JPS62195976A - Original reader - Google Patents

Abstract

PURPOSE:To prevent the elevation in temperature in the device and to reduce the influence of a semiconductor element or the like used in a photoelectric transfer part to the temperature characteristic by providing a heating means for heating a fluorescent lamp, a reference density object and a comparison means for the output of an image sensor, reading the reference density object by the image sensor before an original is read and scanned, and comparing with a reference value to operate the heating means. CONSTITUTION:The reference density object 3 is irradiated by the fluorescent lamp 1 and an image is formed on the image sensor 6 through a 'Celfoc lens(R)' 5. Whether the output of the image sensor 6 at that time is larger or smaller than the reference value of a reference source 9 is compared by a comparator 8. When the out of the image sensor 6 is, for instance, smaller than the reference value, the output of the comparator 8, for instance, a HIGH level is inputted to a CPU 10, a heater power source 12 is controlled and the heater 11 is operated for a fixed time by the timer function of the CPU 10. While the heater 11 operates, the CPU 10 prevents a motor 7 from operating. After the fixed time passes, the operation of the heater 11 is stopped by the CPU 10 to control a motor driving circuit 14 and operate the motor 7 and start a normal original reading and scanning.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a document reading device that scans a document and reads it with an image sensor.

2. Description of the Related Art In general, a document reading device is divided into an optical system and a photoelectric conversion section, and illuminates the document with a fluorescent lamp, an LED array, etc., forms an image on the photoelectric conversion section through an optical lens, and outputs the image as an electrical signal. For models that read documents at a high speed, fluorescent lamps are generally used as illumination lamps.

Conventionally, in such document reading devices, due to the temperature characteristics of fluorescent lamps as shown in Figure 3, when the tube wall temperature of the fluorescent lamps is low (for example, early in the morning in winter), the emitted light from the fluorescent lamps decreases. The magnitude of the luminous flux decreases, which greatly affects the absolute directivity and S/N ratio of the output signal of the read image. In order to prevent this effect, a heater was attached to the fluorescent lamp to keep it at a temperature that would have the least effect.

Problems to be Solved by the Invention However, in the method of attaching a heater to a fluorescent lamp to keep it warm, it is necessary to attach a sensor to detect the temperature of the tube surface of the fluorescent lamp, and thereby control the temperature of the tube surface of the fluorescent lamp to an appropriate temperature. The problem was that it had to be done. Furthermore, hee~
Since the device is constantly controlled and operated, the temperature inside the device increases significantly, which has a problem in that it has a large effect on the temperature characteristics of semiconductor elements used in the photoelectric conversion section.

SUMMARY OF THE INVENTION An object of the present invention is to provide a document reading device that solves the above-mentioned problems by reading a reference density object with an image sensor prior to document reading scanning, comparing it with a reference value, and operating a heating means. It is something.

Means for Solving the Problems In order to solve the above problems, the document reading device of the present invention includes:
a heating means for heating a fluorescent lamp; a comparison means for comparing an output of an image processor obtained by lighting a fluorescent lamp and irradiating a reference density object with a reference density object and a preset reference value prior to document reading scanning; is provided, and when the output of the image sensor is below the reference value, the output of the comparing means does not start the document reading scan, the heating means is operated, and then the document reading scan is started, and the image sensor output is north of the reference value. The apparatus has an operation configuration in which document reading scanning is sometimes started without operating the heating means.

Operation According to the above-mentioned operation configuration, the present invention reads the reference density object with an image sensor prior to document reading scanning, compares it with the reference value, and operates the heating means. The heating means does not need to be operated except when necessary, and the temperature inside the device can be prevented from rising.

Embodiment Hereinafter, a document reading device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of the main parts of a document reading device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 is a fluorescent lamp, a reference density object 3 is provided on an original glass 2, and an original 4 to be read is placed on the scanning direction side.
is placed. 5 is a SELFOC lens, which forms an image on the image sensor 6. 7 is a motor, fluorescent lamp 1,
An integrated SELFOC lens 5 and image sensor 6 is driven in the scanning direction. The output of the image sensor 6 is input to the comparator 8, and the output of the reference source 9, which still has a preset reference value, is also input to the comparator 8. The output of the comparator 8 is input as a control signal to the CPU 1Q, and the output of the GPU lo is used to control the heater power supply 12 that drives the heater 11 of the fluorescent lamp 1, the fluorescent lamp lighting circuit 13 that lights the fluorescent lamp 1, and the motor 1 that drives the motor. Controls the drive circuit 14.

The operation of the document reading device configured as described above will be described below with reference to FIGS. 1 and 2.

