JPH02202167A - Image exposing device - Google Patents

Abstract

PURPOSE:To prevent picture quality from being deteriorated due to oscillation at the part even when interruption/re-start is performed during a reading operation by providing a buffer memory to store image data exceeding one scan data of an optical scanning means at an image processing part, and also providing a control means to control the driving force of a driving means. CONSTITUTION:The image processing part is provided with the buffer memory 25 to store the image data exceeding one scan data of the optical scanning means, and also, is provided with the control means 27 to control the driving force of the driving means 9. The unrequired torque of a motor 9 can be reduced by reducing a motor driving current at a time when the rotation of the motor 9 arrives at a constant rotating state after the reading operation is re- started, which suppresses oscillation in the motor itself or a scanning system. Also, since the scanning system performs no waste reciprocal movement after the interruption of the reading operation, it is not feared that additial time for reading time is attached. In such a way, smooth picture quality equivalent to that in continuous reading can be obtained even an interruption/re-start operation is performed during performing the reading of an image, and also, reading speed can be preveted from being lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image exposure apparatus that sequentially scans an image on a document and exposes the image to a reading means to read the image.

[Prior Art] Conventionally, some image exposure devices that read images on a document read the image while repeatedly interrupting and resuming reading while reading one page of the document. An example of an exposure apparatus is an image scanner connected to a host computer as an image processing apparatus through an R3-232C line or the like.

As shown in FIGS. 9(a) and 9(b), an original P placed on an original platen glass 100 is illuminated with a halogen lamp 101 as a light source, and the reflected light from the illumination is reflected by mirrors 102 and 103. , 104 to a photoelectric conversion element (hereinafter referred to as an image sensor) 105 such as a COD and converted into an electrical signal.
The mirror 102 sequentially scans the document P.
It is used to read images of images.

The image scanner 106 sends the image data to the host computer in response to a data output request signal from the host computer (not shown), and the host computer stores the sent image data once in a buffer memory in the host computer. The image data stored in the buffer memory is sequentially retrieved and image processing is performed. Here, while the host computer is performing image processing (hereinafter referred to as BUSY state)
The above buffer memory is full of image data (hereinafter referred to as B).
(referred to as the UFFERFULL state), the host computer sends a data output stop signal to the image scanner 106 in order to avoid an overflow of sent data, and the image scanner 106 temporarily suspends the reading operation. Then, when the host computer is released from the BUSY state and the image data in the buffer memory becomes empty (hereinafter referred to as the BUFFEREMPTY state), the host computer sends a data output request signal to the image scanner 106 again. The image scanner 106 resumes reading operations.

[Problems to be Solved by the Invention] Incidentally, in the above-mentioned image exposure apparatus, a pulse motor is used as a driving means because position control and speed control are easy. To ensure smooth operation between startup and stop, the motor's rotation speed is gradually increased (hereinafter referred to as slow-up) at startup, and conversely, the motor's rotation speed is gradually decreased (hereinafter referred to as slow-up) when stopped. (hereinafter referred to as slowdown). However, in the image sensor 105 such as COD, it is necessary to keep the reading output uniform, so it is necessary to keep the reading time interval (hereinafter referred to as accumulation time) constant for one scanning line (hereinafter referred to as line). The driving pulse motor has to be suddenly started or stopped using a predetermined driving frequency pulse in a state where the scanning operation is stable both when starting and when stopping (hereinafter referred to as steady state). For this reason, in this type of image exposure apparatus, the number of revolutions of the pulse motor in a steady state must be kept within a range that can follow the driving frequency of the pulse motor, that is, the number of revolutions required to perform the above-mentioned scanning operation. It must be set within the range of the self-start frequency relative to the torque, and it is also necessary to provide a sufficient torque margin in consideration of changes in load due to changes in environmental temperature and reduction in the torque of the motor itself.

