JP2001166398A - Image reader and copying machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader capable of reading both of a black-and- white image and a color image and also capable of reading the black-and-white image without awaiting the completion of the warming-up of a light source required for reading the color image while maintaining the quality of the read image; and a copying machine equipped with the image reader. SOLUTION: After warming up the light source of the image reader in a 1st warming-up period, reading the black-and-white image is permitted, and also after warming up the light source in a 2nd warming-up period, reading the color image is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image reading device and a copying machine provided with the image reading device.

[0002]

2. Description of the Related Art A copying machine has an image reading device, which has a fluorescent lamp 1206 as a light source.

FIG. 9 is a central sectional view of a conventional fluorescent lamp for an image reading apparatus, and FIG. 10 is a partially cutaway side view of the fluorescent lamp of FIG. 9 and 10, the fluorescent lamp 120 is used.
6 has a glass tube 801, and inside the glass tube 801,
A mercury gas and a rare gas 901 are sealed by caps 902 at both ends of the glass tube 801. Further, the glass tube 80
Electrodes 903 of a tungsten coil coated with an electron-emitting substance are provided at both ends of 1, and the electrodes 903 are supported by a stem 904. The base 902 is provided with a conductive portion 905 for supplying a current. A reflection film 804 that reflects light generated inside the glass tube 801 is applied inside the glass tube 801, and a phosphor 803 is applied inside the reflection film 804. The aperture 805 on the side surface of the glass tube 801 is not coated with the reflective film 804 and the fluorescent material 803 to form an optical opening, so that light passes through the aperture 805.

When the fluorescent lamp 1206 is turned on, the electrode 903 is turned on.
The electrons emitted from the semiconductor collide with the mercury electrons, and the mercury electrons are excited to emit ultraviolet rays. The ultraviolet light is applied to the glass tube 80
The phosphor 803 on one inner wall converts the light into visible light having a wavelength unique to the phosphor 803. Light generated inside the glass tube 801 is reflected by the reflection film 804 and is transmitted to the aperture 805.
Is emitted from. The reflection film 804 and the aperture 80
By the action of 5, strong light is emitted in the direction of the arrow in FIG.

FIG. 11 is a perspective view of the fluorescent lamp 1206 shown in FIG.

In FIG. 11, a fluorescent lamp 1206 is supported by a socket 1301.
Current is supplied from the upper pin. The fluorescent lamp 1206 is provided with an aperture section 805 in a required direction. In FIG. 11, strong light is emitted in the direction of the arrow and relatively weak light is emitted in the opposite direction.

[0007] The fluorescent lamp 1206 has a fluorescent lamp light quantity sensor 1201 for measuring the light quantity. A photodiode or the like is used for the light amount sensor 1201, and outputs a current proportional to the light amount of the fluorescent lamp 1206.

In an image reading apparatus, a glass tube 80
The light emitted from the first aperture section 805 is reflected by the light collecting mirror and is emitted to the vicinity of the original reading line on the platen glass. The light reflected from the original reading line is transmitted to the image reading CC via a mirror and a lens.
It is led to D.

The amount of light of the fluorescent lamp 1206 depends on the amount of ultraviolet light emitted from the excited mercury atoms in the glass tube 801 as described above, and is expressed by the product of the power supplied to the fluorescent lamp 1206 and the luminous efficiency. It is. Here, the luminous efficiency decreases when the mercury atom density decreases, due to a decrease in the number of atoms excited by electron collision, and conversely, when the mercury atom density increases, the photon reabsorption probability increases because of the increase in photon reabsorption probability. There is a mercury vapor pressure that decreases and maximizes luminous efficiency.
In addition, the mercury vapor pressure depends on the temperature of the lowest temperature inside the both ends of the glass tube 801 (the coldest part temperature), and there is a coolest part temperature at which the luminous efficiency is maximized.

FIG. 12 is a graph showing the relationship between the temperature of the coldest part or the mercury vapor pressure of the fluorescent lamp 1206 of FIG. 10 and the luminous efficiency.

