JP2002094745A - Lamp-lighting circuit, image reader, lamp-lighting method and storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that can prevent malfunctions of an inverter protection circuit, while improving lighting start delay due to a dark state starting characteristic of a xenon lamp. SOLUTION: When a luminous quantity read by a CCD is less than a prescribed value in lighting of a lamp, the lamp on/off step is repeated at a prescribed timing. When the luminous quantity does not increase even after repetition of retrials for a prescribed number of times, it is discriminated that a fault exists in the lamp, and an inverter and an error signal is fed to a controller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a lamp lighting circuit,
The present invention relates to an image reading device, a lamp lighting method, and a storage medium.

[0002]

2. Description of the Related Art Conventionally, in an image reading apparatus mounted on a copying machine or the like, a halogen lamp or a hot cathode fluorescent lamp has been used as illumination for exposing a document. In recent years, an external electrode-type fluorescent discharge tube in which a plurality of linear or band-shaped external electrodes are arranged on the outer surface of a glass bulb and a high-frequency voltage is applied to these external electrodes to light the external electrodes is often used. It has become

This external electrode type fluorescent discharge tube is obtained by applying a high frequency voltage from the external electrodes to an internal discharge space sandwiched between a plurality of external electrodes disposed on the outer surface of a dielectric glass bulb. , Which causes a discharge in the glass bulb. When this discharge occurs, the discharge current can be increased by making the external electrode a predetermined size, the entire phosphor on the inner surface of the bulb can be effectively excited, and the light output can be greatly increased. be able to.

In a conventional image reading apparatus using such an external electrode type fluorescent discharge tube, a reflected light obtained by turning on a lamp comprising the external electrode type fluorescent discharge tube and scanning an original is optically reflected. The image is read by being reflected by a plurality of mirrors mounted on the table and passing through a lens to form an image on a CCD.

When such an image reading apparatus is mounted on a copying machine, if external light comes in when opening a pressure plate and replacing a document after turning on a lamp, an external electrode type fluorescent lamp is used. Although there is no problem in using the discharge tube, if the inside of the housing of the image reading device is left in a dark state for a long time, such as at night, the next time the external electrode type fluorescent discharge tube is turned on, it takes time to start. (See FIG. 2).

Various measures have conventionally been taken to improve such dark start characteristics. FIG. 8 is a diagram showing a configuration of a conventional external electrode type fluorescent discharge tube for improving dark start characteristics. In FIG.
No. 839, a luminous body b such as an LED or miniature light bulb is arranged near an external electrode type fluorescent discharge tube a as a xenon lamp, and the external electrode type fluorescent discharge tube a is left in a dark state for a long time. Not to be. Also, in FIG. 1B, as shown in Japanese Patent Application Laid-Open No. 88-329903, a conductive chip c for promoting discharge is arranged in this discharge tube, and the starting characteristic when left in a dark state for a long time is shown. To improve.

Separately, the inverter for supplying power to the xenon lamp is provided with a protection circuit for stopping power supply to the lamp during abnormal operation and notifying the control unit of the abnormality.

[0008]

However, when the xenon lamp is delayed in startup due to the dark start characteristic, the high voltage power supply of the inverter is provided with a lighting start voltage.
A voltage equivalent to the open voltage is applied until the lamp is turned on, so that the inverter cannot distinguish from a case where the connector is disconnected or a case where the cable is disconnected.

Normally, in order to detect disconnection of the connector and disconnection of the electric wire, a circuit for detecting an abnormality when an open voltage of 2 seconds or more is applied is set up. Such a case is fully considered.

[0010] At this time, there are many cases where the inverter side judges that there is an abnormality and stops the operation even though there is no disconnection of the connector, a broken wire, or any other abnormality of the inverter.

Since this abnormality detection circuit generally has a latch function, once an abnormality is detected, the lamp cannot be turned on unless the power is turned off.

In view of the above, an image reading apparatus, a lighting control method, and a storage medium are provided which prevent malfunction of an inverter abnormality detection circuit and further improve dark start characteristics without introducing a significant change in the circuit for the above-mentioned problems. The purpose is to do.