Therefore, as shown in Fig. 10, if the number of pulses required to feed the l-line motor is N, and the constant interval period is T, the driving frequency is N/T (ppS), and the driving load is tI (Kg- cm), driving frequency N/T (pps
) is the retraction torque for ts (Kg −am)
Then, the motor starting torque ts (Kg-cm)
is set to satisfy tl<ts<tz, and ts-tI at this time becomes the torque margin Mt.

However, this torque margin Mt should originally be smaller when in a steady state than when starting, but in the conventional example mentioned above, on the contrary, it is much smaller when in a steady state than when starting. It's getting bigger. Furthermore, the excess torque causes vibrations in the motor itself and the scanning system, and especially when stopping, the situation is similar to sudden braking, so the vibrations in the motor itself and the scanning system can be quite severe. Become. In other words, if an interrupt/resume operation is performed in the middle of a read operation, the process shown in FIG. 11(a) will occur.
As shown in (b) of the same figure, the image output after reading a document as shown in FIG. there were.

Therefore, in order to solve this problem, for example, if 1912 minutes of movement is required to perform the slow-up operation, the scanning system is moved back n lines once after the reading operation is interrupted, and when the reading operation is restarted, the accumulation time is 1912 minutes. A method has also been devised in which the image from the line after the reading operation is interrupted is read by completing a slow-up operation during the reading operation, and the image is connected to the image before the interruption, but the time required for reading is significantly longer than that of the conventional example above. It was difficult to obtain a practical operating speed due to the delay.

The present invention has been made to solve the problems of the prior art described above, and its purpose is to prevent the image quality from deteriorating due to vibration at that point even if the reading operation is interrupted/resumed. The objective is to prevent this and eliminate the accompanying decline in reading speed.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides an optical scanning means for scanning a document while irradiating it with light, and a driving means for driving the optical scanning means. and a reading means for reading an image obtained by the optical scanning means, and the image exposure apparatus operates the driving means in synchronization with a drive signal of the reading means,
An image processing section is provided for processing the output from the reading means, and the image processing section has a buffer memory for storing image data for one or more scans of the optical scanning means, and also has a buffer memory for driving the driving means. It was decided to include a control means to control the force.

It is preferable that the driving means has a plurality of levels of driving force, and that the driving force required to stop the scanning operation is set to be equal to or lower than the driving force required for stable scanning operation.

It is also effective to set the capacity of the buffer memory of the image processing section to a capacity that is two or more scans larger than the scan required for the scanning means to perform a stable scanning operation.

[Operation] In the present invention having the above configuration, by reducing the motor drive current when the rotation of the motor reaches a steady state after restarting the reading operation, unnecessary torque of the motor is reduced. It is possible to suppress the occurrence of vibrations in the motor itself and the scanning system.

Furthermore, since the scanning system does not make unnecessary reciprocating movements after the reading operation is interrupted, there is no risk of adding extra time to the reading time.

[Example] A first example of the present invention is shown in FIGS. 1(a), (b) to 5.
1, and its configuration will be explained based on FIG.

Reference numeral 1 denotes a reading sensor such as a CCD as a reading means, which is disposed within the main body 2 of the apparatus.

A document placing glass 3 is provided on the upper surface of the apparatus main body 2, and the document P placed on the document placing glass 3 is exposed and scanned by the optical scanning means 4 to form an image on the reading sensor 1. It is designed to be exposed to light. Here, the light scanning means 4 is composed of a wire-driven lamp unit 5, a mirror unit 6, and a lens 7, and the lamp unit 5 includes an illumination lamp L that illuminates the document P, and an illumination lamp L A first mirror M is provided to reflect the image reflected light from the surface of the original P irradiated by the mirror unit 6 toward the mirror unit 6 side. The mirror unit 6 is provided with a sensor 1 that reads the image light reflected by the first mirror MI.
The second and third mirrors M z , M s that turn back towards
is provided.

