JPH04240630A - Illuminating device for image forming device - Google Patents

Abstract

PURPOSE:To maintain a halogen cycle and to restrain the temperature rise of a contact glass by changing the air quantity of an air blowing means in accordance with the driving situation of a halogen lamp. CONSTITUTION:A halogen lamp controller 602 for turning on light emitting lamps L101-L107 and L201-L206 and a fan driving circuit 603 for driving an illumination cooling fan 115 are connected to a central processing unit 601. The light emitting lamps L101-L107 and L201-L206 are controlled so that illumination distribution required under all the conditions such as the state of an original may be obtained and the air blasting/quantity of the air blowing means 115 is switched in accordance with different heating energy based on the driving situation of the lamp.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination device used in a scanner in an image forming apparatus such as a copying machine.

0002

2. Description of the Related Art In a copying machine, a lamp with high optical power is used as an illumination device to illuminate a document. The heat generated by the light-emitting lamp in this lighting device is large, and in particular, color copying machines that use halogen lamps for exposure processing require a large amount of light, and the heat generated energy must be even larger. , an appropriate amount of exposure cannot be obtained depending on the sensitivity characteristics of the photoreceptor and the spectral transmittance of the color separation filter. Therefore, it may be possible to reduce the heat generation energy of the light-emitting lamp by slowing down the linear speed of the photoreceptor and reducing the amount of light exposure, but this will slow down the copying speed per sheet and increase the amount of light per unit time. Since the number of copies is also reduced, the copying efficiency is reduced.

[0003] Furthermore, a cooling fan is mounted on the travel unit to cool the light emitting lamp (for example,
(Disclosed in Japanese Utility Model Application Publication No. 109157/1983). In this case, if you increase the cooling capacity of the cooling fan and make the cooling air stronger, toner and dust from inside and outside the machine will be more likely to float, and they will adhere to the photoconductor, contact glass, lens system, mirror system, etc. This will have an adverse effect on the copied image. For this reason, it is not desirable to rapidly reduce the heat generation energy (power) of the light emitting lamp. Therefore, in a color copying machine, in order to obtain an appropriate amount of exposure depending on the sensitivity of the photoreceptor and the spectral transmittance of the color separation filter, the light emitting lamp must be able to vary the lamp power over a wide range, and a sufficient range of light amount can be obtained. It is necessary to have it.

0004

[Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, when the light-emitting lamp has a wide range of lamp power, the heat generation energy of the light-emitting lamp also changes. Due to the temperature of the tube wall of the halogen lamp bulb, the halogen cycle does not work properly, making blackening and filament melting more likely. As a result, the lifespan of halogen lamps is significantly shortened, requiring frequent parts replacement and service life.
A problem arises in that service costs are also required.

The present invention has been made in view of the above, and an object of the present invention is to maintain the halogen cycle of the lamp and to suppress the rise in temperature of the contact glass.

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a light-emitting lamp that is composed of a plurality of lamps and that illuminates a reading section of an original, and a light-emitting lamp that reflects light from the light-emitting lamp toward the original. In an illumination device for an image forming apparatus, the illumination device includes a reflector and a mirror mechanism that reflects reflected light from the reading unit to an optical system, and in which the light emitting lamp and the mirror mechanism are mounted on a conveyance member and moved relative to the document. A blowing means disposed near one end of a moving range of the conveying member to cool each of the reflecting plates, and a control means for varying the amount of air blown by the blowing means in accordance with the driving status of the light emitting lamp. An illumination device for an image forming apparatus is provided.

