JPS63235923A - Cooling device for projector of image reader - Google Patents

Abstract

PURPOSE:To prevent the quantity of light from decreasing owing to overcooling by controlling a voltage applied to the driving motor for a fan for cooling a light source so that the voltage is high when the quantity of light of the light source is large or low when said quantity is small. CONSTITUTION:A signal generation part 20 sends out a light quantity control signal for a halogen lamp 8 according to the overexposure or underexposure of a film original. This signal is sent to a 1st power source part 17A and a 2nd power source part 17B and when the film original is overexposed, the output voltage is so controlled as to rotate fans 15 and 16 speedily according to the indication of the signal while the light quantity of the halogen lamp 8 is increased. Further, when the film original is underexposed, the output voltage is so controlled as to rotate the fans 15 and 16 slowly while the light quantity of the halogen lamp 8 is lowered. Consequently, even when the light quantity of the light source is lowered and light is projected on the film original for a long time, the light quantity of the light source is prevented from decreasing.

Description

Detailed Description of the Invention A. Purpose of the Invention [Field of Industrial Application] The present invention is an image reading device incorporated into a facsimile machine, an electrophotographic copying machine, etc., which is particularly capable of reading an image of a film original using transmitted light. The present invention relates to a cooling device for suppressing a rise in temperature of a light source of a projector in an image reading device.

[Conventional technology]

FIG. 3 is a front view showing the overall configuration of a dual-purpose image reading device that can read a projected image of a film original projected by a projector in addition to reading a reflected image from a normal original.

In the figure, reference numeral 1 denotes an original platen glass on which a normal reflective original is placed, 2 a light source lamp that illuminates the image surface of the original on the original platen glass l, and 3 a photoelectric conversion element array such as CCII that converts the reflected image of the original. This is a lens for forming an image on the image sensor 4 consisting of.

A projector 6 for projecting a film original is attached to the upper side of the machine box 5 equipped with the reflection image reading unit.

The projector 6 includes a transparent document holding frame 7 such as a color negative film, a halogen lamp 8 as a projection light source, a reflecting mirror 9, a condenser lens 10, a color balance correction filter 11, and a projected image on the document table glass l. It is equipped with a projection lens 12 that allows

A reflecting mirror 13 that refracts the optical path passing through the projection lens 12 perpendicularly to the surface of the document table glass 1 is arranged above the document table glass l, and below the mirror 13, the light beam is converted into a parallel light beam onto the upper surface of the document table glass l. A Fresnel lens 14 is placed in close contact with the lens for converting the image into . The surface of the Fresnel lens 14 that is in contact with the document table glass l is subjected to light diffusion treatment.

The output from the image sensor 4 that reads the projected image of the film original is A/D converted and converted into approximately 8-bit RGB data.
This is output as digital data and supplied to the image forming unit.

The projector 6 includes a cooling fan 15 for dissipating the heat of the halogen lamp 8, and a fan 16 for cooling the film original, filter 11, etc.

Note that one cooling fan 15 and 16 may be used in common. The cooling fans 15-16 are driven by motors.

In the figure, 17 is a halogen lamp 8 and a cooling fan 15.1
6, which is built into the projector 6. Reference numeral 18 represents a power outlet, and reference numeral 19 represents a power on/off switch.

[Problem that the invention seeks to solve]

When a film original, particularly a color negative film, is used as an original, it is often desired to obtain a reproduced image even if the film is slightly out of proper exposure.

Therefore, the image reading device detects the condition of the film original and issues a light amount control signal to increase the light amount of the halogen lamp 8 when the negative film is overexposed, and to decrease the light amount of the halogen lamp when the negative film is underexposed. The power supply voltage of the halogen lamp is controlled to lower the voltage.

However, when the light intensity of the halogen lamp is increased, the temperature of the inner wall of the projector case reaches over 200°C due to the high heat generated by the lamp, so a powerful cooling fan is required.

However, if a powerful cooling fan is installed to suppress overheating when the light intensity of the halogen lamp is increased as described above, when the halogen lamp is turned on with a reduced light intensity, the cooling fan's air volume remains constant. Otherwise, the halogen lamp will generate less heat and the temperature of the lamp tube wall will drop too much.

As a result, the halogen cycle no longer works properly, causing black halogen compounds to adhere to the inner surface of the tube wall of the lamp, resulting in an extremely low amount of light.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of the reduction in light intensity caused by supercooling that occurs in the light source lamp of a projector that projects a film original onto an image reading device.