The lamp unit 5 and the mirror unit 6 are connected to the lens 7.
It is supported by a pair of rails 8a and 8b so that it can be scanned parallel to the optical axis while maintaining a right angle to the optical axis. Reference numeral 9 denotes a pulse motor as a driving means, which is a driving source for scanning the lamp unit 5 and mirror unit 6, and its rotational force is transmitted to the driving drum 10 via a gear train. Two wires lla and llb are wound around this drive drum 10 and are connected at one point in the middle. One end of each wire lla and llb is fixed to the lamp unit 5 in the middle, and the mirror unit 6 The main body 2 of the device is half-circled around the outer periphery of the pulleys 12a and 12b provided at both ends.
Fixed.

Further, the other end of each wire 11a, 11b is a pulley 12a,
It is connected by a tension spring 13 around half the outer circumference of 12b. Therefore, according to the principle of a movable pulley, the operating speed of the mirror unit 6 is equal to the operating speed of the lamp unit 5.
/2, so the optical path length is always kept constant over the entire scanning range.

Next, the control configuration in this embodiment will be explained based on FIG. 2.

The analog image signal input to the reading sensor 21 is sent to the amplifier 22 and amplified, and then sent to the A/D converter 2.
3, it is converted into a digital image signal and sent to the image processing circuit 24.
is input. The image processing circuit 24 binarizes the digital image signal according to instructions from the CPU 27. That is, the CPU 27 uses the image processing parameters stored in advance in the ROM 28 to control the image processing circuit 24.
It supplies a threshold level for binarization and correction data for shading, and also outputs a drive signal to a motor drive circuit 29 that drives the pulse motor 9. Furthermore, the output from the image processing circuit 24 is divided into two parts, one being sent to the CPU via the buffer memory 25.
The other end is connected to a selector 26 which performs a switching operation according to the output signal of 27, and the other end is directly connected to this selector 26.

Next, an example of the operation in this embodiment will be explained based on FIGS. 2 to 5.

First, the lamp unit 5 and the mirror unit 6 as optical scanning means are normally located at a home position set near the reading start position of the original P by a home position sensor (not shown). Here, when an operation start signal is sent from the host computer (not shown), the image scanner forming the device main body 2 sends a signal from the CPU 27 to the motor drive circuit 29, and this motor drive circuit 29 is synchronized with the drive signal of the reading means. The pulse motor 9 is supplied with the motor drive pulse. The rotation of the pulse motor 9 causes the lamp unit 5 and the mirror unit 6 to
performs a scanning operation and starts reading the image. Furthermore, upon receiving a data output request signal from the host computer, the image scanner sends image data to the host computer.

Generally, a reading sensor 1 such as a COD operates under a clock that is output at regular intervals, and in this embodiment, two clock cycles are required to process one line of image data. There is. That is, as shown in FIG. 3, the image is read in the first cycle, and the read data is transferred in the next cycle. In the figure, Hsync is the image sensor storage time T (msec
), the read synchronization signal, SPM, is Hsyn
This is a pulse motor drive signal that is output in synchronization with c. In this embodiment, four pulses are given to the pulse motor 9 to feed one line. and,
Normally, the image processing circuit 24 and the selector 26 are directly connected, and transfer is performed in the cycle following reading, but when the host computer is in the BUSY state, the buffer memory in this host computer is in the BUSY state.
When the FERFULL state occurs, the host combinator sends a data output stop signal to the image scanner in order to avoid data overflow. Then, CPU27
switches the selector 26 to the buffer memory 25, the image scanner temporarily suspends the reading operation, and the data of the line currently being read is stored in the buffer memory 25. Then, the host computer is released from the BUSY state and the BUFFEREMPTY
When the state is reached, the host computer sends a data output request signal to the image scanner again, so that the image scanner resumes the reading operation, and the CPU 27 first transfers the data read before the interruption from the buffer memory 25 to the host combinator. After sending the image, the selector 26 is switched to the image processing circuit 24 again to enter the normal state.

