JPS60246598A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus using a flash discharge lamp as a light source.

-g. In image forming apparatuses such as copiers, printers, and facsimile machines that use flash discharge lamps as a fixing light source or exposure light source, the flash discharge lamps are designed to continuously emit flashes in a predetermined blinking cycle. It is necessary to reliably supply a constant level of energy to the charging/discharging capacitor for supplying charge to the flash discharge lamp in the necessary cycles. In recent years, there has been a demand for faster copying or printing, and for this reason,
It is necessary to shorten the charging/discharging cycle of charging/discharging capacitors.

By the way, when flashing a flash discharge lamp continuously,
It is necessary to prevent the discharge from remaining active, which tends to occur after a flash occurs. To achieve this, the charging and discharging capacitor should not be charged for a while after the flash discharge lamp has finished discharging. I'm trying to stop it. The time during which charging to the charging/discharging capacitor is stopped is called the "charging prohibition time."

FIG. 1 is an explanatory circuit diagram schematically showing an example of a power supply device for a flash discharge lamp of a copying machine.

In FIG. 1, 2 is a charging circuit connected to an alternating current power source AC, and a charging control circuit 1 and a charging/discharging capacitor 3 are connected in sequence to this charging circuit 2. Electric lights 5 are connected in parallel.

Here, the charging control circuit 1 is a circuit for forming and setting the above-mentioned charging prohibition time, and is composed of a charging control signal generating section 11 and a switch section 12. The charging control signal generating section 11 is connected to a current detector 4 that detects the discharge current of the flash discharge lamp 5, and based on the signal from the current detector 4, the charge control signal generator 11 controls the charging control signal for a certain period of time after the flash discharge lamp 5 starts discharging. It has a function of sending an operation signal to the switch section 12, and the switch section 1
2 has a function of cutting off the current supply path to the charging/discharging capacitor 3 based on this operation signal.

In the figure, 6 is a trigger circuit connected to a trigger electrode 61 disposed along the tube wall of the flash discharge lamp 5. This trigger circuit 6 is driven by a trigger signal inputted to a terminal P corresponding to a target flash generation cycle.

FIG. 2 shows the charging control signal generated by the charging control circuit 1 in the power supply device, the trigger signal for operating the flash discharge lamp 5, the charging/discharging voltage at both ends of the charging/discharging capacitor 3, and the charging/discharging voltage at both ends of the flash discharge lamp 5. 5 is a time chart showing the mutual relationship between discharge currents.

In such a power supply device, the charge control signal generation unit 11 of the charge control circuit 1 generates the n-th charge start signal (
In Fig. 2, it is indicated as "ON". ) is issued, the switch section 12 is turned on and charging of the charging/discharging capacitor 3 is started. And the charging voltage is a predetermined specified voltage■. When a trigger signal is input in this state, the trigger circuit is activated and a high voltage is applied to the trigger electrode 61, which causes the flash discharge lamp 5 to
Dielectric breakdown occurs between the electrodes, and the charge in the charging/discharging capacitor 3 is released, causing a flash of light to occur in the flash discharge lamp 5 due to discharge. On the other hand, the discharge of the flash discharge lamp 5 is detected by the current detector 4, and a charging stop signal (r OFF J in FIG.
Indicated by ) is issued, which turns off the switch section 12 and stops supplying electric charge to the charging/discharging capacitor 3 for a certain period of time set as the charging prohibition period. After the charging prohibition time has elapsed, the charging control signal generating section 11 generates the n+1st charging start signal.
Thereafter, the same process is repeated, and the flash discharge lamp 5 is continuously blinked.

By the way, conventionally, when the n+1st charging of the charging/discharging capacitor 3 starts, the discharge current at the nth discharging of the flash discharge lamp 5 becomes almost zero, as shown by the broken line in FIG. It was set to be done at a later point in time. In other words, the conventional charging prohibition time TOFF is set to a time interval of 10 or more between the two times [, and t8, where t is the start of the nth discharge of the flash discharge lamp 5 and t2 is the end of the discharge. Ta.

However, in this case, for example, if an attempt is made to discharge a flash discharge lamp below a specific value of cycle T, the charging/discharging capacitor 3 will reach the specified charging voltage (2).

Therefore, in order to turn on the flash discharge lamp 5 after reaching the specified charging voltage, the charging/discharging cycle of the charging/discharging capacitor 3 must be lengthened. It is not possible to shorten the flashing cycle of flash discharge lamps. Conventionally, in order to shorten the flashing cycle of flash discharge lamps, means have been adopted to increase the charging speed of the charging/discharging capacitor.

However, according to this method, it is necessary to increase the input current of 1 ta, which causes various problems in terms of standards, etc., and is generally disadvantageous in terms of cost.

