JPH0646763B2 - Image reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to an image reading apparatus which is applied to a facsimile apparatus or the like and which performs reading scanning by conveying an original by a drive system having a step motor as a drive source. Is.

(B) Conventional technology Recently, for the purpose of high-speed and high-definition recording, electrophotographic P
A plain paper recording type facsimile machine incorporating PC (plain paper copying machine) technology has been put into practical use. Such facsimile equipment is disclosed, for example, in Research Institute of Electrical Communication, Vol. 33, No. 11 (1984), pages 197 to 2.
It is disclosed in the article "Ultra-high-speed facsimile device" on page 06.

By the way, as a document reading apparatus in such facsimile apparatus, a document original reading apparatus is used in which a document to be transmitted is placed on a document placing table and a reading system is moved to perform sub scanning. Even in this type of facsimile machine, if a moving document reading device that reads a document while feeding it with a drive system (hereinafter referred to as a feeder) using a step motor as a driving source is added, the so-called "long object" is longer than a predetermined size. It becomes possible to send the manuscript.

(C) Problems to be Solved by the Invention In the above-described conventional reading device, as the reading control, the driving pulse of the step motor and the reading start signal for one line are synchronized, and the document is intermittently read according to the encoding speed. Reading while sending.

However, when the step motor is driven intermittently, there is a problem that the read image is expanded or contracted in the sub-scanning direction due to a response delay between the motor pulse and the drive system.

Therefore, in order to eliminate the image distortion in the sub-scanning direction, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Application Laid-Open No. 9-19466, by applying a fixed number of forward rotation motor pulses continuously and immediately thereafter by applying a reverse rotation pulse, stop braking of a step motor is improved, and reading is performed continuously. An intermittent sub-scanning control method has been proposed, which is started at a certain time after the application of the forward rotation pulse.

However, this method is not preferable because the motor load increases rapidly when the reverse pulse is applied, and the higher the speed, the more the motor is forced to overload. The noise at this time is also a problem.

The present invention provides an image reading apparatus that eliminates distortion in the sub-scanning direction of an image read from a feeder during transmission, reduces noise caused by driving a step motor, and does not force an overload operation on the step motor. To do.

(D) Means for Solving Problems The present invention is a reading means for reading an original sent by a driving system having a step motor as a driving source by photoelectric conversion and outputting a binary image signal, and this reading means. A first storage means for storing the image signal read by the encoding means, an encoding means for processing the image signal into a redundancy suppression encoded signal, and a second storage means for accumulating the image signal to be supplied to this encoding means. The stepping motor is provided with a storage means and a transfer means for transferring the read image signal to the first storage means or the image signal stored in the first storage means to the second storage means. The image signal read by the driving and constant document feeding speed and the reading cycle is transferred to the first storage unit and stored therein, while the image signal is stored from the first storage unit to the second storage unit according to the encoding speed. Transfer to means , Is characterized by encoding.

(E) The working feeder is driven at a constant speed, and the read image signal is transferred to and stored in the page memory.On the other hand, during this transfer, the image signal is encoded from the page memory according to the encoding processing speed. The image signal is transferred to the buffer memory for storage. Therefore, the image distortion caused by the response delay between the motor pulse and the document feeding mechanism can be eliminated.

When transferring from the area of the page memory that stores the image signal read at the start of the feeder to the buffer memory for encoding, consider the delay in the response of the drive system to the motor pulse and thin out the image signal as appropriate. , The image distortion caused by the response delay at the time of the cause was eliminated.

(F) Embodiment FIG. 1 is a block diagram of a facsimile machine to which a document reading device according to an embodiment of the present invention is applied. The facsimile machine includes a system control unit (1), and the system control unit (1) is configured by a micro computer, and its function includes a main controller and an internal memory, and the main controller is shown in FIG. The internal memory includes an area for storing data necessary for transmission processing such as document reading and a flag area for storing various operation states.

The reading device (2) connected to the system control unit (1) comprises a document feeding mechanism driven by a step motor, a light source, an optical lens system, a photoelectric conversion circuit and an image signal binarization circuit. The system control unit (1) is a device for reading the forward rotation pulse of the step motor and the image signal reading start signal in response to the timer interrupt of the microcomputer.
Output to (2). Then, the reading device (2) outputs a binarized image signal for one line as a time-series signal in bit units after a certain time delay from the reading start pulse.

The serial / parallel conversion circuit (hereinafter referred to as S / P circuit) (3) inserted between the reading device (2) and a page memory (4) described later is a bit unit from the reading device (2). The image signal output as a sequence signal is converted into an image signal of byte-series time-series data and output to the system data bus.

