JPH02173738A - Exposing device - Google Patents

Abstract

PURPOSE:To recognize time for maintenance before hindrance occurs as an exposing means by comparing a light quantity in the center part of a fluorescent tube with a light quantity in the end part thereof, detecting the deterioration of the fluorescent tube and giving warning. CONSTITUTION:Exposure is performed by the exposing device 13 provided below an exposure part 9. The exposing device 13 is constituted of the fluorescent tube 14 functioning as the exposing means which has the same length as the maximum width of an original and a reflecting shade 15 provided at the back of the tube 14. By detecting the deterioration of the fluorescent tube 14 based on the ratio of the light quantity in the end part of the tube 14 to that in the center part thereof, the warning is given by a warning generation means 36. For example, a service man call sign generator provided on a control panel is taken as the warning generation means 36. Thus, the fluorescent tube is exchanged before the large deterioration occurs in the image quality of an image formed by a copying device or an image read by an original reader.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an exposure device for a document reading device such as a copying machine or a facsimile machine that uses a fluorescent lamp as an exposure means to expose a document or a photoreceptor.

(Prior Art) Conventionally, copying machines and facsimile machines are examples of devices equipped with this type of exposure device. In a copying machine, there is a document exposure means that illuminates the document and guides the reflected light onto the photoconductor to form an image, or a document exposure unit that illuminates the document and guides the reflected light onto the photoconductor to form an image, or the previous ( (The formation of this electrostatic latent image is repeated many times.) A pre-exposure means is provided to eliminate uneven sensitivity of the photoreceptor due to the influence of the formation of the electrostatic latent image. Furthermore, a document reading device such as a facsimile machine has document exposure means for illuminating the document and forming an image of reflected light on a CCD, which is a one-dimensional photoelectric conversion element.

A halogen lamp or a fluorescent tube is used as a specific light source for these exposure means. However, halogen lamps emit a large amount of infrared rays and far infrared rays, so they generate a lot of heat and have the problem of countermeasures against heat generation. That is, in order to prevent the document glass on which the document is placed from breaking due to this heat generation, careful design of air supply and exhaust is required, and the resulting increase in costs has been a problem. In addition, although fluorescent tubes generate less heat than halogen lamps, the amount of light at the end of the fluorescent tube decreases due to the blackening phenomenon that occurs at the end of the fluorescent tube as time passes, and the light amount distribution becomes uniform in the axial direction of the fluorescent tube. There was a durability problem in that the exposure was not uniform due to the lack of brightness. In addition, the degree of progress of this blackening phenomenon varies depending on usage conditions such as the number of times the fluorescent tube flashes and the ambient temperature, and there is also the problem that it is impossible to predict when maintenance such as replacing the fluorescent tube is required. ing.

An object of the present invention is to detect the deterioration of the exposure ability due to the blackening phenomenon of the fluorescent tube, and to determine the timing of maintenance before it becomes a problem as an exposure means, in order to eliminate the above-mentioned problems of an exposure means using a fluorescent tube. An object of the present invention is to provide an exposure apparatus that can notify the user of the following information.

(Means for Solving the Problems) The present invention provides exposure means for illuminating a document and guiding reflected light to a photoconductor or a light receiving element to read the document, or a photoconductor that illuminates the document in a copying machine or a document reading device. A fluorescent tube is provided as an exposure means for pre-exposure to eliminate sensitivity unevenness of the photoreceptor due to the influence of the previous electrostatic latent image formation before forming an electrostatic latent image by forming an image of reflected light, and a first light amount detection means for detecting the light amount at the central portion in the longitudinal direction; a second light amount detection means for detecting the light amount near the filament at the end of the fluorescent tube; and a value detected by the first light amount detection means. The exposure apparatus includes a calculating means for comparing and calculating a value detected by the second light amount detecting means, and a warning generating means for issuing a warning according to the calculation result by the calculating means.

(Function) According to the present invention having the above configuration, the light amount at the longitudinal center portion of the fluorescent tube detected by the first light amount detection means;
The progress of the blackening phenomenon can be easily detected by comparing the light intensity near the filament at the end of the fluorescent tube detected by the second light intensity detection means, and by issuing a warning, the fluorescent tube can be removed. It can notify you when it is time for maintenance such as replacement. This makes it possible to replace the fluorescent tube before the quality of the image formed by the copying device or the image read by the document reading device is significantly degraded.