SUMMARY OF THE INVENTION [Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention allows an image sensor of an image reading device to read an image of a film original using transmitted light. In a projector that turns on the light source for projecting film originals at a voltage specified by a light intensity control signal emitted by the projector, the voltage applied to the drive motor of the light source cooling fan is set high when the light intensity of the light source is high and low when the light intensity is low. This is a cooling device for a projector in an image reading device, characterized in that the cooling device is configured to control the projector so that

[For production]

When the light intensity of the light source increases due to the light intensity control signal emitted by the image reading device after detecting the state of the film original, the rotation speed of the light source cooling fan increases, and when the light intensity of the light source decreases due to the light intensity control signal, the light source The rotation speed of the cooling fan becomes slow.

〔Example〕

Embodiments of the cooling device of the present invention will be described according to the drawings.

FIG. 1 is an electrical circuit diagram of the cooling device of the present invention, in which a power supply unit 17 is a first power supply section 17 for a halogen lamp 8.
A and a second power supply unit 17B for the cooling fans 15 and 16
and separately. And each power supply section 17A-17B
is connected to the light amount control signal generating section 20. The signal generator 20 generates a light amount control signal for the halogen lamp 8 depending on whether the film document is overexposed or underexposed.

The signal is simultaneously transmitted to the first power supply section 17A and the second power supply section 17B, and when the film original is overexposed, the signal increases the light intensity of the halogen lamp 8 and at the same time causes the fans 15 and 16 to rotate strongly. to control the output voltage.

Further, when the film original is underexposed, the output voltage is controlled so as to reduce the light intensity of the halogen lamp 8 and at the same time weaken the rotation of the fans 15 and 16 (see the input/output characteristics diagram in FIG. 2).

Of the two fans 15-16, the voltage applied to the motor of the fan 16 that cools the film original and the filter 11 may be fixed.

In the embodiment, the rated voltage of the halogen lamp 8 and the rated voltage of the drive motors of the cooling fans 15 and 16 are different, so separate power supply sections 17A-17B are required, but if the rated voltages of both are the same, , one power supply unit can be shared.

The optimal control means in the illustrated embodiment is that when an instruction signal is issued to cause the first power supply unit to output the same voltage as the rated voltage of the halogen lamp, the output voltage of the second power supply unit is
When the first power supply section outputs a voltage that is approximately equal to the upper limit of the rated voltage of the fan motor and the same as the lower limit voltage that lights up the halogen lamp, the output voltage of the second power supply section should be set to approximately equal to the upper limit of the rated voltage of the fan motor. It is preferable to control the voltage to be approximately equal to the lower limit of the rated voltage of the motor.

C. As described in detail of the invention, when the amount of light from the light source for projecting film originals is large, the voltage applied to the drive motor of the light source cooling fan is increased, and when the amount of light from the light source is small, the voltage applied to the drive motor of the fan is increased. By controlling the applied voltage of the drive motor to a low level,
Even if a film original is projected for a long time by reducing the light intensity of the light source, the reduction in the light intensity of the light source can be prevented.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of a projector cooling device of the present invention, FIG. 2 is an input/output characteristic diagram of a power supply section, and FIG. 3 is a front view illustrating the schematic configuration of a conventional image reading device with a projector. 4 is an image sensor, 5 is a machine box, 6 is a projector, 7
1 is a transparent document holding frame, 8 is a light source, 12 is a projection lens, 13
14 is a reflecting mirror, 14 is a Fresnel lens, 15 and 16 are cooling fans, 17 is a power supply unit, 17A is a first power supply section, 17
B is a second power supply section, and 20 is a light amount control signal generation section.

Claims (2)

[Claims] (1) Light source cooling in a projector that causes an image sensor of an image reading device to read the image of a film original using transmitted light, and turns on a light source for projecting the film original at a voltage instructed by a light amount control signal emitted by the image reading device. A cooling device for a projector in an image reading device, characterized in that the voltage applied to a drive motor of a fan is controlled such that it is high when the amount of light from a light source is large and is low when the amount of light is small. (2) The light source for projecting a film original is a halogen lamp, and has a first power supply section for the halogen lamp and a second power supply section for the fan motor, and the first power supply section supplies the same voltage as the rated voltage of the halogen lamp. When the instruction signal to output the halogen lamp is output, the output voltage of the second power supply section is set to be approximately equal to the upper limit of the rated voltage of the fan motor, and the voltage that is the same as the lower limit voltage for lighting the halogen lamp is set at the first power supply section. When the instruction signal to output is output, the output voltage of the second power supply section is controlled to be approximately equal to the lower limit of the rated voltage of the fan motor. Cooling system.