JP2502390Y2 - Lighting equipment for exposure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an exposure illumination device used in a copying machine, a document reading device, or the like.

[Prior Art] Conventionally, as an exposure illuminating device in a slit exposure device that illuminates a document to perform slit exposure of the document image, a light source such as a fluorescent lamp that illuminates the document by turning on by energization and a light source of this light source. A light amount detector that detects the light emission amount, compares the output signal of this light amount detector with a predetermined value, and energizes the light source so that the light emission amount of the light source becomes a predetermined light amount according to the comparison result. A device having a light amount control means for controlling is known from JP-A-60-179729.

[Problems to be solved by the device]

In the above-mentioned document illuminating device, the light amount control means compares the output signal of the light amount detector with a predetermined value and controls the energization of the light source so that the light emission amount of the light source becomes a predetermined light amount based on the comparison result. However, when a light source such as a fluorescent lamp is used for a long period of time, it deteriorates or stains to reduce the light emitting ability, and the rate of the reduction varies depending on the location. . Particularly, in a fluorescent lamp, when the light emission amount of a portion whose light emission amount is detected by the light amount detector is lower than the light emission amount of other portions, scumming occurs on a copied image, which causes cleaning failure of the cleaning device. Will be generated and cause a great deal of damage to the machine.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the above-mentioned drawbacks and to provide an exposure illuminating device capable of preventing the background stain of a copied image without reducing the light amount of the document illumination below the set light amount in all places.

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention is an exposure illuminating device in a slit exposure device for illuminating a document to perform slit exposure of the document image, the light source illuminating the document by energizing to illuminate the document, and the slit exposure. A plurality of light amount detectors that are arranged side by side in the longitudinal direction of the slits of the device to detect the light emission amount of the light source, and the light source is energized by the output signal of the light amount detector that detects the lowest light amount among the plurality of light amount detectors. And a light quantity control means for controlling the light quantity of the light source to be a predetermined light quantity.

[Action]

The light source is turned on by energization to illuminate the document, and the plurality of light amount detectors detect the light emission amount of the light source. Then, the light amount control means controls the energization to the light source so that the light amount of the light source becomes a predetermined light amount by the output signal of the one having detected the lowest light amount among the plurality of light amount detectors.

〔Example〕

 FIG. 2 shows an example of a copying machine to which the present invention is applied.

The automatic document feeder 11 conveys the originals 13 set on the original table 12 by the user one by one by a conveying system and sets them on the original table 14 at a predetermined position. The document on the document table 14 is illuminated by a light source composed of two fluorescent lamps 15 and 16,
The original image is the first mirror 17, the second mirror 18, the third mirror 1.
The image is projected onto the photosensitive drum 22 through the lens 20, the fourth mirror 21, and the slit of the slit plate (not shown). light source
15, 16 and the first scanner 23 including the first mirror 17 and the second scanner 24 including the second mirror 18 and the third mirror 19 are moved at a speed ratio of 2: 1 by a driving device (not shown) to copy the original. Scanning is performed, and the entire original image is slit-exposed on the photosensitive drum 22. The light sources 15 and 16, the first mirror 17, the second mirror 18, the third mirror 19, the lens 20, the fourth mirror 21, the first scanner 23, and the second scanner 24 constitute a slit exposure device.

The photoconductor drum 22 is rotationally driven by a motor and uniformly charged by the corona discharger 25 for charging, and then the eraser 26
As a result, the image non-forming area is discharged, and an electrostatic latent image is formed by projecting the original image by the exposure device. This electrostatic latent image is developed by the developing device 27 and becomes a visible image.

On the other hand, the transfer paper 30 is separated one by one from the selected one of the paper feeding devices 28 and 29 and sequentially supplied, and is transported by the transport system 31 and is transferred onto the photosensitive drum 22 by the transfer corona discharger 32. After the visible image is transferred, it is separated from the photoconductor drum 22 by the separation corona discharger 33 and the separation claw 34. This transfer paper is conveyed by the conveyor belt 35, the visible image is fixed by the fixing device 36, and is ejected to the paper ejection tray 37 as it is in the single-sided copy mode. The photoconductor drum 22 is cleaned by the cleaning device 10 after the transfer paper is separated, and the static eliminator 52 is removed.
To eliminate the charge, and prepare for the next copying operation.

