JP2005184170A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader attaining a required luminous quantity in a time practically causing no problem while extending the service life of a light source (tube) without the need for always applying a voltage with a 100% duty ratio or a maximum permissible voltage to the light source (tube). <P>SOLUTION: A flowchart for explaining lighting processing operations of the light source includes a steps of: (ST2) detecting a temperature T at start of operations; (ST3) discriminating whether or not the detected temperature T is smaller than a prescribed value T1 (T1<T2); (ST4) of deciding that the detected temperature T is low, when the detected temperature T is smaller than the prescribed value T1 and selecting a high applied voltage V1; (ST5) applying lighting drive to the light source 28 by the applied voltage V1; (ST9) selecting an applied voltage V2 being a medium voltage when the detected temperature T is in a relation of T1<T≤T2 (ST8); and (ST10) selecting a low applied voltage V3 when the detected voltage T is greater than the temperature T2 and applying lighting drive to the light source 28 by the applied voltage V2 or V3 for the respective cases. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

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

In general, some image reading apparatuses irradiate a document with light from a light source, take the reflected light into a CCD through an optical system, perform photoelectric conversion, and read image data. In this type of image reading apparatus, a fluorescent tube or a cold cathode tube is often used as a light source. These light sources take some time from turning on until they become sufficiently bright for reading. Therefore, in order to shorten the time from the lighting to the time when reading can be started, a technique of driving at a duty ratio of 100% is proposed until the light source reaches the brightness necessary for reading (for example, Patent Document 1). reference).
JP-A-1-303426

  The time from when the above-described light source is turned on until the amount of light is sufficient for reading varies depending on the environmental temperature at that time. That is, the lower the temperature of the tube (light source), the longer it takes. Conversely, if the tube temperature is high, less time is required. Therefore, as in the technique described in Patent Document 1, when a 100% duty ratio is applied regardless of the temperature, there is a problem in that excessive lighting sometimes occurs and the life of the fluorescent tube or the cold cathode tube is shortened. The present invention has been made paying attention to the above-mentioned problems, and it is not always necessary to apply a duty ratio of 100% or the maximum allowable voltage, so that the lifetime of the light source (tube) is extended and there is no practical problem. Therefore, an object of the present invention is to provide an image reading apparatus that can achieve a necessary light quantity.

  The image reading apparatus includes a light source, a lighting driving unit that drives the light source to turn on, a lighting environment condition detecting unit that detects a lighting environment condition, and a lighting driving start of the light source based on the lighting environment condition detected by the detecting unit. Control means for adjusting the applied power.

  In the image reading apparatus of the present invention, the lighting environment condition is, for example, a temperature, and the detection means is a temperature detection means.

  In the image reading apparatus according to the present invention, the lighting environment condition may be, for example, an elapsed time from the end of the previous reading, and the detection means may be a timer.

  According to the present invention, the lighting environment condition such as the temperature is detected, and the applied power at the start of lighting driving of the light source is adjusted based on the detected lighting environment condition. At a stage where the temperature has not passed so much, the temperature of the fluorescent tube and the cold cathode tube is high to some extent. Therefore, it is not necessary to always apply a 100% duty ratio or the maximum allowable voltage. The necessary amount of light can be achieved in a short time.

  Hereinafter, the present invention will be described in more detail with reference to embodiments. FIG. 1 is a block diagram showing the configuration of a facsimile machine (multifunction machine) according to an embodiment of the present invention.

  In FIG. 1, a CPU (central processing unit) 1 as a main control unit has a function of comprehensively controlling each unit constituting the device. The CPU 1 includes an NCU (Network Control Unit) 2, MODEM 3, ROM 4, RAM 5, image memory 6, display unit 7, operation panel 8, image reading unit 9, printer 10, CODEC (encoder / decoder). : Coder and Decoder) 11 and LAN I / F 12 are connected via a bus 13.

  The NCU 2 is controlled by the CPU 1 to control connection with a telephone line network (PSTN) 14 that is a communication line. Further, the NCU 2 has a function of sending a dial pulse corresponding to a telephone number (including a FAX number) of a communication partner and a function of detecting an incoming call. MODEM3 is an ITU (International Telecommunication Union) -T recommendation T.264. 30, T.M. 4 according to the facsimile transmission control procedure (facsimile communication procedure) according to FIG. 17, V. 27ter, V.I. The transmission data is modulated and the received data is demodulated in accordance with 29. MODEM3 is a V. 8, V. V. using 34. It is also applicable to 34 FAX. Specifically, the MODEM 3 has a function of modulating transmission data, which is a digital signal, into an analog voice signal so as to be sent to the telephone line network 14 via the NCU 2. The MODEM 3 has a function of demodulating an analog voice signal received from the telephone line network 14 via the NCU 2 into a digital signal.

