JPH0433463A - Picture reader - Google Patents

Abstract

PURPOSE:To reduce the power consumption of the entire device by revising maximum power consumption of a heater in response to the power consumed by a moving means and a fluorescent lamp. CONSTITUTION:A temperature sensor unit 12 brings a heater ON signal 16 to a low level when a temperature near a fluorescent lamp 3 is higher than a set temperature and brings the signal to a high level when the temperature near the fluorescent lamp 3 is lower than the set temperature. The heater ON signal 16 is given to an input of an AND gate 13 and a signal NORing (not of OR) a motor drive signal 14 and a lamp lighting signal 15 at a NOR gate 14 is inputted to the other input terminal. Thus, when power is consumed by a motor 2 or the fluorescent lamp 3, no heater heating is implemented independently of the tube temperature of the fluorescent lamp 3. Thus, the maximum rating of a regulated DC power supply is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device that reads an image by scanning an original image and photoelectrically converting each pixel.

[Prior Art] Conventionally, a fluorescent lamp whose lamp tube is filled with a mixed gas of mercury and argon has been widely used as a light source for irradiating a document. The reason for this is that this type of fluorescent lamp is inexpensive and has excellent luminous efficiency, but it has a drawback that the amount of light changes depending on the temperature. Particularly in low-temperature odors, the amount of light decreases significantly, so in order to improve this temperature characteristic, it was necessary to warm the fluorescent lamp using a heating wire or the like.

FIG. 5 explains the configuration of such a conventional image reading device. Power supply unit 1 is AClooV-DC
It supplies 5V, DC; +12V, DC24V.

The reading system unit 20 includes a fluorescent lamp 3 and its lighting circuit 4.
, a CCD sensor 9 and a heater 6.
It functions to read the lines by the CCD sensor 9.

The heater 6 generates heat by applying 24 V DC to both ends of a heating resistor, and is disposed to cover the tube wall of the fluorescent lamp 3 to warm the fluorescent tube.

A temperature sensor unit 12 is disposed near the fluorescent tube and generates a heater ON signal 16. The heater ON signal 16 is at a low level when the temperature of the fluorescent tube is above a preset temperature, and is at a high level when the temperature is below the set temperature. This signal is sent to the control terminal of switch 27. Switch 27 is ON when the control signal is at high level;
It turns OFF when it is at low level.

In the end, the heater 6 is turned off when the temperature of the fluorescent tube is higher than a certain set temperature.
F to lower the temperature, and when the temperature is below a certain setting, turn on heater 6.
By turning on the switch and raising the temperature of the fluorescent tube, the temperature of the fluorescent tube is controlled to be close to the set temperature.

The motor 2 moves the reading system unit 20 via a belt 11 along a traveling guide (not shown). The drive power source is +24V, and when a motor drive signal is output from the CPU 24, the switch 26 is turned on and the voltage is 24V.
Power is supplied to the motor 2 to drive it.

The analog image signal output from the CCD sensor 9 is A
The signal is converted into a digital signal by the /D conversion circuit 21, and then subjected to externally designated image processing in the image processing circuit 22, and then output to an external device via the I/F circuit 23.

The CPU 24 is a ROM (read only memory) 2
The operation of the entire apparatus is controlled in accordance with a sequence stored in advance in 5.

[Problems to be Solved by the Invention] As described in the conventional example, by warming a fluorescent lamp using a heater, it was possible to obtain a light source that maintains a stable amount of light regardless of the ambient temperature. However, since the power consumed by the heater is newly required, there is a problem in that the cost of the power supply increases.

[Means for Solving the Problems] In view of the above-mentioned points, the present invention provides a reading means for illuminating a document image using a fluorescent lamp, focusing the reflected light on an image sensor, and converting the reflected light into an electrical signal; A moving means for moving the reading position of the document image, a heating means for heating the fluorescent lamp using a heater, and a maximum power consumption value of the heater according to the amount of power consumed by the moving means and the fluorescent lamp. and control means for changing the.

[Function] In view of the above-mentioned problems, the present invention reduces the power consumption of the entire device by changing the maximum power consumption value of the heater according to the amount of power consumed by the moving means and the fluorescent lamp. This reduces consumption and allows the use of inexpensive power sources.