The mercury vapor pressure at which the luminous efficiency is maximized depends on the inner diameter of the glass tube 801.
Is 15 mm, the mercury vapor pressure at which the luminous efficiency is maximized is about 1 Pa, and the temperature of the coldest part at that time is about 44 ° C. Normally, when the fluorescent lamp 1206 for lighting is turned on at a use environment temperature, for example, 25 ° C., the temperature of the coldest part when it reaches a heat stable state due to its own heat generation and heat radiation is set to the optimum coldest part temperature. Designed.

FIG. 13 is a block diagram of a light quantity control circuit of the fluorescent lamp 1206 of FIG.

The light quantity control circuit of the fluorescent light 1206 converts the measured light quantity obtained by the fluorescent light quantity sensor 1201 into an amplifier 12.
02, comparator 1203, light intensity controller 120
4. By feeding back to the fluorescent lamp 1206 via the inverter 1205, the light amount of the fluorescent lamp 1206 is controlled to be constant.

In FIG. 13, a light amount signal output from an optical sensor 1201 is converted into a voltage value by an amplifier 1202 and amplified. The comparator 1203 compares the observed voltage value corresponding to the light amount with the voltage value corresponding to the desired light amount and outputs the result. The light amount controller 1204 outputs a pulse width modulation (PWM) signal.

The PWM signal output by the light amount controller 1204 is synchronized (SYN) as shown in FIG.
C) It is controlled in phase with the signal.

FIGS. 14A and 14B are timing charts for explaining the operation of the light amount control circuit of FIG. 13. FIG. 14A shows a case where the light amount is appropriate, and FIG. 14B shows a case where the current value is increased because the light amount is small. (C) shows a case where the current value is reduced because the light amount is large.

When the light quantity of the fluorescent lamp 1206 is proper, the duty becomes a proper value as shown in FIG.
When the light quantity of the fluorescent lamp 1206 is smaller than the desired light quantity, the duty becomes large as shown in FIG. 14B, and when the light quantity of the fluorescent lamp 1206 is larger than the desired light quantity, as shown in FIG.
Control is performed so that the duty is reduced as shown in FIG.

The inverter 1205 receives the input PWM signal.
When the signal is at the “H” level, an alternating current, that is, a lamp current, is supplied to the fluorescent lamp 1206 at a frequency sufficiently higher than the PWM signal (generally, about 10 to 100 times), and the fluorescent lamp 1206 is turned on. At the time of the level, the lamp current is controlled to be cut off and turned off. This turning on / off is repeated according to the cycle of the PWM signal. The frequency of the PWM signal is fluorescent light 1
It is higher than the optical response frequency of turning on / off 206.
That is, although the lighting / extinguishing is electrically repeated in accordance with the cycle of the PWM signal, it looks as if the light is lit with a constant light amount corresponding to the average current value.

As described above, the fluorescent lamp 1206 is controlled by controlling the duty ratio of the lighting / extinguishing cycle so that the light amount becomes constant.

The amount of light of the fluorescent lamp 1206 is
It changes as shown in FIG. 14 according to ON / OFF of the internal current. During a period in which no current flows, light is emitted to some extent due to the persistence of the phosphor 803, but the amount of light is small. However, depending on the type of the fluorescent lamp 1206, this light amount fluctuation width is small, and there is a case where there is no problem in image reading.

On the other hand, an image reading element such as a CCD operates during one cycle of a SYNC signal, that is, during one scanning period.
The read image information is stored as electric charges. That is, C
The output of the CD is an output value having a magnitude obtained by integrating the light amount during one scanning period. Therefore, if the blinking of the fluorescent lamp 1206 and the scanning of the CCD are synchronized in the same cycle, a constant CCD output can be obtained.

As described above, the conventional image reading device is
The monochrome image reading and the color image reading are performed using the fluorescent lamp 1206.

[0023]

However, FIG.
As described in detail below, the conventional image reading apparatus has a problem in that a black-and-white image cannot be read until the warm-up required for reading a color image is completed after the power is turned on.

FIG. 15 is a graph showing a change in the RGB light amount balance of the fluorescent lamp 1206 when the power of the image reading apparatus is turned on. In FIG. 15, the horizontal axis is time. However, the fluorescent lamp 1206 has been warmed up by appropriate means.