(Embodiment) An embodiment of the exposure apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a control block diagram of this embodiment, and FIG. 2 shows a facsimile reading device which is a document reading device equipped with the exposure device of this embodiment. The bundle of originals 2 placed on the original placing table 1 is separated one by one from the one below by a friction pad 3 fixed to the original placing table 1 and a half-moon roller 4 that rotates in contact with this friction pad 3. The paper is then fed to the front conveyance roller pair 5.6. Previous conveyance roller pair 5, 6
The originals 2 are fed one by one to an exposure section 9 consisting of a platen glass 7 and an upper guide 8 provided on the platen glass 7 to press down the originals 2. Light is irradiated onto the original 2 located in the exposure section 9 to perform exposure. A rear conveyance roller pair 10.11 having the same circumferential speed as the front conveyance roller pair 5.6 is arranged downstream of the exposure section 9. The paper is ejected upward.

The exposure is performed by an exposure device 13 provided below the exposure section 9.
It is carried out by This exposure device 13 includes a fluorescent tube 14 as an exposure means having the same length as the maximum width of the document;
and a reflective shade 15 provided behind the fluorescent tube 14. Reflected light 16 irradiated and reflected by the original 2
is reflected by the first mirror 17 located directly below the exposure section 9, further reflected by the second mirror 18 and third mirror 19, passes through the shading correction plate 2o, and is transmitted to the imaging lens 21 by the first mirror 21. C as second light amount detection means
Image is formed on CD22.

FIG. 3 shows an expanded state of the optical system shown in FIG. 2. The same parts as in FIG. 2 are given the same numbers. Fluorescent tube 14
There are filaments 23 at both ends. This fluorescent tube 1
4 illuminates the original 2. Let us now consider a case where there is no document 2, and assume that the virtual line of the upper guide 8 is illuminated. The reflected light from this virtual line passes through a shading correction plate 20 having an angle of view θ and an imaging lens 21, and then passes through the CCD 2.
The image is formed on the second light receiving element array 24. The shading correction plate 20 has a shape that allows a larger luminous flux to pass through as the distance from the optical axis 25 increases. This allows co
The shading correction of the imaging lens 21 in which the amount of peripheral light decreases according to the s'θ law, and the correction of the decrease in the amount of light at the end of the fluorescent tube 14 are performed.

As is well known, the C0D 22 converts the image of the original 2 formed on the light receiving element array 24 into an electrical signal. The C0D 22 of this embodiment is a one-dimensional photoelectric conversion element, and as the original 2 moves in the exposure section 9, it can convert the image of the entire surface of the original into an electrical signal. In this conversion, each element generates a charge according to the amount of light incident on each element, and a signal based on the generated charge is stored in a shift register by a shift pulse given by the clock generation circuit 32 (see FIG. 1). The signals are sequentially output by a transfer lock established by the clock generation circuit 32. The output data is input to the A/D conversion circuit 35,
It is converted into a bit digital signal. After being converted, 2
The image data is inputted to a value converting circuit or a well-known dither circuit for reproducing halftone images, and becomes 1 or O image data. If the document reading device is an image scanner, this image data is output to a printer or host computer, but if the document reading device is a facsimile as in this embodiment, the data is compressed and can be output to a public line. Modulate and output as follows.

The first and second light amount detection means in this embodiment utilize a central light receiving element and an end light receiving element inside the C0D 22, which are light receiving elements arranged in a row. The light amount detection operation using the light receiving element of the C0D22 is performed as follows.

That is, when the facsimile, which is a document reading device, is powered on, a sensor (not shown) confirms that the document 2 does not exist in the exposure section 9. If document 2 exists, the front transport roller pair 5.6 or the rear transport roller pair 10.1
1, the original 2 is ejected. In the absence of the original 2, the fluorescent tube 14 is turned on by a lighting circuit (not shown), and after waiting for about 2 seconds until the lighting state is stabilized, the light amount is detected. At this time, the CCD 22 receives reflected light from the upper guide 8, which is painted to a white level equivalent to the white level of the original 2.