By the way, the pulse motor 9 needs a hold current to flow in order to maintain its stop position in the stopped state (hereinafter referred to as "held"), but its value may be smaller than the current when started, so generally Motor drive circuit 29
For example, in order to switch the current value given to the pulse motor 9 into two stages, a start time and a steady state,
A circuit as shown in the figure is provided. Therefore, using the above circuit, when starting or resuming reading, the hold signal HOLD applied to the transistor Tr is set to Hi.
By setting the voltage to gh, this transistor Tr is turned on and a DC voltage is directly applied to the pulse motor 9. As shown in FIG. 5, if the rotation of the pulse motor 9 reaches a steady state after a scanning time of M lines (M≧1) after reading is started or restarted, the hold signal HOLD is applied from the M+1st line onwards. By setting I-ow to turn off the transistor Tr and applying DC voltage to the pulse motor 9 via the resistor R, the current flowing through the coil of the pulse motor 9 decreases, and accordingly, the torque of the pulse motor 9 decreases. Make it smaller. Here, the resistance R is set so as to give a current value that allows the pulse motor 9 to obtain a torque with a sufficient margin for the required torque in a steady state. Then, while the reading operation is suspended in response to a data output signal from the host computer, the hold signal HOLD is set to T after the above-mentioned current switching is performed.
-ow is maintained. Therefore, the current value given to the pulse motor 9 in the steady state is the same as the current value in the hold state, and the current is smaller than that at the start time, reducing excess torque, so vibrations when the optical scanning means is stopped are reduced. do. Furthermore, since the conventional circuit is used as is, there is no extra cost.

Next, a second embodiment of the present invention will be described based on FIG.

Note that the same parts as in the first embodiment will be described with the same reference numerals.

The circuit used in this embodiment is such that by adding transistors and resistors to the circuit of the first embodiment and increasing the number of bypasses, the current value given to the pulse motor 9 can be switched to three stages: startup, steady state, and hold. Since the hold current in this example is set to a value smaller than the current value in the steady state, vibrations in the hold state and unnecessary temperature rise inside the device main body 2 may occur in the first implementation. It will be less than the example.

Since the other configurations and operations are the same as those of the first embodiment, their explanations will be omitted.

Next, a third embodiment of the present invention is shown in FIGS. 7 and 8,
The control configuration will be explained based on FIG. 7. Note that the same parts as in the first embodiment will be described with the same reference numerals.

The CPU 27 in this embodiment is provided with a RAM 30 that can store image data for lines during the scanning time of M lines (M≧1) of the reading means, assuming that the pulse motor 9 reaches a steady state. It is controlled by the CPU 27. That is, the reading sensor 21
The image signal read by is written to the RAM 30 through the image processing circuit 24 in the next cycle, and then sent to the host computer in the next cycle. The data of the first line after reading is started or resumed is stored in RAM.
data of the second line is transferred to the first area of the RAM.
The order of processing is determined in advance, such as to the area, and the minimum unit from when the host combinator sends a data output request signal until it sends a data output stop signal is one line.

Next, an example of the operation of this embodiment will be explained based on FIG.

First, the read lines after restarting the reading operation are (1), (2), (3), etc., and the previous read lines are (0), (-1), (-2), etc. I will go back in order like this... If a data output stop signal is received while reading line (0), the data on line (-2) in the RAM 30 (data in area P-1 in the figure) is being transferred to the host computer. At the same time, data on line (-1) is being written to area P of the RAM 30. At this time, in the next cycle, area M+ of RAM30
1, the data of line (0) is written. Next, after restarting the reading operation, if the host computer sends a data output stop signal again in the next cycle, the optical scanning means 4 scans only the number of lines (M+1) required for stability as described above, and the host computer Area P to computer
Only the following data is transferred. Furthermore, the line (1
), (2), (3), ... are sequentially stored in RAM3.
However, the data of line (M+1) is written to area M+2 because the data of area M+1 has not been transferred. Then, when the reading operation is restarted next time, the optical scanning means 4 does not start scanning immediately, and first, the data transfer from the RAM 30 is started.
The scanning is performed in the order of area M11.1.2, -M-1, M%M+2, and the optical scanning means 4 resumes scanning at the same time as the transfer of area M starts, and image data is subsequently written to the RAM 30. It begins. That is, while the optical scanning means 4 is continuously scanning, the writing to the RAM 30 is 1.2, .
. . M, 1.2, . . . are repeated in the order, and the read data at the time when the data output stop signal is received is written alternately to area M+1 or M+2.