According to FIG. 15, the Green signal is relatively constant, while the Brue signal decreases and the Red signal further decreases. Moreover, the shape of the change between the Brue signal and the Red signal does not always become the same after the power is turned on, but depends on the environment at that time and the use history of the device.

The light amount sensor 1201 for keeping the light amount of the fluorescent lamp 1206 constant has a standard relative luminous sensitivity characteristic, that is, a characteristic close to the sensitivity of the naked eye, by providing a filter on the surface. In the standard relative luminous efficiency characteristics, Green has the highest sensitivity. Therefore, when the constant light amount dimming unit is used, the light is adjusted so that the Green light amount becomes constant. On the other hand, since the spectrum of the fluorescent lamp 1206 changes due to a change in the temperature distribution of the fluorescent lamp, the amount of Brue light and the amount of Red light change.

The color change of the light source does not cause any problem when a monochrome image is read or when a color image is read in black and white, since the light amount is controlled to be constant.

In the case of reading a color image,
If the amount of change in the amount of Red light is within a certain allowable range, the light source RGB balance can be corrected by the analog image processing unit 221 or the digital image processing unit 223 by reading a standard white board before reading an image. But Brue light and Red
If the light source color changes during the period of reading one image with the light amount exceeding the allowable value, the color reproducibility will deteriorate.

Another problem is that the fluorescent lamp 1 can be used at low temperatures.
There is an infrared problem that is likely to be generated from the 206. Fluorescent light 1
The infrared ray 206 is likely to be generated immediately after the power is turned on in a low-temperature environment, but as the fluorescent lamp 1206 is warmed up, the ratio of the generated infrared ray decreases. The infrared light of the fluorescent lamp 1206 has an adverse effect on both color image reading and black-and-white image reading, but has a more serious adverse effect on color reproducibility particularly when reading a color image.

As described above, in order to maintain the quality of the read image, the warm-up time of the fluorescent lamp 1206 at the time of turning on the power is relatively short in the case of reading a monochrome image, whereas the warm-up time of the fluorescent lamp 1206 is relatively short. In the case of image reading, a relatively long warm-up period is required.

That is, in the case of an image reading apparatus that performs both color image reading and black and white image reading, a problem arises in that black and white image reading cannot be performed until the warm-up required for color image reading is completed after the power is turned on.

An object of the present invention is to provide an image reading apparatus which performs both black and white image reading and color image reading, while maintaining the quality of the read image and without waiting for the completion of warm-up of the light source required for color image reading. An image reading device capable of reading,
And a copying machine provided with the image reading device.

[0033]

According to a first aspect of the present invention, there is provided an image reading apparatus, comprising: a light source for generating light for irradiating a document; a monochrome image reading and color reading device based on the light from the document; An image reading apparatus comprising: an image reading unit that reads an image; a warm-up unit that warms up the light source when the power of the image reading device is turned on; and the warm-up unit warms up the light source for a first warm-up period. After that, the black-and-white image reading by the image reading unit is permitted, and the warm-up unit warms up the light source for a second warm-up period, and thereafter, the color reading by the image reading unit is permitted. Control means for controlling the warm-up means And it features.

According to a second aspect of the present invention, in the image reading apparatus according to the first aspect, the light source is warmed up to a first temperature during the first warm-up period, and the second warm-up is performed. In the up period, the light source is warmed up to a second temperature lower than the first temperature.

According to a third aspect of the present invention, in the image reading apparatus of the second aspect, the light source includes heating means for warming up the light source to the first temperature.

According to a fourth aspect of the present invention, in the image reading apparatus according to any one of the first to third aspects, the light source during normal image reading during the first warm-up period. The light source is turned on with a current larger than the lighting current.

According to a fifth aspect of the present invention, in the image reading apparatus according to any one of the first to fourth aspects, during the second warm-up period, the light source during normal image reading is used. The light source is turned on with a current smaller than the lighting current.

According to a sixth aspect of the present invention, in the image reading apparatus of any one of the first to fifth aspects, the light source comprises a fluorescent lamp.

In order to achieve the above object, a copying machine according to a seventh aspect is provided with the image reading device according to any one of the first to sixth aspects.