Further, in the automatic double-sided copy mode, the original is conveyed from the original table 12 and set at a predetermined position on the original table 14 and then the surface is copied on the surface of the transfer paper as described above and then conveyed by the conveying system. Then, the front and back are reversed by the document reversing unit 38 and the document is set at a predetermined position on the document mounting table 14. At this time, the transfer paper whose surface has been copied exits from the fixing device 36, and then the transfer paper reversing unit 39 reverses the front and back of the transfer paper and discharges it to the double-sided tray 40. Then, the transfer paper is fed from the double-sided tray 40, and the original placing table is placed on the back surface of the transfer paper as in the case of the above-mentioned front side copying.
14 The back side of the original document is transferred and the transfer paper is
Discharged to 37.

FIG. 1 shows a part of the exposure apparatus, and FIG. 4 shows a circuit configuration of the exposure illumination apparatus.

The apertures of the fluorescent lamps 15 and 16 serving as exposure light sources are directed toward the document illumination position 41 on the document mounting table 14, and are driven by the outputs of the ballasts 42 and 43. The light amount detectors 44 and 45 directly detect the light emission amounts of the fluorescent parts of the fluorescent lamps 15 and 16, respectively. As shown in FIG. 6, the light amount detectors 44 include, for example, three light amount detectors 44a and 44b, It consists of 44c. These three light quantity detectors 44a, 44b, 44c are arranged in parallel in the tube longitudinal direction of the fluorescent lamp 15 (the slit longitudinal direction of the slit exposure device) so as to face both ends and the central portion of the fluorescent lamp 15. The amounts of light emitted from both ends and the center of the light 15 are directly detected. Similarly, the light quantity detectors 45 are three light quantity detectors 45a arranged in parallel in the tube longitudinal direction of the fluorescent lamp 16 (the slit longitudinal direction of the slit exposure device) so as to face both ends and the central portion of the fluorescent lamp 16. , 45b, 45c,
The amounts of light emitted from both ends and the center of the fluorescent lamp 16 are directly detected. Light intensity detectors 44a, 44b, 44c and light intensity detectors 45a, 45b, 45c
The greater the number of each, the better. Light intensity detectors 44a, 44b,
The output signals of 44c, 45a, 45b, and 45c are analog / digital converted by the analog / digital converter 53.
It is input to the microcomputer including the ROM 48, the RAM 49 and the interface 50. As shown in FIG. 7, this microcomputer turns on the fluorescent lamps 15 and 16 which are exposure lamps through the dimming control unit 46 and the ballasts 42 and 43, and then 3
From the input signals a, b, c input from the individual light intensity detectors 44a, 44b, 44c via the analog / digital converter 53, the output signal of the lowest level among them (light intensity detectors 44a, 44b, 44c)
Output signal (which has detected the lowest amount of light), and outputs it to the dimming controller 46 as a first selection signal.
Of three light intensity detectors 45a, 45b, 45c
From the input signal a, b, c input from the analog / digital converter 53 from the output signal of the lowest level among them (the output of the one detecting the lowest light amount among the light amount detectors 45a, 45b, 45c) Signal) and outputs it to the dimming controller 46 as a second selection signal. Then, the dimming control unit 46 sets each energization pulse width of the fluorescent lamps 15 and 16 by the first selection signal and the second selection signal from the microcomputer, and sets the dimming control unit 46 and the ballasts 42 and 43. After turning off the fluorescent lamps 15 and 16 via them, the copy mode is set. Then, the dimming control unit 46 compares the first selection signal and the second selection signal with a predetermined comparison value and controls the ballasts 42 and 43 with the error signals, respectively, so that the fluorescent lamps 15 and 16 are controlled.
So that the light intensity of
3 is controlled to control the light amount of the fluorescent lamps 15 and 16. in this case,
The dimming control unit 46 sets the duty ratio t / T ₀ according to the error signal.
By turning ballasts 42 and 43 on / off with
A high frequency output signal having a duty ratio t / T ₀ as shown in FIG. 5 is output from 2,43 to the fluorescent lamps 15,16 to control the light amount of the fluorescent lamps 15,16. Since the light-emitting ability of the fluorescent lamps 15, 16 decreases as the usage period becomes longer, the dimming control unit 46 raises the duty ratio t / T ₀ by the amount of the decrease, and the amount of light emitted by the fluorescent lamps 15, 16 increases. Will be kept constant. Further, the microcomputer selects the output signal of the one having the lowest light intensity among the light intensity detectors 44a, 44b, 44c, and the light intensity detector 45
The output signal of the one that detected the lowest light amount among a, 45b, and 45c is selected. Therefore, in the fluorescent lamps 15 and 16, the duty ratio t / T ₀ becomes higher as the usage period becomes longer, the amount of electricity to the fluorescent lamps 15 and 16 increases, and the light amount control of the fluorescent lamps 15 and 16 is performed. Is performed so that the light emission amount in the place where the light emission amount is the lowest reaches a predetermined light amount set value. As a result, the light amount of the original document illumination does not drop below the predetermined light amount setting value in all places, and problems such as background smearing of copied images and poor cleaning of the cleaning device do not occur. Fluorescent lamps 15 and 16 have a reduced light emission capacity over a long period of use, and the rate of decrease varies depending on the location.The amount of light emitted from the fluorescent lamps 15 and 16 with the highest amount of light emission is set to a predetermined amount. Higher than the value,
This is the extent that the halftone density of the copied image becomes light,
It does not cause a serious problem such as a background stain on the copied image or a cleaning failure of the cleaning device.