  The ROM 4 stores a program for controlling the operation of the entire apparatus. The RAM 5 stores data necessary for control by the CPU 1 and data that needs to be temporarily stored during the control operation. The image memory 6 stores the image data read by the image reading unit 9 in a compressed state. Further, the image memory 6 stores image data received from an external device such as a personal computer via a network (LAN) 15 or image data read from a recording medium in a compressed state (JPEG or the like).

  The display unit 7 displays icons, key buttons, message contents necessary for data transmission / reception, telephone numbers and fax numbers input by operating the operation panel 8, and the like. As the display unit 7, an LCD (Liquid Crystal Display) is used. The operation panel 8 includes a numeric keypad, a mode switching key, a one-touch key, an abbreviated key, a registration key, a start key, a stop key, and the like.

  The image reading unit 9 optically scans and reads image data of a document when performing facsimile transmission, copying, or obtaining scanner data. The image reading unit 9 can also read a color image.

  The image reading unit 9 includes a CCD image sensor 21, an AFE (analog front end) circuit 22, an A / D conversion unit 23, a scanner image processing circuit 24, a scanner mechanism control unit 25, and a temperature detection thermistor. 26, an inverter 27, and a cold cathode tube 28.

  The CCD image sensor 21 reads an image of one scanning line of a document, and sequentially reads the next scanning line image at a predetermined interval. The AFE circuit 22 analog-amplifies the output of the CCD image sensor 21. The A / D converter 23 converts the analog output of the AFE circuit 22 into a digital signal. The scanner image processing circuit 24 performs image processing such as shading correction and gamma correction on the input digital image signal.

  The scanner mechanism control circuit 25 controls the drive voltage applied from the inverter 27 to the cold cathode tube 28 in accordance with the control of the carriage motor (not shown) of the scanner mechanism unit and the temperature detected using the thermistor 26.

  The printer 10 is an electrophotographic printer, and records received image data and image data of a document read by the image reading unit 9 in a copying operation on a recording sheet.

  The CODEC 11 encodes (encodes) the read image data according to the MH, MR, MMR method or the like to transmit or store the image data. Also, the CODEC 11 decodes (decodes) the image data received in a compression-coded state for recording by the printer 10. The LAN I / F 12 is for exchanging data with an external device via a LAN (local area network) 15, and is connected to an external device such as a PC (personal computer) via the LAN I / F 12. . For example, image data to be copied can be received from an external device via the LAN I / F 12.

  FIG. 2 is a diagram showing a scanner mechanism unit and a scanner circuit unit of the image reading unit 9 of the MFP according to this embodiment. The AFE circuit 22 includes a sample hold circuit 22a that takes in an analog signal from the CCD image sensor 21 and an AGC circuit 22b that has a gain adjustment function and amplifies the analog signal. The scanner image processing circuit 24 includes a shading correction circuit 24a, a γ correction table 24b, and a binarization circuit 24c.

  A shading plate 32 is fixed below the support plate 30 on which the glass substrate 31 on which the document is placed is supported. Below the glass substrate 31 and the shading plate 32, an optical system 38 including a CCD image sensor 21, a light source (cold cathode tube) 28, mirrors 34, 35 and 36, and a lens 37 is disposed. The optical system 38 is a carriage. It is configured to be movable.

  Next, the light source drive processing operation at the time of document reading of the MFP according to this embodiment will be described with reference to the flowchart shown in FIG. First, in step ST1, it is determined whether or not it is a start key, that is, whether or not the start key is pressed. When the start key is pressed, the process proceeds to step ST2. In step ST2, the temperature T is detected by the thermistor 26 in the scanner mechanism control circuit 25. Subsequently, the process proceeds to step ST3. In step ST3, it is determined whether or not the detected temperature T is equal to or lower than T1. If the detected temperature T is equal to or lower than T1, the environmental temperature is assumed to be low, and the process proceeds to step ST4. On the other hand, when the temperature T is higher than T1, the process proceeds to step ST8.

  In step ST4, the applied power V1 to the light source 28 is selected. As shown in FIG. 5, this applied voltage V1 is V1> V2> V3, and is the highest voltage among the selected applied voltages. Next, the process proceeds to step ST5. In step ST5, the applied voltage V1 selected by the inverter 27 is applied to the light source 28 and turned on. Subsequently, the process proceeds to step ST6. In step ST6, it is determined whether or not the light amount of the light source 28 has reached a predetermined value. As shown in FIG. 1, a photoelectric sensor 29 is provided and the amount of received light detected by the photoelectric sensor 29 is used for the amount of light. As this received light amount, an output obtained when the shading plate 32 is read by the CCD image sensor 21 may be applied. The process stays at step ST6 until the predetermined value is reached. During this time, the applied voltage V 1 is applied to the light source 28. On the other hand, when the light quantity reaches a predetermined value, the process proceeds to step ST7. In step ST7, the applied voltage is set to the steady lighting voltage V0.