[0007]

[Operation] In the lighting device for an image forming apparatus according to the present invention, the amount of air blown by the air blowing means is switched in accordance with the heat generation energy, which varies depending on the driving status of the light emitting lamp. Therefore, the light-emitting lamp is always maintained properly, reducing abnormal images, filament breakage, etc. caused by uneven light distribution and exposure distribution on the document surface due to lamp blackening.
It is possible to extend the lifespan and reduce the number of parts replaced.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an illumination device according to the present invention and a color copying machine employing the same. Figure 1
As shown in the figure, the color copying machine is equipped with contact glass 1.
16, a mirror member 102 that reflects light reflected from the document toward the exposure position, a lens carriage 103 holding a projection lens, a color separation filter 104 as color separation means, A photosensitive drum 105 that is exposed to light through a projection lens and a color separation filter 104, a black developer 106 for developing colors corresponding to black in color separation, and developing each color other than black, such as green, blue, and red. color phenomenon device 107,
An electric charge remover 108, a photoconductor cleaning device 109 for removing residual toner on the surface of the transferred photoconductor, a transfer drum device 110 around which a transfer sheet (plain paper for recording, etc.) is wrapped, and a transferred recording paper. a fixing device 111 for fixing a toner image on a toner image, and a paper feeding device 112 for supplying specified sheets of paper one by one to the transfer drum device 110.
, a control unit 113 for controlling various driving members such as motors and solenoids, and the lighting device 101, etc., a power supply unit 114 for supplying power to each member and circuit, and cooling the lamp and contact glass of the lighting device 101. A lighting cooling fan 115 and the like are provided for this purpose.

FIG. 2 is a plan view showing the main parts of the lighting device, FIG. 3 is a side sectional view of the lighting device shown in FIG. 2, and FIG. 4 is a side view of the lighting device shown in FIG. 2. A light emitting lamp 201, a main reflector 202, and an opposing reflector 2 are provided at a portion facing the original.
03, a first mirror 301 is provided facing the contact glass 116. As shown in FIG. 2, a plurality of light emitting lamps 201 arranged in a horizontal row are
An opening 30 provided between the elliptic curved main reflector 202 located at the bottom of the main reflector 202 and the upper reflector 302 located above
3 so that its axis is parallel to the optical scanning direction, and the light emitting portion is positioned at each focal plane of the main reflecting plate 202 and the upper reflecting plate 302. In the light from the light emitting lamp 201, the reflected light from the main reflecting plate 202 directly reaches the slit-shaped irradiation part 304 on the contact glass 116, but the reflected light from the upper reflecting plate 302 reaches the tip of the main reflecting plate 202. Opposite reflective plate 305 formed
The upper reflecting plate 302 is also shaped into an elliptic curve so that the light is reflected by the light and reaches the slit-shaped irradiation section 304.

Incidentally, the reflected light from the original on the contact glass 116 passes through a slit 216 provided in a stepped portion between the main reflecting plate 202 and the opposing reflecting plate 203, and passes through the plate spring 3.
The photoreceptor drum 1 is guided to the lens system through the first mirror fixed by the photoreceptor drum 1
05. Further, 203 is a light shielding plate;
04 is an illuminance correction plate, which is attached to the scanner main body 205 together with the main reflection plate 202, the opposite reflection plate 305, and the upper reflection plate 302.
(conveying member) with a set screw 206. Furthermore, 207 is a scanner guide rod, 208 is a side reflection plate, 209 is a lamp power supply cable, 210 is a guide rail, 211 is a printed circuit board for fixing the light emitting lamp 201, and 212 is a lighting unit support.

FIG. 5 is a plan view of a printed circuit board for an illumination lamp. In this embodiment, the light emitting lamps 201 are arranged in a horizontal line on a printed circuit board 211 for illumination lamps as shown in FIG.
Insert and connect the lamp pin terminal 213 into the pin connection hole 502 on the printed circuit 501 of No. 1, and fix the main reflector 202 with the fixing screw 206 so that it is fixed by soldering or the like.
The illumination unit support 212 is fixed to the illumination unit support 212 via a spacer 214 with stepped screws 215 so that the axis of the light emitting lamp is parallel to the optical scanning direction.

The light-emitting lamp 201, as shown in FIG.
Light-emitting lamps L101, L102, L103, L105 are placed at intervals A, B, and C in symmetrical positions centering on the light-emitting lamp L104, which is fixed in alignment with the optical axis XX.
A group of light-emitting lamps consisting of L106 and L107 are arranged at intervals a, b, and symmetrical with respect to the optical axis X-X, respectively.
L201, L202, L203 placed at each position of c,
It is composed of two groups of light emitting lamps, one group consisting of L204, L205, and L206.