In the above exposure apparatus, as shown in FIG. 3, one fluorescent lamp 15 and one reflector 51 may be used as the light source, and one set of the ballast 42 and the light quantity detector 44 may be used.

[Effect of device]

As described above, according to the present invention, there is provided an exposure illumination device in a slit exposure device for illuminating a document to perform slit exposure of the document image, the light source illuminating the document by energizing the document and the slit exposure device. Of a plurality of light amount detectors arranged in parallel in the slit longitudinal direction to detect the light emission amount of the light source, and the light source is energized by an output signal of the one detecting the lowest light amount among the plurality of light amount detectors. Since the light amount control means for controlling the light amount of the light source to a predetermined light amount is provided, the light amount of the document illumination does not fall below the predetermined set light amount in all places, and the background stain of the copy image and the cleaning of the cleaning device are performed. Defects such as defects will not occur.

[Brief description of drawings]

FIG. 1 is a schematic view showing a part of an exposure apparatus in an example of a copying machine to which the present invention is applied, FIG. 2 is a sectional view showing the same copying machine, and FIG. 3 is another copying machine to which the present invention is applied. FIG. 4 is a schematic diagram showing a part of an exposure apparatus in an example, FIG. 4 is a block diagram showing an exposure illumination apparatus in the above copying machine, and FIG. 5 is a waveform diagram showing a conduction waveform of a light source in the exposure illumination apparatus.
The figure is a side view showing the fluorescent lamp and the light amount detector of the copying machine,
FIG. 7 is a flow chart showing the processing flow of the microcomputer in the above-mentioned exposure illumination device. 15,16 ...... Fluorescent lamp, 42,43 ...... Light intensity detector, 46 ...... Dimming control section, 47 to 50 ...... Microcomputer.

Claims (1)

(57) [Scope of utility model registration request] 1. An exposure illumination device in a slit exposure device for illuminating a document to perform slit exposure of a document image, the light source illuminating the document by energizing to illuminate the document, and a slit longitudinal direction of the slit exposure device. A plurality of light amount detectors arranged in parallel to detect the light emission amount of the light source, and the light amount of the light source is supplied to the light source by energizing the light source by the output signal of the one detecting the lowest light amount of the plurality of light amount detectors. An illumination device for exposure, comprising: a light amount control means for controlling the light amount to a predetermined amount.