[0013]

In order to achieve the above object, a lamp lighting device for lighting a lamp having a characteristic that a starting time changes according to a time period when the lamp is left in a dark state according to claim 1 of the present invention. A circuit configured to detect a light amount of the lamp when the light amount is smaller than a predetermined value by the light amount detecting unit after a predetermined time has elapsed since the start of lighting the lamp; Control means for turning off the light once and then turning it on again.

A lamp lighting method for lighting a lamp having a characteristic that a starting time varies according to a time left in a dark state according to claim 11, a light amount detecting step of detecting a light amount of the lamp, A control step of once turning off the lamp and re-lighting the lamp when the light amount is detected to be less than a predetermined value in the light amount detection step after a predetermined time has elapsed from the start of lighting the lamp. It is characterized by.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image reading apparatus according to the present embodiment is applied to a copying machine.

FIG. 1 is a diagram showing the configuration of an image reading apparatus using an external electrode type fluorescent discharge tube according to this embodiment. In this image reading apparatus, reflected light from the original 101 obtained by scanning the original 101 by turning on an external electrode type fluorescent discharge tube (hereinafter also referred to as a lamp) 105 is reflected by a mirror 106 mounted on an optical table 107. , And are reflected by mirrors 108 and 109 mounted on an optical table 110, and form an image on a CCD 112 through a lens 111.

In the present embodiment, a xenon lamp is used as the external electrode type fluorescent discharge tube (lamp) 105,
The lamp 105 is housed in a housing 114 of the image reading device as shown in FIG. FIG. 2 is a characteristic diagram showing a relationship between a time when a xenon lamp used as a lamp for exposing a document is left in a dark state and a start time thereof. If the xenon lamp is left in a dark state for a long time, the starting time becomes long.

FIG. 3 is a block diagram showing a configuration of a control system of the image reading apparatus. The scanner controller 203 includes a well-known CPU 131, a ROM 132, a RAM 133, an I / O
An O interface 134, an image processing unit 135, a timer 137, and the like are connected via a bus 136. The optical table 10 is connected to the I / O interface 134.
An optical motor 202 for driving the scanners 7 and 110 in the sub-scanning direction along the original; a lamp 105 whose lighting is controlled by a scanner controller 203;
4. The operation unit 113 having the copy button 113a is connected. The CCD 112 is connected to a bus 136 in the scanner controller 203 via an A / D conversion circuit 201.

The scanner controller 203 recognizes that the original has been replaced by the pressure plate open / close detection sensor 104 when reading the image of the original, and when the copy button 113a is pressed, turns on the lamp 105 to turn on the optical motor 202.
To move the optical tables 107 and 110 along the original 101 in the sub-scanning direction.

The reflected light from the original 101 obtained by scanning the original 101 passes through the lens
An image is formed on D112. The light output read by the CCD 112 is converted into a digital signal by the A / D conversion circuit 201 and then sent to the scanner controller 203 as image data. The scanner controller 203 transfers the input image data to the image processing unit 135 in the scanner controller, and outputs an output image by a printer (not shown) based on the image data processed by the image processing unit 135.

FIG. 4 is a block diagram of an inverter circuit for supplying power to a xenon lamp.

Reference numeral 401 denotes a high voltage control unit, 402 denotes an abnormality detection circuit, 403 denotes a latch circuit, and 105 denotes a xenon lamp. When 24 V is supplied to the high voltage control unit 401 and the high voltage control unit 401 receives a lamp ON signal, the transformer is driven by a pulse signal from the control IC, and a high voltage for lighting the xenon lamp 105 is generated. that time,
By monitoring the high voltage or the voltage on the primary side of the transformer by the abnormality detection circuit 402, an abnormal state occurring in the inverter is detected. In this embodiment, attention is paid particularly to the open-circuit voltage generated when the connector is disconnected.

If the lamp is turned on when the connector is disconnected or the cable is disconnected, a voltage close to 5000 V is generated in the connector as an open voltage for a long time. Therefore, the abnormality detection circuit 402 and the latch circuit 4
According to 03, when the open voltage continues to be generated for a certain period of time or more, the operation of the high voltage control unit 401 is stopped, and this state is continued until the 24 V power supply is stopped. Basically, the fixed time for detection is determined by the time constant of CR of the latch circuit.