[0040]

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

FIG. 1 is a schematic configuration diagram of a copying machine according to an embodiment of the present invention. The copying machine includes a reader unit 1 as an image reading device and a printer unit 2. In the reader unit 1, the originals 1004 placed on the original feeder 101 are sequentially placed one by one on the original platen glass surface 10.
03. When the original 1004 is transported to a predetermined position on the platen glass surface 1003, the fluorescent lamp 1206 is turned on, and the scanner unit 1012 moves while irradiating the original. The reflected light of the original 1004 is reflected by the mirror 100
6, 1007, 1008 and a lens 1009, and is incident on an image reading CCD 1010. CCD101
The reflected light of the document irradiated to 0 is photoelectrically converted, and the electric signal is transmitted to an image processing unit (not shown).

An image processing unit which performs image processing set by various operation units, described later, has an external switching circuit, and has a selector function for switching a signal from the reader unit 1 to the printer unit 2 or an external device (not shown). are doing.

In the printer unit 2, the laser driver 3
Reference numeral 21 causes the laser light emitting unit 301 to emit laser light corresponding to the image data output from the reader unit 1. The laser beam is applied to the photosensitive drum 302, and the photosensitive drum 302
Is formed with a latent image corresponding to the laser beam. A developer is attached to a portion of the latent image on the photosensitive drum 302 by a developing device 303. The recording paper is fed from one of the cassette 304 and the cassette 305 at a timing synchronized with the start of the laser beam irradiation, and is conveyed to the transfer unit 306.
02 is transferred to a recording paper. The recording paper onto which the developer has been transferred is conveyed to the fixing unit 307 and the fixing unit 3
The developer is fixed on the recording paper by the heat and pressure of 07. The recording paper that has passed through the fixing unit 307 is discharged by discharge rollers 308. Further, when double-sided recording is set, the rotation direction of the discharge roller 308 is reversed, and the flapper 30 is rotated.
9 guides the sheet to the re-feeding conveyance path 310. Refeeding conveyance path 3
The recording paper guided to 10 is transferred to the transfer unit 3 at the timing described above.
06 is fed.

Since the sensitivity of the photosensitive drum 302 changes depending on the environmental temperature, a drum heater 311 and a thermistor 312 for detecting the temperature around the photosensitive drum 302 are provided inside the photosensitive drum 302 to prevent the sensitivity from changing. Is provided. When the temperature around the photosensitive drum 302 is lower than a predetermined value, power is supplied to the drum heater 311. The set value of the thermistor 312 in the photosensitive drum 302 can be set by a control device described later.

The copying machine includes a reader unit 1 and a printer unit 2.
Are contained in one body, but the reader unit 1 and the printer unit 2 may be provided independently of each other, and they may be connected to each other by a communication line.

Hereinafter, a reader unit 1 as an image reading apparatus according to an embodiment of the present invention will be described in detail with reference to FIG.

In FIG. 2, the light emitted from the aperture 805 of the glass tube 801
The light is reflected at 1002 and irradiates near the reading line 1005 of the original 1004 on the platen glass 1003.
Light reflected from the original reading line 1005 is reflected by mirrors 1006, 1007, 1008 and a lens 1009.
Through the CCD 1010. A light-shielding plate 1011 is provided so that light emitted from the back of the glass tube 801 does not directly irradiate the document 1004. Glass tube 801, focusing mirrors 1001 and 1002, light shielding plate 101
Reference numeral 1 denotes one scanner unit 1012 that moves the original surface. In accordance with the movement of the scanner unit 1012, the mirrors 1007 and 1008 move so that the optical path length from the reading line 1005 to the CCD 1010 is kept constant. Further, the reader unit 1 is provided with a platen glass 100.
3 and a white plate 1013 at the same level. The white plate 1013 is used for inspecting the light distribution of the fluorescent lamp, the sensitivity unevenness of the CCD 1010, and the like.

FIG. 3 is a perspective view of the fluorescent lamp 1206 in the image reading apparatus of FIG.

The fluorescent lamp 1206 is supported by a socket 1301 and has a lamp heater 213 so as to cover the glass tube 801 on the side opposite to the aperture 805. The fluorescent lamp 1206 further includes a fluorescent lamp light amount sensor 1201 and a lamp heater 213 for measuring the light amount.
And a lamp heater thermistor 214 for detecting the temperature of the lamp heater. A photodiode or the like is used as the light amount sensor 1201, and outputs a current proportional to the light amount of the fluorescent lamp 1206.