FIG. 6 is a circuit diagram showing details of a control device for driving two groups of light emitting lamps. A CPU (central processing unit) 601 that executes various processes according to preset programs includes a halogen lamp control device 602 for lighting the light-emitting lamps L101 to L107 and L201 to L206, and a halogen lamp control device 602 for driving the lighting cooling fan 115. A fan drive circuit 603 is connected thereto. In this way, the light emitting lamps L are arranged so as to obtain the required illumination distribution under all conditions. For details of this control configuration, see, for example, Japanese Patent Application No. 61-42998.
There is a description in the issue.

W(
An example of the number of watts is as follows. That is, L
101, L104, L107 are 40W, L102, L1
03, L105, L106, L202-L205 is 50
W, L201, and L206 are 60W. The W number of each group is 320W for the L1 halogen lamp group,
The L2 halogen lamp group is 320W, for a total of 64
It becomes 0W. The lamp spacing of each group is as shown in Figure 2.
Left and right with respect to the optical axis X-X, L1 group A = 52mm
, B = 106 mm, C = 153 mm, and L2
The group is a=29mm, b=93mm, c=140mm
are arranged at intervals of By arranging as described above, a light distribution on the document surface as shown in characteristic b in FIG. 7 can be obtained, and by doing so, as shown in characteristic b in FIG.
A flat exposure distribution with little unevenness in illuminance can be obtained even on the surface of the photoreceptor drum.

The numerical values of the graph shown in characteristic b in FIG. 7 are shown in a table as shown in FIG. In the lamp arrangement according to the present invention, as shown in FIG. 10, the light-emitting lamps L104 belonging to the L1 group are arranged on the optical axis XX, and two light-emitting lamps are arranged on each side of the light-emitting lamps L104. By doing this, an appropriate light distribution on the document surface can be obtained regardless of whether halogen lamp group L1 is lit, L2 is lit, or both L1 and L2 are lit. .

Here, the halogen lamp group L1 is set to 85V,
When lit at 320W, the current consumption is 3.76A. Similarly, when the halogen lamp group L2 is turned on at V and 320W, the current consumption is also 3.76A, and the total current consumption is 7.52A. In a conventional lamp configuration using only one lamp, if an 85V, 640W halogen lamp is required (for example, a single lamp requires a lamp power of 320W), it is necessary to change the voltage applied to the lamp. The applied voltage V1 in this case is as follows. That is, V
1 = (W/W0)1/k ×V0, and by substituting numerical values into this formula, V1 = (320/640)1/
1.54×85≒56.5V, R0 =V0 2 /W
0 = 852/640≈51.29Ω, where W is the required lamp power, W0 is the rated lamp power, V0 is the rated lamp voltage, and k is a constant (1.54). In order to make a conventional single lamp 85V, 640W require lamp power of 320W, when the applied voltage is set to 56.5V, the current consumption is V1, where the lamp resistance is R0.
/R0=56.5/11.29=5A. Also,
By drastically lowering the applied voltage, the color temperature variation of the halogen lamp increases. In this way, by switching the lamps divided into two groups, the current consumption is lower than in the case of a single lamp, resulting in power saving.

By the way, when a halogen bulb is used as the light-emitting lamp 201 of a lighting device, for example, the temperature of the inner wall of the bulb prevents the proper halogen cycle from working, making it more likely to blacken or melt the filament, thereby shortening its lifespan. Therefore, appropriate cooling is required to maintain a proper halogen cycle. In order to maintain a constant halogen cycle in a halogen bulb, it is recommended that the bulb wall temperature be within a temperature range of 250°C to 550°C. For this purpose, the lighting cooling fan 115
(In this embodiment, a DC fan motor is used.) As shown by the arrow in FIG.
305 and 302, and further cools the light emitting lamp 201.
It is arranged so that it can be cooled. In addition, the lighting cooling fan 115 also blows air onto the contact glass 116, thereby preventing discoloration and breakage of the contact glass 116 due to an abnormal temperature rise in the lighting device.

