JP2006013834A - Image reading apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize energy saving by turning off a light source at reading disusing time. <P>SOLUTION: Whether or not the platen cover of a platen placing an original is closed is determined, according to whether the reading level of each pixel obtained, by scanning and acquiring the original presser surface of the platen cover is more than a threshold (ST1). If "a cover close" is detected, a timer T is started (ST2, ST3). When the time of the timer T is up and if T hours pass from the "cover close" detection (ST4, ST5), the light source is turned off (ST6). When a key stroke occurs during counting of the timer T or if it becomes the state ("cover open") that it is not the "cover close", the timer T is reset (ST7, ST8), and the light source is turned on (ST9). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image reading apparatus such as a copying machine, a facsimile machine, and a multifunction machine having multiple functions such as a copying function and a facsimile function.

  In general, in an image reading apparatus, light from a light source is irradiated onto a document surface, light from the document surface is converted into data by a photoelectric conversion element, and an image is read. A fluorescent lamp or a cold cathode tube is used as a reading light source of this type of image reading apparatus. Since these light sources take a long time until the amount of light is stabilized after being turned on, a technique (hereinafter referred to as “preliminary lighting”) that is turned on in advance (hereinafter referred to as “preliminary lighting”) has been disclosed. .

On the other hand, as a method for detecting opening / closing of a platen cover, a technique is disclosed in which a document pressing surface (usually white) of a platen cover is read and a determination is made based on the signal level (for example, see Patent Document 2).
JP 2002-135536 A JP 2001-56515 A

  As described in Patent Document 1, the light source is preliminarily lit before reading, but in the case of a flatbed scanner, if the platen cover remains closed for a long time, the scanner may be used after that. You may think that there are few. In such a state, it is preferable from the viewpoint of energy saving to interrupt the preliminary lighting and turn it off.

  The present invention has been made paying attention to the above-mentioned problems, and an object thereof is to provide an image reading apparatus capable of realizing energy saving by skillfully utilizing the technique described in Patent Document 2.

  An image reading apparatus according to the present invention includes a platen on which a document is placed, a light source that illuminates the document, a photoelectric conversion unit that photoelectrically converts light from the document, and a platen cover that opens and closes the platen. Cover detecting means for detecting the closed state of the platen cover, time measuring means for measuring the time during which the closed state is continued by the cover close detecting means, and a light source that turns off the light source when the time measuring means measures a predetermined time Control means.

  In this image reading apparatus, when the platen cover is closed with the light source turned on, and the closed state is detected by the cover close detection means, the closed state time is then counted, and when the predetermined time has elapsed, the light source Turn off the light.

  In this image reading apparatus, it is preferable that the cover closing detection unit detects the platen cover document pressing surface read signal from the photoelectric conversion unit.

  The image reading apparatus may further include a setting unit that sets a predetermined time that the time measuring unit measures.

  According to the present invention, the light source is turned off when a predetermined time elapses after the platen cover is closed, so that power consumption can be reduced and the life of the light source can be extended. Further, since the preliminary lighting is performed, it is possible to detect the closed state of the platen cover by reading the pressing surface of the platen cover, so that energy saving can be realized without newly providing special means.

  Hereinafter, the present invention will be described in more detail with reference to embodiments. FIG. 1 is a block diagram showing the overall configuration of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is configured as a multifunction machine having a facsimile function and a copying function, and includes an MPU 1, an NCU (Network Control Unit) 2, a MODEM 3, a ROM 4, a RAM 5, Image memory 6, display unit 7, operation unit 8, communication CODEC 9, scanner mechanism control circuit 10, motor 11, inverter 12, cold cathode tube 13, CCD 14, read image processing circuit 15 , CODEC 16, image memory 17, CODEC 18, print image processing circuit 19, LED print head 20, print mechanism control circuit 21, and page memory 22.

  The MPU 1 has a function of controlling each unit constituting this apparatus in accordance with a program stored in the ROM 4. The MPU 1 also has a clock function that can measure the passage of a desired time. The NCU 2 controls the connection with the telephone line network (PSTN) 23, transmits a selection (dial) signal corresponding to the destination telephone number (including the FAX number), and detects the calling signal. It has a function. MODEM3 is an ITU (International Telecommunication Union) -T recommendation T.264. 30 based on the facsimile transmission control procedure according to 17, V.R. 27ter, V.I. The transmission data is modulated and the received data is demodulated in accordance with 29. Alternatively, in addition to these, V.P. 34, modulation of transmission data and demodulation of reception data are performed.

  The ROM 4 stores a program for controlling this device. The RAM 5 temporarily stores data processed by the MPU 1. The image memory 6 stores received image data and image data read by a scanner. The display unit 7 displays information transmitted from the apparatus to the operator. The operation unit 8 includes operation key switches such as a numeric keypad, a FAX key, a COPY key, a start key, and a one-touch key. Further, the operation unit 8 allows the operator to set a time for a timer T, which will be described later, to be counted up. In order to transmit image data, the communication CODEC 9 encodes (encodes) the MH, MR, MMR method, etc., and decodes (decodes) the received image data.