FIG. 4 is a block diagram of a control circuit of the fluorescent lamp 1206 in FIG.

In FIG. 4, the light intensity of the fluorescent lamp 206 is reduced by the light control sensor substrate 204 disposed near the fluorescent lamp 1206.
Detected by photodiode 202 above. The light amount signal is converted from a minute current signal into a voltage signal by the preamplifier 203 and input to the amplifier 206. Amplifier 206
Adjusts the light amount signal to an appropriate voltage using an associated variable resistor, and sends it to one comparison input of the comparator 207.

The CPU 208 switches the designated light amount reference signal value and sends it to the other comparison input of the comparator 207.
This switching is a means for switching, for example, when the light amount is particularly reduced when the reflectance of the read image is particularly high. If the reading light amount is a constant value, this switching is not necessary.

The comparator 207 compares the light quantity reference signal with the light quantity signal from the amplifier 206, and outputs the comparison result to the flip-flop 209.

The dimming logic circuit 217 is composed of a gate array and the like, and the flip-flop 209 therein is a SYN
The comparator 207 outputs a light amount comparison signal in synchronization with the C signal. The UP / DOWN counter 210 increases the counter value by a predetermined value according to the result of the light amount comparison signal when the light amount is less than the light amount reference signal. When the light amount is equal to or larger than the light amount reference signal, the counter value is decreased by a predetermined value.

DOWN counter 211 is UP / DOWN
The value of the counter 210 is loaded in synchronization with the SYNC signal, and DOWN count is performed at a predetermined clock. The output PWM signal is at a high level during a period from the time of loading until the carry is output, and at a low level during other periods.

The CPU 208 has an UP / DOWN counter 2
The value of 10 can be read at any time. Also, conversely, CPU
Reference numeral 208 allows a desired value to be written to the UP / DOWN counter 210 at any time. In addition, the CPU 208
The counting operation of the DOWN counter 210 can be stopped. Therefore, the CPU 208 writes, for example, a value corresponding to a duty of the PWM signal of 10% into the UP / DOWN counter 210 and writes the value to the UP / DOWN counter 210.
Is stopped, the fluorescent lamp 1206 is turned on at a constant duty value of 10%, that is, a constant current value.

The dimming logic circuit 217 includes a circuit for generating a control signal for preheating the electrodes of the fluorescent lamp 1206 before lighting.
The inverter 212 preheats the electrode of the fluorescent lamp 1206 in accordance with the preheating control signal before the fluorescent lamp 1206 is turned on, and then turns on in accordance with the PWM signal. The fluorescent lamp 1206 is
The light is turned on only when the PWM signal is at the high level, and is turned off during the low level.

The detected temperature of the thermistor 214 is sent to the CPU 208 via the A / D converter 215,
U208 is connected to the lamp heater 21 via the driver 216.
3 is indicated. This temperature control value may be constant.

The light reflected from the original 1004 is
The light is received at 10, gain-corrected by the analog image processing unit 221, converted into a digital signal by the A / D converter 222, and subjected to shading correction, color correction, density correction, and the like by the digital image processing unit 223. The electric signal processed by the digital image processing unit 223 is sent to the printer unit 2.

FIG. 5 is a block diagram of inverter 212 in FIG.

In FIG. 5, power is supplied by a DC power supply 1901. The drive circuit 1902 is connected to the fluorescent lamp 1
The switch circuit is opened and closed according to the signal of the oscillator 1910 that generates the lighting frequency of 206. Transformer 1903
As a result, an AC voltage necessary for lighting the fluorescent lamp 1206 is generated. The choke coil 1904 is connected to the fluorescent lamp 1206
To control the tube current. The AC switch 1905 turns ON / OF the output of the tube current of the fluorescent lamp 1206 according to the PWM signal by the function of the built-in transistor and diode bridge.
F. This switching frequency is sufficiently higher than the frequency of the oscillator 1910 as described above. Oscillator 190
6. The drive circuit 1907 and the transformer 1908 are inverters for supplying a preheating current. Drive circuit 1907
Is a block diagram of which is shown in FIG.
01 outputs a voltage equal to the input voltage.