When the abnormality is detected by the abnormality detection circuit 402 and the operation is stopped, the abnormality detection circuit 402
Turns off the transistor and sets the error detection signal to the open collector state.

However, even if the connector has not been disconnected or the cable has not been disconnected, when the lamp is turned on, the state becomes the same as the no-load state until discharge starts, and an open voltage is applied to the connector section. There is no problem in normal lighting because it is only a moment.
Is left in a dark state for a long time, and when the lighting transition of the xenon lamp 105 is delayed, an open-circuit voltage is generated for the delayed time. If the lighting delay time is longer than the time for abnormality detection, the abnormality detection circuit of the inverter operates and generates an error detection signal even if the xenon lamp 105 and the inverter circuit are not particularly abnormal.

Therefore, in the present embodiment, the xenon lamp 10
By devising the timing of the ON / OFF signal of No. 5, the abnormality detection circuit does not malfunction even if the lighting of the xenon lamp is delayed due to the dark starting characteristics, and the xenon lamp 105 starts discharging even after being left in the dark for a long time. Easy to do.

FIGS. 5 and 6 are timing charts of a lamp ON / OFF signal at the start of xenon lamp lighting, which is a feature of this embodiment. FIG. 7 is a flowchart showing the present embodiment.

As shown in this timing chart, 24
After V rises and power is supplied to the inverter circuit, a shading adjustment operation at the time of power ON is performed, and then copying is started by pressing a copy button. After the power is turned on, the first time the xenon lamp 105 is turned on is at the time of the power-on and the shading adjustment. FIG. 5 is an enlarged view of the portion.

The xenon lamp 10 is activated by the lamp ON signal.
Operate the inverter circuit so that 5 lights up,
At the time when the light is turned on for 100 ms (S701), the value obtained by reading the light amount of the xenon lamp 105 by the CCD is compared with a predetermined value (S702). As a result of the comparison, if the value is less than the predetermined value, it is determined that the lighting of the xenon lamp 105 has failed, and is turned off for 200 ms (S703), and turned on for 100 ms.
Xenon lamp 10 at / 200 ms OFF timing
5 ON / OFF is repeated. This repetition operation is repeated a maximum of 20 times (S704). If the light amount of the xenon lamp 105 does not reach the predetermined value even after 20 retries, it is determined that the xenon lamp 105 or the inverter circuit is abnormal, and the error signal is set to HIGH. (S70
5). If the read value of the CCD in S702 is equal to or larger than the predetermined value, a normal sequence is executed (S706).

The time of 100 ms ON / 200 ms OFF is determined by the latch circuit 40 in the abnormality detection section of the inverter circuit.
3 is set at a timing such that the capacitor determining the abnormality detection time is not sufficiently charged. Therefore, even if the start of lighting of the xenon lamp 105 is delayed due to the dark start characteristic, the inverter circuit can be prevented from malfunctioning.

Further, since the high voltage is repeatedly applied to both electrodes of the xenon lamp 105 due to the repetition of ON / OFF for a short time, the transition to discharge becomes easy, and even after the xenon lamp 105 is left in a dark state for a long time, Light intensity rises faster.

This processing program is stored in the ROM 132 in the scanner controller 203,
131.

Although the above is an explanation of the present embodiment, the present invention is not limited to the configurations of these embodiments, and the functions described in the claims or the functions of the configurations of the embodiments are achieved. Any configuration that can be applied is applicable.

The present invention may be applied to a system including a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), or may be applied to an apparatus including one device. .

It is needless to say that the present invention can also be applied to a case where the present invention is achieved by supplying a program to a system or an apparatus using a storage medium storing software program modules for realizing the functions of the above-described embodiments. Absent. In this case, the program module itself read from the storage medium implements the novel function of the present invention, and the storage medium storing the program constitutes the present invention.

In the above embodiment, the program module shown in the flowchart of FIG.
32. The storage medium for supplying the program module is not limited to the ROM. For example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, DV
D, a magnetic tape, a nonvolatile memory card, or the like can be used.