[Example] Hereinafter, the present invention will be described in detail based on Examples.

EXAMPLE 11-2 FIG. 1 shows a first embodiment of an image reading device to which the present invention is applied.

Power supply unit 1 is AC 100V to DC: 5V, DC
It supplies f12V and DC24V.

DC5V is the power supply for digital circuits, DC ±12v
is a power supply for the A/D conversion circuit. DC 24V is a power source for driving the motor 2, the lighting circuit 4 of the fluorescent lamp 3, and the heater 6.

The reading system unit 20 includes a fluorescent lamp 3 and its lighting circuit 4.
, the CCD sensor 9 and the heater 6, and a certain 1 on the document.
It works by reading the line with a CCD sensor. That is, one line on the original 10 is irradiated with the fluorescent lamp 3, and the reflected light is imaged onto the light receiving element of the CCD sensor 9 via the optical system 8, thereby performing reading.

Furthermore, the reading system unit 20 is placed on the traveling guide (not shown).
is movably arranged and is driven by a motor 2 via a drive belt 11.

Here, the lighting circuit 4 uses the fluorescent lamp 3 based on 24V DC.
It lights up at high frequency. Heater 6 is DC 24V
is applied to both ends of the heating resistor to generate heat and warm the fluorescent tube of the fluorescent lamp 3. The temperature sensor unit 12 is disposed near the fluorescent tube and outputs a heater ON signal 16. The heater ON signal 16 becomes low level when the temperature of the fluorescent tube reaches or exceeds a preset temperature, and becomes high level when the temperature falls below a preset temperature.

The A/D conversion circuit 21 is a circuit that converts an image signal output from the CCD sensor 9 into a digital signal and outputs the digital signal.

The image processing circuit 22 is a circuit that performs image processing on the data output from the A/D conversion circuit 21.

The interface unit 23 is a circuit that transmits and receives data to and from external devices.

The CPU 24 has a ROM (read only memory) 25
The operation of the entire device is controlled according to a sequence stored in advance. The motor drive signal 14 and lamp lighting signal 15 are signals output from the output port of the CPU 24, and both signals are active high. That is, when it is desired to move the motor, the motor drive signal 14 is set to a high level, and similarly, when it is desired to light the fluorescent lamp 3, the lamp lighting signal 15 is set to a high level.

Next, parts showing the features of this embodiment will be explained.

Similar to the conventional example, the temperature sensor unit 12 is connected to the fluorescent lamp 3.
The heater is turned on when the temperature near the tube is higher than the set temperature.
The signal 16 is set to low/high level, and set to high level when the temperature is lower than the set temperature. Heater ON signal 16 is AND
It is connected to the input of the gate 13, and a signal obtained by NORing the motor drive signal 14 and the lamp lighting signal 15 by the NOR gate 14 is input to the other input terminal. With the above configuration, when electric power is consumed by the motor 2 or the fluorescent lamp 3, heating by the heater is not performed regardless of the tube temperature of the fluorescent lamp 3. This is a feature of the first embodiment.

This control method is most effective when the power consumption of the heater 6 is approximately the same as the total power consumption of the motor 2 and the fluorescent lamp 3. For example, motor 2 and fluorescent lamp 3
and the power consumption value during operation of heater 6 is 15 (W), respectively.
), 10 (W), 25 (W) If there is, DC2
The power consumption of the 4V system can always be kept within 25 (W).

FIG. 2 shows a second embodiment of an image reading device to which the present invention is applied.

The features of this embodiment will be explained.

Similar to the conventional example, the temperature sensor unit 12 is connected to the fluorescent lamp 3.
The heater is turned on when the temperature near the tube is higher than the set temperature.
Set the signal to low-high level, and set it to high level when the temperature is lower than the set temperature. Heater ON signal is AND gate 1
3, and the other input terminal receives the motor drive signal 14 and lamp lighting signal 15 through the NAND gate 14.
A signal obtained by performing NAND (notation of logical product) is input. With the above configuration, when the motor 2 is driven and the fluorescent lamp 3 is lit, the heater does not heat regardless of the tube temperature of the fluorescent lamp 3.

