JPS58168044A - Original reading device - Google Patents

Abstract

PURPOSE:To shorten rise time of lighting of an original illumination lamp and waiting time of an original reading device, by providing a preheater for keeping temp. of the tube wall of said lamp near that of the stationary lighted state. CONSTITUTION:The periphery of a fluorescent lamp 1 for original illumination is covered with a rubber heater 3 except its aperture part 1a. A thermocouple 4 for temp. detection is installed on the heater 3, and connected to a power supply 6 through a control circuit 5 for turning on and off supply of power to maintain temp. of the tube wall of the lamp 1 near that of a stationary lighting time, thus permitting remarkable cutoff of rise time of lighting of the lamp 1, and also shortening of waiting time of a reading device.

Description

[Detailed description of the invention] (1) Technical field of the invention The present invention relates to an electrophotographic copying machine and a facsimile machine.

The present invention relates to a document reading device such as an optical character reading device, and particularly relates to an improvement of a document irradiation lamp.

(2) Background of the Technology In a document reading device, an electric signal corresponding to the document is obtained from the trap by illuminating the surface of the document from a document irradiation lamp trap and detecting the reflected light.

In such document reading devices, the frequency of use increases,
With the demand for improved usability, etc., it is desired to shorten the document processing time.

(3) Prior Art and Problems Fluorescent tube lamps are often used as document irradiation lamps in document reading devices. Immediately after such a fluorescent tube lamp is turned on, the temperature of the tube wall of the lamp is low, so the amount of light emitted from the lamp is small. After lighting, the amount of light emitted by the lamp increases as the temperature of the tube wall increases, but it takes a few tens of seconds until the steady state 11 is reached. It is not possible to read the original document during the rising time of the lamp, resulting in a waiting time for the reading device, which is an obstacle to shortening the original processing time.

(4) Purpose of the Invention The present invention has been made in view of the above-mentioned drawbacks of the prior art.
An object of the present invention is to provide a document reading device with reduced waiting time tIM.

(5) Structure of the Invention In order to achieve this object, the document reading device according to the present invention is provided with a preheating means for maintaining the tube wall temperature of the document irradiation lamp [t constant] near the tube aim degree when the lamp is constantly lit.

(6) Embodiment of the Invention FIG. 1 is a block diagram of a document irradiation lamp preheating means according to the present invention. An aperture type fluorescent tube 1 for irradiating an original is coated with a reflective film 2 on its inner surface except for the aperture 11 so that light is irradiated only from the aperture 11 in the irradiation direction of the original. A rubber heater 3 covers the periphery of the cylindrical tube wall of the fluorescent tube 1 except for the aperture portion 1m, and the rubber heater 3 is provided with an insulating rubber internal pressure heating resistor (not shown) having high heat retention properties. This rubber heater 3 is provided with a thermocouple 4 for detecting temperature, and a control circuit 5 connected to this thermocouple 4 is used for ON/OFF operation (power supply 6t is connected to the rubber heater 3. Fluorescent light for document irradiation of the document reading device) The steady state sK wall temperature of tube 1 is approximately 50°C.

The temperature of the rubber heater 3 is detected by a thermocouple 4, and if the temperature is below 50°C, the power supply 6 is turned on via the control circuit 5, and when it is above 50°C, the power supply 6 is cut off via the control circuit. Fluorescent tube 1 from K by controlling 3 ON-OFF
It is possible to measure the temperature of the tube wall near the tube wall temperature (50°C) during steady lighting. A graph of the rising state when the fluorescent tube 1 is turned on in such a state is shown by concentrated lines in FIG. 2. The vertical axis is the amount of light emitted by the lamp, and the amount of light emitted in a steady state is taken as 1.

The horizontal axis is the lighting time (seconds), and the measurement is carried out at an ambient temperature of 20°C. In the case of a conventional fluorescent tube (shown by a dotted line), it was possible to shorten K by 1/IOK.

Note that the heating means for the fluorescent tube l is not limited to a rubber heater; a suitable heating resistor may be placed at an appropriate position around the tube wall, or hot air (which may further heat the tube wall) may be used. .

(7) As a friend of the detailed description of the invention, the document reading device according to the present invention is provided with a ninth preheating means for keeping the tube wall temperature of the document irradiation lamp near the tube wall temperature during steady lighting. Ninth, the start-up time when the lamp is turned on can be greatly accelerated, and the waiting time of the reading device can be shortened.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a lamp preheating means for document irradiation according to the present invention, and FIG. 2 is a graph showing a ramp-up pattern II of the lamp. 1... Fluorescent tube, 3... Rubber heater, 4...
・Thermocouple, 5...control circuit. 6...Power supply. Patent applicant Fujitsu Ltd. Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate 1) Yukio Patent attorney Akira Yamaguchi Figure 2

Claims (1)

[Claims] 1. A document reading device equipped with a preheating means for keeping the tube wall temperature of the document irradiation lamp near the tube wall temperature during steady lighting.