JP3188489B2 - Flash lamp lighting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flash lamp illuminating device suitable for an image forming apparatus for illuminating a document with a main flash lamp and an auxiliary flash lamp.

[0002]

2. Description of the Related Art FIG. 7 shows a copying system using such a flash lamp illuminating device. This copying system is schematically constituted by a copy processing unit 1 for performing copying, a large-capacity paper feeding unit 2 in which a large amount of transfer paper can be set, and a transfer paper post-processing unit 3 for post-processing transfer paper after copying. Have been. An original 5 is placed on a contact glass 4 at the upper part of the copy processing unit 1.
An automatic document feeder (ADF) 6 that automatically conveys an image is provided.

The original 5 on the contact glass 4 is illuminated diagonally from below by flash lamps 7, 30 and reflectors 8, 31 and reflecting mirrors 9, 32.
An image is formed on the belt-shaped photoconductor 13 by the mirror 10, the lens 11, and the mirror 12, and an electrostatic latent image is formed on the photoconductor 13. The surface of the photoconductor 13 is charged in advance by the charger 14 before the exposure, and a copy of the electrostatic latent image on the photoconductor 13 can be obtained by charging, exposure, development, transfer, and fixing in a known electrophotographic process. .

Here, at the tip of the contact glass 4,
A white pattern 15 having a reference white density is formed. The white pattern 15 is illuminated by the flash lamps 7 and 30 before scanning the original 5 so that a latent image is formed on the photoconductor 13, and the potential of the latent image is detected by a potential sensor. 16.
As shown in FIG. 8, when the applied voltage of the flash lamps 7 and 30 is constant, the potential detected by the potential sensor 16 deteriorates the photoconductor 13 and the flash lamps 7 and 30 as the number of runs, that is, the number of copies increases. Higher.

Therefore, the potential of the white pattern 15 is detected by the potential sensor 16 and, as shown in FIG.
By controlling the 30 applied voltages, a predetermined range of white level can be realized. In this case, the applied voltage of the flash lamps 7, 30 is always controlled at a constant voltage ratio in order to stabilize the copied image of the original 5.

[0006]

However, in the above-mentioned conventional copying system, the voltage applied to the flash lamps 7 and 30 is always controlled at a constant voltage ratio.
There is a problem that the timing of the change of each light amount of the flash lamps 7 and 30 with respect to the potential fluctuation on the line 3 varies, and it is not possible to realize an appropriate copied image. In addition, if any one of the flash lamps 7 and 30 is replaced, the light amount balance of the flash lamps 7 and 30 is lost, resulting in an abnormal image.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a flash lamp illuminating device capable of always realizing an appropriate image.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides first and second flash lamps for illuminating a document and a reference white, and the first and second flash lamps for illuminating the reference white. Potential detecting means for detecting a potential of a latent image of a white pattern formed on the photoreceptor by being illuminated by the first and second flash lamps so that the potential detected by the potential detecting means is constant. each applied voltage and a control Gosuru control means, said control means further each applied electrostatic the ratio of change in the respective applied voltage
It is characterized in that the lighting control is set to a fixed ratio different from the pressure ratio .

[0009]

[0010]

In the above construction, the first and second flash lamps are provided.
Is different from the ratio of each applied voltage.
Since the lighting control is set at a certain ratio , the light amount balance of the first and second flash lamps can be maintained even when one of the first and second flash lamps is replaced. Therefore, an appropriate image can always be realized.

[0011]

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of a flash lamp lighting device according to the present invention, FIG. 2 is a side view showing a main part of the flash lamp lighting device of FIG. 1, and FIG. 3 shows the flash lamp lighting device of FIG. FIG. 4 is a graph showing the relationship between the applied voltage and the amount of light of the flash lamps of FIGS. 1 to 3, FIG. 5 is an explanatory diagram showing a control method of the flash lamps of FIGS. 1 to 4, and FIG. FIG. 6 is an explanatory diagram showing a flash lamp control method when the flash lamp is replaced.

In FIG. 1, in this embodiment, one flash lamp 7 constitutes a main flash lamp, and two flash lamps 30a and 30b constitute auxiliary flash lamps. The main flash lamp 7 is a CPU 3
8 (central processing unit), a lighting voltage is applied from the main lamp power supply 35, and the auxiliary flash lamps 30a, 30
For 0b, the lighting voltage is applied from the auxiliary lamp power supply 36 under the control of the CPU 38. The main lamp power supply 35 and the auxiliary lamp power supply 36 rectify the commercial power supply 37, etc., and change the lighting voltage to the main flash lamp 7 and the auxiliary flash lamp 30.
a, 30b.

As described above , a white putter that is a reference white color
Flash lamps 7, 30a, 30b
The white pattern formed on the photoreceptor 13 by being illuminated by
The potential of the latent image is detected by the potential sensor 16,
The data is taken into the CPU 38 via the potential control plate 40. C
The PU 38 instructs the main lamp power supply 35 and the auxiliary lamp power supply 36 with a charge command, a light emission command, and a discharge command in 5 bits each based on the electric potential detected by the electric potential sensor 16, and the main lamp power supply 35 and the auxiliary lamp power supply 36 Notifies the CPU 38 of charging completion, light emission detection, and overvoltage information. The program of the CPU 38 and the control data of the main lamp power supply 35 and the auxiliary lamp power supply 36 as shown in FIG. 5 and FIG. , CP
It has a U38 work area and the like.