  In step ST8, it is determined whether or not the temperature T is higher than T1 and equal to or lower than T2 (T1 <T ≦ T2). If the determination is “Yes”, it is determined that the environmental temperature is an intermediate temperature, and the process proceeds to step ST9. On the other hand, if the temperature T is higher than T2, the environmental temperature is assumed to be high, and the process proceeds to step ST10.

  In step ST9, since the detected temperature T is an intermediate temperature, V2 is selected as the applied voltage. In step ST10, since the detected temperature is high, V3 is selected as the applied voltage. Subsequent to step ST9 or step ST10, the process proceeds to step ST5. Then, the light source 28 is driven to turn on with the selected applied voltage V2 or V3.

  In this embodiment, it is determined whether the detection temperature is low temperature, medium temperature, or high temperature. However, the level is determined in more detail, or it is detected in two levels or continuously, and applied accordingly. The voltage may be controlled.

  As another embodiment for controlling the applied voltage according to the environment, a timer for counting the elapsed time from the end of the previous reading may be provided, and the applied voltage may be controlled according to the elapsed time by this timer. The light source drive processing operation at the time of document reading according to this embodiment will be described with reference to the flowchart shown in FIG.

  In step ST11, it is determined whether or not the key is a start key. When the start key is pressed, the process proceeds to step ST12. In step ST12, an elapsed time t from the end of the previous reading is read from the timer. Next, the process proceeds to step ST3. In step ST3, it is determined whether the read elapsed time t is t1 or more. When the elapsed time t is equal to or longer than t1, it is assumed that a long time has passed since the light source 28 is turned off and the temperature of the light source 28 has decreased, and the process proceeds to step ST14. On the other hand, if the elapsed time t is smaller than t1, the process proceeds to step ST18.

  In step ST14, an applied voltage V1 (V1> V2> V3> V0) to the light source 28 is selected. Next, the process proceeds to step ST15. In step ST15, the applied voltage V1 is applied to the light source 28 to turn on the light source 28. Subsequently, the process proceeds to step ST16. In step ST16, it is determined whether or not the light amount of the light source 28 has reached a predetermined value. The process stays at step ST16 until the predetermined value is reached. During this time, the applied voltage V 1 is applied to the light source 28. On the other hand, if it becomes a predetermined value, it will transfer to step ST17. In step ST17, the applied voltage is set to the steady lighting voltage V0.

  In step ST18, it is determined whether the elapsed time t is smaller than t1 and is t2 or more (t1> t2). If the determination is “yes”, it is determined that the elapsed time is medium, and the process proceeds to step ST19. On the other hand, if the elapsed time is shorter than t2, the elapsed time is assumed to be short, and the process proceeds to step ST20.

  In step ST19, since the elapsed time t is medium, V2 is selected as the applied voltage. In step ST20, since the elapsed time t is small, V3 is selected as the applied voltage. Next, following step ST19 or step ST20, the process proceeds to step ST15. Then, the light source 28 is driven to turn on with the selected applied voltage V2 or V3.

  In this embodiment as well, the elapsed time is determined as one of three stages, large, medium, and small. However, the stages are detected more finely, or in two stages or continuously, and accordingly. The applied voltage may be controlled.

1 is a block diagram showing a schematic configuration of a facsimile machine (multifunction machine) in which the present invention is implemented. It is a figure explaining the principal part of the image reading part of the facsimile apparatus of the embodiment. It is a flowchart explaining the lighting process operation | movement of the light source of the image reading part of the facsimile apparatus. It is a flowchart explaining the lighting process operation | movement of the light source of the image reading part of the facsimile machine of other embodiment. It is a figure which shows the relationship between the detection temperature of the same embodiment facsimile apparatus, and the lighting application voltage to a light source.

Explanation of symbols

1 CPU
9 Image Reading Unit 21 CCD Image Sensor 22 AFE Circuit 23 A / D Converter 24 Scanner Image Processing Circuit 24a Shading Correction Circuit 24b Gamma Correction Table 24c Binarization Circuit 25 Scanner Mechanism Control Circuit 26 Thermistor 27 Inverter 28 Light Source (Cold Cathode Tube) )
32 Shading plate 38 Optical system

Claims (3)

  Based on the light source, the lighting driving means for lighting the light source, the lighting environment condition detecting means for detecting the lighting environment condition, and the lighting environment condition detected by the detecting means, the applied power at the start of the lighting driving of the light source is adjusted. An image reading apparatus comprising a control unit.   The image reading apparatus according to claim 1, wherein the lighting environment condition is a temperature, and the detection unit is a temperature detection unit.   The image reading apparatus according to claim 1, wherein the lighting environment condition is an elapsed time from the end of the previous reading, and the detection unit is a timer.

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