After waiting for 2 seconds, the CPU 30 inputs the light amount detection signal to the counter control circuit 31, as shown in FIG. 1, which is a block diagram of this embodiment. The counter control circuit 31 causes the counter A to clock in in synchronization with the first shift pulse given from the clock generation circuit 32 after inputting this light amount detection signal.
Set OD address A and COD address B in counter B. These COD addresses A and B are a point A that is illuminated by the center part of the fluorescent tube 14 and a point B that is illuminated by the end part of the fluorescent tube 14.
These points correspond to the points (see FIG. 3), respectively. After that, these counters A and B subtract each counter A and B by the transfer lock given from the clock generation circuit 32, and when the counter reaches O, each gate A and B is opened, and A of COD address A and B is subtracted. The /D converted values DA and DB are input to the divider 33. The divider 33 receives the A/D converted value D.
The ratio of A and Da, ie, D8/DA, is input to the comparator 34, and the comparator 34 compares /DA with a comparison value of 0.75 (this value will be described later).

In this case, if 0.75≦D I / D A, it is determined that the fluorescent tube 14 has not deteriorated and is turned off to complete the initialization and wait for the next scan.On the other hand, if 0.75>D a
/DA, the warning generating means 36 issues a warning. This warning generating means 36 is, for example, a serviceman call sign generator provided on an operation panel (not shown).

Next, FIGS. 4(a) and 4(b) show the output of C0D22 when detecting the amount of light. In FIG. 4(a), the horizontal axis is C
Take the lengthwise distance (COD address) of CD22,
The output of each light receiving element of C0D22 is plotted on the vertical axis. The solid line indicates the fluorescent tube 14 when it is still new, and the broken line indicates the fluorescent tube 14 after it has been lit for 500 hours. The two sets of graphs indicate the installation environment temperature where the document reading device is installed, respectively, at 25°C and 15°C.
That is. In addition, Fig. 4(b) shows the output of the light receiving element near the center of C0D22 (address A), the horizontal axis shows the time after lighting starts, and each of the four graphs shows the installation environment temperature where the document reading device is installed. It is a changed version of .

As can be seen from FIGS. 4(a) and 4(b) above, the amount of light of the fluorescent tube 14 depends on the environmental temperature (more precisely, the tube wall temperature of the fluorescent tube 14) due to its light emission principle, and the temperature is approximately 38°C. The amount of light is the largest, and therefore, the amount of light changes greatly depending on the temperature of the installation environment where the document reading device is installed and the temperature of the tube wall due to the heat generated by the fluorescent tube 14 itself.

Further, as can be seen from FIG. 4(a), in the initial state, the output of the C0D 22 is substantially flat in its length direction due to the function of the shading correction plate 20. That is, at 25°C, the output value a is flat, and at 15°C, the output value d is flat. On the other hand, after 500 hours of lighting, the amount of light at the end of the fluorescent tube 14 has decreased (see the broken line in the figure). This is because a blackening phenomenon (referred to as an anode spot or end band) occurred at the end of the fluorescent tube 14. In addition, the amount of light in the center area has decreased slightly due to the deterioration of the phosphor due to this blackening phenomenon. In a state where this blackening phenomenon occurs, the output ratio at addresses A and B of the CCD 22, which is the light intensity ratio between the center part and the end part of the fluorescent tube 14, is as follows.
For the fluorescent tube 14 at 25°C, the two ratios are the same value, and -
f We become. This value is constant regardless of the tube wall temperature of the fluorescent tube 14, etc. According to the inventors' measurements, this value ÷ =
When ÷<0.75, the image quality of images formed by the copying device and images read by the reading device begins to be affected. Therefore, the comparison value in FIG. 1 is set at 0.75.

Furthermore, as can be seen from the above explanation, by dividing the value of the light amount at the end of the fluorescent tube 14 by the value of the light amount at the center of the fluorescent tube 14 using the divider 33 as shown in the block diagram of FIG.
Deterioration of the fluorescent tube 14 can be detected without being affected by temperature.

Note that the serviceman call sign does not put the document reading device into a deadlock state, but rather prompts the user to report a maintenance request.

As explained above, according to this embodiment, the fluorescent tube 14 is
By detecting the deterioration of , it is possible to detect the deterioration regardless of the environmental temperature.