Therefore, in this embodiment, even if the data output stop signal from the host computer is sent before the optical scanning means reaches a steady state, the vibration of the optical scanning means can be suppressed.

Since the other configurations and operations are the same as those of the first embodiment, their explanations will be omitted.

Although each of the above embodiments has been described assuming that the number of pulses required to feed one line is four, the present invention can be implemented regardless of the number of pulses.

Furthermore, although an example has been described in which gears and wires are used as the drive transmission means and a 1:1/2 optical system is used as the optical scanning means, the present invention is not limited to this. It can also be applied to an integrated type that incorporates a mirror, lens, and image sensor into one unit as an optical scanning means.

[Effects of the Invention] As explained above, in the present invention, by reducing unnecessary torque of the driving means and suppressing vibrations in the driving means itself and the scanning system, it is possible to eliminate interruptions/interruptions during image reading.
Even when a restart operation is performed, the same smooth image quality as continuous scanning can be obtained.

Furthermore, since no extra time is added to the reading time, there is no reduction in reading speed.

[Brief explanation of the drawing]

FIG. 1(a) is a cross-sectional view showing the entire first embodiment of the present invention, FIG. 1(b) is a longitudinal sectional view of FIG. 1(a), and FIG. 2 is a control block in the first embodiment. 3 is a timing chart of data transfer in the first embodiment, FIG. 4 is a circuit diagram used for control of the first embodiment, FIG. 5 is a control timing chart of the circuit shown in FIG. 4, and FIG. 6 is a timing chart of data transfer in the first embodiment. The figure is a circuit diagram used for control of the second embodiment of the present invention, FIG. 7 is a control block diagram of the third embodiment of the present invention, FIG. 8 is a timing chart of data transfer in the third embodiment, and FIG. Figure (a) is a plan view showing the entire conventional example, Figure 9 (b) is a longitudinal sectional view of figure (a), Figure 10 is a frequency-torque characteristic curve diagram of the pulse motor, and Figure 11 (a). 11(b) is an example of an output obtained by reading the original shown in FIG. 11(a) with a conventional scanner. Explanation of symbols 1...Reading sensor (reading means) 2...Device body 3...Document placement glass 4...Light scanning means 5...Lamp unit 6...Mirror unit 7... Lenses 8a, 8b...Rail 9...Pulse motor (driving means) 1o...Drive drum lla, llb...Wires 12a, 12b...Pulley 13...Tension spring 21...Reading sensor 22... t1M unit 23... A/D converter 24... Image processing circuit 25... Buffer memory 26... Selector 27... CPU 28... ROM 29... Motor drive circuit 30 ...RAM HOLD Figure 11 (Q) (b) 7Q5 Figure 9<a) 7(/4 Figure 10

Claims (3)

[Claims] (1) an optical scanning means that scans the original while irradiating it with light;
An image exposure apparatus comprising a driving means for driving the optical scanning means and a reading means for reading an image obtained by the optical scanning means, and for operating the driving means in synchronization with a drive signal of the reading means. An image processing section is provided for processing the output, and the image processing section has a buffer memory for storing image data for one scan or more of the optical scanning means, and a control unit for controlling the driving force of the driving means. An image exposure apparatus characterized by comprising means. (2) The driving means has a plurality of levels of driving force, and the driving force required to stop the scanning operation is set to a value equal to or lower than the driving force required for stable scanning operation. The image exposure apparatus described. (3) The capacity of the buffer memory of the image processing section is set to a capacity larger than the number of scans required for the scanning means to perform a stable scanning operation by at least two scans. Image exposure device.