In the above configuration, the fluorescent lamps 1206-2
Immediately before lighting, an AC preheating current proportional to the preheating control signal is supplied to the two electrode units. Further, a voltage is applied between the electrodes at both ends of the fluorescent lamp 1206, and discharge, that is, lighting is started.

According to this circuit, even when the lamp is not lit, the preheating current corresponding to the preheating control signal is supplied to the fluorescent lamp 1206.
To each of the two electrodes.

FIG. 7 is a block diagram of a temperature control circuit for the lamp heater 213 and a preheating control circuit for the electrodes of the fluorescent lamp 1206.

In FIG. 7, the thermistor 214 and the lamp heater 213 are mounted as close to the fluorescent lamp 1206 as possible. The thermistor 214 outputs a voltage corresponding to the temperature of the fluorescent lamp 1206 based on the resistance ratio with respect to the resistor 301. According to this circuit, the higher the temperature, the lower the resistance of the thermistor 214. Therefore, the higher the temperature, the lower the voltage. Buffer 302 outputs a voltage equal to the voltage of thermistor 214. A / D converter 215 converts the voltage value into a digital value. The CPU 208 reads the voltage value converted into the digital value and converts the voltage value into a temperature value.
13, and if it is higher than the desired temperature, the lamp heater 213 is turned off.

The D / A converter 303 is connected to the fluorescent lamp 120
6 generates a voltage for preheating control of the electrodes of
2 is applied to the electrode portion of the fluorescent lamp 1206. The desired preheating voltage value is specified by the CPU 208 as described above. Such preheating at the time of turning off the fluorescent lamp 1206 (hereinafter, referred to as “preheating”)
This is referred to as "standby preheating". ) Is a numerical value different from the preheating voltage value required immediately before lighting, usually a value smaller than the preheating voltage value immediately before lighting.

However, the low temperature detection accuracy of the thermistor 214 is low, and the temperature of the fluorescent lamp is monitored when the fluorescent lamp is turned on in addition to the temperature control of the lamp heater 213.
If abnormal heat generation occurs when the fluorescent lamp 1206 is turned on, the CPU 208 is notified of this. CPU 208
In this case, the lighting of the fluorescent lamp 1206 is stopped for safety reasons. If the fluorescent lamp 1206 is continuously turned on, the temperature of the thermistor 214 may exceed 100 ° C. even during normal reading. Therefore, the thermistor 214 detects a high temperature such as 100 ° C. or 150 ° C. with a certain degree of accuracy. The resistance value of the thermistor 214 decreases as the temperature increases.

Therefore, in the circuit of FIG. 7, in order to ensure the accuracy of the thermistor 214 at high temperature, the resistance 30
1 has a somewhat low resistance value. Conversely, in order to accurately detect a low temperature, the resistance of the resistor 301 is high. Therefore, it is impossible to simultaneously detect the high temperature and the low temperature with one temperature detecting means with high accuracy. If the low-temperature detection accuracy is low, it is determined that the temperature is not low even though the environment is low, and the image is read in a state where infrared rays are generated by warming up in a short time and color reproducibility is deteriorated. Conversely, if the high-temperature detection accuracy is poor, the control temperature of the lamp heater 213 while the fluorescent lamp is turned off is deviated and the mercury distribution state at the start of lighting of the fluorescent lamp 1206 becomes unstable, or the normal reading is performed during continuous lighting of the fluorescent lamp. There is a possibility that the reading operation may be interrupted by determining that the fluorescent lamp is at a high temperature and is in a dangerous state even though the temperature is operable.

FIG. 8 is a flowchart showing warm-up control processing of a fluorescent lamp by the image reading apparatus according to the embodiment of the present invention. This process is executed by the CPU 208.

In FIG. 8, first, the power of the image reading apparatus is turned on (step S1). This allows the CPU
Reference numeral 208 performs initial settings of I / O ports, error checking of devices, and the like.

Next, the following first warm-up process is performed. That is, the lamp heater 213 is energized to set the first temperature of the fluorescent lamp 1 at a first temperature higher than the temperature at the time of normal image reading.
206 is warmed up (step S3), and at the same time, the fluorescent lamp 1206 is fully lit (step S4), and this full lighting is continued until the first warm-up processing period elapses (step S5).