A page memory (4) acting as a first storage means is connected to the system control unit (1), and the page memory (4) outputs the image signal output from the reading device (2) to the S / P circuit (3). ) Converts it into an image signal of byte-series time series data and stores it. The page memory (4) includes a storage area for a predetermined number of pages (for example, one page of the document). A buffer memory circuit (5) acting as a second storage means for accumulating an image signal to be supplied to the encoding means is a system control section (1).
Connected to the page memory (4) and interposed between the page memory (4) and the encoding circuit (6), the buffer memory circuit (5) includes a first buffer memory (5a) and a second buffer memory (5a).
The image signal including b) is stored for one line. In this way, the reason why the buffer memory is divided into two is that if there is only one buffer memory, the code processing operation must be stopped during data transfer from the page memory (4), and the code speed becomes slow and high speed. This is because it cannot support transmission. In other words, the buffer memory is divided into a code memory and a transfer memory, and the roles are alternately shared to prevent the code speed from decreasing. The coding circuit (5) converts the image signal stored in the buffer memory (5a) or (5b) line by line into a redundancy suppression coded signal such as a Modeihaed Huffman code. Encoding circuit (5) is 1
When the encoding of the lines, for example, the encoding of the image information written in the buffer memory (5a) is completed, the next 1
The line memory, that is, the encoding of the buffer memory (5b) is started, and the encoded buffer memory (5a) is set to the writable state, and the system control unit (1) is encoded from the page memory (4). The image signal transfer request signal to the buffer memory (5b) is output. When the transfer for one line corresponding to the transfer request is completed, the system control unit (1) clears the transfer request signal.

The encoded image signal encoded by the encoding circuit (6) is transmitted via a modem (not shown).

DMA (Direct Memory Access) controller
(7) is an S / P in response to a command from the system control unit (1).
The image signal output from the circuit (3) to the system data bus is DMA transferred to the page memory (4), or the image signal is DMA transferred from the page memory (4) to the buffer memory (5a) or (5b). is there.

The system controller (1) reads the image signal and controls the DMA transfer to the page memory (4) in parallel, and if there is a transfer request from the encoding circuit (6), the page memory of the image signal for one line DMA controller (7) immediately after transfer to
Against page memory (4) to buffer memory (5a)
Or (5b) is instructed to transfer image signals, and page memory is
DM from (4) to buffer memory (5a) or (5b)
A is transferred.

FIG. 2 is a timing chart showing transfer timings of image signals by the system controller (1) and the DMA controller (7).

In FIG. 2, A is a motor pulse applied to the step motor, and the drive system starts operation in response to this motor pulse, and the original is conveyed by one line. Further, the original is read by the CCD or the like of the reading device (2) in synchronization with this motor pulse. (B) is a read transfer busy signal that indicates that the image signal is being transferred to the page memory (4).
It is output in synchronization with the falling edge of (A). (C) is an image signal transfer request signal from the page memory to the buffer memory (5a) or (5b), which is the buffer memory (5a) or (5
It falls due to the end of the image signal transfer to b). (D) is a memory-to-memory transfer busy signal indicating that the image data is being transferred to the buffer memory (5a) or (5b) and is output during the transfer of the image signal to the page memory (4).

FIG. 3 is a schematic side view showing the relationship between the reading position of the reading device and the position of the document detecting sensor. The document feeding and reading operation for a predetermined line (L line) after the document detecting sensor (21) is turned off. By doing so, the reading operation of the document is completed. In FIG. 3, (22) is a document feed roller driven by a step motor, (23) is a document, (21) is a document position detection sensor, and (24) is a document reading position. The distance between the document position sensor (21) and the reading position (24) corresponds to the document feed pitch (L) line.

FIG. 4 is a response characteristic diagram showing the relationship between the motor pulse and the document feeding displacement when the step motor is started.

In FIG. 4, the broken line shows the reading position with respect to the motor pulse, and in the present embodiment, when the data is transferred to the buffer memory for encoding, the lines marked with X in the figure are thinned out to make the reading pitch constant. Distortion is eliminated. That is, in consideration of the response characteristics of the driving source such as the step motor, the thinned lines are determined so as to have a constant pitch.

Next, the specific operation of this embodiment will be described with reference to FIGS.

The operation of the system control unit will be mainly described along the flow chart of FIG.

When the transmission operation is started, a motor pulse is output in step S1, the original is conveyed by one line, and the process proceeds to step S2. In step S2, the image signal read for one line is DMA-transferred to the page memory (4) by the DMA controller (7).
Then, the process proceeds to step S3. In step S3, it is determined whether or not the document detection sensor has detected the end of the document. Immediately after the start of the transmission operation, it is determined that the document end has not been detected, and the process proceeds to step S4. Step S4
Then, it is determined whether or not there is a transfer request to the buffer memory (5a) or (5b). That is, since the transfer request signal is output when the encoding process of the first line and the encoding circuit (6) is completed, it is determined that the transfer request is present in the case of the first line, and the process proceeds to step S5. move on.
If the encoding circuit (6) is in the process of encoding, no transfer request is output, so it is determined that there is no transfer request, and the process proceeds to step S6. In step S6, it is determined whether or not the reading is stopped, that is, whether or not the entire transmission document is written in the page memory (4). If the reading is not stopped in step S6, the process proceeds to step S7. If the reading is stopped, the process proceeds to step S4 and waits until the coding circuit (6) finishes the coding process in steps S4 and S6. In step S7, it is determined whether or not the step motor is stopped. If the step motor is stopped, the process returns to step S2 to wait for the 1-line fractional signal to be transferred to the page memory. S
Return to 1. Therefore, even during the encoding process of the encoding circuit (6), the image signal from the original document which moves at a constant speed at a predetermined pitch is read and written in the page memory (4).