  The scanner mechanism control circuit 10 performs control such as moving the scanner mechanism for reading a document by driving the motor 11 or the like in accordance with a command from the MPU 1. The cold cathode tube 13 is a light source for image reading, and is driven by the inverter 12. The CCD 14 is a sensor for image reading, and has a photoelectric conversion function for scanning a document surface and converting it into data. As shown in FIG. 2, the cold cathode tube 13 includes mirrors 24, 25, 26, a lens 27, and a CCD 14 to form an optical system 30 as a scanning unit. The platen cover 29 is opened and closed with respect to the document table (platen) 28 with the front side as an axis. Light from the cold-cathode tube 13 passes through a glass substrate 28 a of a document table (platen) 28 and is irradiated onto a document surface placed on the glass substrate 28 a, and the reflected light passes through mirrors 24, 25, 26 and a lens 27. The light is received by the CCD 14. The CCD 14 reads an image of one scanning line of a document illuminated with light, and sequentially reads the next scanning line image at a predetermined interval. When the document is not placed on the glass substrate 28a, the light from the cold cathode tube 13 is applied to the lower surface of the document pressing surface 29a of the platen cover 29 in a state where the platen cover 29 is closed, is reflected, and the CCD 14 Reads the white background of the document pressing surface 29a.

  The read image processing circuit 15 takes in a read image signal from the CCD 14 and executes desired read image processing. The read image processing circuit 15 will be described in detail later. The CODEC 16 is used for encoding / decoding when the read image is processed. Similarly, the image memory 17 stores image data at the time of read image processing.

  The CODEC 18 is used for encoding / decoding image data during print image processing. The print image processing circuit 19 reads out image data to be printed stored in the page memory 22, performs image processing, and supplies print data, a clock signal, a strobe signal, and the like to the LED print head 20.

  As shown in FIG. 3, the read image processing circuit 15 includes an AFE (analog front end) circuit 31, an A / D converter 32, a shading correction circuit 33, an edge enhancement circuit 34, a γ correction circuit 35, An error diffusion circuit 36, a binarization circuit 37, a selector 38, an S / P (serial / parallel) conversion circuit 39, a register 40 for storing a threshold value, a comparator 41, and a counter 42 are provided.

  The AFE circuit 31 analog-amplifies the image signal output from the CCD 14 and outputs it. The A / D converter 32 converts the analog signal from the AFE circuit 31 into a digital signal. The shading correction circuit 33 corrects and outputs the output of the AFE circuit 31 at the time of document reading with the shading correction data stored in the built-in shading RAM. The edge enhancement circuit 34 further performs edge enhancement processing on the data after shading correction. The γ correction circuit 35 outputs an output value corresponding to the input value based on the set gamma correction characteristic. The output of the γ correction circuit 35 is input to an error diffusion circuit 36, a binarization circuit 37, and a comparator 41. One of the data subjected to the error diffusion processing by the error diffusion circuit 36 and the data binarized by the binarization circuit 37 is selected by the selector 38, subjected to direct / parallel conversion by the S / P conversion circuit 39, and output. Is done. The AFE circuit 31, A / D converter 32, shading correction circuit 33, edge enhancement circuit 34, γ correction circuit 35, error diffusion circuit 36, binarization circuit 37, selector 38 and S / P conversion circuit 39 are as follows: This is a circuit unit provided in a well-known read image processing circuit.

  The register 40 stores a threshold value Th for comparison with the read level. The threshold value Th is input from the register 40 to the other input terminal of the comparator 41. The comparator 41 compares the pixel data input from the γ correction circuit 35 with the threshold value Th from the register 40, and outputs a high level indicating that the input data value is larger than the threshold value Th. The counter 42 increments by 1 when each pixel is at a high level, and counts a predetermined value N (counting up). The register 40, the comparator 41, and the counter 42 are circuit units that are characteristically provided in the read image processing circuit of this embodiment. Here, the output of the γ correction circuit 35 and the threshold Th are compared digitally by the comparator 41, but the output of the AFE circuit 31 and the analog threshold may be compared by an analog comparator.

  In this embodiment of the image forming apparatus, when the light source (cold cathode tube) 13 is turned on and the reading of the document is completed by the CCD 14, it is detected whether or not the platen cover 29 is closed, and it is detected that the platen cover 29 is closed. Then, the time during which the state, that is, the state in which the platen cover 29 is closed continues, is counted, and when the duration reaches a predetermined value, the light source (cold cathode tube) 13 is turned off.

  Whether or not the platen cover 29 is closed is determined by irradiating light from the light source onto the document pressing surface 29a (back surface: white) of the platen cover 29, reading the light from the platen cover with the CCD 14, and comparing the γ correction circuit 35 with the comparator. The value input to 41 is compared with the threshold value Th for determination. The time during which the platen cover is closed is counted by a timer T built in the MPU 1.