[0037]

According to the present invention, it is possible to prevent a malfunction of the lighting circuit due to a delay in the rise of the lamp illuminance due to the dark start, and to realize a lamp lighting circuit which is easy to shift to lighting.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a document reading apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a relationship between a lamp leaving time in a dark state and a starting time.

FIG. 3 is a block diagram illustrating a configuration of a control system of the image reading apparatus.

FIG. 4 is a block diagram illustrating a configuration of an inverter circuit.

FIG. 5 is a timing chart showing the operation of the embodiment of the present invention.

FIG. 6 is a timing chart showing the operation of the embodiment of the present invention.

FIG. 7 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 8 is a diagram showing an example of a conventional measure for improving dark start.

[Explanation of symbols]

 105 Xenon lamp 401 High voltage control unit 402 Abnormality detection circuit 403 Latch circuit

Claims (20)

[Claims] 1. A lamp lighting circuit for lighting a lamp having a characteristic that a starting time changes according to a time left in a dark state, wherein: a light amount detecting means for detecting a light amount of the lamp; Control means for turning off the lamp once and turning it on again when the light quantity detection means detects that the light quantity is less than a predetermined value after a predetermined time has elapsed from the start. Lamp lighting circuit. 2. The lamp lighting circuit according to claim 1, wherein the control means repeats turning on and off the lamp. 3. The lamp lighting circuit according to claim 2, further comprising: an inverter circuit for lighting the lamp; and abnormality detecting means for detecting abnormality. 4. The abnormality detecting device according to claim 3, wherein the abnormality detecting means has a latch function, and when an abnormality is detected, stops an inverter function of the inverter circuit and keeps the state until power is turned off. A lamp lighting circuit. 5. The lamp lighting circuit according to claim 3, wherein a time for detecting abnormality by the abnormality detecting means is set by a time constant of the circuit. 6. The lamp lighting circuit according to claim 3, wherein the timing of turning on and off in the repetition sequence of turning on and off is set in consideration of a time for abnormality detection by the abnormality detection means. 7. The lamp lighting circuit according to claim 6, wherein the timing of the repeating sequence of turning on and off can be arbitrarily set. 8. The abnormality detecting means according to claim 2, wherein the light amount of the lamp does not exceed the predetermined value even when the lighting and the turning off are repeated a predetermined number of times. A lamp lighting circuit characterized by determining that: 9. The lamp lighting circuit according to claim 8, wherein the predetermined number can be set arbitrarily. 10. An image reading apparatus which irradiates an original with a lamp lit by the lamp lighting circuit according to claim 1 and reads an image of the illuminated original. 11. A lamp lighting method for lighting a lamp having a characteristic that a starting time changes according to a time left in a dark state, wherein: a light amount detecting step of detecting a light amount of the lamp; A control step of once turning off the lamp and then turning it on again when the light amount is detected to be less than a predetermined value in the light amount detection step after a predetermined time has elapsed from the start. Lamp lighting method. 12. The lamp lighting method according to claim 11, wherein in the control step, turning on and off of the lamp is repeated. 13. The lamp lighting circuit according to claim 12, further comprising an abnormality detecting step of detecting an abnormality. 14. The method according to claim 13, wherein when an abnormality is detected in the abnormality detecting step, an inverter function of an inverter circuit for lighting the lamp is stopped, and the state is maintained until the power is turned off. Lamp lighting method characterized by the above-mentioned. 15. The lamp lighting circuit according to claim 13, wherein a time for detecting abnormality in the abnormality detecting step is set by a time constant of the circuit. 16. The lighting / light-off timing in the lighting / light-off repeating sequence according to claim 13,
The lamp lighting method is set in consideration of a time for detecting abnormality in the abnormality detecting step. 17. The lamp lighting method according to claim 16, wherein the timing of the repeating sequence of turning on and off can be arbitrarily set. 18. The abnormality detection step according to claim 12, wherein the light amount of the lamp does not become equal to or more than the predetermined value even after the lighting and turning off are repeated a predetermined number of times. A lamp lighting method characterized by determining that 19. The lamp lighting method according to claim 18, wherein the predetermined number can be set arbitrarily. 20. A storage medium storing the lamp lighting method according to claim 11 as a program module.