Moreover, this means that even if the power is turned off after reading the original 2 in the original reading device and then turned on immediately, and the temperature of the tube wall of the fluorescent tube 14 remains high, the fluorescent lamp 14 will not be correctly It becomes possible to detect the degree of deterioration. Therefore, in the above description, the light amount is detected 2 seconds after the power is turned on and the fluorescent tube 14 is turned on. However, since deterioration of the fluorescent tube 14 can be detected without being affected by temperature, it is possible to detect the amount of light during document reading. The amount of light may be detected between the originals 2 or after reading the originals.

In the above embodiments, a facsimile machine using a moving document reading method in which the document 2 is moved and read as shown in FIG. A mirror scanning type facsimile that moves a mirror that reflects light from a fluorescent tube and irradiates the document while fixed on the document, or a close sensor scanning type facsimile that moves a close sensor and fluorescent light placed close to the document. The present invention can also be implemented in a copying machine. In this case, the reflected light for light intensity detection is not the reflected light from the upper guide 8 as in the above embodiment, but the reflected light from a white plate installed at one end of the document table glass in parallel with the COD, which is the light receiving element. do.

Furthermore, in the above embodiments, the light amount between the center and one end of the fluorescent tube 14 was compared, but in other embodiments, both ends were compared and the ratio of either end was the limit. It is also possible to issue an alarm when the value is exceeded. Since the blackening phenomenon of the fluorescent tube 14 does not proceed evenly at both ends, but may be uneven, deterioration of the fluorescent tube 14 can be detected more reliably in this manner.

Furthermore, in the above embodiment, the light receiving elements at the center and end portions of the C0D 22 were used as the first and second light amount detection means, but in other embodiments, a dedicated sensor may be used instead of the CCD 22. It is possible.

(Effects of the Invention) As is clear from the above description, according to the exposure apparatus of the present invention, deterioration of the fluorescent tube can be detected and a warning can be issued by comparing the light amount at the center and the end of the fluorescent tube. When the user receives this warning, the user can call a service person and carry out maintenance such as replacing the fluorescent light. Moreover, the deterioration of the fluorescent tube can be accurately detected by comparing and calculating the detected light amount, regardless of the tube wall temperature of the fluorescent tube or the installation environment temperature.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram of an embodiment of the exposure apparatus of the present invention, FIG. 2 is a schematic vertical sectional view showing the main parts of a facsimile equipped with the exposure apparatus of the present embodiment, and FIG. 3 is a control block diagram of an embodiment of the exposure apparatus of the present invention. A perspective view showing the unfolded state of the optical system, Figures 4(a) and 4(b) are the third
It is a graph figure showing the output of COD which is a light quantity detection means of a figure. Explanation of symbols 3...Friction pad 2...Document 4...Half-moon roller 5.6...Front conveyance roller pair 7...Platen glass 8...Upper guide 9...
Exposure section 10.11... Rear conveyance roller pair 12... Paper ejection tray 13... Exposure device 14.
...Fluorescent tube (exposure means) 15...Reflector 17.18.19...Mirror 20...Shading correction plate 21...Imaging lens 22...COD (light receiving element, 1st. 2) 33...Divider 34...Comparator 36...
Warning generating means Fig. 4 (0) Fig. 4 Cb) and C in 1

Claims (2)

[Claims] (1) In a copying device or a document reading device, an exposure means for illuminating the document and guiding the reflected light to a photoreceptor or a light receiving element to read the document, or an exposure means for forming an image of the reflected light on the photoreceptor and electrostatically infiltrating the document. A fluorescent tube is provided as an exposure means for pre-exposure to eliminate uneven sensitivity of the photoreceptor due to the influence of the previous electrostatic latent image formation before forming an image, and a second tube is provided to detect the amount of light at the longitudinal center of the fluorescent tube. a first light amount detection means; a second light amount detection means for detecting the light amount near the filament at the end of the fluorescent tube; a value detected by the first light amount detection means; and a value detected by the second light amount detection means. What is claimed is: 1. An exposure apparatus comprising: a computation means for performing a comparison computation between the computation means; and a warning generation means for issuing a warning according to the computation result of the computation means. (2) The exposure apparatus according to claim 1, wherein the calculation means is a division circuit.