  In the apparatus of this embodiment, the pressing surface of the platen cover is white, and the capture (read) signal from the CCD 14 when the cover is closed is at the level indicated by a in FIG. Compared with the level of the threshold Th, a> Th. When the platen cover is not completely closed, the capture signal from the CCD 14 is Th> b, assuming a level indicated by b in FIG.

  Of course, dirt and dust may adhere to the holding surface of the platen cover. In this case, even if the cover is completely closed, the capture signal at that time is as shown by c in FIG. In some cases, it may be lower than the threshold Th.

  Therefore, here, in order to detect “cover closed”, the number of pixels whose reading level is larger than the threshold Th is integrated by comparing not only the output of the γ correction circuit 35 and the threshold value but also for each pixel. I am doing so. Specifically, the input signal from the γ correction circuit 35 and the threshold value Th are compared by the comparator 41 for each pixel of one line, and the number of the input signals larger than the threshold value Th is counted by the counter 42. The counter 42 outputs a carry signal with N counts. This Carry signal is a signal indicating the “cover closed” state.

  In the image forming apparatus of this embodiment, the light source (cold cathode tube) 13 is turned on / off by repeating interrupt processing at a predetermined timing after completion of reading. This interrupt processing operation will be described with reference to the flowchart shown in FIG.

  When this interrupt routine is entered, it is determined in step ST1 whether or not the cover is closed. If the Carry signal, that is, the high signal indicating “cover closed” is output from the counter 42 in FIG. 2, the process proceeds to step ST2. On the other hand, when the output from the counter 42 is a low signal, that is, a signal indicating that “the cover is not closed” (“the cover is open”), the process proceeds to step ST7. In step ST2, it is determined whether or not the timer T is being counted. If the count of the timer T is started at the first “cover closed”, the process proceeds to step ST4. On the other hand, if not counting yet, the process proceeds to step ST3. In step ST3, the timer T starts counting. Subsequently, the process proceeds to step ST4.

  In step ST4, it is determined whether or not a key operation has been performed. Here, for example, if the copy key is operated next, the key operation is performed before the timer T expires, and the process proceeds to step ST8. On the other hand, if there is no key operation, the process proceeds to step ST5.

  In step ST5, it is determined whether or not the timer T has counted up. In a state where the platen cover 29 is closed, when the time T elapses after “cover closed” is detected, the timer T expires. Thereby, it transfers to step ST6. On the other hand, if the timer T is not counted up, the process returns from this interrupt process. In step ST6, the light source (cold cathode tube) 13 is turned off. The time T can be set to an appropriate value in consideration of how much time the platen cover is closed after the user determines the usage status for each device, and the operation is less likely thereafter. This setting can be performed, for example, by operating a key of the operation unit 8.

  In step ST7, it is determined whether or not the timer T is being counted. If “cover closed” is already detected in the previous stage and the timer T is counting, the process proceeds to step ST8. On the other hand, if the timer T is not counting, the process returns.

  In step ST8 subsequent to step ST7, the state is not “cover closed”, that is, “cover open”, and the timer T is being counted, but it is not necessary to maintain the timer count, so the timer T is counted. Stop and reset. Then, the process proceeds to step ST9, and the light source 13 is turned on. In step ST8 following step ST4, the key T is operated, so that the timer T is also stopped and reset in preparation for the corresponding processing operation. In step ST9, the light source 13 is turned on.

1 is a block diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure explaining the reading optical system of the image forming apparatus of the embodiment. 2 is a block diagram illustrating a configuration of a read image processing circuit of the image forming apparatus according to the embodiment. FIG. FIG. 6 is a flowchart for explaining interrupt processing of the image forming apparatus according to the embodiment. FIG. 6 is a diagram illustrating a read signal level when the platen cover is closed and when the platen cover is opened in the image forming apparatus according to the embodiment.

Explanation of symbols

1 MPU
7 Display unit 8 Operation unit 10 Scanner mechanism control circuit 13 Cold cathode tube (light source)
14 CCD
15 Scanned Image Processing Circuit 28 Document Platen (Platen)
29 Platen Cover 31 AFE Circuit 32 A / D Converter 33 Shading Correction Circuit 34 Edge Enhancement Circuit 35 Gamma Correction Circuit 40 Register (Threshold Storage)
41 Comparator 42 Counter

Claims (3)

In an image forming apparatus including a platen on which an original is placed, a light source that illuminates the original, a photoelectric conversion unit that photoelectrically converts light from the original, and a platen cover that freely opens and closes the platen.
Cover closing detection means for detecting the closed state of the platen cover, timing means for measuring the time during which the closed state has been continued by the cover closing detection means, and light source control means for turning off the light source when the timing means measures a predetermined time An image reading apparatus comprising:   The image reading apparatus according to claim 1, wherein the cover closing detection unit detects the cover based on a reading signal of the platen cover original pressing surface from the photoelectric conversion unit.   3. The image reading apparatus according to claim 1, further comprising a setting unit configured to set a predetermined time to be measured by the time measuring unit.

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