Furthermore, in order to deal with the case where the temperature inside the lighting device rises abnormally, a thermal fuse 6 is installed as shown in FIG.
04 is provided. This thermal fuse 604 is connected between the intermediate connection point between the lamp groups L1 and L2 and the control terminal of the halogen lamp control device 602, and is installed in the pin connection hole 503 shown in FIG. 5 provided on the illumination lamp printed circuit board 211. The pin portion of the pedestal is inserted and connected, and the mounting pedestal is fixed by soldering or the like so that the plane portion of the mount is perpendicular to the printed circuit board 211. The sensing surface of the thermal fuse 604 is equipped with a cylindrical insulating tube (made of materials such as Teflon or silicone as heat resistance is required).
It is attached to the printed circuit board 211 so as to cover it with the printed circuit board 211.

The temperature overrise prevention means may be used, for example, if an overvoltage is continuously applied to the light emitting lamp 201 due to an abnormality in the lighting device (a short circuit accident when a bidirectional thyristor is used as a control element), or if the lighting cooling fan 115 This is provided to prevent the discoloration and breakage of the contact glass 116, the falling off (separation) of the light emitting lamp 201 from the printed circuit board, and the burning of the printed circuit board due to an abnormal temperature rise in the lighting device due to an abnormality (stoppage) of the lighting device. Then, when the temperature rises to the set temperature, the halogen lamp control device 602 cuts off the application of voltage to the groups of light emitting lamps L1 and L2. As the temperature overrise prevention means, for example, a thermoswitch may be used in addition to a thermal fuse.

The lighting cooling fan 115 cools the reflecting plates 202, 302, 305, the light emitting lamp 201, and the lighting lamp printed circuit board 211 as described above. Thus, the cooling air from the lighting cooling fan 115 is actively sent to the lower surface of the lighting unit support 212 by the bending part 308 which is formed by bending one side of the lighting device support 307 of the scanner body 205 downward. In addition, as shown in FIG.
The cooling air that has passed through an opening 309 made in the seating surface of the light emitting lamp 201 according to the position of the light emitting lamp 201,
The reflecting plates 202, 302, and 305 are also cooled.

FIG. 11 is a circuit diagram showing details of the fan drive circuit 603. This fan drive circuit 603 is mainly composed of two switch circuits consisting of a Darlington transistor 1101 and a Darlington transistor 1102 provided corresponding to fan trigger signal 1 and fan trigger signal 2, respectively, and the emitter of each transistor is , different power supply voltages (+24V and +15V) are applied, and the voltage applied to the lighting cooling fan 115 serving as the load can be selected. Note that diodes 1103 and 1 connected to the collector of each transistor
104 is provided to prevent one output voltage from being applied as a reverse voltage to the other circuit.

FIG. 12 is a flowchart showing the lighting cooling fan switching process. In controlling luminescent lamps,
For each exposure, the light emitting lamp groups L1 and L2 and the lamp output voltage are switched to obtain an appropriate amount of exposure. However, when only the light emitting lamp L1 or L2 is lit,
If both light-emitting lamp groups L1 and L2 are turned on at the same time, there will be a difference in color temperature of the light-emitting lamps, and light-emitting lamp group L1
Alternatively, when any one of the light-emitting lamp groups L2 is turned on, the lamp wall temperature becomes low, and conversely, when both light-emitting lamp groups L1 and L2 are turned on at the same time, the lamp wall temperature becomes high. Therefore, it is necessary to keep the lamp wall temperature constant by changing the air volume of the lighting cooling fan 115 depending on the copy mode (black and white copy mode, single color mode, full color mode), and to operate an appropriate halogen cycle. . In this embodiment, for example, each color exposure (BK
: black, B: blue, G: green, R: red) by switching the lighting of the light emitting lamps L1 and L2.
The air volume of the lighting cooling fan 115 is changed.