The present invention has been made against the above background, and an object of the present invention is to provide an image forming apparatus that can continuously blink a flash discharge lamp in a short flash discharge cycle and has excellent high speed performance. An image forming apparatus comprising a flash discharge lamp and a power supply device for operating the flash discharge lamp, wherein the power supply device supplies a charge to the flash discharge lamp. The battery includes a charging/discharging capacitor, a charging circuit that supplies charge to the charging/discharging capacitor, and a charging control circuit that controls the operating timing of the charging circuit, and has a charge prohibition time of T in the charging/discharging capacitor. ,
F, 3 of the above-mentioned flash discharge lamp (when the time interval from the start of discharge to the end of discharge is 'Fo', the formula % formula % holds true).

Hereinafter, the present invention will be explained in detail with reference to FIGS. 1 and 2.

TOFF is the time point 1 when the flash discharge lamp 5 starts discharging. The time interval from to the discharge end point t2 is T. Then, the following formula +
11.

To ≦TOFF The (n+1)th charging of the capacitor 3 is started.

Here, the time interval T from the start of discharge of the flash discharge lamp 5 to the end of discharge. is the value when the charging prohibition time T OFF is set sufficiently long. This is done in consideration of the fact that the discharge end point t2 of the flash discharge lamp 5 becomes a substantially constant value if the charge inhibition time 'I''OFF is made sufficiently long.

Note that the discharge start time L1 of the flash discharge lamp 5 refers to the time when a discharge current begins to flow through the flash discharge lamp 5, and can almost be considered as the time when the trigger signal is manually input. Further, the discharge end time t2 of the flash discharge lamp 5 refers to the time when the discharge current of the flash discharge lamp starts to decrease discontinuously in a current region of 0.1 A or less.

The charging speed of the charging/discharging capacitor 3 in such a flash discharge lamp power supply device is set to 0.5 to 15 ν/sec in order to effectively satisfy the above formula (1). This charging speed can be set by specifying the capacity, circuit constants, input voltage, etc. of the charging/discharging capacitor 3.

Next, an experimental example regarding the range of charging prohibition time shown in equation (1) will be described.

The experiment was conducted using the power supply device shown in FIG. 1 according to the following procedure.

That is, the charging speed of the charging/discharging capacitor 3 is set to a specific value, and the time interval T0 from the discharge start time t to the discharge end time t2 in the flash discharge lamp 5 is set as the charging prohibition time T. The measurement was carried out by setting F to a sufficiently long value.

Next, charging prohibition time T. □ was changed in short steps, and the flash discharge lamp 5 was turned on at each step, and it was examined whether the discharge state was maintained continuously even after the flash discharge lamp 5 was turned on.

Furthermore, experiments similar to those described above were conducted at various charging speeds.

The flash discharge lamp used in the experiment was a typical one used in copying machines, with an inner diameter of 10 sn, an arc length of 287 mm, and a filled gas of xenon (atmospheric pressure at 25°C: 100 Torr).
r). The charging voltage of the charging/discharging capacitor in the experiment was 600 V.

The results of the experiment are shown in Table 1. In Table 1, C represents the capacity of the charging/discharging capacitor. The evaluation of the experiment is ``○'' if no continuous discharge occurred, and ``×'' if continuous discharge occurred.
Expressed as

Table 1 From the results above, charging prohibition time T. It has been confirmed that, at various charging speeds, if the value of F is 4 To or more, the flash discharge lamp reliably generates flash without causing continuous discharge in the flash discharge stack.

As described above, the present invention provides continuous discharge even if the charging prohibition time of the charging/discharging capacitor in the flash discharge lamp type #I device is shorter than the time required for the discharge of the flash discharge lamp to completely end. Based on this knowledge, we experimentally set the shortest charging prohibition time. As a result, according to the present invention, it is possible to significantly shorten the charging prohibition time without requiring any special equipment, and therefore, speeding up of image formation is achieved by shortening the flash discharge cycle of the flash discharge lamp. .

[Brief explanation of the drawing]

Fig. 1 is an explanatory circuit diagram showing an outline of a power supply device for operating a flash discharge lamp that constitutes a copying machine, and Fig. 2 is a time chart for explaining the operation of this circuit. 1... Charging control circuit 11...Charging control signal generation section

Claims (1)

[Claims] 1) An image forming apparatus comprising a flash discharge lamp and a power supply device for operating the flash discharge lamp, wherein the power supply device includes a charging/discharging capacitor that supplies charge to the flash discharge lamp. , a charging circuit that supplies charge to the charging/discharging capacitor, and a charging control circuit that controls the operating timing of this charging circuit, and the charge/discharge capacitor has a charge prohibition time of TOF.
F. An image forming apparatus characterized in that the following formula holds true, where To is a time interval from the start of discharge to the end of discharge of the flash discharge lamp. 2) The image forming apparatus according to claim 1, wherein the charging rate of the charging/discharging capacitor is 0.5 to 15 KV/sec.