After the elapse of the first warm-up processing period, the gain of the CCD 1010, that is, the gain of the analog image processing unit 221 is adjusted by reading the white plate 1013 (FIG. 2) by the image reading device, and the monochrome image reading permission state is set. (Step S6). The adjustment may not be necessary for some devices.

Next, the following second warm-up process is performed. That is, in step S7, the CPU 208 determines whether or not a black-and-white reading command has been received, and if so, reads an image while keeping the image reading light amount of the fluorescent lamp 1206 as it is (step S8). To read a black and white image with a color image reading CCD, use Green
There is a method of using only the signal as a black and white signal, and a method of using each of the RGB added values as a black and white signal.

If it is determined in step S7 that the CPU 208 has not received the monochrome reading command, the fluorescent lamp 120
6 is switched to the minimum current lighting value (step S
9) This minimum current lighting is continued until the second warm-up processing period elapses. The minimum current lighting means that the fluorescent lamp 1206 is turned on at a minimum current value at which the lamp is normally turned on. During this time, the lamp heater 213 is turned off.
At F, the fluorescent lamp 1206 is warmed up to a second temperature lower than the temperature at the time of normal image reading.

During the second warm-up processing period,
When the CPU 208 receives a new black-and-white image reading command, the CPU 208 reads a black-and-white image while keeping the image reading light amount of the fluorescent lamp 1206 as it is (step S8). Second
Regardless of whether black-and-white image reading has occurred during the warm-up processing period, the end time of the second warm-up processing does not change. Fluorescent light 1206 even during the image reading period
Is considered to be warming up.

After the elapse of the second warm-up processing period, the light amount of the fluorescent lamp 1206 is returned to the image reading light amount and the white plate 1013 is read, whereby the CCD 101 is read.
RGB balance of 0, that is, R of the analog image processing unit 221
The balance of GB is adjusted (step S11). This adjustment may not be necessary for some devices.

After the above processing, the fluorescent lamp 1206 is turned off (step S12), and the predetermined temperature control of the lamp heater 213 is restarted (step S13). By the processing in step S13, the color / monochrome image reading permission state, that is,
A state in which both color image reading and black and white image reading can be accepted is achieved.

In the following step S14, the CPU 208 determines whether or not a color image reading command has been received, and if so, executes the color image reading (step S15).
6 is turned off and the temperature of the lamp heater 213 is kept constant to stand by (step S16), and this processing ends.

According to the process of FIG. 8, the light source is warmed up to the first temperature immediately after the power of the image reading apparatus is turned on (step S1) (step S3), and after the light source is warmed up to the first temperature. Then, the monochrome image reading is executed (step S8), and the heating of the light source is switched to the minimum current lighting to warm up to the second temperature (step S8).
9). As a result, the light source is turned on during the second warm-up period with a smaller current than during normal reading, so that both ends of the fluorescent lamp can be preheated for a short time, and a color image with better read image quality can be read. Becomes After the light source is warmed up to the second temperature, color image reading is performed (step S15), so that the image reading apparatus is turned on (step S15).
1), first warm-up period during which neither color image reading nor black-and-white image reading is performed (steps S3 to S5)
And a second warm-up period (steps S7 to S10) in which a color image is not read but a black-and-white image is read if there is a command. Accordingly, while maintaining the quality of the read image, the monochrome image can be read without waiting for the completion of the warm-up of the light source required for reading the color image.

In the above embodiment, the fluorescent lamp 1206 as a light source for the image reading apparatus is
3, but the present invention can be applied to a light source without the lamp heater 213.

In the above embodiment, the fluorescent lamp 1206 is used as the light source for the image reading apparatus. However, the present invention can be applied to other light sources that are easily affected by the environmental temperature.

[0082]

As described above in detail, according to the image reading apparatus of the first aspect, when the image reading apparatus is powered on, the first warm-up period during which neither color image reading nor black-and-white image reading is performed. A second warm-up period in which monochrome image reading is performed without performing color image reading can be provided. As a result, the completion of warm-up of the light source required for color image reading can be achieved while maintaining the quality of the read image. A black-and-white image can be read without waiting.

