the optical system is moved relative to the original to read the original, but the original may be read by moving the optical system eight times.

〔Effect of the invention〕

As explained above, according to the present invention, since it is configured as described above, it is possible to provide an image reading device that can immediately stop reading scanning in response to a temporary stop request from an external device. There is.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of an embodiment of the present invention, and FIG. 2 is an actual 2if! of the present invention! A block diagram showing an example of the configuration of example ii, FIG. 3(A) is an interface circuit 20 according to an embodiment of the present invention.
7. FIG. 3 ([l) is a circuit diagram showing an example of the configuration of a bidirectional interface circuit according to an embodiment of the present invention. FIG. 4 (8) and FIG. 4 (B) 5 is a time chart of the signals shown in FIGS. 3(A) and 3(B), and FIG. 6 is a flowchart showing an example of the image reading processing procedure by the CPU 208. FIG. It is a time chart of the signal. 12...CC01 206...Selector, 207...Interface circuit, 208...CPU, 250...External device. 1'1 1 Massage the buttocks too Aisagi 11 Sweep 1 hit NEET + 2' CCD 13 CCD 14゛ Resoz 15 1, Seijizuki Hoonie 16 Oimura Miu- 17゛ Blur r '7 Glass 18 1 Separate 19 Figure 5 2 Force bar 20 Pulling Motor Figure 1 Figure 4 (A)

Claims (1)

[Scope of Claims] 1) An image reading device comprising: a reading means for reading a document image; and a transfer means for transmitting information on the read document image to an external device, wherein the image reading device comprises: a reading means for reading a document image; and a transfer means for transmitting information on the read document image to an external device; An image reading apparatus characterized in that the image reading apparatus further comprises a judgment means for judging whether or not the external device can transfer the image, and a document reading stop means for immediately stopping reading the document if the result of the judgment is that the transfer is not possible. Device.