If it is determined in step S4 that there is a transfer request, the process proceeds to step S5, and in step S5, it is determined whether or not the step motor has just been started. That is, since there is a response delay of the drive system immediately after the start of start-up as shown in FIG. 4, whether or not the predetermined number of lines before sending to the constant speed pitch immediately after start-up is considered in consideration of this response delay. To judge.

In step S5, if the number of lines is a predetermined number after the start of activation, the process proceeds to step S8. In step S8, the operation of keeping the reading pitch constant is performed. That is, the line marked with X in FIG. 4 does not transfer to the buffer memory, and
The lines to be transferred to the buffer memory are determined so that the read lines are thinned and transferred so that only the marked lines are transferred, and the read address of the page memory (4) is controlled to proceed to step S9. In step S9, the determined line is transferred from the page memory (4) to the buffer memory (5a).
Alternatively, DMA transfer is performed to (5b), the process proceeds to step S10, and after the transfer request is cleared in step S10,
It proceeds to step S11. In step S11, it is determined whether the transfer of all lines to the buffer memory is completed. Immediately after the transmission, it is determined that the transfer of all the lines has not been completed, the process proceeds to step S4, and the above-described operation is repeated. If it is determined in step S11 that the transfer of all lines has been completed, the document is discharged in step S12, and the operation is ended by waiting until the encoding processing of all lines is completed in step S13. If it is determined in step S5 described above that it is not immediately after the start-up, that is, if the document is sent line by line at a constant pitch, the process proceeds to step S14. In step S14, the read address of the page memory (4) is controlled, DMA transfer is performed from the page memory (4) to the buffer memory (5a) or (5b), and the process proceeds to step S10 to step S4 or step S12. Then, the above operation is repeated.

On the other hand, when the document detection sensor detects the document end, in step S3, it is determined that the document end has been detected, and the process proceeds to step S15. After the end detection, reading of a predetermined number of lines is completed, that is, the document detection position from the document detection sensor. It is determined whether or not the number of lines (L lines) corresponding to the above has been read, and if not read, step S4
The operation is repeated until the predetermined number of lines are read. When it is determined in step S15 that the predetermined number of lines have been read, the motor stop flag and the read stop flag are set in step S16, the motor and the reading are stopped, and the process proceeds to step S4 until the encoding of all lines is completed. S4 to S13
The above-mentioned operation is repeated until, and a series of operations is completed after the encoding is completed.

As described above, in the present embodiment, at a portion where the reading pitch is different due to the response delay at the time of start-up, the image signals are thinned out so that the reading pitch becomes constant and transferred to the buffer memory for encoding, and thereafter, the reading is performed at a constant pitch. The image signal is stored in the page memory. Then, the image signal is transferred from the page memory to the buffer memory for encoding while passing through the interval of storing the image signal in the page memory, and during encoding, the image signal is stored in the page memory at a constant pitch without stopping the step motor. Remembered.

(G) Effect of the Invention As described above, according to the present invention, the image distortion caused by the response delay between the motor pulse and the document feeding mechanism in the reading device of the facsimile apparatus using the step motor as a driving source is reduced by the step motor. Since it can be solved without applying reverse braking etc. to the motor, it is possible to read more quietly without overloading the motor, and it is also possible to read in parallel during encoding processing, so high-speed reading is possible. Become.

[Brief description of drawings]

FIG. 1 is a block diagram of a facsimile apparatus according to an embodiment of the present invention, FIG. 2 is a timing chart showing transfer timing of image signals, FIG. 3 is a schematic side view showing an example of a reading apparatus, and FIG. FIG. 5 is a response characteristic diagram showing the relationship between the motor pulse and the document feeding displacement, and FIG. 5 is a flow chart showing the operation of the system controller. (1) …… System control unit, (2) …… Reading device, (4)…
… Page memory, (5) …… buffer memory circuit, (6) ……
Encoding circuit, (7) ... DMA controller.

Claims (2)

[Claims] 1. A reading unit for reading a document sent by a driving system having a step motor as a driving source by photoelectric conversion and outputting a binary image signal, and a first memory for storing the image signal read by the reading unit. Means, encoding means for processing the image signal into a redundancy suppression encoded signal,
Second storage means for accumulating the image signal to be supplied to the encoding means, the read image signal in the first storage means, or the image signal stored in the first storage means in the second storage means A step of driving the step motor at a constant speed at the time of reading, transferring an image signal read at a constant document feeding speed and a reading cycle to the first storage means and storing the image signal at an encoding speed. An image reading apparatus characterized in that the image signal is transferred from the first storage means to the second storage means in response thereto and is encoded. 2. The first storage means area storing the image signal read by the reading means at the time of starting and stopping the step motor is read at the time of transfer from the first storage means to the second storage means. The image reading apparatus according to claim 1, wherein the read address of the first storage unit is controlled so that the line interval becomes a predetermined interval.