According to the image reading apparatus of the third aspect, it is possible to efficiently warm up the light source to the first temperature.

According to the image reading device of the fourth aspect, the light source is turned on with a current larger than that during normal reading during the first warm-up period, so that a black-and-white image can be read in a shorter time.

According to the image reading apparatus of the present invention, since the light source is turned on with a smaller current than during normal reading during the second warm-up period, both ends of the fluorescent lamp can be preheated for a short time. Color image reading with better read image quality is possible.

According to the copying machine of the present invention, a good read image can be obtained both in the case of reading a black-and-white image and in the case of reading a color image. The image can be read quickly without waiting for a long time as described above.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a copying machine according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an image reading device according to an embodiment of the present invention.

FIG. 3 is a fluorescent lamp 120 in the image reading apparatus of FIG.
6 is a perspective view of FIG.

FIG. 4 is a block diagram of a control circuit of the fluorescent lamp 1206 in FIG.

FIG. 5 is a circuit block diagram of an inverter 212 in FIG.

FIG. 6 is a block diagram of a drive circuit 1907 in FIG.

FIG. 7 is a block diagram of a temperature control circuit of the lamp heater 213 and a preheating control circuit of the electrodes of the fluorescent lamp 1206.

FIG. 8 is a flowchart showing a warm-up control process of a fluorescent lamp by the image reading device according to the embodiment of the present invention.

FIG. 9 is a central sectional view of a conventional fluorescent lamp for an image reading device.

FIG. 10 is a partially cutaway side view of the fluorescent lamp 1206 of FIG. 9;

11 is a perspective view of the fluorescent lamp 1206 of FIG.

12 is a graph showing the relationship between the temperature of the coolest part or the mercury vapor pressure of the fluorescent lamp 1206 in FIG. 10 and the luminous efficiency.

FIG. 13 is a block diagram of a light amount control circuit of the fluorescent lamp 1206 in FIG.

14A and 14B are timing charts for explaining the operation of the light amount control circuit. FIG. 14A shows a case where the light amount is appropriate, FIG. 14B shows a case where the current value is large because the light amount is small, and FIG. The case where the current value is reduced is shown.

FIG. 15 shows a fluorescent lamp 120 when the power of the image reading apparatus is turned on.
6 is a graph showing RGB light quantity balance fluctuation of No. 6;

[Explanation of symbols]

 204 Dimming Sensor Substrate 208 CPU 213 Lamp Heater 214 Thermistor 801 Glass Tube 805 Aperture 1001, 1002 Condensing Mirror 1003 Platen Glass 1004 Document 1005 Reading Line 1006, 1007, 1008 Mirror 1009 Lens 1010 CCD 1011 Shielding Plate 1012 Scanner Unit 1201 Light intensity sensor 1206 Fluorescent lamp 1301 Socket

Claims (7)

[Claims] 1. An image reading apparatus comprising: a light source for generating light for irradiating a document; and image reading means for reading a monochrome image and a color image based on the light from the document. A warm-up means for warming up the light source at the time of turning on, and after the warm-up means warms up the light source for a first warm-up period, the image reading means permits the monochrome image reading and the warm-up means Control means for warming up the light source for a second warm-up period, and thereafter controlling the warm-up means so as to permit color image reading by the image reading means. 2. During the first warm-up period, the light source is warmed up to a first temperature, and during the second warm-up period, the light source is warmed up to a second temperature lower than the first temperature. 2. The image reading apparatus according to claim 1, wherein the image reading apparatus warms up to a temperature. 3. The image reading apparatus according to claim 2, wherein the light source includes a heating unit that warms up the light source to the first temperature. 4. The light source according to claim 1, wherein during the first warm-up period, the light source is turned on with a current that is larger than a lighting current of the light source during normal image reading. An image reading device according to claim 1. 5. The light source according to claim 1, wherein, during the second warm-up period, the light source is turned on with a current smaller than a lighting current of the light source during normal image reading. An image reading device according to claim 1. 6. The image reading apparatus according to claim 1, wherein the light source is a fluorescent lamp. 7. A copying machine provided with the image reading device according to claim 1.