As shown in the flowchart of FIG. 12, the copy mode is started by pressing a copy button (not shown) on the operation section (STEP 1). BK
, G, R exposure, the light emitting lamp group L1 or L2
If only one of the lights lights up (STEP 2, 7)
To do this, turn off the fan trigger 1 signal and turn off the fan trigger 2 signal.
By turning on the signal, +15V is applied to the lighting cooling fan 115, and the lighting cooling fan 115 rotates (STEP 8). In the case of B exposure, the light emitting lamp group L1
, L2 are lit (STEP 3), by turning off the fan trigger 2 signal and turning on the fan trigger signal 1, +24 is sent to the lighting cooling fan 115.
V is applied, and the lighting cooling fan 115 rotates (ST
EP4). Then, when the copy operation stops (STEP
5) Both the fan trigger 1 signal and the fan trigger 2 signal are turned OFF, and the lighting cooling fan 115 stops rotating (STEP 6).

In this embodiment, the air volume of the lighting cooling fan is changed; however, temperature detection elements are provided at appropriate locations on the copy size, lighting voltage, lighting device, and contact glass, and the lighting is adjusted based on the calculation results. By changing the air volume of the cooling fan in stages, a more stable halogen cycle of the light-emitting lamp can be obtained.

[0025]

As is clear from the foregoing, according to the present invention, there is provided a light-emitting lamp that is composed of a plurality of lamps and that illuminates the document reading section, and a reflector that reflects the light of the light-emitting lamp toward the document. and a mirror mechanism for reflecting the reflected light from the reading section to an optical system, and the illumination device of the image forming apparatus is mounted on a conveyance member and moved relative to the document, wherein the light emitting lamp and the reflection lamp are mounted on a conveying member and moved relative to the document. A blowing means is provided near one end of the moving range of the conveying member to cool each of the plates, and a control means is provided for varying the amount of air blown by the blowing means in accordance with the driving status of the light emitting lamp. Therefore, the light-emitting lamp is always maintained properly, reducing abnormal images and filament breakage caused by uneven light distribution and exposure distribution on the document surface due to lamp blackening, extending the service life and facilitating parts replacement. It is possible to reduce the

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of a lighting device according to the present invention and a lighting device of a copying machine to which this lighting device is applied.

FIG. 2 is a plan view showing the main parts of the lighting device.

FIG. 3 is a side sectional view of the lighting device shown in FIG. 2;

FIG. 4 is a side view of the lighting device shown in FIG. 2.

FIG. 5 is a plan view of a printed circuit board for an illumination lamp.

FIG. 6 is a circuit diagram showing details of a control device for driving two groups of light emitting lamps.

FIG. 7 is a characteristic diagram showing a light distribution on a document surface according to the present invention.

8 is an exposure distribution characteristic diagram corresponding to the characteristics shown in FIG. 8. FIG.

9 is a characteristic table showing numerical values the characteristics shown in FIG. 7. FIG.

FIG. 10 is an explanatory diagram of the arrangement of lamps in the present invention.

FIG. 11 is a circuit diagram showing details of a fan drive circuit.

FIG. 12 is a flowchart showing lighting cooling fan switching processing.

[Explanation of symbols]

101 Lighting device
102 Mirror member 103 Lens carriage 10
5 Photosensitive drum 115 Lighting cooling fan 2
01 Light emitting lamp 202 Main reflector
205 Scanner body 301 First mirror
601 CPU 602 Halogen lamp control device 603 Fan drive circuit 604 Thermal fuses 1101, 1102 Darlington transistors L101 to L107 Light emitting lamps L201 to L206 Light emitting lamps

Claims (1)

[Claims] 1. A light-emitting lamp that is composed of a plurality of lamps and that illuminates a document reading section, a reflector that reflects light from the light-emitting lamp toward the document, and a reflector that directs the reflected light from the reading section to an optical system. In the illuminating device of the image forming apparatus, the illumination device includes a mirror mechanism for reflecting the light, and is mounted on a conveyance member and moved relative to the document, the movement range of the conveyance member in order to cool each of the light emitting lamp and the reflection plate. 1. An illumination device for an image forming apparatus, comprising: a blowing means disposed near one end of the blowing means; and a control means for varying the amount of air blown by the blowing means in accordance with the driving status of the light emitting lamp.