FIG. 2 shows a time chart of the main parts of the document reading device according to the embodiment of the present invention (however, only the forward path of document reading scanning is shown). A control signal is input to the light lamp lighting circuit 13 and the fluorescent lamp 1 is turned on. A reference density object 3 is irradiated with a fluorescent lamp 1, and an image is formed on an image sensor 6 through a SELFOC lens 5. A comparator 8 determines whether the output of the image sensor 6 at that time is larger or smaller than the reference value of the reference source 9.
are compared. When the output of the image sensor 6 is smaller than the reference value, the output of the comparator 8 (for example, HIGH level) is inputted to the CPU 10 to control the heater power supply 12,
The heater 11 is operated for a certain period of time by the timer function of cptzo. While the heater 11 is operating, the CPU 10 prevents the motor 7 from operating. Then, after a certain period of time has elapsed, the CPU 10 stops the operation of the heater 11, controls the motor and drive circuit 14, operates the motor end, and starts normal document reading scanning. On the other hand, when the output of the image sensor 6 is larger than the reference value, the output of the comparator 8 (for example, LOW level) is input to the CPU 10, controls the heater power supply 12, and controls the motor drive circuit 14 without operating the heater 11. is controlled, the motor 7 is operated, and normal document reading scanning is immediately started.

Further, as a second embodiment in which the output of the image sensor 6 is smaller than the reference value, the output of the image sensor 6 and the reference value of the reference source 9 are sequentially compared after the signal to start reading the original is input. Since the output of the image sensor 6 is smaller than the reference value in the first comparison, the output of the comparator 8 (for example, HIGH level) is input to the CPU 10, and the operation of the heater 11 is started. By successive comparison, the Nth
When the output of the image sensor 6 becomes larger than the reference value in the second comparison, the output of the comparator 8 becomes LOW level, and the output is input to the CPU 10, which controls the heater power supply 12 and stops the operation of the heater 11. .

Then, the motor drive circuit 14 is also controlled, and the motor 7 is operated to start normal document reading and scanning.

Note that the first operation example is effective when performing document reading and scanning intermittently and continuously, but the second operation example is particularly effective when performing document reading and scanning continuously.

Further, the reference density object 3 may also be used as a reference original for the seeding correction of the fluorescent lamp 1 and the image sensor 6.

As described above, according to this embodiment, the reference density object is read by the image sensor prior to document reading scanning, and the comparison is made with the reference value to operate the heater of the heating means, so that the heating means is operated except when necessary. This is not necessary and can prevent the temperature inside the device from rising.

Effects of the Invention As detailed above, according to the present invention, the reference density object is read by an image sensor prior to document reading scanning, and the heating means is operated by comparing it with the reference value, thereby constantly controlling and operating the heating means. Since the heating means is operated only under the necessary conditions, it is possible to prevent excessive temperature rise inside the device and reduce the effect on the temperature characteristics of the semiconductor elements used in the photoelectric conversion section. be able to.

Further, there is an advantage that unnecessary power is not consumed because the heating means is not operated except when necessary. Furthermore, since the image sensor used to read the document obtains information equivalent to the surface temperature of the fluorescent light, there is no need to install a temperature sensor to detect the surface temperature of the fluorescent light. There is no need for control, and the excellent effect of simplifying both the mechanical and circuit configurations can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the main parts of a document reading apparatus according to an embodiment of the present invention, FIG. 2 is a time chart of the main parts, and FIG. 3 is a characteristic diagram showing the temperature characteristics of a fluorescent lamp. 1...Fluorescent lamp, 3...Reference density object, 6...Image sensor, 7...Motor, 8...Comparator, 9 ...Reference source, 10
...CPU, 11...Heater. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure [rJ 2 Figure 4 Signed vines 2-12 Taisho, hF9 start Yanitare 1-cho--------------------------T-Imagining Gojato b Ticket luck 11 and above, Scoot button - 1 - L - 1
t-metsu 3rd illustration - tool return (0)

Claims (3)

[Claims] (1) A fluorescent lamp that illuminates the original, an image sensor that receives reflected light from the original, a heating unit that heats the fluorescent lamp, a reference density object, and a fluorescent lamp that turns on the fluorescent lamp prior to scanning the original. Comparing means is provided for comparing the output of the image sensor obtained by irradiating the reference density object with a preset reference value, and when the output of the image sensor is less than the reference value, the document is read by the output of the comparing means. The document reading scan is started after the heating means is operated without starting scanning, and when the output of the image sensor is equal to or higher than a reference value, the document reading scan is started without operating the heating means. A document reading device characterized by: (2) The document reading device according to claim 1, wherein the heating means is operated for a certain period of time. (3) The document reading device according to claim 1, wherein the heating means is operated for a period of time until the output of the image sensor matches a preset reference value.