Next, the detailed configurations of the main flash lamp 7 and the auxiliary flash lamps 30a and 30b will be described with reference to FIGS. As shown in detail in FIG. 3, the main flash lamp 7 has, for example, a radius of 75 mm and a central angle of 120 mm.
An arc-shaped lamp having a central angle of 120 ° is used as the reflecting mirror 9. Therefore, the light emitted from the main flash lamp 7 is sequentially reflected by the reflecting shade 8 and the reflecting mirror 9 having a semicircular side cross section, and uniformly illuminates the contact glass 4 from below.

The auxiliary flash lamps 30a and 30b are
Smaller than main flash lamp 7 with a central angle of 60 °
Are disposed on the left and right sides of the contact glass 4, respectively. Auxiliary flash lamps 30a, 30
b, respectively, are sequentially reflected by the reflectors 31a, 31b and the reflectors 32a, 32b, then by the common reflector 33, and from the diagonally lower side opposite to the main flash lamp 7, the right and left sides of the contact glass 4. Light half. Incidentally, inside the auxiliary flash lamps 30a and 30b, light shielding plates 34a and 34b for preventing flare, respectively, are provided.
34b are arranged. Therefore, since the main flash lamp 7 and the auxiliary flash lamps 30a and 30b illuminate the contact glass 4 from different directions, the shadow of the document can be prevented.

Here, since the relationship between the applied voltage and the light amount of the main flash lamp 7 and the auxiliary flash lamps 30a and 30b can be represented by a substantially linear function as shown in FIG. By controlling the lamp power supply 36, the respective light amounts of the main flash lamp 7 and the auxiliary flash lamps 30a and 30b can be controlled.

In this embodiment, as an example, as shown in FIG. 5, the main flash lamp 7 and the auxiliary flash lamp 30 are used.
The control data D0 to D4 of 5 bits (32 steps) such that the applied voltages of a and 30b become 10: 1 are previously stored in the RO.
Stored in M39, the CPU 38 reads out control data D0 to D4 corresponding to each optimum applied voltage based on the potential detected by the potential sensor 16, controls the main lamp power supply 35 and the auxiliary lamp power supply 36 simultaneously,
The control data of 41 is updated.

In this case, when the use of the main flash lamp 7 and the auxiliary flash lamps 30a, 30b is started at the same time, control is performed so that the applied voltages of the main flash lamp 7 and the auxiliary flash lamps 30a, 30b become 10: 1. However, if the main flash lamp 7 is replaced due to variations in the life of each other, for example, the life of the main flash lamp 7 is short, if the control is performed at 10: 1,
Since the amount of light from the main flash lamp 7 increases, the amount of light from the auxiliary flash lamps 30a and 30b becomes insufficient, causing image unevenness.

Therefore, in this embodiment, when the main flash lamp 7 is replaced, 1000 V of step "0" is applied to the main flash lamp 7 as shown in FIG. 6, and the auxiliary flash lamps 30a, 30b are applied. By applying 115V in step "3", image unevenness can be prevented. Then, when the light amount decreases due to the potential detected by the potential sensor 16, 1050V of step "1" is applied to the main flash lamp 7 and 1 of step "4" is applied to the auxiliary flash lamps 30a and 30b.
Image unevenness can be prevented by applying a voltage of 20 V and controlling the ratio of the change to be constant.

In the example shown in FIG. 6, when the main flash lamp 7 is replaced, control is performed so that the initial values of the main flash lamp 7 and the auxiliary flash lamps 30a and 30b, ie, steps "0" and "3" are different. However, instead, after setting the same steps “0” and “0”, control may be performed so that the ratio of the change of each applied voltage is increased so as to be constant.

[0022]

As described above, according to the first aspect of the present invention, each of the applied voltages of the first and second flash lamps
Is set to control the lighting to a constant ratio different from the ratio of the applied voltages, so that one of the first and second flash lamps is replaced. In addition, it is possible to maintain the light amount balance between the first and second flash lamps, and thus to always realize an appropriate image.

[0023]

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a flash lamp lighting device according to the present invention.

FIG. 2 is a side view showing a main part of the flash lamp lighting device of FIG. 1;

FIG. 3 is a plan view showing the flash lamp lighting device of FIG. 2;

FIG. 4 is a graph showing the relationship between the applied voltage and the amount of light of the flash lamp shown in FIGS.

FIG. 5 is an explanatory diagram showing a control method of the flash lamp in FIGS. 1 to 4;

FIG. 6 is an explanatory diagram showing a flash lamp control method when the main flash lamp is replaced.

FIG. 7 is a side view showing a copying system using the flash lamp lighting device of the present invention.

FIG. 8 is a graph showing the relationship between the number of runs and white potential in the copying system of FIG. 7;

FIG. 9 is an explanatory diagram showing a control method of a flash lamp lighting device in the copying system of FIG. 7;

[Explanation of symbols]

 7 Main flash lamp 16 Potential sensor 30a, 30b Auxiliary flash lamp 35 Main lamp power supply 36 Auxiliary lamp power supply 38 CPU (central processing unit) 39 ROM (read only memory)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI G03G 15/04 112 (58) Investigated field (Int.Cl. ⁷ , DB name) G03G 15/04-15/04 120 G03G 15 / 00 303 G03G 21/00 370-512 G03B 27/54-27/58 G03B 27/72-27/80

Claims (1)

(57) [Claims] A first flash lamp for illuminating a document and a reference white; and a latent pattern of a white pattern formed on a photoreceptor by illuminating the reference white by the first and second flash lamps. with a potential detection means for detecting the potential of the image, and a control Gosuru control means each applied voltage of the first and second flash lamps as was detected potential becomes constant by the potential detection means, wherein control means further the ratio of change in the applied voltage
A flash lamp illuminating device characterized in that lighting control is performed at a fixed ratio different from the ratio of the applied voltages .