This control method is most effective when the power consumption value of the heater 6 is approximately equal to the power consumption value of the motor 2 and the power consumption value of the fluorescent lamp 3. For example, if the power consumption value during operation of the motor 2, fluorescent lamp 3, and heater 6 is approximately 15 (W), the power consumption of the DC 24V system is always 30 (W).
).

FIG. 3 shows a third embodiment of an image reading device to which the present invention is applied.

The features of this embodiment will be explained.

Similar to the conventional example, the temperature sensor unit 12 is connected to the fluorescent lamp 3.
The heater is turned on when the temperature near the tube is higher than the set temperature.
The signal 16 is set to low/high level, and set to high level when the temperature is lower than the set temperature. Heater ON signal 16 is AND
It is connected to the input of the gate 13, and a signal obtained by inverting the lamp lighting signal by the inverter 14 is input to the other input terminal. With the above configuration, when the fluorescent lamp 3 is turned on, heating is not performed by the heater regardless of the tube temperature of the fluorescent lamp 3.

In this control method, the power consumption value of the motor 2 is
It is most effective when the power consumption value is larger than the power consumption value of the heater 6 and approximately equal to the power consumption value of the heater 6. For example, the power consumption values during operation of motor 2, fluorescent lamp 3, and heater 6 are
15 (V1), 10 (1#), 15 CW
), the power consumption of the DC 24V system is always 25
(W) or less.

FIG. 4 shows a fourth embodiment of an image reading device to which the present invention is applied.

The features of this embodiment will be explained.

A feature of this embodiment is that the maximum power consumption value of the heater 6 is changed in stages according to the amount of power consumed by the motor 2 and the fluorescent lamp 3.

Similar to the conventional example, the temperature sensor unit 12 is connected to the fluorescent lamp 3.
The heater is turned on when the temperature near the tube is higher than the set temperature.
The signal 16 is set to low/high level, and set to high level when the temperature is lower than the set temperature. Heater ON signal 16 is connected to a control terminal of switch 28. switch 29
, which controls the heater 31, is turned on when the motor drive signal 14 is at a low level. switch 30
is for controlling the heater 32, and is turned on when the lamp lighting signal 15 is at a low level. With the above configuration, no power is consumed in the heater 1 when the fluorescent lamp is turned on. Furthermore, no power is consumed by the heater 2 while the motor is being driven.

In this control method, the power consumption value when the heater 31 is turned on is almost equal to the power consumption value of the motor 2, and the heater 32
It is most effective when the power consumption value when the fluorescent lamp 3 is turned on is approximately equal to the power consumption value of the fluorescent lamp 3. For example, the power consumption values during operation of the motor 2, fluorescent lamp 3, heater 31, and heater 32 are 15 (W), 10 (W), and 15 (W), respectively.
(W), 10 (W), the power consumption of the DC 24V system can always be kept within 25 (W).

In addition, in the conventional example and the first to fourth embodiments, the temperature control of the fluorescent lamp was all by a control method of turning the heater ON-OFF in order to bring the temperature closer to the set temperature.
For example, a method may be used in which the heater is always turned on. Since the gist of the present invention is to change the maximum value of power consumed by the heater, it can be applied to any temperature control method.

[Effects of the Invention] By implementing the present invention as described above, the maximum rated value of the DC power source can be kept low, and an inexpensive image reading device can be provided.

2 is a block diagram illustrating a second embodiment of an image reading device to which the present invention is applied; FIG. 3 is a block diagram explaining a third embodiment of an image reading device to which the present invention is applied; FIG. 5 is a block diagram illustrating a fourth embodiment of an image reading apparatus to which the present invention is applied, and FIG. 5 is a block diagram illustrating a conventional image reading apparatus.

2...Motor, lO...manuscript, 20... Reading system unit.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram illustrating a first embodiment of an image reading device to which the present invention is applied;

Claims (1)

[Scope of Claims] 1) A reading means for illuminating an original image using a fluorescent lamp, focusing the reflected light on an image sensor and converting it into an electrical signal, and a moving means for moving the reading position of the original image. and a heating means for heating the fluorescent lamp using a heater; and a control means for changing the maximum power consumption value of the heater according to the amount of power consumed by the moving means and the fluorescent lamp. Characteristic image reading device.